Registration Dossier
Registration Dossier
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EC number: 203-539-1 | CAS number: 107-98-2
Toxicological information
Endpoint summary
Administrative data
Key value for chemical safety assessment
Effects on fertility
Link to relevant study records
- Endpoint:
- two-generation reproductive toxicity
- Remarks:
- based on test type (migrated information)
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Study period:
- 08/1984-02/1986
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: No information on GLP compliance is available, but the method is well described.
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to other study
- Principles of method if other than guideline:
- RACB protocol" after Morrissey et al., Fundam Appl Toxicol. 13:747-777
- GLP compliance:
- not specified
- Limit test:
- no
- Species:
- mouse
- Strain:
- CD-1
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River Breeding Laboratories
- Age at study initiation: (P) x 11 wks; (F1) x 74 ± 10 days
- Weight at study initiation: details unavailable in the abstract
- Fasting period before study: no
- Housing: details unavailable in the abstract
- Diet (e.g. ad libitum): details unavailable in the abstract
- Water (e.g. ad libitum): ad libitum
- Acclimation period: details unavailable in the abstract
ENVIRONMENTAL CONDITIONS
- Temperature (°C): details unavailable in the abstract
- Humidity (%): details unavailable in the abstract
- Air changes (per hr): details unavailable in the abstract
- Photoperiod (hrs dark / hrs light): details unavailable in the abstract - Route of administration:
- oral: drinking water
- Type of inhalation exposure (if applicable):
- not specified
- Vehicle:
- water
- Details on exposure:
- PGME was administered in drinking water available ad libitum. The amount of test chemical required for each dose level was mixed with an appropriate amount of drinking water.
- Details on mating procedure:
- - M/F ratio per cage: 1:1
- Length of cohabitation: 14 weeks
- - Proof of pregnancy: [vaginal plug] referred to as [day 0/day 1] of pregnancy
- Further matings after two unsuccessful attempts: [no] - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Aliquots of representative water formulations were sent to Midwest Research institute (MRI) for chemical analyses. Reference aliquots were within 99 and 104 per cent of the intended concentrations except for one sample during Task 4 which was 112 per cent.
- Duration of treatment / exposure:
- Exposure period: Before mating, through gestation, and post-birth
Premating exposure period (males): 7 days
Premating exposure period (females): 7 days - Frequency of treatment:
- Daily
- Details on study schedule:
- Task 1 - Dose range finding study (2 weeks) at dose levels of 0, 0.25, 0.5, 1.0, 2.5 and 5 per cent in drinking water
Task 2 - Continuous breeding phase employing a vehicle control group (40 males + 40 females) and 3 dose groups (20 males + 20 females) at doses of 0, 0.5, 1.0 and 2.0 per cent in drinking water, Eleven week old male and female CD-1 mice were exposed during the 7-day premating period, after which they were randomly paired (1:1, male:female) within each dose group and cohabited for 14 weeks. New-born litters were evaluated and immediately sacrificed. After production of 4 litters, pups from the 5th litter (after 98 days of cohabitation) were selected for Task 4 (20 males + 20 females)Task 4 - Pups from the control and the 2% group were weaned 3 weeks after delivery. Animals were mated at 74 ± 10 (64-84) days of age. Mating was continued for 7 days. - Remarks:
- Doses / Concentrations:
2.0 %
Basis:
nominal in water - Remarks:
- Doses / Concentrations:
1.0 %
Basis:
nominal in water - Remarks:
- Doses / Concentrations:
0.5 %
Basis:
nominal in water - No. of animals per sex per dose:
- Task 1 - not specified
Task 2 - vehicle control (40 males + 40 females), 3 dose groups (20 males + 20 females)
Task 4 - 20 males + 20 females - Control animals:
- yes, concurrent vehicle
- Details on study design:
- no data
- Positive control:
- not applicable
- Parental animals: Observations and examinations:
- Task 1
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: not specified
DETAILED CLINICAL OBSERVATIONS: No data
BODY WEIGHT: Yes
- Time schedule for examinations: not specified
FOOD CONSUMPTION: No data
WATER CONSUMPTION: Yes
- Time schedule for examinations: not specified, data presented as a daily average
Task 2
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: not specified
DETAILED CLINICAL OBSERVATIONS: No data
BODY WEIGHT: Yes
- Time schedule for examinations: weekly
FOOD CONSUMPTION: No data
WATER CONSUMPTION: Yes
- Time schedule for examinations: not specified, data presented as a daily average
Task 4
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: not specified
DETAILED CLINICAL OBSERVATIONS: No data
BODY WEIGHT: Yes
- Time schedule for examinations: at weaning, first day of cohabitation and weekly thereafter
FOOD CONSUMPTION: no data
WATER CONSUMPTION: Yes
- Time schedule for examinations: daily water consumption also monitored on a weekly basis begining with the week of cohabiation
-OTHER: Sperm morphology and vaginal cytology evaluations were conducted at necropsy - Oestrous cyclicity (parental animals):
- In animals from the Task 4 group, vaginal smears were prepared for 7 consecutive days prior to necropsy
- Sperm parameters (parental animals):
- Parameters examined in [F2] male parental generations:
[epididymis weight, seminal vesicle, prostate gland weight, sperm motility, sperm morphology] - Litter observations:
- STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: [not specified]
PARAMETERS EXAMINED
The following parameters were examined in [F1 / F2 ] offspring:
[number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural abnormalities]
GROSS EXAMINATION OF DEAD PUPS:
[yes, for external and internal abnormalities] - Postmortem examinations (parental animals):
- details unavailable in the abstract
- Postmortem examinations (offspring):
- Newborn litters were evaluated and immediately sacrificed, other details unavailable in the abstract
- Statistics:
- details unavailable in the abstract
- Reproductive indices:
- Fertility index, other details unavailable in the abstract
- Offspring viability indices:
- number of litters/pair, number of live pups/litter and sex ratio
- Clinical signs:
- no effects observed
- Body weight and weight changes:
- no effects observed
- Food consumption and compound intake (if feeding study):
- no effects observed
- Organ weight findings including organ / body weight ratios:
- not specified
- Histopathological findings: non-neoplastic:
- not specified
- Other effects:
- not examined
- Reproductive function: oestrous cycle:
- not examined
- Reproductive function: sperm measures:
- not examined
- Reproductive performance:
- no effects observed
- Dose descriptor:
- NOAEL
- Effect level:
- 1 885 mg/kg bw/day (actual dose received)
- Sex:
- male/female
- Clinical signs:
- no effects observed
- Mortality / viability:
- no mortality observed
- Body weight and weight changes:
- effects observed, treatment-related
- Sexual maturation:
- not examined
- Organ weight findings including organ / body weight ratios:
- effects observed, treatment-related
- Gross pathological findings:
- not specified
- Histopathological findings:
- not specified
- Dose descriptor:
- NOAEL
- Generation:
- F1
- Effect level:
- 1 885 mg/kg bw/day (actual dose received)
- Sex:
- male/female
- Dose descriptor:
- NOAEL
- Generation:
- F2
- Effect level:
- 1 885 mg/kg bw/day (actual dose received)
- Sex:
- male/female
- Reproductive effects observed:
- not specified
- Conclusions:
- NOAELs occurred at the dose level of 1885 mg/kg bw day. Effects seen did not include reproductive toxicity related to mating, fertility indices, or offspring viability. The effects on parental organ weights (epididymis and prostate) may have been secondary to body weight decreases which paralleled these decreases in magnitude.
- Executive summary:
Propylene glycol monomethyl ether (PGME), a solvent used in industry, was tested for reproductive toxicity in Swiss CD-1 mice using the RACB protocol (Morrissey et al., Fundam Appl Toxicol 13:747-777 [1989]). It was part of a series of glycol ethers and congeners evaluated for structure-activity correlations using this design. Data collected on body weights, dinical signs, and food/water consumption during the dose-range-finding segment (Task 1) were used to set concentrations for the main study (Task 2) at 0.5, 1.0, and 2.0% PGME in drinking water. These concentrations produced calculated consumption estimates of approximately 0.95, 1.9, and 3.3 g/kg/day. During Task 2, no changes in body weight or water consumption were found in any of the exposure groups. There was no reduction in the number of litters per pair, the number of live pups per litter, or the viability of those pups. Mean pup weight adjusted for litter size was reduced by 4% at the top dose level. In the absence of an adverse effect on fertility, Task 3, the crossover test to identify the affected sex, was not conducted. Task 4, the evaluation of the second generation, was conducted with the control and high dose groups only. The reduced pup weight at birth, noted in the first four litters, continued postnatally, with males and females weighing approximately 14% less than controls during nursing. Male body weights were apprQximately 8% lower than controls during the mating period, while female body weights during the mating period were not affected by PGME treatment. Mating and fertility indices were unaffected by PGME, as were the number and viability of the F2 offspring. After the F2 pups were delivered, evaluated, and killed, the adult Fl mice in the control and 2% PGME groups were killed and necropsied. While female body weight was not affected by PGME exposure, body weight-adjusted liver weight was increased by 7.5%. Male body weights in the 2% PGME group were 8% lower than controls, while relative epididymis and prostate weights were reduced by 9 and 8%, respectively. In summary, there was some evidence of probable developmental toxicity, expressed as reduced pup weights, but no evidence of reproductive toxicity expressed as reduced litters or pup numbers. This F1 pup weight effect was seen in the absence of an effect on Fo adult body weight. Environmental Health Perspectives - Vol 105, Supplement * February 1997 233
- Endpoint:
- two-generation reproductive toxicity
- Remarks:
- based on test type (migrated information)
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 06/1995-02/1997
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP-report according to OECD guideline 416
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)
- GLP compliance:
- yes (incl. QA statement)
- Limit test:
- no
- Species:
- rat
- Strain:
- Sprague-Dawley
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River Breeding Laboratory, Kingston, NY
- Age at study initiation: 6 weeks
- Weight at study initiation: (P) Males: g; Females: 120-121 g; (F1) Males: x-x g; Females: x-x g
- Fasting period before study: none
- Housing: singly in wire mesh stainless steel cages
- Use of restrainers for preventing ingestion (if dermal): yes/no
- Diet (e.g. ad libitum): ad libitum except during inhalation exposure
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 2 weeks
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C
- Humidity (%): 40-60%
- Air changes (per hr): 12-15
- Photoperiod (hrs dark / hrs light): 12/12 - Route of administration:
- inhalation: vapour
- Type of inhalation exposure (if applicable):
- whole body
- Vehicle:
- unchanged (no vehicle)
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus:14.5m3 (2.4 m wide x 2.4 m high x 2.4 m deep with pyramidal top)
- Method of conditioning air: the various concentrations of PGME were generated using a glass J-tube method. Liquid PGME was metered into a glass J-tube assembly through which a preheated stream of approximately 90 liters per minute of compressed air was passed to vaporize the test material. The compressed air was heated to the minimum extend necessary to facilitate complete vaporization of the test material (approximately 65°C for the 300 ppm chamber, 115°C for the 1000 ppm chamber and 150-170°C for the 3000 ppm chamber). The compressed air and PGME vapors were diluted and mixed with room temperature air to the desired concentration at a flow rate of 2900 liters per minute into whole-body inhalation chambers.
- Temperature, humidity, pressure in air chamber: 22°C, 40-60%, The chambers were operated at a slightly negative pressure relative to the surrounding area.
- Air flow rate: 2900 liters per min
- Air change rate: 12 changes per hour
TEST ATMOSPHERE
- Brief description of analytical method used:
- Samples taken from breathing zone: yes/no - Details on mating procedure:
- Breeding of the P1 and P2 adults commenced after approximately 10 weeks of treatment. Each female was placed with a single male from the same exposure group (1:1 mating) until pregnancy occurred or two weeks had elapsed. During each breeding period, daily vaginal lavage samples were evaluated for the presence of sperm as an indication of mating. The day on which sperm were detected or a vaginal plug was observed in situ
was considered day 0 of gestation. Sperm and plug positive females were then removed from the male’s cage and placed back into wire mesh, stainless steel cages. If mating did not occur during the two weeks, the animals were separated without further opportunity for mating. For the P2 mating, cohabitation of male and female litter mates was avoided. - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- The concentration of PGME in the breathing zone of the animals in each chamber was measured at least once per hour using a MIRAN 1A infrared spectrophotometer (Foxboro Analytical, Norwalk, CT) at a wavelength of 10.2 microns. The spectrophotometer was calibrated using standards having a known PGME vapor concentration contained in 90 liter SARANÒ or Tedlar film gas bags prior to the first exposure and approximately monthly thereafter. Daily checks of the spectrophotometer were performed prior to each exposure period using a single PGME standard concentration. In addition, the amount of PGME used each day was recorded and the nominal concentration (amount of PGME used / total chamber airflow) of PGME was calculated. Prior to the start of the study, each of the chambers to be used were checked to ensure that a uniform distribution of vapors occurred within the animal’s breathing zone.
- Duration of treatment / exposure:
- Exposure period: Before mating, through gestation, and post-birth.
Premating exposure period (males): 5 days/week prior to mating; 7 days/week post mating
Premating exposure period (females): 5 days/week prior to mating; 7 days/week post mating - Frequency of treatment:
- 6 hr/day
- Details on study schedule:
- Groups of 30 male and 30 female rats were exposed to 0, 300, 1000 or 3000 ppm PGME via inhalation, for 6 hours/day, 5 days/week prior to mating, and 6 hours/day, 7 days/week during mating, gestation and lactation. Treatment of the first generation parental (P1) rats began at approximately 6 weeks of age. After approximately 10 weeks of exposure (5 days/week, excluding holidays), P1 rats were mated (one male to one female of the respective treatment group) to produce the F1a litters. To aid in the interpretation of F1a litter weight data which indicated non dose-related decreased litter weights at 300 and 1000 ppm PGME (statistically identified for 300 ppm PGME day 14 females only) and to confirm significant findings noted for the 3000 ppm litters, the P1 adults were mated a second time to produce an F1b litter. Mating of the P1 adults for the second time
commenced approximately one week following weaning (3 weeks of age) of the last F1a litter. Initially, 30 males and 30 females from each treatment group were randomly selected from the F1a litters and assigned to treatment groups to become the second generation parents (P2). However, soon after exposure of the F1a weanlings commenced (1-3 days beginning on postnatal day 22) it became apparent that the weanlings in all dose groups were too small to be singly housed in wire mesh inhalation cages and to go without feed during the exposure period. Therefore, exposures were stopped. Weanlings in all dose groups appeared lethargic/weak following exposures and did not appear interested in feed or water. Given the limitations of starting the F1a litters at such a young age, and space limitations within the exposure chambers which precluded the simultaneous maintenance of the P1 and P2 generation animals, the decision was made to terminate the F1a weanlings and to choose the second generation parents from the F1b litters. Following weaning (3 weeks of age) of the F1b litters, 30 males and 30 females from each treatment group were randomly selected to become the P2 generation. To avoid the aforementioned problems with the F1a litters, exposure of the F1b weanlings/P2 adults began on their respective postnatal day 28. After approximately 10 weeks of treatment, the P2 adults were bred to produce the F2 litters. Exposures of P1 and P2 adults rats to PGME continued until the adults were sent to necropsy. All rats were housed continuously in exposure chambers following the initial exposure to PGME, except during late gestation and throughout the lactation period, when female rats were housed outside of the exposure chambers in nesting boxes. Maternal rats were not exposed to PGME after day 20 of gestation through the fourth day postpartum, in order to allow for parturition and initiation of lactation. During the lactation period, pups were not placed in the exposure chambers, but remained in the nesting boxes separated from the dam for
approximately 6 hours/day on lactation days 5 through 21. - Remarks:
- Doses / Concentrations:
3000 ppm
Basis:
nominal conc. - Remarks:
- Doses / Concentrations:
1000 ppm
Basis:
nominal conc. - Remarks:
- Doses / Concentrations:
300 ppm
Basis:
nominal conc. - No. of animals per sex per dose:
- 30
- Control animals:
- yes, concurrent no treatment
- Details on study design:
- - Dose selection rationale: Rats were exposed to target concentrations of 0, 300, 1000 or 3000 ppm PGME. These concentrations corresponded to oral equivalent doses of approximately 0, 396, 1325 and 3974 mg/kg/day assuming ventilation rates of 1 l/min/kg and 100 percent absorption. The
calculated middle and high dose oral equivalents exceeded the 1 g/kg/day oral limit dose as defined by both the EPA (EPA, 1985) and OECD (OECD, 1981). The chosen concentrations were selected by the sponsor and based upon the results of the inhalation toxicity studies conducted previously.
- Rationale for animal assignment (if not random): random by body weight - Positive control:
- none
- Parental animals: Observations and examinations:
- CAGE SIDE OBSERVATIONS: Yes
Each rat on study was observed twice daily (a.m. and p.m.) for mortality, morbidity and moribundity as well as availability of feed and water. In addition, changes in behavior or demeanor and indications of overt toxicity were evaluated during the a.m. or p.m. observation.
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: A thorough clinical examination was conducted on all animals prior to the start of the study and weekly thereafter. This examination included evaluations of the skin and fur, mucous membranes, respiration, nervous system and behavior pattern. All adult rats found dead or in moribund condition were submitted for a gross pathologic examination. Adult rats found dead after normal working hours were refrigerated until a necropsy could be performed. All pups found dead, or pups that were euthanized in moribund condition, were examined to the extent possible for defects and/or cause of death and preserved in neutral, phosphate-buffered 10% formalin. Cannibalized pups were examined to the extent possible and discarded.
BODY WEIGHT: Yes
- Time schedule for examinations: All P1 animals had body weights recorded weekly during the 10-week pre-breeding treatment period, beginning on or before the first week of the study. Body weights for males were recorded weekly throughout the course of the study. Sperm and plug positive females were weighed on days 0, 7, 14 and 21 of gestation. Females that delivered litters were weighed on days 1, 4, 7, 14, and 21 of lactation. A similar schedule was followed for the P2 generation.
FOOD CONSUMPTION AND COMPOUND INTAKE: Feed consumption was not measured in this study - Oestrous cyclicity (parental animals):
- Estrous cycle length and normality were evaluated daily by vaginal lavage (Cooper et al., 1993) for all P1 and P2 females starting three weeks prior to the F1a and F2 matings only, and continued throughout cohabitation.
- Sperm parameters (parental animals):
- At termination, samples of sperm from the right distal cauda epididymis from the first ten P1 and P2 males sacrificed in each exposure group were collected for evaluation of sperm motility. Sperm motility was determined with the use of the Hamilton-Thorn (HTM) Intergrated Visual Optical System (IVOS) motility analyzer (Hamilton-Thorn Research, Beverly, Massachusetts). Images of all samples for motility analyses were captured on an
optical disk and kept as raw data. The entire left cauda epididymis was weighed and then minced in saline to enumerate the total number of sperm (cauda reserves). Sperm counts were performed manually using a hemocytometer. Additionally, slides were prepared from sperm samples obtained from the left cauda epididymis for possible morphological evaluation and saved, but were not evaluated as no effects were noted on sperm counts or
motility. - Litter observations:
- All litters were examined as soon as possible after delivery. The following parameters were recorded for each litter: total litter size on the day of parturition (day 0), the number of live and dead pups on days 0, 1, 4, 7, 14, and 21 postpartum, and the sex and the weight of each pup on days 1, 4, 7, 14, and 21 of lactation. Any visible physical abnormalities or demeanor changes in the neonates were recorded during the lactation period.
- Postmortem examinations (parental animals):
- A complete necropsy of all P1 and P2 adults was conducted by a team of trained individuals, including and directly supervised by a veterinary pathologist. The scheduled necropsy was performed after the last litter of the respective generation had been weaned, with the following exception: P1 adult males were necropsied early as it was determined that the age of the P1 adult population at the completion of the F1b lactation phase would have precluded any additional breeding of these adults. The rats were fasted overnight, anesthetized with methoxyflurane and euthanized by decapitation. The eyes were visually examined in situ through a moistened glass slide gently pressed against the cornea. Tissues routinely collected (Table 3) were saved from these rats and preserved in neutral, phosphate-buffered 10% formalin, with the following exceptions: testes and epididymides were preserved in Bouin's fixative. The lungs were infused with formalin to their approximate normal inspiratory volume. The nasal cavity was flushed with formalin via the pharyngeal duct to ensure rapid fixation of the tissue. Moribund rats and those dying spontaneously were necropsied in a similar manner. However, body and organ weights were not recorded.
The following organs of the first ten P1 and P2 parental animals sacrificed were weighed: ovaries or testes, left epididymis (total and cauda), seminal vesicles (with coagulating glands and their fluids), prostate, brain, liver, kidneys, lungs, adrenal glands, spleen, and thymus, and the organ-to-body weight ratios calculated.
Histologic examination of potential target organs and reproductive tissues was performed on the control and high concentration groups. Examination of tissues from the low and middle groups was limited to those tissues which demonstrated treatment-related histologic changes at the high concentration; those tissues were the liver and ovaries. Grading for atrophic ovaries was based primarily on the number of recognizable corpora lutea of any stage. In near optimal sections the grades were as follows: Very Slight, 16- 25 corpora lutea; Slight, 6-15; and Moderate, £5. If sections were less than complete, the presence of large cystic follicles and the density of corpora lutea were also considered. A complete set of histologic slides from all tissues listed in Table 3, was prepared from all rats that died spontaneously or were euthanized in a moribund condition, and were examined in an attempt to determine cause of death. - Postmortem examinations (offspring):
- One pup/sex/exposure concentration from the first ten F1 and F2 litters to be weaned was given a complete necropsy by a team of trained individuals including and under the direct supervision of a veterinary pathologist. In order to control for variation in body and organ weight, pups selected for a complete necropsy were euthanized at the same age (postnatal day 22). Pups were anesthetized with methoxyflurane and euthanized by decapitation. Terminal body weights were recorded. Gross pathologic examination and preservation of tissue samples (Table 3) was performed as described above for adults.
For the F1 and F2 pups that were examined macroscopically (one/sex of the first ten litters/concentration weaned), the following organs were weighed: ovaries or testes, brain, heart, liver, kidneys, adrenal glands, spleen and thymus. Organ to body weight ratios were calculated.
Organs that demonstrated treatment-related effects (decreased absolute or relative weight) in weanlings chosen for necropsy were examined microscopically in the control and high concentration groups and included the liver, spleen, thymus and testes. These tissues were chosen for histologic examination because their absolute and/or relative organ weights were depressed (at least one statistically significantly, the other with the same downward difference) in one or more generations of high concentration weanlings. Examination of tissues from the low and middle groups was not conducted as the morphologic changes observed among the high concentration weanlings were clearly related to severe body weight depressions, and because these organ weight changes were not statistically significant at the lower exposure concentrations. - Statistics:
- Body weights, gestation/lactation body weight gains, organ weights, sperm count per gram of cauda epididymis and percent motile sperm were first evaluated by Bartlett’s test for equality of variances. Based upon the outcome of Bartlett’s test, either a parametric or nonparametric analysis of variance (ANOVA) was performed. If the ANOVA was significant, a Dunnett’s test or the Wilcoxon Rank-Sum test with Bonferroni’s correction was performed. Gestation length, average time to mating, litter size, age at vaginal opening and age at preputial separation were analyzed using a nonparametric ANOVA. If the ANOVA was significant, the Wilcoxon Rank-Sum test with Bonferroni’s correction was performed. Statistical outliers were identified by the method of Grubbs (1969), but were only excluded from analysis for documented, scientifically sound reasons. Fertility indices were analyzed by the Fisher exact probability test and Bonferroni’s correction was used for multiple testing of groups in comparison to a single control. Evaluation of the neonatal sex ratio was performed by the binomial distribution test. Survival indices and other incidence data among neonates were analyzed using the litter as the experimental unit by the Wilcoxon test as modified by Haseman and Hoel (1974).
- Reproductive indices:
- see statistics
- Offspring viability indices:
- see statistics
- Clinical signs:
- effects observed, treatment-related
- Body weight and weight changes:
- effects observed, treatment-related
- Food consumption and compound intake (if feeding study):
- effects observed, treatment-related
- Organ weight findings including organ / body weight ratios:
- effects observed, treatment-related
- Histopathological findings: non-neoplastic:
- no effects observed
- Other effects:
- not examined
- Reproductive function: oestrous cycle:
- no effects observed
- Reproductive function: sperm measures:
- no effects observed
- Reproductive performance:
- no effects observed
- Dose descriptor:
- NOAEL
- Effect level:
- 300 ppm
- Clinical signs:
- no effects observed
- Mortality / viability:
- no mortality observed
- Body weight and weight changes:
- effects observed, treatment-related
- Sexual maturation:
- no effects observed
- Organ weight findings including organ / body weight ratios:
- effects observed, treatment-related
- Gross pathological findings:
- no effects observed
- Histopathological findings:
- effects observed, treatment-related
- Dose descriptor:
- NOAEL
- Generation:
- F1
- Effect level:
- 1 000 ppm
- Dose descriptor:
- NOAEL
- Generation:
- F2
- Effect level:
- 1 000 ppm
- Reproductive effects observed:
- not specified
- Conclusions:
- The NOAEL for paternal toxicity is 300 ppm and for offspring toxicity is 1000 ppm. Effects appear secondary to parental weight loss.
- Executive summary:
The objective of this two-generation inhalation reproduction study was to evaluate the effects of propylene glycol monomethyl ether (PGME) on the reproductive capability and neonatal growth and survival of rats. Groups of 30 male and 30 female Sprague-Dawley rats, approximately 6 weeks of age, were exposed to 0, 300, 1000 or 3000 ppm PGME via inhalation, for 6 hours/day, 5 days/week prior to mating and 6 hours/day, 7 days/week during mating, gestation and lactation for two generations. Inhalation exposure of adult male and female rats to 1000 (females only) and 3000 (males and females) ppm PGME resulted in dose-related parental effects. Toxicity in 3000 ppm PGME P1 and P2 males and females was evidenced primarily as an increased incidence of sedation for several weeks early in the exposure regimen and significant decreases in body weights, which achieved decrements of as much as 20 and 21% relative to controls, respectively. Decreased body weights in the P1 and P2 high concentration females generally persisted throughout the pre-breeding, gestation and lactation phases of the study. Additional effects noted among P1 and P2 adult females exposed to 3000 ppm PGME included lengthened estrous cycles, decreased fertility, decreased ovary weights and an increased incidence of histologic ovarian atrophy. The effects on fertility, estrous cyclicity and ovarian weight/histology appeared to be interrelated and associated with the significant decreases in 3000 ppm PGME female body weights and general toxicity/nutritional stress throughout the test period. No treatment-related differences in sperm counts or motility were observed among P1 or P2 adult males. Neonatal effects observed at 3000 ppm PGME consisted of decreased pup body weights, reduced pup survival and litter size, increased time to vaginal opening or preputial separation, and histopathologic observations in the liver and thymus of weanling rats. These neonatal effects also were considered secondary to maternal toxicity, particularly with respect to the compromised nutritional status of the maternal animals of the 3000 ppm PGME group. In the 1000 ppm PGME group, mild parental toxicity was evidenced by slightly decreased pre-mating body weights among P1 and P2 females, but was not accompanied by any statistically significant effects on parental reproduction or neonatal survival, growth or development. There were no treatment-related parental or neonatal effects related to exposure of rats to 300 ppm PGME. In conclusion, the no-observed-effect-level (NOEL) for fertility and reproductive effects in this two-generation inhalation reproduction study was 1000 ppm PGME.
Referenceopen allclose all
CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS) - There were no significant chemical related clinical signs of toxicity during the Task 2 co-habitation phase and there were no mortality during the 14 weeks of cohabitation
BODY WEIGHT (PARENTAL ANIMALS) - Body weights were comparable
DRINKING WATER CONSUMPTION (PARENTAL ANIMALS) - The average daily consumption of dosed water by animals in the 3 treatment groups were comparable to controls
REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS) - details unavailable in abstract
REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS) - details unavailable in abstract
REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS) - details unavailable in abstract
ORGAN WEIGHTS (PARENTAL ANIMALS) - details unavailable in abstract
GROSS PATHOLOGY (PARENTAL ANIMALS) - details unavailable in abstract
HISTOPATHOLOGY (PARENTAL ANIMALS) - details unavailable in abstract
BODY WEIGHT (PARENTAL ANIMALS) - Body weights were comparable
DRINKING WATER CONSUMPTION (PARENTAL ANIMALS) - The average daily consumption of dosed water by animals in the 3 treatment groups were comparable to controls
REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS) - details unavailable in abstract
REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS) - details unavailable in abstract
REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS) - details unavailable in abstract
ORGAN WEIGHTS (PARENTAL ANIMALS) - details unavailable in abstract
GROSS PATHOLOGY (PARENTAL ANIMALS) - details unavailable in abstract
HISTOPATHOLOGY (PARENTAL ANIMALS) - details unavailable in abstract
Task 2
VIABILITY (OFFSPRING) - The proportion of pups born alive were slightly but significantly reduced at 0.5 and 1.0% dose levels
CLINICAL SIGNS (OFFSPRING) - details unavailable in abstract
BODY WEIGHT (OFFSPRING) - The absolute and adjusted live pup weights were not affected, except in the 2 % dose group
SEXUAL MATURATION (OFFSPRING) - details unavailable in abstract
ORGAN WEIGHTS (OFFSPRING) - details unavailable in abstract
GROSS PATHOLOGY (OFFSPRING) - details unavailable in abstract
HISTOPATHOLOGY (OFFSPRING) - details unavailable in abstract
OTHER FINDINGS (OFFSPRING) - PGME treatment had no adverse effect with respect to the number of litters per pair, thenumber of live pups per litter and the sex ratio. The cumulative number of days to litter were unaffected by PGME treatment. Pups delivered by breeding pairs inthe 2% PGME group were consistently smaller at delivery and through 14 days of maturation except for live female pup weight at delivery
Task 4
VIABILITY (OFFSPRING) - details unavailable in abstract
CLINICAL SIGNS (OFFSPRING) - details unavailable in abstract
BODY WEIGHT (OFFSPRING) - Animals in the 2% dose group consistently weighed less than the control group at delivery and through weaning and maturation
SEXUAL MATURATION (OFFSPRING) - details unavailable in abstract
ORGAN WEIGHTS (OFFSPRING) - There were no significant differences in the body weight and absolute weights of kidney and liver in the female mice, while relative weights of liver were significantly higher in the 2% dose group. In the male mice absolute and relative weights of epididymis, seminal vesicle and prostate glands were significantly lower as compared to the control dose group.
GROSS PATHOLOGY (OFFSPRING) - details unavailable in abstract
HISTOPATHOLOGY (OFFSPRING) - details unavailable in abstract
OTHER FINDINGS (OFFSPRING) - Parameters such as sperm motility, sperm density and the incidence of abnormal sperm were not affected by PGME treatment upto dose levels of 2%. Similarily estrous cyclicity remained unaffected by PGME treatment
VIABILITY (OFFSPRING) - The proportion of pups born alive were slightly but significantly reduced at 0.5 and 1.0% dose levels
CLINICAL SIGNS (OFFSPRING) - details unavailable in abstract
BODY WEIGHT (OFFSPRING) - The absolute and adjusted live pup weights were not affected, except in the 2 % dose group
SEXUAL MATURATION (OFFSPRING) - details unavailable in abstract
ORGAN WEIGHTS (OFFSPRING) - details unavailable in abstract
GROSS PATHOLOGY (OFFSPRING) - details unavailable in abstract
HISTOPATHOLOGY (OFFSPRING) - details unavailable in abstract
OTHER FINDINGS (OFFSPRING) - PGME treatment had no adverse effect with respect to the number of litters per pair, thenumber of live pups per litter and the sex ratio. The cumulative number of days to litter were unaffected by PGME treatment. Pups delivered by breeding pairs inthe 2% PGME group were consistently smaller at delivery and through 14 days of maturation except for live female pup weight at delivery
Task 4
VIABILITY (OFFSPRING) - details unavailable in abstract
CLINICAL SIGNS (OFFSPRING) - details unavailable in abstract
BODY WEIGHT (OFFSPRING) - Animals in the 2% dose group consistently weighed less than the control group at delivery and through weaning and maturation
SEXUAL MATURATION (OFFSPRING) - details unavailable in abstract
ORGAN WEIGHTS (OFFSPRING) - There were no significant differences in the body weight and absolute weights of kidney and liver in the female mice, while relative weights of liver were significantly higher in the 2% dose group. In the male mice absolute and relative weights of epididymis, seminal vesicle and prostate glands were significantly lower as compared to the control dose group.
GROSS PATHOLOGY (OFFSPRING) - details unavailable in abstract
HISTOPATHOLOGY (OFFSPRING) - details unavailable in abstract
OTHER FINDINGS (OFFSPRING) - Parameters such as sperm motility, sperm density and the incidence of abnormal sperm were not affected by PGME treatment upto dose levels of 2%. Similarily estrous cyclicity remained unaffected by PGME treatment
There were no changes in body weight or food consumption in any of the first generation exposure groups except for a 4% reduction in pup weight at the highest dose tested. In the second generation exposure groups, reductions in male and female body weight were noted (14% reduction during nursing; 8% reduction in body weight in males during and after mating, and epididymus and prostate weights were 9 and 8% below controls in males, respectively). There was no evidence of reproductive toxicity; mating and fertility indices, and the number and viability of F1 and F2 offspring were not affected. Among F1 offspring, mean pup weight was decreased in the 2% group. F2 offspring from the 2% group displayed reduced pup weight at birth, which continued postnatally during nursing. At sacrifice, female body weights in the 2% group were lower than controls; absolute testis, and relative epididymis and prostate weights were also reduced. F1 female body-weight-adjusted liver weights were increased
CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
At 3000 ppm PGME, sedation as evidenced by incoordination and decreased activity which resolved by the next exposure day was observed in both
sexes immediately following the first exposure to PGME and continued to be observed through test day 32 in males, and test day 23 in females. Sedation was not observed in males or females exposed to 300 or 1000 ppm PGME at any time during the study. No other treatment-related observations regarding behavior or demeanor were observed in P1 adults males at any exposure concentration during the entire study or in P1 adult females at any exposure concentration during the pre-mating, gestation or lactation periods. Six P1 adult females were found dead prior to the scheduled necropsy. Cause of death and other relevant information is summarized in Text Table 1. Detailed gross and histopathologic observations for these animals may be found in the individual animal pathology data, starting with Appendix Table 58. The deaths of these rats were not considered treatment-related. All other rats survived to the scheduled termination.
P2 adults and F2 litters: A single 1000 ppm male, 95B0860, died early on test day 72. No prior clinical observations were made on this male. The only gross observation made for this male was congested viscera. Additionally, inflammation of the heart and atrophy of the pancreas was noted during histopathologic examination. The cause of death for this male was not determined. All other P2 adults survived the test period and were necropsied on
the scheduled date of termination. Similar to the P1 adults, P2 male and female rats exposed to 3000 ppm PGME exhibited sedation, initially evidenced as incoordination following their first exposure to PGME (postnatal day 28). Incoordination was resolved within approximately one week of initial exposure to PGME vapors followed by approximately one week of decreased activity observed immediately following daily exposures. Incoordination and sedation observed during and post-exposure resolved by the next exposure day during this interval. Sedation was not observed in males or females
exposed to 300 or 1000 ppm PGME at any time during the study. The only other treatment-related observation noted was vaginal bleeding, which was noted among five high dose females late in the study (gestation/lactation phase). In three of the five cases the vaginal bleeding was associated with the pending delivery of a litter. In the other two cases the bleeding stopped, however, no litters were delivered. Of these two females, only one had histopathologic indications of a prior pregnancy (pigment laden macrophages in the uterus). No other treatment-related observations regarding behavior or demeanor were observed in P2 adults males at any exposure concentration during the entire study or in P2 adult females at any exposure concentration during the pre-mating, gestation or lactation periods.
BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Mean body weight data for P1 males and females, including the F1a/F1b gestation and lactation periods (females only) and interim body weight data collected between the F1a and F1b breeding (females only), are presented in Tables 10 through 19. Body weights of 3000 ppm PGME males were significantly decreased relative to control values beginning on test day 7 and remained decreased throughout the study, with statistical significance achieved on days 7, 14, and 77-168. Body weights of males exposed to 300 or 1000 ppm PGME were not significantly different from controls at any time during the study. Pre-mating body weights of 3000 ppm PGME females were significantly decreased beginning on test day 7 and remained decreased throughout the pre-mating period. In fact, mean body weight in the high concentration group was approximately 10% lower than control values by the end of the pre-mating period. Body weights of high concentration dams remained significantly decreased throughout most of the F1a and F1b gestation periods, and the first one to two weeks of the F1a and F1b lactation periods. Body weight gains of 3000 ppm PGME females were not affected during the F1a or F1b gestation phases or the respective first week of lactation. Compensatory increases in body weight gains relative to controls were noted during the last two weeks of lactation (F1a and F1b) for the 3000 ppm PGME dams. Dams exposed to 1000 ppm PGME during the pre-mating phase exhibited slight decreases in body weight, with the decreases statistically identified only on test days 7, 14 and 63. No significant effects on body weight were observed among 300 ppm females during the pre-mating period. Additionally, no significant differences in F1a or F1b gestation or lactation body weights or body weight gains were noted for 300 or 1000 ppm females relative to controls.
Mean body weights of P2 males and females, including the F2 gestation and lactation period (females only) are presented in Tables 20 through 25. Body weights of 3000 ppm PGME males were significantly decreased (20%) relative to controls at the beginning of the P2 exposures and remained decreased throughout the study (9% decrease on day 70, the end of the pre-mating period). Body weights of the P2 males exposed to 300 or 1000 ppm PGME were not affected at any time during the study. Pre-mating body weights of 3000 ppm PGME females were significantly decreased (21%) at the beginning of the P2 exposures and remained decreased throughout the pre-mating period (16% decrease on day 70, the end of the pre-mating period). Body weights of high concentration dams were also significantly decreased throughout the F2 gestation period, and the first one to two weeks of the F2 lactation period. Body weight gains of 3000 ppm PGME females were significantly decreased on gestation days 14-21, resulting in a statistically identified overall decrease on gestation days 0-21 as well. Compensatory increases in body weight gains relative to controls were statistically identified during lactation days 7-14 and 14-21, resulting in an overall increase in body weight gain for the entire lactation period (days 1-21) for the 3000 ppm PGME dams. Dams exposed to 1000 ppm PGME during the pre-mating period exhibited slight decreases in body weight, relative to control values, with the decreases statistically identified only on test days 63 and 70. No significant effects on body weight were observed among 300 ppm PGME females during the pre-mating period. Additionally, no significant differences in P2/F2 gestation or lactation body weights or body weight gains were noted for 300 or 1000 ppm PGME females relative to controls.
REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS)
Estrous cyclicity data collected for ten P1 females per exposure concentration are presented in Table 26. Although not statistically identified, dams exposed to 3000 ppm PGME had a slight increase in the mean number of days per cycle as well as a resultant decrease in the mean number of estrous cycles observed per dam prior to placement with males for the F1a mating. Additionally, cycling slides obtained for four out of ten high exposure females were noted as exhibiting atypical cellularity. No effects on mean number of days per cycle or number of cycles per dam were noted for 300 or 1000 ppm dams. Estrous cycle length and normality were not evaluated prior to the F1b mating.
P2 estrous cyclicity data collected for ten P2 females per exposure concentration are summarized in Table 27. Dams exposed to 3000 ppm PGME had a statistically significant increase in the mean number of days per cycle as well as a statistically significant decrease in the mean number of estrous cycles observed per dam prior to placement with males for the F2 mating. This was consistent with the slight trend for increased cycle length and decreased number of cycles noted in P1 females for the F1a mating. Also, as for the P1 females, atypical cellularity was noted among the cycling slides for four high exposure females. No effects on mean number of days per cycle or number of cycles per dam were noted for 300 or 1000 ppm PGME dams.
REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS)
Summaries of mean sperm counts and sperm motility (percent motile and progressively motile sperm) observed for ten P1 males per exposure concentration: No treatment-related differences in sperm counts or motility were observed for any exposure concentration tested. A significant increase in the number of progressively motile sperm obtained from P1 3000 ppm PGME males was considered spurious as a similar effect was not observed in the subsequent P2 generation.
Summaries of mean sperm counts and sperm motility (percent motile and progressively motile sperm) observed for ten P2 males per exposure concentration: No treatment-related differences in sperm counts or motility were observed for any exposure concentration tested.
REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
No treatment-related effects were observed on male or female P1 adult reproductive indices, gestation survival index, pup sex ratios, gestation length, or time to mating at any exposure concentration for the F1a mating/litters. Survival of pups from 3000 ppm PGME litters was significantly decreased relative to controls on lactation days 1 and 4. Survival of 3000 ppm PGME pups was also decreased, although not statistically identified, on lactation days 14 and 21. No effects on survival were observed for 300 or 1000 ppm PGME F1a litters at any time.
Reproductive indices and pup survival for P2 adults and their F2 litters: At 3000 ppm PGME, P2 male and female fertility was lower (not statistically
identified) than controls and recent historical control ranges (Table 31), while male and female conception rates were identified as significantly lower than controls, also falling outside the range of recent historical control values. No effects were observed on the P2 male or female mating index, gestation survival, pup sex ratios, gestation length, or time to mating. However, survival of 3000 ppm PGME F2 pups was significantly decreased relative to controls on lactation days 1 and 4. No treatment-related effects were observed on P2/F2 male or female reproductive indices, gestation survival, pup survival indices, pup sex ratios, gestation length, or time to mating at 300 or 1000 ppm PGME.
ORGAN WEIGHTS (PARENTAL ANIMALS)
Organ weight data (absolute and relative) for P1 males and females: Males exposed to 3000 ppm PGME exhibited statistically significant increases in relative testes, brain and kidney weights as well as a decrease in absolute and relative thymus weight. These effects were considered likely secondary to the significant decrease in mean P1 male body weight at this exposure concentration (probable decreased feed intake and resultant nutritional stress). No other significant effects on any other organ weights were observed among P1 3000 ppm PGME males. There were no treatment-related effects on terminal body weights or organ weights of males exposed to 300 or 1000 ppm PGME. P1 females exposed to 3000 ppm PGME had significantly higher relative adrenal, liver, and lung weights, when compared to controls, also primarily because of significantly lower body weights, however the interpretation of the liver weights is more complicated and will be discussed. No significant differences were observed for organ weights of P1 300 or 1000 ppm PGME females relative to controls.
Organ weight data (absolute and relative) for P2 males and females: P2 males exposed to 3000 ppm PGME exhibited statistically significant increases in relative liver, lung and seminal vesicle weights. Trends were similar, but not significant in P1 3000 ppm males, and again are interpreted primarily as the result of decreased body weight. No other significant effects on any other organ weights were observed among P2 3000 ppm PGME males. There were no treatmentrelated differences in organ weights of P2 males exposed to 300 or 1000 ppm PGME. P2 females exposed to 3000 ppm PGME had significantly decreased brain (absolute) and ovary (absolute and relative) weights relative to controls. The brain weights of the highexposure
P2 females will be discussed in the context of the entire study. The decreased ovary weights noted at 3000 ppm PGME appeared consistent with an increased incidence of ovarian atrophy observed histologically at this concentration. No other significant differences in any other organ weights were noted for 3000 ppm P2 females relative to controls. There were no treatment-related differences in organ weights of P2 females exposed to 300 or 1000 ppm PGME.
GROSS PATHOLOGY (PARENTAL ANIMALS)
No treatment-related gross pathologic changes were observed among the P1 and P2 adults at any exposure concentration.
HISTOPATHOLOGY (PARENTAL ANIMALS)
An increased incidence of histologic ovarian atrophy and decreased ovarian weight was observed among the 3000 ppm PGME P1 females and was interpreted to be the result of non-specific toxicity and nutritional stress (see Discussion). Histologically, typical atrophic ovaries had fewer, or no, corpora lutea, and multiple large cystic and atretic follicles. There was no apparent increase in follicular atresia (identified by apoptotic granulosa cells) among developing follicles. Primordial and all subsequent stages in follicular maturation were evaluated qualitatively; they appeared to be present in normal numbers and were of normal appearance.
Similar to the P1 adults, an increased incidence of histologic ovarian atrophy associated with decreased ovarian weight was observed among the P2 3000 ppm PGME females and likewise was interpreted to be the result of non-specific toxicity and nutritional stress (see Discussion). Similar to the P1 females, typical P2 atrophic ovaries had fewer, or no, corpora lutea, and multiple large cystic and atretic follicles and there was no apparent increase in follicular atresia (identified by apoptotic granulosa cells) among developing follicles. Primordial cells and all subsequent cell stages in follicular maturation appeared to be present in normal numbers and were of normal appearance.
At 3000 ppm PGME, sedation as evidenced by incoordination and decreased activity which resolved by the next exposure day was observed in both
sexes immediately following the first exposure to PGME and continued to be observed through test day 32 in males, and test day 23 in females. Sedation was not observed in males or females exposed to 300 or 1000 ppm PGME at any time during the study. No other treatment-related observations regarding behavior or demeanor were observed in P1 adults males at any exposure concentration during the entire study or in P1 adult females at any exposure concentration during the pre-mating, gestation or lactation periods. Six P1 adult females were found dead prior to the scheduled necropsy. Cause of death and other relevant information is summarized in Text Table 1. Detailed gross and histopathologic observations for these animals may be found in the individual animal pathology data, starting with Appendix Table 58. The deaths of these rats were not considered treatment-related. All other rats survived to the scheduled termination.
P2 adults and F2 litters: A single 1000 ppm male, 95B0860, died early on test day 72. No prior clinical observations were made on this male. The only gross observation made for this male was congested viscera. Additionally, inflammation of the heart and atrophy of the pancreas was noted during histopathologic examination. The cause of death for this male was not determined. All other P2 adults survived the test period and were necropsied on
the scheduled date of termination. Similar to the P1 adults, P2 male and female rats exposed to 3000 ppm PGME exhibited sedation, initially evidenced as incoordination following their first exposure to PGME (postnatal day 28). Incoordination was resolved within approximately one week of initial exposure to PGME vapors followed by approximately one week of decreased activity observed immediately following daily exposures. Incoordination and sedation observed during and post-exposure resolved by the next exposure day during this interval. Sedation was not observed in males or females
exposed to 300 or 1000 ppm PGME at any time during the study. The only other treatment-related observation noted was vaginal bleeding, which was noted among five high dose females late in the study (gestation/lactation phase). In three of the five cases the vaginal bleeding was associated with the pending delivery of a litter. In the other two cases the bleeding stopped, however, no litters were delivered. Of these two females, only one had histopathologic indications of a prior pregnancy (pigment laden macrophages in the uterus). No other treatment-related observations regarding behavior or demeanor were observed in P2 adults males at any exposure concentration during the entire study or in P2 adult females at any exposure concentration during the pre-mating, gestation or lactation periods.
BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Mean body weight data for P1 males and females, including the F1a/F1b gestation and lactation periods (females only) and interim body weight data collected between the F1a and F1b breeding (females only), are presented in Tables 10 through 19. Body weights of 3000 ppm PGME males were significantly decreased relative to control values beginning on test day 7 and remained decreased throughout the study, with statistical significance achieved on days 7, 14, and 77-168. Body weights of males exposed to 300 or 1000 ppm PGME were not significantly different from controls at any time during the study. Pre-mating body weights of 3000 ppm PGME females were significantly decreased beginning on test day 7 and remained decreased throughout the pre-mating period. In fact, mean body weight in the high concentration group was approximately 10% lower than control values by the end of the pre-mating period. Body weights of high concentration dams remained significantly decreased throughout most of the F1a and F1b gestation periods, and the first one to two weeks of the F1a and F1b lactation periods. Body weight gains of 3000 ppm PGME females were not affected during the F1a or F1b gestation phases or the respective first week of lactation. Compensatory increases in body weight gains relative to controls were noted during the last two weeks of lactation (F1a and F1b) for the 3000 ppm PGME dams. Dams exposed to 1000 ppm PGME during the pre-mating phase exhibited slight decreases in body weight, with the decreases statistically identified only on test days 7, 14 and 63. No significant effects on body weight were observed among 300 ppm females during the pre-mating period. Additionally, no significant differences in F1a or F1b gestation or lactation body weights or body weight gains were noted for 300 or 1000 ppm females relative to controls.
Mean body weights of P2 males and females, including the F2 gestation and lactation period (females only) are presented in Tables 20 through 25. Body weights of 3000 ppm PGME males were significantly decreased (20%) relative to controls at the beginning of the P2 exposures and remained decreased throughout the study (9% decrease on day 70, the end of the pre-mating period). Body weights of the P2 males exposed to 300 or 1000 ppm PGME were not affected at any time during the study. Pre-mating body weights of 3000 ppm PGME females were significantly decreased (21%) at the beginning of the P2 exposures and remained decreased throughout the pre-mating period (16% decrease on day 70, the end of the pre-mating period). Body weights of high concentration dams were also significantly decreased throughout the F2 gestation period, and the first one to two weeks of the F2 lactation period. Body weight gains of 3000 ppm PGME females were significantly decreased on gestation days 14-21, resulting in a statistically identified overall decrease on gestation days 0-21 as well. Compensatory increases in body weight gains relative to controls were statistically identified during lactation days 7-14 and 14-21, resulting in an overall increase in body weight gain for the entire lactation period (days 1-21) for the 3000 ppm PGME dams. Dams exposed to 1000 ppm PGME during the pre-mating period exhibited slight decreases in body weight, relative to control values, with the decreases statistically identified only on test days 63 and 70. No significant effects on body weight were observed among 300 ppm PGME females during the pre-mating period. Additionally, no significant differences in P2/F2 gestation or lactation body weights or body weight gains were noted for 300 or 1000 ppm PGME females relative to controls.
REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS)
Estrous cyclicity data collected for ten P1 females per exposure concentration are presented in Table 26. Although not statistically identified, dams exposed to 3000 ppm PGME had a slight increase in the mean number of days per cycle as well as a resultant decrease in the mean number of estrous cycles observed per dam prior to placement with males for the F1a mating. Additionally, cycling slides obtained for four out of ten high exposure females were noted as exhibiting atypical cellularity. No effects on mean number of days per cycle or number of cycles per dam were noted for 300 or 1000 ppm dams. Estrous cycle length and normality were not evaluated prior to the F1b mating.
P2 estrous cyclicity data collected for ten P2 females per exposure concentration are summarized in Table 27. Dams exposed to 3000 ppm PGME had a statistically significant increase in the mean number of days per cycle as well as a statistically significant decrease in the mean number of estrous cycles observed per dam prior to placement with males for the F2 mating. This was consistent with the slight trend for increased cycle length and decreased number of cycles noted in P1 females for the F1a mating. Also, as for the P1 females, atypical cellularity was noted among the cycling slides for four high exposure females. No effects on mean number of days per cycle or number of cycles per dam were noted for 300 or 1000 ppm PGME dams.
REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS)
Summaries of mean sperm counts and sperm motility (percent motile and progressively motile sperm) observed for ten P1 males per exposure concentration: No treatment-related differences in sperm counts or motility were observed for any exposure concentration tested. A significant increase in the number of progressively motile sperm obtained from P1 3000 ppm PGME males was considered spurious as a similar effect was not observed in the subsequent P2 generation.
Summaries of mean sperm counts and sperm motility (percent motile and progressively motile sperm) observed for ten P2 males per exposure concentration: No treatment-related differences in sperm counts or motility were observed for any exposure concentration tested.
REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
No treatment-related effects were observed on male or female P1 adult reproductive indices, gestation survival index, pup sex ratios, gestation length, or time to mating at any exposure concentration for the F1a mating/litters. Survival of pups from 3000 ppm PGME litters was significantly decreased relative to controls on lactation days 1 and 4. Survival of 3000 ppm PGME pups was also decreased, although not statistically identified, on lactation days 14 and 21. No effects on survival were observed for 300 or 1000 ppm PGME F1a litters at any time.
Reproductive indices and pup survival for P2 adults and their F2 litters: At 3000 ppm PGME, P2 male and female fertility was lower (not statistically
identified) than controls and recent historical control ranges (Table 31), while male and female conception rates were identified as significantly lower than controls, also falling outside the range of recent historical control values. No effects were observed on the P2 male or female mating index, gestation survival, pup sex ratios, gestation length, or time to mating. However, survival of 3000 ppm PGME F2 pups was significantly decreased relative to controls on lactation days 1 and 4. No treatment-related effects were observed on P2/F2 male or female reproductive indices, gestation survival, pup survival indices, pup sex ratios, gestation length, or time to mating at 300 or 1000 ppm PGME.
ORGAN WEIGHTS (PARENTAL ANIMALS)
Organ weight data (absolute and relative) for P1 males and females: Males exposed to 3000 ppm PGME exhibited statistically significant increases in relative testes, brain and kidney weights as well as a decrease in absolute and relative thymus weight. These effects were considered likely secondary to the significant decrease in mean P1 male body weight at this exposure concentration (probable decreased feed intake and resultant nutritional stress). No other significant effects on any other organ weights were observed among P1 3000 ppm PGME males. There were no treatment-related effects on terminal body weights or organ weights of males exposed to 300 or 1000 ppm PGME. P1 females exposed to 3000 ppm PGME had significantly higher relative adrenal, liver, and lung weights, when compared to controls, also primarily because of significantly lower body weights, however the interpretation of the liver weights is more complicated and will be discussed. No significant differences were observed for organ weights of P1 300 or 1000 ppm PGME females relative to controls.
Organ weight data (absolute and relative) for P2 males and females: P2 males exposed to 3000 ppm PGME exhibited statistically significant increases in relative liver, lung and seminal vesicle weights. Trends were similar, but not significant in P1 3000 ppm males, and again are interpreted primarily as the result of decreased body weight. No other significant effects on any other organ weights were observed among P2 3000 ppm PGME males. There were no treatmentrelated differences in organ weights of P2 males exposed to 300 or 1000 ppm PGME. P2 females exposed to 3000 ppm PGME had significantly decreased brain (absolute) and ovary (absolute and relative) weights relative to controls. The brain weights of the highexposure
P2 females will be discussed in the context of the entire study. The decreased ovary weights noted at 3000 ppm PGME appeared consistent with an increased incidence of ovarian atrophy observed histologically at this concentration. No other significant differences in any other organ weights were noted for 3000 ppm P2 females relative to controls. There were no treatment-related differences in organ weights of P2 females exposed to 300 or 1000 ppm PGME.
GROSS PATHOLOGY (PARENTAL ANIMALS)
No treatment-related gross pathologic changes were observed among the P1 and P2 adults at any exposure concentration.
HISTOPATHOLOGY (PARENTAL ANIMALS)
An increased incidence of histologic ovarian atrophy and decreased ovarian weight was observed among the 3000 ppm PGME P1 females and was interpreted to be the result of non-specific toxicity and nutritional stress (see Discussion). Histologically, typical atrophic ovaries had fewer, or no, corpora lutea, and multiple large cystic and atretic follicles. There was no apparent increase in follicular atresia (identified by apoptotic granulosa cells) among developing follicles. Primordial and all subsequent stages in follicular maturation were evaluated qualitatively; they appeared to be present in normal numbers and were of normal appearance.
Similar to the P1 adults, an increased incidence of histologic ovarian atrophy associated with decreased ovarian weight was observed among the P2 3000 ppm PGME females and likewise was interpreted to be the result of non-specific toxicity and nutritional stress (see Discussion). Similar to the P1 females, typical P2 atrophic ovaries had fewer, or no, corpora lutea, and multiple large cystic and atretic follicles and there was no apparent increase in follicular atresia (identified by apoptotic granulosa cells) among developing follicles. Primordial cells and all subsequent cell stages in follicular maturation appeared to be present in normal numbers and were of normal appearance.
VIABILITY (OFFSPRING)
No treatment-related effect observed.
CLINICAL SIGNS (OFFSPRING)
No treatment-related effect observed.
BODY WEIGHT (OFFSPRING)
Significant body weight decreases observed among the 3000 ppm PGME weanlings relative to controls.
SEXUAL MATURATION (OFFSPRING)
No treatment-related effect observed.
ORGAN WEIGHTS (OFFSPRING)
Mean absolute and relative organ weights and terminal body weights were collected for ten males and females per exposure concentration (F1a and F1b). Several organ weights changes (absolute or relative) were noted for male and female weanlings from F1a 3000 ppm PGME litters. F1a 3000 ppm PGME males had statistically identified decreases in absolute kidney, liver, spleen, and testes weights, while high concentration F1a females exhibited decreased absolute heart, and thymus weights and increased relative brain and kidneys weights. All of the differences identified at 3000 ppm PGME apeared to be secondary to significant decreases in male and female pup body weights at the time of necropsy/weaning (see Table 34) and were entirely consistent with nutritional stress. No significant organ weight changes were noted for F1a 300 or 1000 ppm PGME male or female weanlings. High concentration F1b male and female weanlings had significantly decreased absolute brain weights (males and females) and increased relative heart weights (males only). As with the F1a weanlings, these changes were likely due to the significant body weight decreases observed among the 3000 ppm PGME weanlings relative to controls. F1b males from 1000 ppm PGME litters were noted as having statistically identified decreases in absolute brain weight. This change was not considered toxicologically significant as relative brain weight was not affected and similar decreases were not observed among the F1a or F2 3000 ppm PGME males. A statistically significant increase in relative heart weight in 300 ppm PGME F1b males and females was considered spurious and unrelated to treatment as no dose-response was observed and similar increases were not observed in the F1a or F2 weanlings. Similarly, a significant increase in relative adrenal weight observed for 300 ppm F1b females was not consistent with data generated for the F1a or F2 generations, nor was a dose response observed. No significant organ weight changes were identified for 1000 F1b ppm PGME females.
F2 males at 3000 ppm PGME exhibited significant weight changes (absolute and/or relative) for all organs weighed and included the following: adrenals, brain, heart, kidneys, liver, spleen, testes, and thymus. F2 3000 ppm PGME females exhibited similar changes, however, only absolute brain and spleen weights were statistically identified. As with the 3000 ppm PGME F1a and F1b weanlings, organ weight changes noted for the F2 3000 ppm PGME males and females were likely secondary to significant body weight decrements (see Table 37) relative to control values and nutritional stress. A statistically significant decrease in relative thymus weight was identified for F2 300 ppm PGME males. As this effect was not dose-related and was not observed among the F1a or F1b 300 or 1000 ppm PGME males, it was considered a spurious finding. No other significant organ weight changes were noted for 300 or 1000 ppm PGME F2 males or females.
GROSS PATHOLOGY (OFFSPRING)
There were no gross lesions identified at the F1a or F1b necropsy that were associated with PGME exposure. There were no treatmentrelated gross lesions identified in the F2 males or females at any exposure concentration.
HISTOPATHOLOGY (OFFSPRING)
Histologically, the livers of F1a and F1b 3000 ppm PGME weanlings often lacked the normal degree of glycogen vacuolation; glycogen depletion was diagnosed and recorded. This finding, along with an increase in thymic single cell necrosis, is consistent with nutritional stress. Although spleen weights were in general depressed, no particular cell compartment was identified as contributing disproportionately, and no necrosis was observed, so no histopathologic correlate was recorded. Similarly, testicular weights for the F1a and F1b 3000 ppm PGME males were decreased, however, they were also histologically normal for their slightly earlier stage of development. Also, it should be recalled that the high-exposure P2 males, selected from the F1b pups, demonstrated normal testicular weights and histopathology, as well as sperm count and motility.
Changes similar to those observed in the F1a and F1b weanlings were noted histologically in the livers and thymus of F2 3000 ppm PGME weanlings suggesting some degree of nutritional stress. Despite weight changes observed, no histopathologic observations were noted in the spleens of 3000 ppm PGME F2 males or females. The testes of 3000 ppm PGME F2 males were also histologically normal, despite decreases noted in weight relative to controls.
No treatment-related effect observed.
CLINICAL SIGNS (OFFSPRING)
No treatment-related effect observed.
BODY WEIGHT (OFFSPRING)
Significant body weight decreases observed among the 3000 ppm PGME weanlings relative to controls.
SEXUAL MATURATION (OFFSPRING)
No treatment-related effect observed.
ORGAN WEIGHTS (OFFSPRING)
Mean absolute and relative organ weights and terminal body weights were collected for ten males and females per exposure concentration (F1a and F1b). Several organ weights changes (absolute or relative) were noted for male and female weanlings from F1a 3000 ppm PGME litters. F1a 3000 ppm PGME males had statistically identified decreases in absolute kidney, liver, spleen, and testes weights, while high concentration F1a females exhibited decreased absolute heart, and thymus weights and increased relative brain and kidneys weights. All of the differences identified at 3000 ppm PGME apeared to be secondary to significant decreases in male and female pup body weights at the time of necropsy/weaning (see Table 34) and were entirely consistent with nutritional stress. No significant organ weight changes were noted for F1a 300 or 1000 ppm PGME male or female weanlings. High concentration F1b male and female weanlings had significantly decreased absolute brain weights (males and females) and increased relative heart weights (males only). As with the F1a weanlings, these changes were likely due to the significant body weight decreases observed among the 3000 ppm PGME weanlings relative to controls. F1b males from 1000 ppm PGME litters were noted as having statistically identified decreases in absolute brain weight. This change was not considered toxicologically significant as relative brain weight was not affected and similar decreases were not observed among the F1a or F2 3000 ppm PGME males. A statistically significant increase in relative heart weight in 300 ppm PGME F1b males and females was considered spurious and unrelated to treatment as no dose-response was observed and similar increases were not observed in the F1a or F2 weanlings. Similarly, a significant increase in relative adrenal weight observed for 300 ppm F1b females was not consistent with data generated for the F1a or F2 generations, nor was a dose response observed. No significant organ weight changes were identified for 1000 F1b ppm PGME females.
F2 males at 3000 ppm PGME exhibited significant weight changes (absolute and/or relative) for all organs weighed and included the following: adrenals, brain, heart, kidneys, liver, spleen, testes, and thymus. F2 3000 ppm PGME females exhibited similar changes, however, only absolute brain and spleen weights were statistically identified. As with the 3000 ppm PGME F1a and F1b weanlings, organ weight changes noted for the F2 3000 ppm PGME males and females were likely secondary to significant body weight decrements (see Table 37) relative to control values and nutritional stress. A statistically significant decrease in relative thymus weight was identified for F2 300 ppm PGME males. As this effect was not dose-related and was not observed among the F1a or F1b 300 or 1000 ppm PGME males, it was considered a spurious finding. No other significant organ weight changes were noted for 300 or 1000 ppm PGME F2 males or females.
GROSS PATHOLOGY (OFFSPRING)
There were no gross lesions identified at the F1a or F1b necropsy that were associated with PGME exposure. There were no treatmentrelated gross lesions identified in the F2 males or females at any exposure concentration.
HISTOPATHOLOGY (OFFSPRING)
Histologically, the livers of F1a and F1b 3000 ppm PGME weanlings often lacked the normal degree of glycogen vacuolation; glycogen depletion was diagnosed and recorded. This finding, along with an increase in thymic single cell necrosis, is consistent with nutritional stress. Although spleen weights were in general depressed, no particular cell compartment was identified as contributing disproportionately, and no necrosis was observed, so no histopathologic correlate was recorded. Similarly, testicular weights for the F1a and F1b 3000 ppm PGME males were decreased, however, they were also histologically normal for their slightly earlier stage of development. Also, it should be recalled that the high-exposure P2 males, selected from the F1b pups, demonstrated normal testicular weights and histopathology, as well as sperm count and motility.
Changes similar to those observed in the F1a and F1b weanlings were noted histologically in the livers and thymus of F2 3000 ppm PGME weanlings suggesting some degree of nutritional stress. Despite weight changes observed, no histopathologic observations were noted in the spleens of 3000 ppm PGME F2 males or females. The testes of 3000 ppm PGME F2 males were also histologically normal, despite decreases noted in weight relative to controls.
At 3000 ppm, toxicity in the P1 and P2 adults was marked, as
evidenced by sedation during and after exposure for several
weeks, and mean body weights which were as much as 21% lower
than controls. This marked parental toxicity was accompanied
by lengthened estrous cycles, decreased fertility, decreased
ovary weights, reduced pup survival and litter size, slight
delays in puberty onset, and histologic changes in the liver
and thymus of the F1 and F2 offspring. At 3000 ppm, there
was an increase in histologic ovarian atrophy in P1 and P2
females, and at 1000 ppm, there was a decrease in pre-mating
body weight in the P1 and P2 females. No treatment-related
differences in sperm counts or motility were observed among
the P1 or P2 males.
Effect on fertility: via oral route
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- NOAEL
- 1 885 mg/kg bw/day
- Species:
- mouse
- Quality of whole database:
- Good (Klimisch 2)
Effect on fertility: via inhalation route
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- NOAEC
- 3 740 mg/m³
- Species:
- rat
- Quality of whole database:
- Good (Klimisch 1)
Effect on fertility: via dermal route
- Endpoint conclusion:
- no study available
Additional information
NOAELs observed in a two-generation reproductive study on exposure to propylene glycol methyl via inhalation were 300 ppm (1122 mg/m3) for adult rats and 1,000 ppm (3740 mg/m3) for offspring. Sedation and decreased body weight in adults was accompanied by lengthened estrous cycles, decreased fertility, decreased ovary weights and associated ovarian atrophy, reduced pup survival and litter size, slight delays in pubertal indices, and histological changes in the liver and thymus (in offspring) at the highest dose tested (3000 ppm). However, the nature of these effects and the close correlation with decreased maternal body weights suggest that these effects were secondary to general toxicity and/or nutritional stress. In another study, male rats exposed to 200 or 600 ppm PGME via inhalation (6 hours/day for 10 days) showed no effects on the testes. For oral exposures, a NOAEL of 1% in drinking water in a two-generation mice reproduction study was reported. Reduced pup weights, and in the second generation reduced adult body weights, and a decrease in epidydimal and prostate weights were observed at the highest dose tested (2% in drinking water). Effects on fertility were seen at relatively high doses in the presence of slight systemic toxicity.
In these study, the most relevant NOAEC was 1000 ppm seen in the 2-generation study based on effects seen on females at 3000 ppm. Based on molecular weight, this concentration is equivalent to approximately 3740 mg/m3.
Short description of key information:
A GLP-study according to OECD guideline 416 is available for propylene glycol methyl ether. This study is supported by a two-generation study in mice and a 10-day inhalation study, both non-GLP.
Justification for selection of Effect on fertility via oral route:
This is the longest duration oral exposure study available
Justification for selection of Effect on fertility via inhalation route:
GLP report according to OECD guideline 415
Justification for selection of Effect on fertility via dermal route:
There are studies available for the oral and the inhalation route
Effects on developmental toxicity
Description of key information
A GLP-study according to OECD guideline 414 is available for propylene glycol methyl ether. This study is supported by several non-GLP studies.
Link to relevant study records
- Endpoint:
- developmental toxicity
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 4 (not assignable)
- Qualifier:
- no guideline followed
- GLP compliance:
- not specified
- Species:
- rat
- Strain:
- other: CFE
- Route of administration:
- other: oral gavage & subcutaneous
- Duration of treatment / exposure:
- days 1-21 of gestation
- Frequency of treatment:
- 1 injection/day
- Remarks:
- Doses / Concentrations:
0, 0.05; 0.1; 0.2; 0.4; 0.8 ml/kg
Basis: - Control animals:
- yes, concurrent vehicle
- Details on study design:
- Sex: female
Duration of test: 21 days - Dose descriptor:
- NOAEL
- Effect level:
- >= 0.8 other: ml/kg bw
- Basis for effect level:
- other: maternal toxicity
- Dose descriptor:
- NOAEL
- Effect level:
- >= 0.8 other: ml/kg bw
- Basis for effect level:
- other: teratogenicity
- Abnormalities:
- not specified
- Developmental effects observed:
- not specified
- Conclusions:
- No teratogenic effects were observed under the conditions of this study. Hence, the NOAEL for maternal toxicity and teratogenicity in rats is greater than 0.8 ml/kg bw.
- Endpoint:
- developmental toxicity
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1983
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP-study equivalent to OECD guideline 414.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 414 (Prenatal Developmental Toxicity Study)
- Principles of method if other than guideline:
- Method: other
- GLP compliance:
- yes
- Limit test:
- no
- Species:
- rabbit
- Strain:
- New Zealand White
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River Breeding Laboratories
- Age at study initiation: adullt females
- Weight at study initiation: 3.5-4.5 kg
- Fasting period before study: not required
- Housing: individually housed in wire-bottomed cages
- Diet (e.g. ad libitum): Certified Laboratory Animal Chow, except during exposure
- Water (e.g. ad libitum): Municipal water except during exposure
- Acclimation period: two weeks prior to breeding
ENVIRONMENTAL CONDITIONS
- Temperature (°C): approximately 22 °C
- Humidity (%): approximately 50%
- Air changes (per hr): not specified in the report
- Photoperiod (hrs dark / hrs light): 12:12 (light:dark cycle) - Route of administration:
- inhalation
- Type of inhalation exposure (if applicable):
- whole body
- Vehicle:
- unchanged (no vehicle)
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Rochester type stainless steel and glass inhalation chambers
- Method of holding animals in test chamber: not specified in the report
- Source and rate of air: filtered air
- Method of conditioning air: not specified in the report
- Temperature, humidity, pressure in air chamber: approximately 21 °C and 50% RH
- Air flow rate: 750 liters/minute
- Air change rate: not specified in the report
- Treatment of exhaust air: not specified in the report
- Vapors were generated by metering the liquid test substance at calculated rates into glass vaporization tubes which were swept into the chamber inlet ducts with compressed air with compressed air where there was further mixing and dilution with incoming air by turbulence. The compressed air was preheated to the minimum extent required for complete vaporization, using a compressed air flameless heat torch. Total chamber airflow was maintained at approximately 750 liters/minute.
TEST ATMOSPHERE
- Brief description of analytical method used: The nominal concentration (ratio of the amount of PGME vaporized to the total amount of air through the chamber) was calculated for each chamber on a daily basis. The actual concentration of PGME in each exposure chamber was measured 1-2 times/hour by infrared spectroscopy using a MIRAN I infrared gas analyser at a wave-length of ~ 3.5 µm.
- Samples taken from breathing zone: not specified in the report - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Target concentrations - 0, 500, 1500 and 3000 ppm
Analytical concentrations - 0, 505 ± 10, 1506 ± 15 and 3009 ± 23 ppm
Refer to Attachment 1 for further details - Details on mating procedure:
- - Impregnation procedure: [artificial insemination]
- If cohoused: not applicable
- Verification of same strain and source of both sexes: [no]
- Proof of pregnancy: the day of artificial insemination referred to as [day 0 ] of pregnancy - Duration of treatment / exposure:
- days 6-18 of gestation
- Frequency of treatment:
- 6 hours/day
- Duration of test:
- 29 days
- Remarks:
- Doses / Concentrations:
0 ppm (nominal)
Basis:
analytical conc.
0 ppm - Remarks:
- Doses / Concentrations:
500 ppm (nominal)
Basis:
analytical conc.
505 ± 10 ppm - Remarks:
- Doses / Concentrations:
1500 ppm (nominal)
Basis:
analytical conc.
1506 ± 15 ppm - Remarks:
- Doses / Concentrations:
3000 ppm (nominal)
Basis:
analytical conc.
3009 ± 23 ppm - No. of animals per sex per dose:
- 31-33 inseminated rabbits
- Control animals:
- yes, concurrent vehicle
- Details on study design:
- Sex: female
Duration of test: 29 days
- Dose selection rationale: Based on range finding (probe) study, refer to HET K-005539-014, listed under reference
- Rationale for animal assignment: Randomization of test animals was done on day 0 of gestation, using computer-generated tables of random numbers - Maternal examinations:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily throughout the experimental period
BODY WEIGHT: Yes
- Time schedule for examinations: gestation days 6, 9, 12, 15, 19 and 29
FOOD CONSUMPTION: No
WATER CONSUMPTION: No
POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 29
- Organs examined: all organs
OTHER: Maternal liver weights were recorded at the time of cesarean section and sections of maternal liver were preserved in 10% formalin but were not evaluated histologically - Ovaries and uterine content:
- The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes - Fetal examinations:
- - External examinations: Yes: [all per litter]
- Soft tissue examinations: Yes: [half per litter]
- Skeletal examinations: Yes: [all per litter]
- Head examinations: No - Statistics:
- Statistical evaluation of the frequency of alterations and of resorptions among litters and the fetal population was made by the modified Wicoxon test. Analysis of the percentage of pregnancy and other incidence data was made by the Fisher exact probability test. The fetal sex ratio was analyzed by a binomial distribution test. Analysis of other data was done by parametric or non-parametric analysis of variance followed by either Dunnett's test or Wilcoxon's rank sum test with a Bonferroni correction, as appropriate. For food and water consumption data, statistical outliers were identified by a sequential outlier test
- Indices:
- Per cent pregnant, preimplantation loss, per cent implantations resorbed, per cent litters with resorptions, per cent dead fetuses, sex ratio
- Historical control data:
- not provided
- Details on maternal toxic effects:
- Maternal toxic effects:yes
Details on maternal toxic effects:
Signs of mild and transient CNS depression (viz. mild lethargy) were observed among approximately half of the maternal rabbits exposed to 3000 ppm of PGME for the first 1-2 days of exposure, with rapid accomodation occurring subsequently. There were six deaths among maternal rabbits during the course of study; one among the control and 500 ppm groups and four among 3000 ppm animals. Of these one death at 3000 ppm was attributed to pneumonia and the cause of death among the remaining 3 animals was not determined. There were no statistically identified difference in body weight and weight gain, absolute and relative liver weight among any of the exposure groups. There were no statistically significant differences in any of the reproductive parameters in any of the PGME exposed rabbits when compared to controls. - Dose descriptor:
- NOAEL
- Effect level:
- 1 500 ppm
- Basis for effect level:
- other: maternal toxicity
- Details on embryotoxic / teratogenic effects:
- Embryotoxic / teratogenic effects:no effects
Details on embryotoxic / teratogenic effects:
The incidence of major malformations observed externally, internally or by skeletal examination, whether considered individually or collectively in each exposure group, was not statistically significantly different from the control incidence. A number of minor malformations were observed among all exposure groups, including controls and the incidence was not statistically significant when compared to controls and there was no consistent pattern indicative of any treatment related effects. - Dose descriptor:
- NOAEL
- Effect level:
- 3 000 ppm
- Basis for effect level:
- other: teratogenicity
- Abnormalities:
- not specified
- Developmental effects observed:
- not specified
- Conclusions:
- Based on the results of the study, the NOAEL for maternal toxicity was 1500 ppm and NOAEL for teratogenicity was 3000 ppm
- Executive summary:
In this study, New Zealand White rabbits were exposed by inhalation to Propylene Glycol Monomethyl Ether (PGME) during pregnancy (GD6 -GD18) at doses of 0, 500, 1500 and 3000 ppm. This test was performed according to a method similar to OECD guideline 414.
Signs of mild and transient CNS depression (viz. mild lethargy) were observed among approximately half of the maternal rabbits exposed to 3000 ppm of PGME for the first 1-2 days of exposure, with rapid accomodation occurring subsequently. There were six deaths among maternal rabbits during the course of study; one among the control and 500 ppm groups and four among 3000 ppm animals. Of these one death at 3000 ppm was attributed to pneumonia and the cause of death among the remaining 3 animals was not determined. There were no statistically identified difference in body weight and weight gain, absolute and relative liver weight among any of the exposure groups. There were no statistically significant differences in any of the reproductive parameters in any of the PGME exposed rabbits when compared to controls.
The incidence of major malformations observed externally, internally or by skeletal examination, whether considered individually or collectively in each exposure group, was not statistically significantly different from the control incidence. A number of minor malformations were observed among all exposure groups, including controls and the incidence was not statistically significant when compared to controls and there was no consistent pattern indicative of any treatment related effects.
Based on the results of the study, the NOAEL for maternal toxicity was 1500 ppm and NOAEL for teratogenicity was 3000 ppm
Referenceopen allclose all
Rat fetus showed a delayed ossification of the skull at the highest dose given. There were no effects on the number of young born.
Table 1: Exposure concentration and chamber
conditions
Table 2: Body weights and Liver weights of
pregnant rabbits
Table 3: Summary of Cesarean Section Data
Table 4: Incidence of fetal alterations
among litters of rabbits
Effect on developmental toxicity: via oral route
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- NOAEL
- 920 mg/kg bw/day
- Species:
- rat
- Quality of whole database:
- acceptable
Effect on developmental toxicity: via inhalation route
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- NOAEC
- 11 058 mg/m³
- Species:
- rabbit
- Quality of whole database:
- Good (Klimisch 1)
Effect on developmental toxicity: via dermal route
- Endpoint conclusion:
- no study available
- Quality of whole database:
- There are studies available via the oral and inhalation routes
Additional information
In all studies, maternal toxicity was found at high doses (mainly CNS depression and decrease food consumption with decrease body weight gain). In fetuses, slight effects were seen: delayed ossification in some studies (sternebral or skull) but always in presence of maternal toxicity. No teratogenic effects were observed at doses up to 3,000 ppm by inhalation route in rats or rabbits, or 1 ml/kg by oral route in rats, mice and rabbits. In the 2-generation studies, foetotoxic effects were seen only concurrently with maternal toxicity (3000 ppm by inhalation in rats (11220 mg/m3) and 2% in drinking water in mice.) These kind of effects (delayed ossification) are often reported concurrently with the maternal effects described in the available studies. Due to the low toxicity of propylene glycol methyl ether and the fact that no specific developmental effects were observed at relatively high doses without maternal toxicity, it can be concluded that developmental toxicity of propylene glycol methyl ether is of no concern.
The NOAEL for developmental toxicity via inhalation is therefore the top dose of 3000ppm, equivalent to 11058 mg/m3. Via the oral route, the NOAEL is 1 ml/kg bw, equivalent to approximately 920 mg/kg bw.
Justification for selection of Effect on developmental toxicity: via oral route:
Only studies available for the oral route
Justification for selection of Effect on developmental toxicity: via inhalation route:
GLP-study equivalent to OECD guideline 414.
Justification for classification or non-classification
No effects on fertility or specific developmental effects were observed with propylene glycol methyl ether in the absence of maternal toxicity. As such, this substance does not meet the criteria for classification for reproductive or developmental toxicity,
Additional information
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