(E)-7,11-dimethyl-3-methylenedodeca-1,6,10-triene

Endpoint summary

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 ossification^αin:
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.