Registration Dossier

Administrative data

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records
Reference
Endpoint:
one-generation reproductive toxicity
Remarks:
based on test guideline
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The reliability is based on read across for a structural analogue compound, myrcene (CAS 123-35-3). See read across justification section 13. The myrcene study report was conclusive and done following protocol similar to OECD 415 and according to GLP. Minor deviations from standard test guidelines and/or minor methodological deficiencies did not affect the quality of the relevant results.
Justification for type of information:
Myrcene and Farnesene have similar chemical structures and therefore are expected to have similar physical/chemical characteristics. Thus, read across of myrcene data is a reasonable approach.
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]
Deviations:
yes
Remarks:
mating conditions (1 male for 3 females); food consumption not followed; bodyweight frequency
GLP compliance:
not specified
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Fa. Winkelmann, Borchen, Germany
- Housing: Housed in macrolon type 3 cage with wood shavings as bedding
- Diet (e.g. ad libitum): Standard pelleted diet (Altromin 1324, Lage, Germany), ad libitum
- Water (e.g. ad libitum): Tap water, ad libitum
- Acclimation period: Three weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 1 °C
- Humidity (%): 50 ± 5%
- Photoperiod (hours dark / hours light): 12 hours dark / 12 hours light
Route of administration:
oral: gavage
Vehicle:
peanut oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Test material was dissolved in peanut oil
Details on mating procedure:
M/F ratio per cage: 1:3
- Length of cohabitation: 2 hours/day
- Proof of mating: Sperm in vaginal smear referred to as Day 0 of pregnancy
- Further matings after two unsuccessful attempts: Yes, mating procedure was repeated every working day until all three females became sperm-positive or, alternatively, for 15 mating sessions extending over 3 weeks
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
no data
Duration of treatment / exposure:
-Male rats: 91 days prior to mating and during the mating period
- Female rats: 21 days prior to mating, during the mating period and during pregnancy and lactation until Day 21 after parturition
Frequency of treatment:
once daily
Details on study schedule:
none
Remarks:
Doses / Concentrations:
0 mg/kg bw
Basis:
actual ingested
Remarks:
Doses / Concentrations:
100 mg/kg bw
Basis:
actual ingested
Remarks:
Doses / Concentrations:
300 mg/kg bw
Basis:
actual ingested
Remarks:
Doses / Concentrations:
500 mg/kg bw
Basis:
actual ingested
No. of animals per sex per dose:
15 males and 45 females per dose
Control animals:
yes, concurrent vehicle
Details on study design:
none
Positive control:
no
Parental animals: Observations and examinations:
All Fo-males and -females were evaluated for weight development, mortality and signs of toxicity

- Pregnant females were observed for weight gain, signs of abortion, dystocia and prolonged duration of pregnancy
Oestrous cyclicity (parental animals):
No data
Sperm parameters (parental animals):
Parameters examined in all male parental generations: Testis weight, sperm count in testes and cauda epididymis
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: No

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, signs of physical development and the days on which developmental landmarks (incisor eruption, fur development or eye opening) appeared

GROSS EXAMINATION OF DEAD PUPS:
- No; possible cause of death was not determined for pups born or found dead
Postmortem examinations (parental animals):
SACRIFICE
- Male animals: All surviving animals were sacrificed by decapitation and autopsied at the end of the mating period
- Maternal animals: One-third of surviving females were sacrificed on Day 21 of pregnancy for cesarean examinations. All mothers were killed for post mortem examination on postnatal Day 21

GROSS NECROPSY
- All major organs were inspected macroscopically

HISTOPATHOLOGY / ORGAN WEIGHTS
Male animals:
- Organ weights: Liver, kidney, spleen, heart, thymus, brain and testes were weighed
- Histological examinations: Livers and one of the two testes were histologically examined

OTHERS
Cesarean examination:
- Gravid uterus was weighed with its contents
- Resorption as well as living and dead fetuses were counted
- Number of implantation sites were determined
- All living fetuses were immediately weighed and examined for externally visible malformations
- All fetuses were examined for skeletal anomalies
Postmortem examinations (offspring):
Not applicable
Statistics:
Statistical evaluation was performed using a MINITAB program (MTB, University of Pennsylvania, 1984), and a difference was considered statistically significant at P < 0.05.
- Data were analyzed by one-way analysis of variance (ANOVA) followed by Kruskal-Wallis test
- Differences between groups were tested by two-tailed Student t-test or Mann-Whitney U-test
- Proportions were analyzed by the chi-square test or, alternatively, by the Fischer exact test
Reproductive indices:
- Mating index = [No. of sperm-positive females ÷ No. of mated females] x 100
- Pregnancy index = [No. of pregnant females ÷ No. of sperm-positive females] x 100
Offspring viability indices:
- % of stillbirths = [No. of stillbirths/total of pups born] x 100
- % of pups dead = [No. of pups dead/No. of viable pups on Day 1] x 100
Clinical signs:
no effects observed
Body weight and weight changes:
not specified
Food consumption and compound intake (if feeding study):
not specified
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
no effects observed
Other effects:
not specified
Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
no effects observed
CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
- Mortality: No deaths were observed
- Clinical signs: No signs of toxicity were apparent

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
- No statistically significant differences in body weight gain between the control and the treated rats were observed

REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS)
- No treatment-related effect was found either on the number of spermatids in the testis or on the number of spermatozoa in the cauda epididymis

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
- No treatment-related effects were observed on mating and pregnancy index
- No treatment-related adverse effects were observed on duration of pregnancy or labor

ORGAN WEIGHTS (PARENTAL ANIMALS)
- At 500 mg/kg bw/day: Slight increase in both absolute and relative weights of liver and kidneys were observed

HISTOPATHOLOGY (PARENTAL ANIMALS)
- Microscopic evaluation revealed no morphological alterations in the liver or testicular tissues of male rats
Dose descriptor:
NOAEL
Effect level:
300 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Increase in liver and kidney weights in parental animals at 500 mg/kg bw/day
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:
no effects observed
Gross pathological findings:
effects observed, treatment-related
Histopathological findings:
not examined
VIABILITY (OFFSPRING)
- Slight increase in the resorption rate (3.0% vs. 10.5% in control vs. 500 mg/kg bw group, respectively) and a parallel decrease in the ratio of live fetuses per implantation site (97.0% vs. 89.5% in control vs. 500 mg/kg bw group, respectively) were observed at 500 mg/kg bw/day.
- A slight retardation in the appearance of incisor eruption, primary coat and eye opening were observed but this effect was not considered to be dose-related and the delay was more evident with incisor eruption (300 mg/kg bw/day) and eye opening (100 and 300 mg/kg bw/day).
- See table 1 for detailed data

MORTALITY (OFFSPRING)
- No differences were observed between control and treatment groups on the first day of life (stillbirths) or throughout lactation (postnatal Day 2-21).

BODY WEIGHT (OFFSPRING)
- No differences between control and treated groups were found with regard to maternal or offspring weight changes during the lactation period.

GROSS PATHOLOGY (OFFSPRING)
- Frequency of skeletal malformations: No differences between control and treated groups were observed at doses up to 300 mg/kg bw/day, but the frequency of skeletal malformations was increased at 500 mg/kg bw/day (35.4% vs. 64.7% in control vs. 500 mg/kg bw group, respectively). However, this effect was attributed to spontaneous strain-specific increase in the occurrence of anomalies such as fused os zygomatic, dislocated sternum (non-aligned sternebrae) and lumbar extra ribs.
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
300 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Increased resorption rate and a higher frequency of fetal skeleton anomalies observed in the 500 mg/kg bw/day group
Reproductive effects observed:
not specified

Table 1: Physical signs of postnatal development of offspring of rats treated orally with β-myrcene (0, 100, 300 and 500 mg/kg bw/day)

Postnatal day

Primary coat (%)

Incisor eruption (%)

Eye opening (%)

0

100

300

500

0

100

300

500

0

100

300

500

7

78

67*

48*

59*

1.4

-

-

-

-

-

-

-

8

99

94

95

90

2.8

38

4.2

1.5

-

-

-

-

9

100

100

100

97

41

79

27*

33*

-

-

-

-

10

-

-

-

100

78

99

57*

81

-

-

-

-

11

-

-

-

-

98

100

87*

100

-

-

-

-

12

-

-

-

-

100

-

98

-

-

-

-

-

13

-

-

-

-

-

-

100

-

3.5

4.1

0.6

3

14

-

-

-

-

-

-

-

-

26

12

5.4

40

15

-

-

-

-

-

-

-

-

68

43*

37*

50*

16

-

-

-

-

-

-

-

-

93

73*

73*

87

17

-

-

-

-

-

-

-

-

100

83*

100

99

18

-

-

-

-

-

-

-

-

-

98

-

100

19

-

-

-

-

-

-

-

-

-

100

-

-

* P < 0.05 compared to controls (chi-square test).

Conclusions:
The no-observed-adverse-effect level (NOAEL) for toxic effects on fertility and general reproductive performance of β-myrcene via oral route was reported to be 300 mg/kg bw/day in Wistar rats.
Executive summary:

A study was conducted to investigate the effects of β-myrcene on fertility and general reproductive performance in Wistar rats similarly to OECD Guideline 415.

 

β-Myrcene (0, 100, 300 and 500 mg/kg bw/day) in peanut oil was administered daily by gavage to male Wistar rats (15/group) for 91 days prior to mating and during the mating period, as well as to females (45/group) continuously for 21 days before mating, during mating and pregnancy, and throughout the period of lactation up to postnatal Day 21. All Fo-males and -females were evaluated for weight development, mortality and signs of toxicity. Pregnant females were observed for weight gain, signs of abortion, dystocia and prolonged duration of pregnancy. Parameters examined in all male parental generations include testis weight, sperm count in testes and cauda epididymis. On Day 21 of pregnancy one-third of the females of each group were submitted to cesarean section. Resorption, implantation, as well as dead and live fetuses were counted. All fetuses were examined for external malformations, weighed and examined for skeleton evaluation. The remaining dams were allowed to give birth to their offspring. The progeny was examined at birth and subsequently up to postnatal Day 21. Mortality, weight gain and physical signs of postnatal development were evaluated.

An increase in liver and kidney weights were observed in male and female rats at 500 mg/kg bw/day but in the absence of associated pathology. No other sign of toxicity was noted in parental male and female rats exposed to β-myrcene. The test material did not affect the mating index or the pregnancy index. No sign of maternal toxicity and no increase in externally visible malformations were observed at any dose level. At the highest dose tested (500 mg/kg bw/day) there was a slight increase in resorption rate (3% v 5% in controls) and a higher frequency of fetal skeleton anomalies were reported. The latter was not considered to be treatment related but were attributed to an increase in spontaneous strain-specific findings. No adverse effect on postnatal weight gain was noted but days of appearance of primary coat, incisor eruption and eye opening were reported to be slightly delayed in exposed offspring; these minor developmental findings were however not dose related and it is questionable if they were related to treatment.

 

In conclusion, the no-observed-adverse-effect level (NOAEL) for toxic effects on fertility and general reproductive performance of β-myrcene by the oral route was reported to be 300 mg/kg bw/day in Wistar rats.

The findings were not however clearly treatment or dose related, hence 300 mg/kg/day is probably a conservative NOAEL.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
300 mg/kg bw/day
Study duration:
chronic
Species:
rat
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

β-Myrcene (0, 100, 300 and 500 mg/kg bw/day) in peanut oil was administered daily by gavage to male Wistar rats (15/group) for 91 days prior to mating and during the mating period, as well as to females (45/group) continuously for 21 days before mating, during mating and pregnancy, and throughout the period of lactation up to postnatal Day 21. All males and -females were evaluated for weight development, mortality and signs of toxicity. Pregnant females were observed for weight gain, signs of abortion, dystocia and prolonged duration of pregnancy. Parameters examined in all male parental generations include testis weight, sperm count in testes and cauda epididymis. On Day 21 of pregnancy one-third of the females of each group were submitted to caesarean section. Resorption, implantation, as well as dead and live fetuses were counted. All fetuses were examined for external malformations, weighed and examined for skeleton evaluation. The remaining dams were allowed to give birth to their offspring. The progeny was examined at birth and subsequently up to postnatal Day 21. Mortality, weight gain and physical signs of postnatal development were evaluated.

 

An increase in liver and kidney weights were observed in male and female rats at 500 mg/kg bw/day but in the absence of associated pathology. No other sign of toxicity was noted in parental male and female rats exposed to β-myrcene. The test material did not affect the mating index or the pregnancy index. No sign of maternal toxicity and no increase in externally visible malformations were observed at any dose level. At the highest dose tested (500 mg/kg bw/day) an increased resorption rate and a higher frequency of fetal skeleton anomalies were reported. The latter was not considered to be treatment related but were attributed to an increase in spontaneous strain-specific findings. No adverse effect on postnatal weight gain was noted but days of appearance of primary coat, incisor eruption and eye opening were reported to be slightly delayed in exposed offspring; these minor developmental findings were not dose related however and were probably not related to treatment.

 

In conclusion, the no-observed-adverse-effect level (NOAEL) for toxic effects on fertility and general reproductive performance of β-myrcene by the oral route was reported to be 300 mg/kg bw/day in Wistar rats. The findings were not however clearly treatment or dose related and hence 300 mg/kg/day is considered to reflect a conservative NOAEL.



Short description of key information:
There are no studies on the effects of farnesene on fertility. The evaluation is based on read-across to data on the structurally related material β-myrcene. See read across justification section 13
The no-observed-adverse-effect level (NOAEL) for toxic effects on fertility and general reproductive performance of β-myrcene via oral route was reported to be 300 mg/kg bw/day in Wistar rats. The effects were however relatively minor, not dose related and probably reflect a conservative NOAEL.

Justification for selection of Effect on fertility via oral route:
Read across to β-myrcene. See read across justification section 13.
The reliability of Klimisch 2 is based on read across for a structural analogue compound, myrcene (CAS 123-35-3). The myrcene study report was conclusive and done following protocol similar to OECD 415 with minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Although a NOAEL of 300 mg/kg/day was reported by the study authors, the effects on delayed development were small, not dose related and probaly not treatment related. Hence the reported NOAEL is probably a conservative value.

Effects on developmental toxicity

Description of key information
No studies were identified on the developmental toxicity of farnesene. The key study was based on read across to the structurally related compound β-myrcene, which reported a no-observed-adverse-effect level (NOAEL) for maternal toxicity and for embryo-foetotoxicity of administered orally (gavage) of 500 mg/kg bw/day in Wistar rats.
Although a NOAEL of 500 mg/kg/day was reported by the study authors, the possibility that effects on delayed development reported at 1200 mg/kg/day were secondary to the severe maternal toxicity cannot be precluded. Hence the reported developmental NOAEL is probably a conservative value.
Link to relevant study records
Reference
Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The reliability is based on read across for a structural analogue compound, myrcene (CAS 123-35-3). See read across justification section 13 The myrcene study report was conclusive and done following protocol similar to OECD 414 with minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Justification for type of information:
Myrcene and Farnesene have similar chemical structures and therefore are expected to have similar physical/chemical characteristics. Thus, read across of myrcene data is a reasonable approach.
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
mating conditions (1 male for 3 females); food consumption not followed; bodyweight only recorded at Day 0, 6, 16 and 20 of gestation
GLP compliance:
not specified
Limit test:
no
Species:
rat
Strain:
Wistar
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Oswaldo Cruz Foundation Central Animal House breeding stock
- Housing: Housed in plastic cages with wood shavings as bedding
- Diet (e.g. ad libitum): Nuvital diet for laboratory animals, Nuvilab Ltd, Curitiba, Brazil; ad libitum
- Water (e.g. ad libitum): Tap water; ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-23 °C
- Photoperiod (hours dark / hours light): 12 hours dark / 12 hours light
Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Test material was dissolved in corn oil
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
None
Details on mating procedure:
Impregnation procedure: Cohoused
- If cohoused:
- M/F ratio per cage: 1:3
- Length of cohabitation: 2 h
- Proof of mating: Sperm in vaginal smear referred to as Day 0 of pregnancy
Duration of treatment / exposure:
10 days (Day 6-15 of pregnancy)
Frequency of treatment:
once daily
Duration of test:
20 days
Dose / conc.:
0 mg/kg bw/day
Dose / conc.:
250 mg/kg bw/day
Dose / conc.:
500 mg/kg bw/day
Dose / conc.:
1 200 mg/kg bw/day
No. of animals per sex per dose:
Treated females: 22-36; pregnant females: 16-29
Control animals:
yes, concurrent no treatment
Details on study design:
Control animals: as no statistically significant difference was found between the untreated and the vehicle treated control animals, in any of the parameters analysed, the data of both groups were pooled and were thereafter designated the control group.
Maternal examinations:
BODY WEIGHT: Yes
- Time schedule for examinations: Days 0, 6, 16 and 20 of pregnancy
Ovaries and uterine content:
The uterine content was examined after termination: Yes, animals were sacrificed on Day 20 for caesarean examinations
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of living and dead foetuses: Yes
- Number of implantations: Yes
- Number of resorptions: Yes
Fetal examinations:

- External examinations: Yes [all living foetuses]; weighed and examined for externally visible malformations
- Soft tissue examinations: Yes [5-7 litters per group]: evaluated for visceral malformations; heart, lungs, thymus, liver, spleen and kidneys were weighed and microdissected
- Skeletal examinations: Yes [all the remaining litters]
Statistics:

- Statistical analysis was by one way analysis of variance or, alternatively, by the Kruskal-Wallis test whenever the data did not fit a normal distribution
- Statistically significant differences between groups were tested by using a two sided Student's t-test or the Mann-Whitney U-test
- Proportions were analysed by the chi-square test
- Difference was considered to be statistically significant at P < 0.05
Indices:
na
Historical control data:
na
Details on maternal toxic effects:
Maternal toxic effects:yes. Remark: significant decreased body weight gain (1200 mg/kg)

Details on maternal toxic effects:
At 250 and 500 mg/kg bw /day: No treatment-related effects

At 1200 mg/kg bw/day:
- Mortality: 1/29 dams died on Day 11 of pregnancy
- Body weights: Statistically significant decrease in weight gain during days 6-11 of pregnancy (17.3 ± 7 g vs. 3.2 ± 13.2 g in control vs. 1200 mg/kg group, respectively)
- Cesarean examination: Number of visible implantation sites was significantly reduced (12.6 ± 2.2 vs. 10.2 ± 2.9 in control vs. 1200 mg/kg group, respectively)
Dose descriptor:
NOAEL
Effect level:
500 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:

- Body weight: Treatment-related effects on foetal weight were only very slight, or even insignificant, if the litter is taken as the statistical unit of analysis
- External examinations: Increased frequency of irregularly positioned hind paws was observed in 1200 mg/kg bw/day group
- Visceral examinations: Visceral malformations such as enlarged ureters associated with an enlarged renal pelvis (one control foetus and one in 1200 mg/kg group), shorter ureter (one control foetus and one in 250 mg/kg bw/day group) and accessory (seventh) lobe in the liver (three foetus in 250 mg/kg bw/day group)
- Skeletal examinations: Increased incidence of delayed ossification and minor gross structural anomalies in the foetal skeleton were observed in 1200 mg/kg bw/day group
Dose descriptor:
NOAEL
Effect level:
500 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Developmental toxicity
Abnormalities:
effects observed, treatment-related
Localisation:
other: signs of retardation and of anomalies in the foetal skeleton observed at 1200 mg/kg bw/day
Developmental effects observed:
yes
Lowest effective dose / conc.:
1 200 mg/kg bw/day
Treatment related:
yes
Relation to maternal toxicity:
not specified
Dose response relationship:
not specified
Relevant for humans:
not specified

Table 1. Occurrence of delayed ossification in foetuses of rats treated orally with β-myrcene on Days 6-15 of pregnancy

 

β-Myrcene (mg/kg bw)

Treatment

0

250

500

1200

Foetuses examined (no.)

114

106

116

209

Percentage of foetuses with signs of delayed ossificationαin:

Skull bones

4.4

0.9

3.4

9.6*

Caudal vertebrae

7

2.8

6

37.8*

Forelimbs/metacarpus

2.6

0

0.9

9.1*

Hind limbs/metatarsus

5.3

2.8

3.4

29.2*

αSigns of delayed ossification: not ossified (whole bone is not stained), poorly ossified (whole bone is poorly stained), and irregular spongy bones.

* P < 0.05; chi-square test

Conclusions:
In a read-across study, the no-observed-adverse-effect level (NOAEL) for maternal toxicity and for embryo-foetotoxicity of β-myrcene administered orally (gavage) was reported to be 500 mg/kg bw/day in Wistar rats.
Executive summary:

A study was conducted to evaluate the embryo-foetotoxic potential of β-myrcene in the Wistar rats similarly to OECD Guideline 414.

β -Myrcene (250, 500 and 1200 mg/kg bw/day) in corn oil was given orally to Wistar rats from Day 6 to 15 of pregnancy. Two control groups, one received vehicle only and another without treatment, were also studied simultaneously. All rats were weighed on Day 0, 6, 16 and 20 of pregnancy. Caesarean sections were performed on Day 20 of pregnancy, and the number of resorptions and implantation sites were recorded. Foetuses were weighed and examined for external, visceral and skeletal malformations.

A significant effect (decrease) on maternal body weight gain (~ 82%%) was seen during gestation days 6 to 11, at 1200 mg/kg. There was also an increased incidence of delayed foetal ossification in the 1200 mg/kg dose group. At lower dose levels no maternal or foetal effects were observed that were considered to be related to treatment. The possibility that the delay in skeletal ossification seen in foetuses at 1200 mg/kg may have been caused indirectly by the significant maternal toxicity cannot be precluded.

In conclusion, the no-observed-adverse-effect level (NOAEL) for maternal toxicity and for embryo-foetotoxicity of β -myrcene administered orally (gavage) was reported to be 500 mg/kg bw/day in Wistar rats. This effect may however have arisen due to the significant maternal toxicity seen at 1200 mg/kg, rather than due to a direct effect of myrcene.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
500 mg/kg bw/day
Study duration:
chronic
Species:
rat
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 read-across study, β -Myrcene (250, 500 and 1200 mg/kg bw/day) in corn oil was given orally to Wistar rats from Day 6 to 15 of pregnancy. Two control groups, one received vehicle only and another without treatment, were also studied simultaneously. All rats were weighed on Day 0, 6, 16 and 20 of pregnancy. Caesarean sections were performed on Day 20 of pregnancy, and the number of resorptions and implantation sites were recorded. Foetuses were weighed and examined for external, visceral and skeletal malformations.

A significant effect (decrease) on maternal body weight gain (~ 82%%) was seen during gestation days 6 to 11, at 1200 mg/kg. There was also an increased incidence of delayed foetal ossification in the 1200 mg/kg dose group. At lower dose levels no maternal or foetal effects were observed that were considered to be related to treatment. The possibility that the delay in skeletal ossification seen in foetuses at 1200 mg/kg may have been caused indirectly by the significant maternal toxicity cannot be precluded.

In conclusion, the no-observed-adverse-effect level (NOAEL) for maternal toxicity and for embryo-foetotoxicity of β -myrcene administered orally (gavage) was reported to be 500 mg/kg bw/day in Wistar rats. Although a NOAEL of 500 mg/kg/day was reported by the study authors, the possibility that effects on delayed development reported at 1200 mg/kg/day were secondary to the severe maternal toxicity cannot be precluded. Hence the reported developmental NOAEL is probably a conservative value.


Justification for selection of Effect on developmental toxicity: via oral route:
Read across to β-myrcene.
The reliability of Klimisch 2 is based on read across for a structural analogue compound, myrcene (CAS 123-35-3). The myrcene study report was conclusive and done following protocol similar to OECD 414 with minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.
Although a NOAEL of 500 mg/kg/day was reported by the study authors, the possibility that effects on delayed development reported at 1200 mg/kg/day were secondary to the severe maternal toxicity cannot be proecluded. Hence the reported developmental NOAEL is probably a conservative value.

Justification for classification or non-classification

The no-observed-adverse-effect level (NOAEL) for toxic effects on fertility and general reproductive performance of β-myrcene via oral route were reported to be 300 mg/kg bw/day in Wistar rats. It is not clear from the data presented whether the findings were caused by treatment with myrcene.

The no-observed-adverse-effect level (NOAEL) for maternal toxicity and for embryo-foetotoxicity of β-myrcene administered orally (gavage) was reported to be 500 mg/kg bw/day in Wistar rats. Significant maternal toxicity was evident at 1200 mg/kg and hence the possibility that this may have caused embryo-foetotoxicity cannot be precluded.

It is considered that the data available do not meet the criteria for classification as toxic to reproduction.

Additional information