Menthyl acetate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Data waiving:

other justification

Justification for data waiving:

other:

Reproductive effects observed:

not specified

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

Screening for reproductive/developmental study:

Screening for reproductive/developmental study could be waived since according to REACH (Regulation (EC) No 1907/2006, Annex VIII, column 2, paragraph 8.7.1), this study does not need to be conducted if a pre-natal developmental toxicity study is available.

Two-generation reproductive toxicity:

There is no reproductive toxicity data on Menthyl acetate.

Justification for read across: Menthol is the major metabolite of Menthyl acetate in experimental animals. It is anticipated that Menthol is rapidly formed from the Menthyl acetate during and after uptake through the gastrointestinal tract. It is therefore possible to use experimental data on Menthol for read across as described in the Read-Across Justification (see section 13). Menthyl acetate is hydrolysed in mammals to menthol and acetic acid. Investigations on toxicokinetics show that L-, D-, D/L- and the unspecified menthol are well absorbed via the oral route. For all the isomers, elimination is rapid and mainly occurs as glucuronic acid conjugates via urine, minor amounts via faeces (RIFM, 2008). Significant differences in toxicokinetic properties of menthol isomers were not reported. The available toxicity data indicate very similar toxicity profiles for D-, L-, D/L-menthol and the unspecified menthol isomer mixture. In mammalian species the low toxicity is manifested in LD50 values generally near or greater than 2000 mg/kg bw in acute studies, limited toxicity in repeated dose studies, and no effects in teratology evaluations. Irritation to skin and eyes was slight to moderate (RIFM, 2008). D/L-menthol is a racemic mixture of the D- and L- isomers and contains both isomers in equal proportion. Data gaps for Menthyl acetate can therefore be filled by the respective results with the racemic mixture or the D-menthol isomer. Due to above discussion, to this endpoint, reproductive properties of Menthyl acetate can be thought equivalent to the tested substance DL-Menthol (The NOAEL in chronic study on rats was determined > 375 mg/kg bw/d).

Two-generation reproductive toxicity study could be waived since histopathological examinations of the reproduction organs of rats and mice did not show any changes in repeated dose toxicity studies of D/L-menthol and also in carcinogenicity studies of D/L- menthol, we can anticipate the same conclusion for Menthyl acetate.

Short description of key information:
According to REACH (Regulation (EC) No 1907/2006, Annex VIII, column 2, paragraph 8.7.1), the screening for reproductive/developmental toxicity does not need to be conducted if a pre-natal developmental toxicity study is available.
No changes were observed during the histopathological examinations of the reproductive organs of rats and mice in repeated dose toxicity studies and in carcinogenicity studies following the exposure to the different menthol isomers: D/L menthol. Therefore, no study on toxicity to reproduction needs to be conducted.

Effects on developmental toxicity

Description of key information

NOEL (maternal/teratogenicity/fetotoxicity) = 277 mg/kg bw/day Menthyl acetate (data derived from L-menthone study with maternal, teratogenicity and fetotoxicity NOEL = 218 mg/kg bw/day, a maximal given dose)

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1973

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented Restriction: no full macroscopic examination; no data on statistical evaluation

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included as attachment to the same record

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The structural correlation of menthol (source chemical) to menthyl acetate (target chemical) consists of the 3-menthyl carbon skeleton which is presented as a secondary alcohol in case of menthol and as a related ester in menthyl acetate. Menthol is regarded as metabolite of this compound in mammals (WHO, 1999). In summary, both chemicals will have comparable mode of action with regard to the covered endpoints:

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)

Source chemical
L-Menthol / DL-Menthol (racemic)
MW: 156.27
CAS: 2216-51-5 (L-Menthol)
CAS: 15356-60-2 (D-Menthol)
CAS: 89-78-1 (DL-Menthol)

Target chemical
Menthyl acetate (racemic)
MW: 198.30
CAS: 89-48-5

3. ANALOGUE APPROACH JUSTIFICATION

- Hydrolyse
In general, menthyl esters, like menthyl acetate are hydrolysed in mammals to menthol and their respective carboxylic acids. Ester hydrolysis is catalysed by classes of enzymes recognized as carboxylesterases or acetylesterases (Heymann, 1980; WHO, 1999). These enzymes occur in most mammalian tissues (Heymann, 1980; WHO, 1999) but predominate in hepatocytes (Heymann, 1980). In humans, menthyl esters such as methyl acetate are expected to be hydrolysed to yield menthol and their respective saturated aliphatic carboxylic acids (WHO, 1999).

4. DATA MATRIX
see attachment

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: unspecified

GLP compliance:

no

Species:

rat

Strain:

Wistar

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

VEHICLE
- Amount of vehicle (if gavage): 10 ml/kg bw

Details on mating procedure:

Virgin adult were mated with young adult males (observation of the vaginal sperm plug was considered Day 0 of gestation)

Duration of treatment / exposure:

gestation days 6-15

Frequency of treatment:

daily

Duration of test:

10 consecutive days

No. of animals per sex per dose:

25 females per dose
No of pregnant animals (2.18, 10.15, 47.05, 218 mg/kg bw): 22, 23, 23, 22

Control animals:

yes, sham-exposed

other: NEGATIVE CONTROL: 25 pregnant... (see attached file)

Maternal examinations:

CAGE SIDE OBSERVATIONS:No data

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: day 0, 6, 11, 15, 20

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day #20
- Organs examined: urogenital tract

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes / No / No data
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: No data
- Number of implantations: Yes
- Number of resorptions: Yes

Fetal examinations:

- External examinations: Yes: 1/3 per litter
- Soft tissue examinations: Yes: 1/3 per litter
- Skeletal examinations: Yes: 2/3 per litter
- Head examinations: No data

Other :
- Fetus weight : Yes: all per litter
- Abnormalities/malfunctions : Yes: all per litter

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
No clinical signs of maternal toxicity

Dose descriptor:

NOEL

Effect level:

218 mg/kg bw/day

Based on:

other: L-Menthol

Basis for effect level:

other: maternal toxicity

Dose descriptor:

NOEL

Effect level:

277 mg/kg bw/day

Based on:

other: Menthyl acetate

Basis for effect level:

other: maternal toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No clinical signs of fetotoxicity

Dose descriptor:

NOEL

Effect level:

218 mg/kg bw/day

Based on:

other: L-Menthol

Basis for effect level:

other: teratogenicity

Dose descriptor:

NOEL

Effect level:

218 mg/kg bw/day

Based on:

other: L-Menthol

Basis for effect level:

other: fetotoxicity

Dose descriptor:

NOEL

Effect level:

277 mg/kg bw/day

Based on:

other: Menthyl acetate

Basis for effect level:

other: teratogenicity

Dose descriptor:

NOEL

Effect level:

277 mg/kg bw/day

Based on:

other: Menthyl acetate

Basis for effect level:

other: fetotoxicity

Abnormalities:

not specified

Developmental effects observed:

not specified

Maternal toxicity:

- Survival of dams: no deaths

- Body weight of dams: no compound-related changes compared to control (only positive control treated mice showed decreased body weight gain)

Fetotoxicity :

- Death : no dead fetuses in dosage groups (3 deaths in positive control)

- Average fetus weight: no change in treated groups compared to controls

- Abnormalities/malfunctions (no. of fetuses affected/no. of litters affected) (sham control, pos. control, 1.85, 8.59, 39.9, 185.5 mg/kg bw)

- Skeletal findings:

sternebrae (incomplete oss.): 80/22, 94/18, 92/20, 93/22, 101/19, 92/19

sternebrae (missing): 14/6, 11/19, 11/8, 17/5, 11/4, 0/22

skull (incomplete closure): 41/16, 114/19, 46/15, 63/16, 67/20, 49/17

- Soft tissue abnormalities:

pos. control: 7 pups with meningoencephalocele and spina bifida

10.15 mg/kg: 1 pup: petechiae, 1 pup: anophthalmia

47.05 mg/kg: 2 pups anophthalmia, 2 pups: gastroschisis,1 pup hydrocephalus

All other findings were completely in the range of spontaneous abnormalities found in negative controls.

ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC):

- Organ weights P and F1: no

- Histopathology P and F1:

P: urogenital tract, number of implantation and resorption sites

F1: All fetuses were examined grossly, one-third of fetuses of each litter underwent detailed visceral examinations employing 10x magnification, two-third were examined for skeletal defects

Conclusions:

L-Menthol was not embryo- or fetotoxic and had no teratogenic properties in well performed gavage studies in rat at non-maternally toxic doses (218 mg/kg bw).

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

277 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

All developmental toxicity / teratogenicity studies (in mouse, rat, rabbit and hamster) are reliable with restrictions.

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

There is no developmental toxicity data on Menthyl acetate.

- Read across from L-menthol:

Teratogenicity studies with L-menthol were conducted in rats, mice, hamsters and rabbits (Morgareidge1973). In all four developmental toxicity studies, maternally toxic dose levels were not used. For Wistar rats the doses of 2.18, 10.15, 47.05 and 218.0 mg/kg bw/d were administered by gavage from gestation day 6 to 15. There was no maternal toxicity and foetotoxicity. Therefore the NOEL derived for maternal and fetal toxicity and teratogenicity in rats can be determined as 218.0 mg/kg bw/d. For CD-1 Mice the doses of 1.85, 8.59, 39.9 and 185.0 mg/kg bw/d were administered from gestation day 6 to 15. There was no maternal toxicity and foetotoxicity. The NOEL derived for maternal and fetal toxicity and teratogenicity was 185.0 mg/kg bw/d. For Rabbits the doses of 4.25, 19.75, 91.7 and 425.0 mg/kg bw/d were administered to from gestation day 6 to 18. Few of the rabbits died or aborted before day 29 (at 4.25 mg/kg bw/d 2 animals died on day 13, at 19.75 mg/kg bw/d 3 animals died on day 13, at 91.7 mg/kg bw/d 1 animals died on day 11, at 425.0 mg/kg bw/d 4 animals died on day 14), however, these effects were not dose related and are not considered to be a consequence of test substance toxicity, but due to administration errors. There was no maternal toxicity and foetotoxicity. The NOEL derived for maternal and fetal toxicity and teratogenicity was therefore 425.0 mg/kg bw/d. For Syrian hamsters the doses of 4.05, 21.15, 98.2 and 405.0 mg/kg bw/d were administered during gestation days 6-10. There was no maternal toxicity and foetotoxicity. The NOEL for maternal and fetal toxicity and teratogenicity was therefore 405.0 mg/kg bw/d. Since only a NOEL for these 4 species could be derived and no developmental or foetotoxic effects were observed we can consider that L-Menthol has inconclusive developmental toxicity and teratogenic properties.

Justification for selection of Effect on developmental toxicity: via oral route:
Reliable with restrictions teratogenicity study in rats.

Justification for classification or non-classification

No changes were observed during the histopathological examinations of the reproductive organs of rats and mice in the combined repeated dose and 2 years carcinogenicity toxicity studies following exposure to the different menthol isomers: D/L menthol. Therefore, no toxicity to reproduction study need to be conducted. Based on the above stated read-across assessment from L-menthol on the reproduction toxicity potential, Menthyl acetate is deemed not to be toxic to the reproduction and accordingly do not need to be classified according to Council Directive 2001/59/EC (28th ATP of Directive 67/548/EEC) and according to CLP (Regulation (EC) No 1272/2008 of the European Parliament and of the Council) as implementation of UN-GHS in the EU.

The L-Menthol has no developmental toxicity and no teratogenicty properties in well performed gavage studies in various species (rat, mouse, rabbit, hamster) at the highest dose of 185 (for mice) to 425 (for rabbits) mg/kg bw. Since we could only derived a NOEL for these 4 species we can consider that the L-menthol has inconclusive developmental or teratogenicity hazard. Based on the above stated read-across assessment from L-Menthol of the developmental toxicity/teratogenicity potential, Menthyl acetate could not be classified for developmental toxicity/teratogenicity according to Council Directive 2001/59/EC (28th ATP of Directive 67/548/EEC) and according to CLP (Regulation (EC) No 1272/2008 of the European Parliament and of the Council) as implementation of UN-GHS in the EU.