Ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no study available

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

The mouse has a pharmacokinetically distinct profile as compared to the rat and monkey. Therefore, the mouse is not the appropriate or preferred test species for human risk assessment with this substance. The substance, in deionized water, was administered orally by gavage to Crl:CD1(ICR) mice, at doses of 0.1, 0.5, and 5 mg/kg/day. There were no effects on reproduction (mating, fertility, or copulation indices, number of days between pairing and coitus, and gestation length). Test substance-related higher mean body weights, body weight gains, and food consumption were observed in the 5 mg/kg/day , but were not considered adverse. Increased liver weights and microscopic hepatocellular hypertrophy, consistent with peroxisome proliferation, were present in male and female F0 adults administered 0.5 or 5 mg/kg/day. Single cell necrosis of hepatocytes was also present in male mice in the 0.5 mg/kg/day dose group and in the males and females of the 5 mg/kg/day dose group. All other test substance-related microscopic changes in the livers of F0 male and female mice occurred at the 5 mg/kg/day dose level and included increased mitotic figures, lipofuscin pigment, and focal necrosis (females only). Microscopic renal tubular cell hypertrophy was present in F0 males given 0.5 and 5 mg/kg/day. An increase in mean absolute kidney weight was also present in body sexes given 5 mg/kg/day. No test substance-related effects were noted on postnatal survival. Lower mean offspring body weights and body weight gains were noted in the F1 males and females in the 5 mg/kg/day group during the pre-weaning period. Evaluation of the plasma levels of the test substance in dams and their offspring indicate that in mice, in utero exposure of fetuses to the test substance results in plasma concentrations that are less than those of the orally dosed dam, and that little or no exposure to nursing pups occurs during lactation. Also, the plasma kinetics of the test substance in juvenile mice directly dosed beginning at weaning appeared to be equivalent to those of adult mice. Based on these results, the no-observed-adverse-effect level (NOAEL) for reproductive toxicity was 5 mg/kg/day, as no effects on reproduction were observed at any of the doses levels tested. The NOAEL for systemic toxicity in F0 male mice was 0.1 mg/kg/day based on the low incidences of single cell necrosis observed in the liver at 0.5 mg/kg/day. The NOAEL for systemic toxicity in both maternal animals and their offspring was 0.5 mg/kg/day. In maternal animals, this NOAEL was based on microscopic changes in the liver at 5 mg/kg/day. In the offspring, the NOAEL was based on body weight decrements in the F1 males and females in the 5 mg/kg/day group during the pre-weaning period. However, as discussed previously, the mouse has a pharmacokinetically distinct profile as compared to the rat and monkey. Therefore, the mouse is not the appropriate test species for human risk assessment with this test substance.

Effects on developmental toxicity

Description of key information

Oral: NOAEL; OECD 414, rat. NOAEL for developmental toxicity was 10 mg/kg/day based on early deliveries and lower mean fetal weights at 100 mg/kg/day and higher. Reliability = 1.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study was selected as the key study because the information provided for the hazard endpoint is sufficient for the purpose of classification and labeling and/or risk assessment.

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

Remarks:

The study was conducted according to the guideline in effect at the time of study conduct.

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)

Deviations:

no

Remarks:

The study was conducted according to the guideline in effect at the time of study conduct.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crl:CD(SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: approximately 12 weeks
- Weight at study initiation: 228 g to 285 g
- Housing: individually housed (except during mating) in solid bottom cages (plastic maternity cages) containing ground corncob nesting material
- Diet: PMI Nutrition International, LLC Certified Rodent LabDiet® 5002, ad libitum
- Water: Reverse osmosis-purified (on-site), ad libitum
- Acclimation period: 14 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.3°C to 22.0°C)
- Humidity (%): 43.5% to 51.1%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
GAVAGE
- Solvent Used: deionized water
- Preparation frequency and procedure: A 150 mg/mL stock solution of the test substance was prepared weekly for use in preparing the test substance dosing formulations. The stock solution was stirred during preparation and overnight in the refrigerator.
The test substance formulations were prepared approximately weekly as dilutions of the stock solution as single formulations for each dosage level, divided into aliquots for daily dispensation, and stored refrigerated, stirring overnight in the refrigerator. The test substance formulations were stirred continuously throughout the preparation, sampling, and dose administration procedures.
The first dosing formulations were visually inspected by the study director’s designee and were found to be visibly homogeneous and acceptable for
administration.
- Adjusted for purity: yes

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

Stability and resuspension homogeneity were established in a previous study. Test substance formulations were stable following 12 days of refrigerated (2-8°C) storage at concentrations of 0.01 and 100 mg/mL and were homogeneous after resuspension following 12 days of refrigerated storage (2-8°C). Therefore, stability and resuspension homogeneity analyses were not conducted in this study.

Prior to the initiation of dose administration, samples for homogeneity determination were collected from the top, middle, and bottom strata of the 1 and 100 mg/mL dosing formulations; the middle stratum of these formulations were used for concentration determination. Samples were also collected from the middle stratum of the 10 mg/mL formulation and the vehicle control for concentration analyses prior to the initiation of dose administration. Samples for concentration analyses were collected from the middle stratum of each dosing formulation (including the vehicle formulation administered to the control group) from the formulations prepared for the last week of dose administration. The analyzed dosing formulations were within the SOP range for suspensions (85% to 115%) and were homogeneous. Based on these results, the protocol-specified dosages of test article were administered to the animals. The test article was not detected in the vehicle formulation that was administered to the control group

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: following positive evidence of mating
- Proof of pregnancy: the presence of a vaginal copulatory plug or the presence of sperm in a vaginal lavage was evidence of mating, that day was considered Gestation Day 0

Duration of treatment / exposure:

Gestation Days 6 to 20

Frequency of treatment:

Daily

Duration of test:

21 days

No. of animals per sex per dose:

22 females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dosage levels were selected based on the results of previous studies and were provided by the Sponsor after consultation with the Study Director.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: recorded on gestation days 0 and 6-21 (daily)

FOOD CONSUMPTION: Yes
- Food consumption for each animal determined: recorded on gestation days 0 and 6-21 (daily).

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21
- Organs examined: thoracic, abdominal, and pelvic cavities were opened and the contents (uterus, ovaries, kidneys and liver) were examined.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- 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: all per litter
- Skeletal examinations: Yes: all per litter
- Head examinations: Yes: all per litter

Statistics:

see Materials and Methods below

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Original Study:

One female in the 1000 mg/kg/day was found dead on gestation day 20. This female had lower mean body weight gains and/or food consumption compared to the control group during gestation days 12-18. The test substance-related liver and kidney changes (moderate coagulative necrosis in the liver and fibrin thrombi in the glomerular capillaries) noted microscopically were considered the cause of death in this animal. Four and 9 females in the 100 and 1000 mg/kg/day groups, respectively, delivered early on gestation day 21. The mortality in the 1000 mg/kg/day group and early deliveries in the 100 and 1000 mg/kg/day groups were considered test substance-related. All other females survived to the scheduled laparohysterectomy.

Test substance-related clinical findings were noted in the 1000 mg/kg/day group and consisted of yellow material on various body surfaces and salivation or evidence thereof (clear material around the mouth). No test substance-related clinical findings were observed in the 10 and 100 mg/kg/day groups.

A transient mean body weight loss was observed in the 1000 mg/kg/day following administration of the first dose (gestation days 6-7), resulting in a lower mean body weight gain during gestation days 6-9. Correspondingly lower mean food consumption was also observed in the 1000 mg/kg/day group. The lower mean body weight gain early in gestation was considered test substance-related. Mean body weight gain was also lower in this group during gestation days 18-21 and when the entire treatment period (gestation days 6-21) was evaluated. The lower mean body weight gain late in gestation in this group as well as a lower mean gravid uterine weight and lower mean body weight on gestation day 21 (8.4% lower than the control group) was attributed to the test substance-related lower mean fetal body weights observed at 1000 mg/kg/day, supported by the lack of effect on mean net body weight and net body weight gain. Mean body weights, body weight gains, net body weights, net body weight gains, gravid uterine weights, and food consumption in the 10 and 100 mg/kg/day groups were similar to the control group, with the following exception. A lower mean gravid uterine weight was noted in the 100 mg/kg/day group and was attributed to the lower mean fetal weights observed in this group.

An edematous pancreas was noted in 2 females that delivered early in the 1000 mg/kg/day group at necropsy; the relationship of this finding to the test substance is uncertain. Other macroscopic findings occurred in single females and/or are not uncommon in females that deliver. Higher mean liver weights were noted in the 100 and 1000 mg/kg/day group females, and higher mean kidney weight was observed in the 1000 mg/kg/day group. There were no microscopic correlates to the higher mean kidney weight. Focal necrosis of the liver was noted in some females in the 100 and 1000 mg/kg/day groups in a dose-related manner. In addition, test substance-related hepatocellular hypertrophy was noted at 1000 mg/kg/day; hypertrophy was morphologically consistent with a PPARα agonist.

Follow-Up Study:

There was a dose-related increase in the number of dams found delivered in their cages on the morning of GD 21. There were 0 and 3 dams found delivered at 0 and 1000 mg/kg/day, respectively. Mean foetal weight, mean net maternal weight, and mean maternal food consumption was lower than controls at 1000 mg/kg/day. There was a test substance-related increased in the incidence of wet fur at 1000 mg/kg/day. Mean maternal kidney and liver weights were increased, and microscopic changes in the liver at 1000 mg/kg included increased hepatocellular hypertrophy and focal coagulative necrosis.

Dose descriptor:

NOAEL

Effect level:

10 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
Mean fetal weights were 8.8% and 28.1% lower in the 100 and 1000 mg/kg/day groups, respectively. No test substance-related effects on mean fetal weight were noted in the 10 mg/kg/day group. Intrauterine survival was not affected by test substance administration at any dosage level.

There were no test substance-related fetal malformations. A higher mean litter proportion of 14th rudimentary ribs was observed in the 1000 mg/kg/day group, resulting in a higher mean litter proportion of total skeletal variations and total developmental variations. Although considered test substance-related, the increase in the number of fetuses with this finding was not considered adverse because it has been suggested that 14th rudimentary ribs are resorbed during postnatal development. No test substance-related developmental variations were observed in the 10 and 100 mg/kg/day groups.

Dose descriptor:

NOAEL

Effect level:

10 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: The no-observed-adverse-effect level (NOAEL) for developmental toxicity was considered to be 10 mg/kg/day based on early deliveries and lower mean fetal weights at 100 and 1000 mg/kg/day.

Abnormalities:

not specified

Developmental effects observed:

not specified

Conclusions:

This study and the conclusions which are drawn from it fulfill the quality criteria (validity, reliability, repeatability).
NOAEL maternal toxicity = 10 mg/kg/bw
NOAEL developmental toxicity = 10 mg/kg/bw

Executive summary:

The objective of the study was to determine the potential of the test substance to induce developmental toxicity after maternal exposure during the critical period of organogenesis, to characterize maternal toxicity at the exposure levels tested, and to determine a no-observed-adverse-effect level (NOAEL) for maternal and developmental toxicity. to 3 groups of 22 bred female Crl:CD(SD) rats once daily from gestation day 6 through 20. Dosage levels were 10, 100, and 1000 mg/kg/day. A concurrent control group of 22 bred females received the vehicle (deionized water) on a comparable regimen.The no-observed-adverse-effect level (NOAEL) for maternal and developmental toxicity was considered to be 10 mg/kg/day based on mortality and lower mean body weight gains and food consumption at 1000 mg/kg/day and early deliveries, microscopic findings in the liver (focal necrosis), and lower mean fetal weights at 100 and 1000 mg/kg/day. At 1000 mg/kg/day, there were additional test substance-related effects that were not considered adverse and consisted of higher kidney and liver weights and hepatocellular hypertrophy. To verify the findings of an apparent dose-related increase in dams that delivered litters just prior to scheduled euthanasia and caesarean section on gestation day 21, a study was conducted using the same experimental design, but was limited to a control group and a group dosed at 1000 mg/kg/day. Under the conditions of the follow-up study, test substance-related findings were observed that were consistent with and confirmed the findings of the original study. Findings included reductions in maternal body weight and food consumption, increased early deliveries, reduced foetal weight, increased maternal liver and kidney weight, microscopic hepatocellular hypertrophy and focal necrosis in the liver. These findings were consistent with those of the original study with the test material at this same dose level.

Effect on developmental toxicity: via oral route

Dose descriptor:

NOAEL

10 mg/kg bw/day

Species:

rat

Additional information

Female Crl:CD(SD) rats were exposed to the test substance via gavage once daily from gestation day 6 through 20 at doses of 10, 100, and 1000 mg/kg/day . The no-observed-adverse-effect level (NOAEL) for maternal and developmental toxicity was considered to be 10 mg/kg/day based on mortality and lower mean body weight gains and food consumption at 1000 mg/kg/day and early deliveries, microscopic findings in the liver (focal necrosis), and lower mean fetal weights at 100 and 1000 mg/kg/day. At 1000 mg/kg/day, there were additional test substance-related effects that were not considered adverse and consisted of higher kidney and liver weights and hepatocellular hypertrophy.

Justification for selection of Effect on developmental toxicity: via oral route:
OECD Guideline, GLP study

Justification for classification or non-classification

The substance has been evaluated in a battery of acute, repeated-dose, and genotoxicity studies. The test substance has low acute toxicity in laboratory animals, and the results of a battery of in vitro and in vivo genotoxicity studies demonstrate that the substance is not genotoxic. The sentinel effects in these studies, liver toxicity, was consistent with the known effects of PPAR_α agonists on the rodent liver. Effects on offspring were mostly limited to body weight decrements at maternally toxic doses. Therefore, the substance was not uniquely toxic to the offspring. The substance was not embryolethal or teratogenic in rats and produced no effects on fertility or prenatal development in mice at any of the doses tested, including the maternally toxic doses. In addition, no target organ weight or pathological changes were produced in reproductive or endocrine organs of rats or mice in repeated dose oral studies. Based on these considerations, the substance does not need to be classified for reproductive/developmental toxicity according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008. Detailed justification for non classification is provided in the following paragraphs.

Based on the results of biochemical studies (liver β-oxidation) as well as microscopic changes observed in the liver of rodents, the substance is a member of a diverse class of compounds known as peroxisome proliferators. Compounds in this class activate peroxisome proliferator alpha (PPARα). PPARα is a nuclear receptor involved in lipid homeostasis, as well as other physiologic processes. In rodents, peroxisome proliferators characteristically produce effects in the liver including hepatocellular hypertrophy and cell proliferation, as well as liver cell injury. It is well established that compounds in this class produce liver toxicity in rodents and that humans are relative non-responders to these liver effects (Cunningham et al., 2010). As with other peroxisome proliferators, the most sensitive target organ effects following exposure to the substance in rodents occur in the liver and include increased liver weight, microscopic hepatocellular hypertrophy, and liver necrosis. 

Developmental and Reproductive Toxicity Studies with the substance

The developmental and reproductive toxicity of the substance has been evaluated in a developmental toxicity study in rats (OECD Guideline 414; OPPTS Guideline 870.3700) and a modified one-generation reproduction toxicity study in mice (OECD Guideline 421; U.S. EPA OPPTS Guideline 870.3550). Consistent with previous toxicity studies with this material, liver toxicity, including liver necrosis was the sentinel effect observed in maternal animals in these studies, with effects on offspring occurring only at maternally toxic doses. Pathological evaluation of reproductive and endocrine organs has also been conducted as part of the 90-day oral studies in rats and mice (DuPont-17751-1026; DuPont-18405-1307). Dose levels in these studies were the same as those used in the respective developmental and one-generation reproductive studies in rats and mice. No test substance-related effects on organ weights or histopathology of endocrine or reproductive organs were observed at any of the doses tested. The result of the developmental and reproductive toxicity studies with the substance are discussed in more detail below.

Developmental Toxicity Study in Rats

In a developmental toxicity study in rats, the substance in deionized water was administered orally by gavage to 3 groups of 22 bred female Crl:CD(SD) rats once daily from gestation day 6 through 20. Dosage levels were 0, 10, 100, and 1000 mg/kg/day. The dosing protocol and end points evaluated were in accordance with OECD Guideline 414 and OPPTS Guideline 870.3700.

Maternal toxicity was present in the 100 and 1000 mg/kg/day dose groups. At 1000 mg/kg/day, test substance-related death occurred in one dam. Test substance-related mortality was also seen in 3 of 20 female rats after 8 - 37 days of treatment with 1000 mg/kg/day in a previous 90-day study with the substance (DuPont-17751-1026), indicating that 1000 mg/kg/day represents an excessively toxic dose level in female rats. In the current developmental toxicity study, liver changes including increased liver weights (34% above control), microscopic hepatocellular hypertrophy (in 19/22 dams) and focal liver necrosis (in 5/22 dams) were also observed in dams at this dose level of 1000 mg/kg/day. Increased liver weight (12.1% above control) and focal liver necrosis (in 2/22 dams) were also present in dams in the 100 mg/kg/day group. The liver changes observed in dams in the 100 and 1000 mg/kg/day dose groups were consistent with the known PPAR_α activity of the test material and were similar to those seen in the previous 90-day study in rats with the substance. Although clinical chemistry parameters were not evaluated in this study, in the previous 90-day study, changes in some serum lipid and protein parameters (decreased cholesterol and globulin) that are also consistent with a PPAR_α agonist were observed at 100 and/or 1000 mg/kg/day. 

Four of 22 pregnant females in the 100 mg/kg/day group and 9 of 21 females in the 1000 mg/kg/day group delivered early in the morning on gestation day 21. When allowed to deliver naturally, Sprague-Dawley rats normally deliver on gestation day 22 but may range from day 21-23 post coitus (Holsen et al., 2006). The historical mean gestation length in rats (from reproduction studies where natural delivery is allowed to occur) for the conducting laboratory is 21.9 days (n = 97 studies) with a range of 21.5 to 22.3 days. Therefore, the early morning deliveries (prior to scheduled Caesarian section on day 21) in some animals in the 100 and 1000 mg/kg/day groups were considered to be a test substance-related effect manifest as delivery a few hours prior to the more typical delivery time. The significance of this finding is uncertain, as parturition in dams delivering early was otherwise normal, all their offspring were delivered alive, and there was no evidence of increased resorptions compared to those dams sacrificed at the scheduled Caesarian section. Also, while mean fetal weights in the 1000 mg/kg/day group were decreased relative to controls (discussed below), the body weights of fetuses that were delivered early were not different from those of offspring at this same dose level that were delivered by scheduled Caesarian section. The timing of parturition in rats–unlike humans–is luteal-dependant, with progesterone withdrawal as an important initiator. In humans, the best evidence suggests maternal serum progesterone does not play a dominant role in human parturition, and that parturition in humans has significantly different regulators and mediators than rats (Mitchell and Taggert, 2009). Therefore, the slight effects (in hours) on the timing of parturition in rats at these high dose levels is unlikely to be of relevance to humans.  

The maternal toxicity noted at 1000 mg/kg/day was associated with decreases in fetal weight (approximately 28% below controls). Fetal weights were also slightly decreased (8.8%) in the 100 mg/kg/day group. The only fetal malformations observed in the study occurred in 2 fetuses from 2 different litters in the 10 mg/kg/day group, and no malformations were observed in the other groups, including the 1000 mg/kg/day group. A higher mean litter proportion of the skeletal variation, 14th rudimentary rib, was observed in the 1000 mg/kg/day group, but this finding was not considered adverse, as 14th rudimentary ribs are resorbed during postnatal development (Holson et al, 2006; Wickramaratne, 1988). No test substance-related developmental variations were observed in the 10 and 100 mg/kg/day groups.

The conclusions drawn from this OECD 414 developmental toxicity study are that the top dose of 1000 mg/kg/day was extremely toxic to the dams, and included lethality and liver toxicity. The mid-dose of 100 mg/kg/day also produced maternal toxicity based on low incidences of liver necrosis. Despite this maternal toxicity, the only developmental toxicity observed was a small decrease in gestation length, but with no evidence of embryolethality or malformations in the embryos. Changes at 100 mg/kg/day were limited to a very slight decrease (less than 10%) in fetal body weight. 

 

Oral (Gavage) Reproduction/Developmental Toxicity Screening Study with the substance in Mice

A modified one-generation reproduction toxicity study was conducted in mice with the test substance (DuPont-18405-1037), but at lower dose levels compared to those used in studies with rats. In mice, as in rats, the most sensitive target organ toxicity following administration of the test substance occurs in the liver, with changes typical of a PPAR_α agonist. However,both male and female mice show greater sensitivity to these effects compared with the rat. Thus, in a 28-day oral study, changes in female mice given 30 mg/kg/day included increased liver weight (to double the control group mean); 2- to 3-fold elevations in some liver enzymes; microscopic hepatocellular hypertrophy and single cell liver necrosis; and a 9-fold elevation in hepatic β-oxidation activity–an indicator of PPAR_α activation. Less severe liver changes (a 34% increase in liver weight, minimal to mild hepatocellular hypertrophy, and a 6-fold elevation in hepatic β –oxidation) were noted in females in the 3 mg/kg/day dose group, and no effects were observed at 0.1 mg/kg/day. In contrast, no liver effects were produced in female rats administered 30 mg/kg/day for 28-days. These differences between rats and mice are likely due in large part to pharmacokinetic differences between the species. The elimination half-life of the substance is approximately 10 hours in female mice compared to about 1 hour in female rats, and plasma levels in mice following repeated dosing are approximately 10-fold higher compared with rats. In this regard, rats are more kinetically similar to primates (half-life in female monkeys about 2 hours).

In the modified one-generation reproduction toxicity study in mice (DuPont-18405-1037), the substance in deionized water was administered orally by gavage to groups of 25 male and female Crl:CD1(ICR) mice at dosage levels of 0, 0.1, 0.5, and 5 mg/kg/day. The study was conducted in accordance with OECD Guideline 421 and U.S. EPA OPPTS Guideline 870.3550, but also included a number of enhancements that provided a more comprehensive assessment of fertility and developmental endpoints. These included the following: 

• Parental males were dosed for 10 weeks prior to mating and thus were dosed throughout an entire cycle of the seminiferous epithelium.


• Parental females, in addition to being dosed for 2-weeks before mating and during gestation, were dosed through lactation to assess potential lactational effects.


• To assess effects in juvenile offspring, 1 male and 1 female F₁generation pup/litter were selected at weaning and were directly dosed from post natal day (PND) 21 to PND 40.


• The F₁ generation males and females were evaluated for clinical observations, gross findings, body weights, and food consumption, as well as indicators of sexual development (balanopreputial separation and vaginal patency).

No test substance-related effects were observed on F₀ reproductive performance (mating, fertility, or copulation indices, and mean days between pairing and coitus), mean gestation length, the process of parturition, mean numbers of implantation sites, or unaccounted-for sites. In addition, there were no effects on the anatomic pathology of reproductive organs at any of the dose levels tested. In dams, systemic toxicity was observed at 5 mg/kg/day (at 0.5 and 5 mg/kg/day in males) and was primarily associated with liver effects. Liver weights in the 5 mg/kg/day female group were markedly increased (up to 2-fold compared to controls in dams), and microscopic changes in the liver at this dose level included hepatocellular hypertrophy (in all dams), single cell liver necrosis (in 21/24 dams) and focal coagulative necrosis (in 5/24 dams). Similar changes were present in males at 0.5 and 5 mg/kg/day. As noted previously, similar liver effects were produced in 28-day, as well as 90-day, studies in mice with the substance (DuPont-18405-1307). In those studies, liver toxicity was further confirmed by increases in liver-related clinical chemistry parameters including alanine amino transferase, sorbitol dehydrogenase, and alkaline phosphatase. These liver changes are consistent with those observed in rodents with other peroxisome proliferators, and as noted previously, are of questionable relevance to humans.

In F₁ offspring, the mean numbers of pups born, live litter size, percentage of males at birth, postnatal survival, the general physical condition, and post weaning survival were unaffected by test substance administration at all dosage levels. Effects on offspring occurred only at the high dose (5 mg/kg/day) which also produced maternal toxicity. There were no effects on pup body weights at birth, but lower mean body weights and body weight gains were observed in F₁ males and females in the 5 mg/kg/day group during the pre-weaning period. This resulted in slight delays (within laboratory historical control range) in the attainment of balanopreputial separation and vaginal patency of 2.6 days and 3.4 days respectively, at which time the body weight of treated pups were similar to those of controls at attainment (no statistically significant differences in body weight at attainment). Therefore, these delays were attributed to the effects on mean body weight observed in this group during the pre-weaning period and were not considered to be a direct effect of test substance administration (Carney et al., 2004; Ashby and Lefevre, 2000).

The no-observed-adverse-effect level (NOAEL) for effects on fertility was greater than 5 mg/kg/day, the highest dose tested, as no effects on reproduction were observed at any of the doses levels tested. The NOAEL for systemic toxicity was 0.5 mg/kg/day in dams (0.1 mg/kg/day in males) based on liver toxicity at higher doses. No embryolethality, malformation, or effects on offspring survival were observed at any dose levels tested. Primary effects on offspring were limited to decreased body weight gain during the preweaning period and a small and not biologically significant delay in sexual maturation of the pups at the maternally toxic dose of 5 mg/kg/day. Thus the NOAEL for offspring was also 0.5 mg/kg/day. 

Conclusions

The substance has been evaluated in a developmental toxicity study in rats and an enhanced one-generation reproduction study in mice. The sentinel effects in these studies, liver toxicity, was consistent with the known effects of PPAR_α agonists on the rodent liver. The publications identified since the last update (Blake et al. 2020; Conley et al. 2019, Conley et al. 2021 and Cope et al. 2021) do not change this interpretation. The data presented by Chappel et al. (2020) (reported in the additional toxicological information section) compellingly and conclusively show that the only molecular signals observed following dosing with HFPO-DA were PPAR_α, a mode of action that has limited relevance to humans. In fully OECD test guideline, GLP-compliant studies, effects on offspring were mostly limited to body weight decrements at maternally toxic doses. Therefore, the substance was not uniquely toxic to the offspring. The substance was not embryolethal or teratogenic in rats and produced no effects on fertility or prenatal development in mice at any of the doses tested, including the maternally toxic doses. In addition, no target organ weight or pathological changes were produced in reproductive or endocrine organs of rats or mice in repeated dose oral studies. Based on these considerations, the substance does not need to be classified for reproductive/developmental toxicity according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.

 

References

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Carney, E.W.; Zablotny, T.L.; Marty, M.S.; Crissman, J.W.; Anderson, P.; Woolhiser, M.; Holsapple, M. The effects of feed restriction during in utero and postnatal development in rats. Toxicological Sciences2004,82, 237-249.

Cunningham, M.L., Collins, B.J., Hejtmancik, M.R., Herbert, R.A., Travlos, G.S., Vallant, M.K., Stout, M.D. Effects of the PPARα agonist and widely used antihyperlipidemic drug gemfibrozil on hepatic toxicity and lipid metabolism. 2010, PPAR Research, Volume 2010, Article ID 681963

DuPont-17751-1026. A 90-day oral (gavage) toxicity study of H-28548 in rats with a

28-day recovery.2009, Unpublished data.

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