Linalool

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

In a reproductive and developmental toxicity screening test similar to OECD guideline 421, coriander oil containing 72.9% linalool was tested. Females were treated with 0, 250, 500, and 1000 mg coriander oil/kg bw/d. The LOEL was 829 mg linalool/kg bw/d. The NOAELs of 365 mg linalool /kg bw/d are based on reduced body weight and food consumption, reduced delivered litter sizes and increased pup mortality when compared to controls. Effects on pups are likely related to maternal toxicity. There was no evidence on adverse effects on female fertility

 

Effects of the test substance was furthermore assessed using a read-across approach from the supporting substance dehydrolinalool (structural analogue or surrogate). In a screening study for reproductive/developmental toxicity according to OECD guideline 421, several and significant effects of dehydrolinalool were seen in females and offspring (abnormalities of the urinary system, reduced pup live birth index and pup viability) at the highest dose group of 750 mg/kg/day. For males, no effects were seen up to the highest dose level. The NOAEL for females and offspring was set at 200 mg/kg/day, for males the NOAEL was established as 750 mg/kg bw/day.

Link to relevant study records

Reference

Reference 1

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

21 June 1988 - 4 December 1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

Study was conducted according to an equivalent of OECD guideline 421 and under GLP conditions.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)

Deviations:

yes

Remarks:

only females were dosed

Principles of method if other than guideline:

Study was conducted according to an equivalent of OECD guideline 421, only females were dosed.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crl:CD (SD)BR

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Portage, Michigan
- Age at study initiation: (P) 10 wks
- Weight at study initiation: (P) Females: 187-232 g
- Housing: Individually
- Diet: Ad libitum, Certified Rodent Chow
- Water: Ad libitum, filtered local water (chlorine added)
- Acclimation period: one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-25
- Humidity (%): 35-65
- Air changes (per hr): min. 10
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Test article dissolved in corn oil at concentrations of 0, 50, 100 and 200 mg/mL.

DIET PREPARATION
- Rate of preparation of diet: Weekly

VEHICLE
- Concentration in vehicle: 0, 50, 100 and 200 mg/mL
- Amount of vehicle: 5 mL/kg, adjusted daily on the basis of individual body weights
- Lot/batch no.: APR0789B, APR1489A and 80299

Details on mating procedure:

- M/F ratio per cage: 1/1
- Length of cohabitation: max. 7 days
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
- After successful mating each pregnant female was caged (how): Individually

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

Study summaried in record "Developmental toxicity / teratogenicity_TIF00009_2006_KEY_rat" shows that linalool is stable in corn oil

Duration of treatment / exposure:

7 days prior to cohabitation.
After cohabitation until day 4 of lactation or day 25 of presumed gestation.

Frequency of treatment:

Once daily

Details on study schedule:

Not relevant

Dose / conc.:

829 mg/kg bw/day (actual dose received)

Remarks:

Equivalent to 1000 mg coriander oil/kg bw/day

Dose / conc.:

365 mg/kg bw/day (actual dose received)

Remarks:

Equivalent to 500 mg coriander oil/kg bw/day

Dose / conc.:

183 mg/kg bw/day (actual dose received)

Remarks:

Equivalent to 250 mg coriander oil/kg bw/day

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Based on toxicity studies that were conducted earlier

Positive control:

Not necessary

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily
- Cage side observations checked: Viability

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Two times during acclimation period and daily during dosage period

BODY WEIGHT: Yes
- Time schedule for examinations: Daily during dosage period

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

Oestrous cyclicity (parental animals):

Not performed

Sperm parameters (parental animals):

Not relevant, males were not dosed

Litter observations:

STANDARDISATION OF LITTERS
Not relevant, termination of study on day 4 postpartum

PARAMETERS EXAMINED
The following parameters were examined in F1 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; possible cause of death was determined for pups born or found dead.

Postmortem examinations (parental animals):

SACRIFICE
- Maternal animals: All surviving animals on day 4 or 5 of lactation. Dams that did not deliver litter on day 25 of presumed gestation, were sacrificed that day.

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations including gross lesions and placement of implantation sites.

HISTOPATHOLOGY
Tissues of dams (gross lesions, ovaries) were preserved for possible future evaluation.

Postmortem examinations (offspring):

SACRIFICE
No data

GROSS NECROPSY
- Pups that died were subjected to postmortem examinations and examined for the cause of death.
- Gross necropsy consisted of external examination for gross lesions.

HISTOPATHOLOGY / ORGAN WEIGTHS
Tissue of litter (gross lesions) were preserved for possible future evaluation.

Statistics:

Parametric
- Bartlett's test: For homogeneity of variance
- Dunnett's test
- Covariance analysis T-test
Nonparametric
- Kruskal-Wallis
- Dunn's test
- Fisher's Exact Test
Test for proportion data
- Variance test for homogeneity of the binomial distribution

Reproductive indices:

Pregnant rats/rats mated

Offspring viability indices:

Pups surviving 4 days/liveborn pups

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:

not examined

Histopathological findings: non-neoplastic:

not examined

Reproductive function: oestrous cycle:

not examined

Reproductive performance:

no effects observed

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
Excess in salivation was noted at all dose groups being significant for middle and high dosage group. Significant number of rats in the 1000 mg/kg/day group had urine-stained abdominal fur during premating period and 1-2 rats in this group showed ataxia and/or decreased motor activity infrequently during the premating and/or gestation periods. However, excess salivation was not considered to be evidence for strong toxicity and was therefore considered as non-adverse.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Biologically remarkable decreases in body weight gain and feed consumption occurred for the 1000 mg/kg/day dosage group rats during premating (significant after first dosage). During gestation, biologically remarkable increase in weight and feed consumption occurred for each group given the test article. Statistically significant increases in body weight gain occurred for the low and high dosage group rats and statistically significant increases in absolute and relative feed consumption values occurred for each group given the test article. These effects decreased in severity during lactation.

Dose descriptor:

NOAEL

Effect level:

500 mg/kg bw/day (actual dose received)

Sex:

female

Basis for effect level:

other: decreased food consumption, body weight

Key result

Dose descriptor:

NOAEL

Remarks:

linalool

Effect level:

365 mg/kg bw/day (actual dose received)

Sex:

female

Basis for effect level:

other: decreased food consumption, body weight

Clinical signs:

no effects observed

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

VIABILITY (OFFSPRING)
Pup mortality was significantly increased for litters of dams given 1000 mg/kg/day corianders oil. When comparing implantation averages to delivered litter size in the 1000 mg/kg/day, the litter size was more decreased as compared to other groups. This indicates more resorptions in the high dosage group.

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

500 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: decreased litter size; increased pup mortality

Key result

Dose descriptor:

NOAEL

Remarks:

linalool

Generation:

F1

Effect level:

365 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: decreased litter size; increased pup mortality

Key result

Reproductive effects observed:

not specified

Not relevant

Conclusions:

The maternal NOEL for coriander oil (containing 72.9% linalool) was below 250 mg/kg/day, based on clinical signs, such as salivation and altered body weight gains and feed consumption. These changes were not considered to be evidence for strong toxicity, hence the NOAEL was set higher at 500 mg/kg/day. The highest-dosage (1000 mg/kg/day) group had reduced delivered litter sizes, indicating in utero deaths, and siginifcant incidences of pup mortality in the first four days postpartum. No adverse effects regarding mating, fertility or duration of gestation or parturition occurred in any treatment group including the high-dose at 1000 mg/kg/day. Clear adverse effects on reproductive performance and pup development occurred at 1000 mg/kg/day, that also resulted in significant maternal clinical signs, significant inhibition of average maternal weight gain before mating and significant increases in maternal weight gain and feed consumption during gestation. In the absence of significant toxicity to the dams, B10 did not affect the reproductive performance or the developmental parameters of pups. The effects observed on reproduction and development are not, therefore, uniquely reprotoxic or developmentally toxic effects but general toxic effects.

The maternal and developmental NOAELs were established to be 500 mg/kg/day. This corresponds with a NOAEL of 365 mg linalool/kg bw/day. It can be concluded that linalool does not need to be classified as toxic to reproduction based on the criteria outlined in Annex I of Regulation (EC) No.1272/2008.

Executive summary:

A reproductive and developmental toxicity screening test (similar to OECD 421) was performed. Female rats were orally (gavage) administered 0, 250, 500 and 1000 mg/kg/day of coriander oil (containing 72.9% linalool). Males were excluded from the test system. Females were dosed throughout the 7-day premating period, mating, gestation and lactation (post-natal day 4). The rats were observed for clinical signs, weight, feed consumption and were necropsied and examined for gross lesions. Litter (F1) were examined for number, viability, weight, sex ratio and external morphology of the pups. Delivered pups were additionally examined for viability, clinical signs and body weight during a 4-day postparturition period.

Excess in salivation was noted in all groups being significant for middle and high dosage group. A significant number of rats in the 1000 mg/kg/day group had urine-stained abdominal fur during premating period and 1-2 rats in this group showed ataxia and/or decreased motor activity infrequently during the premating and/or gestation periods.

Biologically remarkable decreases in body weight gain and feed consumption occurred for the 1000 mg/kg/day dosage group rats during premating (significant after first dosage). During gestation, biologically remarkable increase in weight and feed consumption occurred for each group given the test article. Statistically significant increases in body weight gain occurred for the low and high dosage group rats and statistically significant increases in absolute and relative feed consumption values occurred for each group given the test article. These effects decreased in severity during lactation.

No adverse effects on mating, fertility or the durations of gestation or parturition occurred for female rats given dosages of linalool as high as 1000 mg/kg/day.

Pup mortality was significantly increased for litters of dams given 1000 mg/kg/day linalool. When comparing implantation averages to delivered litter size in the 1000 mg/kg/day, the litter size was more decreased as compared to other groups. This indicates more resorptions in the high dosage group.

The maternal NOEL for coriander oil was below 250 mg/kg/day, based on clinical signs, such as salivation and altered body weight gains and feed consumption. These changes were not considered to be evidence for strong toxicity, hence the NOAEL was set higher at 500 mg/kg/day. The highest-dosage (1000 mg/kg/day) group had reduced delivered litter sizes, indicating in utero deaths, and siginifcant incidences of pup mortality in the first four days postpartum. No adverse effects regarding mating, fertility or duration of gestation or parturition occurred in any treatment group including the high-dose at 1000 mg/kg/day. Clear adverse effects on reproductive performance and pup development occurred at 1000 mg/kg/day, that also resulted in significant maternal clinical signs, significant inhibition of average maternal weight gain before mating and significant increases in maternal weight gain and feed consumption during gestation. In the absence of significant toxicity to the dams, B10 did not affect the reproductive performance or the developmental parameters of pups. The effects observed on reproduction and development are not, therefore, uniquely reprotoxic or developmentally toxic effects but general toxic effects.

The maternal and developmental NOAELs were established to be 500 mg/kg/day. This corresponds with a NOAEL of 365 mg linalool/kg bw/day. It can be concluded that linalool does not need to be classified as toxic to reproduction based on the criteria outlined in Annex I of Regulation (EC) No. 1272/2008.

Reference 2

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

03 March - 08 October 1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Study was conducted according to OECD 421 and under GLP conditions. Due to the read-across purpose it was given a Klimisch 2 rating, in accordance with the ECHA Practical guide #6 on the reporting of read-across in IUCLID. Linalool and Dehydrolinalool have almost identical chemical structures. The only difference is the triple bond at position 1 in Dehydrolinalool compared to a double bond at the same position in Linalool. Both substances have almost identical physical-chemical properties. Therefore, it is assumed that toxicological properties are as well comparable.

Qualifier:

according to guideline

Guideline:

OECD Preliminary Reproduction Toxicity Screening Test (Precursor Protocol of GL 421)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Fü-Albino (RORO)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Biological Research Laboratories Ltd., CH-4414 Füllinsdorf, Switzerland
- Age at study initiation: no data
- Weight at study initiation: (P) Males: 266-272 g; Females: 180-184 g
- Housing: Individually (female + male during mating), wire mesh cages until mating, macrolon cages during post-mating period
- Diet: Kliba 343 pellets
- Water: Ad libitum, tap water
- Acclimation period: 1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): 55 +/- 10
- Air changes (per hr): fully air conditioned, no further details
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Type of inhalation exposure (if applicable):

other: Not relevant

Vehicle:

other: rape seed oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Test compound formulated in vehicle and stored in a refrigerator. During dosing the solution was moved by the use of a magnetostirrer. Preparation is done each 3 weeks. Formulation in rape seed oil is homogenous and stable for 3 weeks.

DIET PREPARATION
- Administration not by diet (gavage)

VEHICLE
- Amount of vehicle: 5 mL/kg bw/day for each dose

Details on mating procedure:

- M/F ratio per cage: 1/1
- Length of cohabitation: Overnight
- Proof of pregnancy: Copulary plug, referred to as day 0 of gestation
- Further matings after two unsuccessful attempts: Yes (for 13 consecutive days with same male)
- After successful mating each pregnant female was caged: Individually
- Any other deviations from standard protocol: females without evidence of coitus were autopsied after the mating period and their organs grossly examined. Their uteri were examined for implantation sites. Some animals without evidence of coitus were found to be pregnant and have fetuses at autopsy. The fetuses were discarded and judged as resorptions.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Not relevant

Duration of treatment / exposure:

Males: 2 weeks prior to mating and during 2 week mating period up to day 4 of lactation of the respective litter
Females: 2 weeks prior to mating and during 2 week mating period, during gestation and lactation up to day 4 of lactation

Frequency of treatment:

Daily

Details on study schedule:

No data

Dose / conc.:

750 mg/kg bw/day (actual dose received)

Dose / conc.:

200 mg/kg bw/day (actual dose received)

Dose / conc.:

50 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

20

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: A preceding dose-range finding study on 8 mated female rats per group was done. They were treated with dehydrolinalool at doses of 0, 250, 500 or 1000 mg/kg/day. The highest dose showed significant clinical observations (piloerection, reduced activity, hypersalivation) so it was reduced to 750 mg/kg/day. Clinical observations disappeared after this reduction and therefore 750 mg/kg/day was selected as highest dose. Oral route was selected because it is the recommended administration route by regulative authorities.
- Rationale for animal assignment: Random

Positive control:

Not necessary

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: At least once daily
- Cage side observations: All changes of behaviour and general condition, signs of pharmacological effects etc.

BODY WEIGHT: Yes
- Time schedule for examinations:
Males: Weekly
Females: Weekly during premating and mating, on day 0 of gestation, weekly thereafter and on days 1 and 4 of lactation (birth date of F1-generation = day 1 of lactation)

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Not applicable (gavage study)

Oestrous cyclicity (parental animals):

not examined

Sperm parameters (parental animals):

Parameters examined in [P] male parental generations: Testes weight

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: No, all offspring sacrificed on day 4

PARAMETERS EXAMINED
The following parameters were examined in [F1] offspring: number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical abnormalities

GROSS EXAMINATION OF DEAD PUPS:
yes, for external and internal abnormalities; possible cause of death was determined for pups born or found dead

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals were sacrificed and autopsied after day 4 of lactation of respective female
- Maternal animals: All surviving animals were allowed to litter spontaneously and to rear their young up to day 4 of lactation. Date of parturition was recorded (birth date = day 1 of lactation). Then the animals were killed. Females that did not litter were sacrificed about one week after expected date of parturition. Females which died during study were autopsied.

GROSS NECROPSY
- Gross necropsy consisted of macroscopical examination of kidneys, lungs and liver. Testes was weighed. Uteri was examined for implantation sites. Ovaries were preserved and the number of corpora lutea was recorded.

Postmortem examinations (offspring):

SACRIFICE
- The F1 offspring was sacrificed at 4 days of age.
- These animals were subjected to postmortem examinations (macroscopic and microscopic examination) as follows: Externally examined for anomalies.

GROSS NECROPSY
- Gross necropsy consisted of visceral examination (anomalies) according to the method of Barrow and Taylor. Visceral examination in the 50 and 200 mg/kg/day groups was limited to urogenital system. Determination of sex was done at necropsy.

Statistics:

Descriptive statistics + significance tests (chi-square and fisher's exact test for categorical values, ANOVA and Dunnett's test for normally distributed values, Kruskal-Wallis-Test and Mann-Whitney-Wilcoxon-Test for all other parameters).

Reproductive indices:

Female mating index, female fertility index, female gestation index, male mating index, male fertility index.

Offspring viability indices:

Pup live birth index, pup viability index.

Clinical signs:

effects observed, treatment-related

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:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

not examined

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

effects observed, treatment-related

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
Hypersalivation in both sexes at high dose group, sedation/ataxia in some females of high dose group. Hypersalivation was not considered an adverse effect. 3 females of the 750 mg/kg bw/day group died/were sacrificed during pre-mating period, another 3 died during delivery.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
At 750 mg/kg the pup live birth index and pup viability index were slightly reduced, when compared with the concurrent control. This is likely related to observed maternal toxicity. Moreover, dams with delivery complications were observed at the dose of 50 mg/kg (1 dam) and at 750 mg/kg (3 dams). The delivery complications may be related to sedating effect of the test substance as evidenced by clinical signs at high dose level (750 mg/kg bw/day).

Key result

Dose descriptor:

NOAEL

Effect level:

200 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

female

Basis for effect level:

clinical signs

mortality

Key result

Dose descriptor:

NOAEL

Effect level:

750 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: No adverse effects

Remarks on result:

not determinable due to absence of adverse toxic effects

Clinical signs:

no effects observed

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, treatment-related

Histopathological findings:

not examined

VIABILITY (OFFSPRING)
Pup viability index significantly reduced in high dose group and possibly by toxic effect in treated dams.

GROSS PATHOLOGY (OFFSPRING)
Most frequently observed abnormalities in 750 mg/kg/day group (hydronephrosis, convoluted and/or hydroureter and retardation in renal and testicular development) were mainly noted in pups; belonging to mothers with delivery problems. They are likely to be linked to maternal toxicity.

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

200 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

not specified

Basis for effect level:

viability

other: Abnormalities of urinary system in 750 mg/kg/day group

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

750 mg/kg bw/day (actual dose received)

System:

urinary

Organ:

other: Abnormalities of urinary system

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

Key result

Reproductive effects observed:

not specified

Linalool and Dehydrolinalool are liquids at room temperature and have a boiling point of 197 - 198°C. The slight differences in vapor pressure (Linalool: 0.27 hPa at 25°C, Dehydrolinalool: 0.11 hPa at 20°C), water solubility (Linalool: 1.56 g/L at 25°C, Dehydrolinalool: 2.45 g/L at 20°C), and log Pow (Linalool: 2.9 at 20°C, Dehydrolinalool: 2.61 at 25°C) are mainly the result of different testing temperatures. Vapor pressure favors evaporation, water solubility and logPow indicate that both substances may favor organic apolar environment.

 

Acute oral and dermal toxicity data reveal for both substances an LD50 of more than 2000 mg/kg bw. Acute inhalation toxicity was not tested by standard means. However, there were no deaths at a concentration of 3.2 mg Linalool/L and 1.0 mg Dehydrolinalool/L. Thus, the LC50s are greater than 3.2 mg Linalool/L and 1.0 mg Dehydrolinalool/L. Linalool and Dehydrolinalool are both skin and eye irritants as pure substances. Dilutions of 30% concentration and below for both substances show no eye irritant potential. Neither Linalool nor Dehydrolinalool showed sensitizing potential in human studies. It was shown that oxidation of Linalool should be prevented due to strong skin sensitising properties of the decomposition products.Therefore, Linalool is usually protected by antioxidants.

Overall, mutagenicity and genotoxicity testing was unremarkable. Both substances were negative in the Ames test and in an in vivo micronucleus test. Linalool was also negative in an in vitro chromosome aberration test and in an in vitro forward mutation testing. Although Dehydrolinalool was positive in the in vitro chromosomal aberration test in the absence of metabolic activation, the next higher Tier test i.e. the in vivo MNT in the bone marrow was clearly negative. 

Two repeated toxicity studies, 2 reprotoxicity screening studies, and a developmental toxicity study using gavage application for Linalool (either applied in coriander oil at 72.9% Linalool or as pure substance) and / or Dehydrolinalool showed the following consistent results: Histopathologically, male animals had alpha-2u-globulin nephropathy after application of both substances. Liver (and kidney) weights were increased in both sexes with some indication of metabolic enzyme induction in the liver. Hypersalivation and sedation / ataxia were consistently noted in almost all studies. In one oral study, gavage application resulted in (fore)stomach lesions which might be the result of the irritant properties. In a repeated dermal toxicity study, the skin irritant properties of Linalool were confirmed. The relevant oral NOAEL for Linalool was determined to be 117 mg/kg bw/d; Dehydrolinalool has an oral NOAEL of 200 mg/kg bw/d. The difference in the NOAELs is the result of the dose-setting regime. The NOAEL for dermal DNEL was 250 mg/kg bw/d.

Linalool (applied in coriander oil at 72.9% Linalool) was only tested for female fertility without showing an effect. Dehydrolinalool, however, was tested for male and female fertility and showed no adverse effect. Linalool was tested with regard to developmental toxicity / teratogenicity in two studies: screening test (applied in coriander oil at 72.9%) and full guideline compliant developmental toxicity study (pure substance). Both studies showed no evidence of adverse effects on foetuses and pups at doses which were not maternal toxic. Dehydrolinalool was also tested negative for this endpoint in a screening assay. From the data it is concluded that both substances are neither developmental toxic nor teratogenic at doses not being maternally toxic. However, at maternal toxic doses, reduced litter sizes and increased pup mortality was noted for both substances.

 

Conclusions:

Several and significant effects of dehydrolinalool were seen in females (sedation/ataxia) and offspring (abnormalities of the urinary system, reduced pup live birth index and pup viability) at the highest dose group of 750 mg/kg/day. For males, no effects were seen up to the highest dose level. The NOAEL for females and offspring was set at 200 mg/kg/day, for males the NOAEL was established as 750 mg/kg bw/day.

Executive summary:

Dehydrolinalool was tested in a preliminary reproductive toxicity screening test (OECD) in rats. 20 animals per sex and group were given the test article formulated in rape seed oil at doses of 0 (control), 50, 200 or 750 mg/kg/day (administration volume 5 mL/kg/day). The administration period for both sexes was through premating (2 weeks), mating (up to 2 weeks) and gestation up to day 4 of lactation.

 

3 females died/were sacrificed during pre-mating period and 3 females died/were sacrificed with delivery complications at the highest dose group. Body weight development and food consumption was comparable in all experimental groups. Hypersalivation was observed in males and females at 750 mg/kg throughout the study. However, this was not considered relevant for NOAEL derivation. Females at the highest dose groups showed sedation/ataxia during gestation and lactation. The duration of gestation, mean number of implantations, resorption rate, mean number of pups per litter, mean pup weight, sex ratio were not significantly affected by the treatment in either dose group. In addition, no signs of teratogenic action were observed in any pup of dams which survived the scheduled date of necrospsy in any dose group.

However, at 750 mg/kg the pup live birth index and pup viability index was slightly reduced, when compared with the concurrent control. Moreover, dams with delivery complications were observed at the dose of 50 mg/kg (1 dam) and at 750 mg/kg (3 dams). No delivery complications were noted in the mid dose group (200 mg/kg) and therefore the finding at low dose level was not considered adverse due to missing dose-response relationship. The incidence of abnormalities in the urinary system and of renal and testicular development was increased at 750 mg/kg mainly due to pups of dams which died or were sacrificed during the delivery. Reduced live birth index is as well to a great extent realted to delivery problems.

 

It may be concluded that dehydrolinalool does not adversely affect mating and fertility of males and females when administered in rape seed oil by oral gavage to rats from 2 weeks premating through day 4 of lactation up to 750 mg/kg/day, the highest dose tested. Delivery complications were noted at 50 and 750 mg/kg/day. The pup live birth index and pup viability index was slightly decreased at the maternally toxic dose of 750 mg/kg/day. An increased incidence of abnormalities of the urinary system and of impaired renal and testicular development was noted in pups of mothers treated with 750 mg/kg/day. However, most of the observed abnormal pups belong to those dams which died or were sacrificed moribund during delivery. No adverse effects on the reproductive indices and on the developing conceptus/pup were noted up to 200 mg/kg/day. The no-observed-adverse-effect-levels (NOAEL) were set at 200 mg/kg/day for the offspring and dams. The NOAEL was 750 mg/kg bw/day for males.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

365 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Guideline study

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Reproduction and developmental toxicity screening assay, rat, RL1

In a reproduction and developmental toxicity screening assay, Coriander oil containing 72.9% linalool was tested. Females were treated with 0, 250, 500, and 1000 mg coriander oil/kg bw/d. The LOEL was 829 mg linalool/kg bw/d. The NOAELs of 365 mg linalool /kg bw/d are based on reduced body weight and food consumption, reduced delivered litter sizes and increased pup mortality when compared to controls. Effects on pups are likely related to maternal toxicity. There was no evidence on adverse effects on female fertility. (Hoberman 1989).

 

Reproduction and developmental toxicity screening assay, rat, read-across

In a reproduction/developmental toxicity screening test with dehydrolinalool, a structural comparable substance, dehydrolinalool was administered at 0, 50, 200, and 750 mg/kg bw/d. Basis for NOAEL derivation was mortality, sedation and ataxia in females and hydronephrosis, convoluted and / or hydroureter and retardation in renal and testicular development in pups delivered from dams with delivery complications only. This is likely related to the severe maternal toxicity observed as evident by clinical signs. There was no adverse effect on male and female fertility. The NOAEL for maternal and developmental toxicity was 200 mg/kg bw/d.

Short description of key information:

Reproduction / Developmental Toxicity Screening Test (OECD 421, GLP):

- NOAEL maternal toxicity: 365 mg/kg bw/day

- NOAEL developmental toxicity: 365 mg/kg bw/day

Effects on developmental toxicity

Description of key information

Developmental Toxicity Study in rats (ICH guideline (FDA, 1994), GLP):

- NOAEL maternal toxicity: 500 mg/kg bw/day

- NOAEL developmental toxicity: 1000 mg/kg bw/day

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 November 2005 - 7 July 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study was conducted according to a FDA guideline and under GLP conditions.

Qualifier:

according to guideline

Guideline:

other: ICH Guideline on detection of toxicity to reproduction for medicinal products (FDA, 1994)

Deviations:

no

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
- Source: Charles River Laboratories, Inc.
- Age at arrival: approx. 62 days
- Weight at study initiation: 207-253 g
- Housing: Individually, except during cohabitation with male
- Diet: Ad libitum, rodent diet
- Water: Ad libitum, local water
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-26
- Humidity (%): 30-70
- Air changes (per hr): >10
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES:
From: 14 November 2005
To: 9 December 2005

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Suspensions of the test article were prepared weekly at the testing facility. Prepared formulations were stored at room temperature, protected from light.

VEHICLE
- Concentration in vehicle: 25, 50 or 100 mg/mL (different dosing groups)
- Amount of vehicle: 10 mL/kg
- Lot/batch no.: 015K0115

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentration, homogeneity and stability of test samples prepared during study were within acceptable range of +/- 15% error, +/- 5% RSD and +/- 10% error, respectively.

Details on mating procedure:

- Impregnation procedure: Cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: max. 5 days
- Proof of pregnancy: Vaginal plug or sperm in vaginal smear referred to as day 0 of pregnancy

Duration of treatment / exposure:

11 days (GD 7-17)

Frequency of treatment:

Once daily

Duration of test:

26 days (including 21 days of gestation)

No. of animals per sex per dose:

25

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
Dosages were selected on the basis of a dosage-range study (TIF00008) with the same test article.

1000 mg/kg/day (limit dose) has been selected as the high dose for this definitive study. This dosage, 1000 mg/kg/day, was not expected to affect body weights and/or feed consumption, or result in adverse clinical observations. Based on these data, dosages of 0 (Vehicle), 250, 500 and 1000 mg/kg/day of Linalool were recommended for the developmental toxicity study in rats. The 250 mg/kg/day dosage was expected to be a no-observable-adverse-effect-level (NOAEL) for both maternal and embryo-fetal toxicity, and the 1000 mg/kg/day dosage was expected to produce minimal maternal toxicity and little or no developmental toxicity.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily during study (weekly during acclimatisation period)
- Cage side observations: Viability

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Twice daily (before and approx. 3 hours after dosage administration) during dosing period and once daily during postdosage period

BODY WEIGHT: Yes
- Time schedule for examinations: Daily

FOOD CONSUMPTION: Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, on DGs 0, 7, 10, 12, 15, 18 and 21

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day #21
- Organs examined by gross necropsy: thoracic, abdominal and pelvic viscera, uterus and ovary.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: Number of live and death fetuses. Placenta was examined for size, color and shape.

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter

Statistics:

Clinical observations and other proportional data were analyzed using the Variance Test for Homogeneity of the Binomial Distribution.
Continuous data (e.g., body weights, body weight changes, feed consumption values and litter averages for percent male fetuses, percent resorbed conceptuses, fetal body weights and fetal anomaly data) were analyzed using Bartletts Test of Homogeneity of Variances and the Analysis of Variance, when appropriate [i.e., Bartletts Test was not significant (p>0.001)]. If the Analysis of Variance was significant (p=0.05), Dunnetts Test was used to identify the statistical significance of the individual groups. If the Analysis of Variance was not appropriate [i.e., Bartletts Test was significant (p=0.001)], the Kruskal-Wallis Test was used, when less than or equal to 75% ties were present. In cases where the Kruskal-Wallis Test was statistically significant (p=0.05), Dunns Method of Multiple Comparisons was used to identify the statistical significance of the individual groups. If there were greater than 75% ties, Fishers Exact Test was used to analyze the data. Count data were evaluated using the procedures described above for the Kruskal-Wallis Test.

Historical control data:

Not relevant

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
- All rats survived until scheduled sacrifice
- All clinical observations were considered unrelated to linalool
- Body weight gains were reduced by 11% (not significant) in the 1000 mg/kg/day group during the dosage period as compared to controls
- Absolute and relative feed consumption were significantly reduced in the 1000 mg/kg/day group during dosage. Postdosage the absolute and relative feed consumption were significantly increased as compared to controls. No effects were seen in the other treatment groups

Key result

Dose descriptor:

NOAEL

Effect level:

500 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
- Litter averages appeared normal, as well as all placentae.
- No gross external, soft tissue or skeletal fetal alterations appeared to be caused by linalool in the dosage groups up to 1000 mg/kg/day. No dosage-dependent effects or significant differences were observed. This was confirmed by historical control data.

Key result

Basis for effect level:

other: no teratogenic effects

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Abnormalities:

no effects observed

Key result

Developmental effects observed:

not specified

Not relevant

Conclusions:

Under the conditions of this study, the No Observed Adverse Effect Level (NOAEL) for maternal toxicity of linalool was established to be 500 mg/kg/day because of effects on weight gain and feed consumption (reversible after treatment period). For developmental toxicity a NOAEL of 1000 mg/kg/day was found. Based on the results of this study, linalool does not need to be classified for maternal and developmental toxicity according to the criteria outlined in Annex I of Regulation (EC) No 1272/2008.

Executive summary:

One hundred pregnant Crl:CD(SD) rats were randomly assigned to four dosage groups (Groups I through IV), 25 rats per group. The test article, Linalool, or the vehicle, Corn Oil, was administered orally (via gavage) once daily on days 7 through 17 of gestation (GDs 7 through 17) at dosages of 0 (Vehicle), 250, 500 and 1000 mg/kg/day to rats in Groups I through IV, respectively. All rats were examined for clinical observations of effects of the test article, abortions, premature deliveries and deaths. Body weights and feed consumption were recorded. All rats were sacrificed and gross necropsy of the thoracic, abdominal and pelvic viscera was performed. Fetuses were weighed and examined for sex, gross external, soft tissue and skeletal alterations.

All prepared formulations were acceptable for use on this study. All rats survived until scheduled sacrifice. There were no clinical observations or gross lesions that were considered related to Linalool. During the dosage period, body weight gains were reduced by 11% in the 1000 mg/kg/day dosage group. The reductions were not statistically significant and probably reflected the reductions in feed consumption that occurred in this dosage group. During the postdosage period, body weight gains in the 1000 mg/kg/day were increased over the vehicle control group value.

Absolute and relative feed consumption values were reduced or significantly reduced (by 7%) in the 1000 mg/kg/day dosage group for the entire dosage period in comparison to the vehicle control group values. During the postdosage period, absolute and relative feed consumption values were signficantly higher than vehicle control values. This observation corresponded to the increase in body weight gains in the 1000 mg/kg/day dosage group during this same period.

Pregnancy occurred in 20 to 23 rats per dosage group. No Caesarean-sectioning or litter parameters were affected by dosages of linalool as high as 1000 mg/kg/day. No other gross external, soft tissue or skeletal fetal alterations (malformations or variations) were caused by dosages of linalool as high as 1000 mg/kg/day. All ossification site averages were comparable and did not significantly differ from the vehicle control group values.

On the basis of these data, the maternal No Observable Advers Effect Level (NOAEL) of linalool is 500 mg/kg/day. The 1000 mg/kg/day dosage of linalool caused non-significant reductions in body weight gain and also reduced absolute and relative feed consumption values during the dosage period. However, following the completion of the dosage period, these effects of linalool were reversed (i.e., increases in body weight gains and feed consumption).

The developmental No Observed Adverse Effect Level (NOAEL) is 1000 mg/kg/day. There were no adverse effects on embryo-fetal development as evaluated in this study, and based on these data, linalool does not need to be classified for maternal and developmental toxicity according to the criteria outlined in Annex I of regulation (EC) No 1272/2008.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Guideline study

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

In a developmental toxicity study, linalool was applied to pregnant rats from GD 7 to 17 at 0, 250, 500, 1000 mg/kg bw/d. The NOAEL for maternal toxicity of 500 mg/kg bw/d is based on reduced body weights and food consumption compared to controls. There were no effects on foetuses. Linalool was not teratogenic. (Cimildoro 2006)

Justification for classification or non-classification

Based on the result that all NOAELs for developmental toxicity are identical to or exceed the NOAELs for maternal toxicity, reproduction and developmental toxicity is not expected. Therefore, it is concluded that linalool does not need to be classified as toxic to reproduction based on the criteria outlined in Regulation (EC) No 1272/2008, as amended for fifteenth time in Regulation (EU) No 2020/1182.