Citronellyl acetate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

Toxicity to reproduction:

- NOAEL: 300 mg/kg bw/day (OECD 421, dermal, test substance Geraniol Extra)

- NOAEL: 1000 mg/kg bw/day (OECD 421, oral, test substance Geraniol 60)

Additional information

No data on toxicity to reproduction are available for citronellyl acetate. However data from the metabolically and structurally related geraniol and nerol are taken into account for further assessment. Citronellyl acetate is expected to hydrolyze to citronellol and acetic acid. Citronellol, geraniol, and nerol and the respective esters are close structural relatives. Nerol and geraniol are cis/trans isomers (3,7-dimethyl-6-octen-1-ol) and citronellol is the dihydro analogue of geraniol. Therefore, the structural similarity warrant the read across approach for the given endpoint.

A dermal reproduction / developmental toxicity screening test with geraniol according to OECD 421 performed in Wistar rats (BASF SE, 2010) has been taken as most relevant study, since the dermal route is the most relevant of systemic exposure to fragrance materials (acc. to Cadby et al.; Consumer Exposure to Fragrance Ingredients: Providing Estimates for Safety Evaluation, Regulatory Toxicology and Pharmacology 36, 246–252 (2002)). 

An associated 10 day range finding study with 3 female rats per dose using doses of 1000, 750, 500 and 300 mg/kg bw/day led to different grades of skin irritation (scales and erythema) at doses of 500 - 1000 mg/kg bw/d, and no clinical findings of the treated skin in the 300 mg/kg bw/day group. Based on these findings, doses of 0, 50, 150 and 450 mg/kg bw/day were chosen for the definitive reproduction screening study. The test substance was administered to 10 male and 10 female young Wistar rats dissolved in corn oil. Application area was the intact clipped skin of the back (dorsal and dorsolateral areas of the trunk; not less than 10% of the body surface). The first clipping was carried out at least 24 hours before the randomization. The rats were reclipped at least once a week (depending on the hair growth). Dermal application of the test-substance preparations to the clipped intact dorsal skin was carried out with 3 -mL syringes and a semiocclusive dressing (4 layers of absorbent gauze and stretch bandage). The test-substance preparation was applied to the dorsal skin with the syringe in each case. After removal of the dressing, the application area was washed with lukewarm water. Application was daily for at least six hours.

During the course of the study the initial high dose (450 mg/kg bw/day) turned out to be intolerable for the rat skin (strong irritation reactions), so that from day 10 onward the high dose had to be reduced to 300 mg/kg bw/day. About 2 weeks after the beginning of treatment, animals were mated to produce a litter. Mating pairs were from the same dose group. Pregnant females were allowed to give birth and the offspring was brought up until postnatal day (PND) 4. The study was terminated with the sacrifice of the pups on PND 4 and of lactating dams shortly thereafter.

Regarding clinical examinations, only signs of local dermal toxicity were observed for males and females at all dose levels. No changes in food consumption and body weight data were seen at any dose level.

Fertility indices for male and female animals were not impaired by test-substance administration.

Regarding pathology, there were no treatment-related necropsy or histological findings in ovaries, testes or epididymides associated with dermal administration of the test substance. The local minimal inflammatory reactions in the skin of treated males (all dose groups) and females (highest dose group only) were regarded as related to treatment and adverse.

Therefore, the NOAEL for fertility for geraniol is shown to be >300 mg/kg bw/day via the dermal route. Systemic exposure to geraniol is limited by the strong local irritation effects.

 

Furthermore, a study according to OECD 421 using the oral route of exposure was performed with the reaction mass of geraniol and nerol (E- and Z-isomer, 60:40 -mixture) (BASF SE, 2010).

The test substance was administered to groups of 10 male and 10 female young Wistar rats dissolved in corn oil, via daily gavage. The dose levels were 0, 100, 300 and 1000 mg/kg body weight/day. About 2 weeks after the beginning of treatment, animals were mated to produce a litter. Mating pairs were from the same dose group. Pregnant females were allowed to give birth and the offspring was brought up until postnatal day (PND) 4. The study was terminated with the sacrifice of the pups on PND 4 and of lactating dams shortly thereafter.

All mid- and high-dose as well as some low-dose animals of both sex showed transient salivation for a few minutes immediately after each treatment. This was likely to be induced by the unpleasant taste of the test substance or by local irritation of the upper digestive tract. It is neither considered to be a sign of systemic toxicity nor as adverse.

Clinical observations indicated distinct toxicity in the exposed parental animals of the high dose group (1000 mg/kg bw/d) but not in the animals of the mid- and low-dose group.

A reduction of food consumption in high dose males and females and decreased body weights in high dose males has been observed. In high dose females a significant body weight loss was observed during lactation.

The test compound did not adversely affect fertility of the F0 generation parental animals at all dose levels as there were no changes of male/female mating and fertility indices, time until successful copulation, duration of pregnancy and mean number of implantations.

The NOAEL for fertility has been set at 1000 mg/kg bw/d and the NOAEL for parental systemic toxicity has been set at 300 mg/kg bw/d based on decreased food consumption and effects on body weights.

 

Overall, data from structurally and metabolically related substances do not give indications for adverse effects on fertility. However a testing proposal for an extended one-generation reproductive toxicity study in rats, oral route (test method: OECD 443) for geraniol is currently evaluated by ECHA.

 

The design of the planned study, i.e. extended one-generation reproductive toxicity study in rats, oral route (test method: OECD 443) without extension of Cohort 1B to mate the F1 animals to produce the F2 generation until weaning (see UICLID Chapter 7.8.1) does allow to address both endpoints, i.e. pre/post-natal developmental toxicity and adverse effects on fertility. Therefore, the data obtained need to be assessed if they meet the criteria for classification concerning adverse effects on fertility and developmental toxicity and if they are adequate to support a robust risk assessment.

In the comments sent to ECHA on 19^thMarch 2012 and 19^thSeptember 2012 the Registrant has communicated an overall testing strategy covering both pure geraniol (CAS No. 106-24-1, EC No. 203-377-1) and the related reaction mass (EC No. 906-125-5). This strategy has been further specified in the member state committee meeting on 23^thOctober 2012. The Registrant has proposed to initially perform a one-generation reproductive toxicity study in rats with pure geraniol (CAS No. 106-24-1, EC No. 203-377-1) without Cohort 1B. In order to avoid redundant testing and for animal welfare reasons, a tiered testing strategy based on a one-generation reproductive toxicity test using pure geraniol in combination with the reproductive toxicity data on pure nerol as outlined above is considered appropriate. An assessment for the necessity of further tests with citronellyl acetate will be made based on the outcome of this evaluation and potential results of the study under discussion.

Effects on developmental toxicity

Description of key information

Developmental toxicity/teratogenicity

- NOAEL: 300 mg/kg bw/day (OECD 414, oral, test substance Geraniol Extra)

- NOAEL: 300 mg/kg bw/day (OECD 414, oral, test substance Geraniol 60)

 

Additional information

No data on developmental toxicity are available for citronellyl acetate. However data from the metabolically and structurally related geraniol and nerol are taken into account for further assessment. Citronellyl acetate is expected to hydrolyze to citronellol and acetic acid. Citronellol, geraniol, and nerol and the respective esters are close structural relatives. Nerol and geraniol are cis/trans isomers (3,7-dimethyl-6-octen-1-ol) and citronellol is the dihydro analogue of geraniol. Therefore, the structural similarity warrant the read across approach for the given endpoint.

A dermal reproduction / developmental toxicity screening test with geraniol according to OECD 421 performed in Wistar rats (BASF SE, 2010) has been taken as most relevant study, since the dermal route is the most relevant of systemic exposure to fragrance materials (acc. to Cadby et al.; Consumer Exposure to Fragrance Ingredients: Providing Estimates for Safety Evaluation, Regulatory Toxicology and Pharmacology 36, 246–252 (2002)). 

Ten Wistar rats per sex and dose (0, 50, 150 and 300 mg/kg bw/day) were treated daily with geraniol dissolved in corn oil for at least six hours on the clipped intact dorsal skin (semiocclusive dressing). About 2 weeks after the beginning of treatment, animals were mated to produce a litter. Mating pairs were from the same dose group. Treatment of the dams was discontinued from GD 20 onward. Pregnant females were allowed to give birth and the offspring was brought up until postnatal day (PND) 4. The study was terminated with the sacrifice of the pups on PND 4 and of lactating dams shortly thereafter.

The live birth indices as well as the rate of stillborn pups was comparable between all test groups and the control and reflected the normal range of biological variation inherent in this strain. None of the pups died during lactation in the control group and in all test groups. F1 pups did not show adverse clinical signs up to scheduled sacrifice.

Therefore, also the NOAEL for developmental toxicity / teratogenicity is shown to be >300 mg/kg bw/day via the dermal route.

 

In contrast, the oral screening study with the reaction mass of geraniol and nerol (E- and Z-isomer) described in the chapter “Effects on fertility” (BASF SE, 2010) showed effects on pup survival. The dose levels were 0, 100, 300 and 1000 mg/kg body weight/day. About 2 weeks after the beginning of treatment, animals were mated to produce a litter. Mating pairs were from the same dose group. Pregnant females were allowed to give birth and the offspring was brought up until postnatal day (PND) 4. The study was terminated with the sacrifice of the pups on PND 4 and of lactating dams shortly thereafter.

Pregnancy was unaffected at the low-dose. However, there is an alert for a dose-dependent adverse effect of the test substance on pre-/postnatal development of the F1 offspring at mid and high-dose level (300 and 1000 mg/kg bw/d). For the high-dose a lower live birth index (89 %) was noted. Pup survival until PND 4 was decreased by 25% and average pup body weight on PND 4 was decreased by 18%. The reduced live birth index was due to losses in only one animal in the group (all others showed no losses). The significantly reduced postnatal offspring weight/weight gain during the first 4 days after birth are likely related to maternal toxicity and ability to care and nurse for the pups as evidenced by clinical observations, empty stomachs in 10% of pups and significantly reduced feed consumption and body weights during the lactation period. Overall, it may be considered that the pup effects seen are secondary to maternal toxicity which effects pup care and nursing.

At the mid dose level, the same effects were noted, but at a lesser incidence and no significant effect on weight/weight gain was observed. The mid-dose also had a lower live birth index (94%). The slightly higher (non-significant) number of stillborns may well be contributed to the greater litter size in this group, which leaves the adverse effects on development of offspring in the mid-dose group to be limited to a slightly reduced pup survival (-9%). At least partially, the reduced pup survival may be secondary to a disturbance of maternal care as it became obvious by empty stomachs in pups which have been observed in 5% of mid-dose. In addition, findings in the mid dose appear to be limited to one animal. This animal appears to have maternal toxicity issues as evidenced by clinical observations (pups not properly nursed and insufficient maternal care of the pups), significantly reduced food consumption and empty stomachs in the pups. These effects are similar to those seen at the top dose and it may therefore be concluded that maternal toxicity in this one animal is also responsible for the effects seen. The findings in this one animal appear to be an outlier in this group and excluding this animal from the data would show no significant findings vs. controls. No such findings were noted at the low-dose.

Overall, maternal toxicity as evidence by lack of care of the pups, significantly reduced food consumption in the dams and empty stomachs in the pups appears to be responsible for the findings seen at the top and mid dose groups. Effects are mainly due to one animal each at either dose group. The observed findings show a questionable correlation between the effects seen on maternal toxicity and effects seen on the offspring. Hence, their relevance based only on this screening study is doubtful and more complete studies at tolerated doses are required.

Toxicity to reproduction: other studies

Additional information

No data available.

Justification for classification or non-classification

The present data on reproductive toxicity are not sufficient to fulfill the criteria laid down in 67/548/EEC and regulation (EU) 1272/2008.