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

Toxicity to reproduction

Administrative data

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.

Cross-reference

Reason / purpose for cross-reference:

read-across: supporting information

Reference

Endpoint:

one-generation reproductive toxicity

Remarks:

based on test guideline

Type of information:

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

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 source

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.

Data source

Reference

Reference Type:

publication

Title:

Study of the effects of beta-myrcene on rat fertility and general reproductive performance

Author:

Paumgartten FJ, De-Carvalho RR, Souza CA, Madi K, Chahoud I.

Year:

1998

Bibliographic source:

Brazil J Med Biol Res., 31 (7

Materials and methods

Test guideline

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

Test material

Test material information

Constituent 1

Reference substance name:

7-methyl-3-methyleneocta-1,6-diene

EC Number:

204-622-5

EC Name:

7-methyl-3-methyleneocta-1,6-diene

Cas Number:

123-35-3

Molecular formula:

C10H16

IUPAC Name:

1,​6-​Octadiene, 7-​methyl-​3-​methylene-

Constituent 2

Reference substance name:

beta-myrcene

IUPAC Name:

beta-myrcene

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): beta-myrcene
- Molecular formula (if other than submission substance): C10H16
- Molecular weight (if other than submission substance): 136.24
- Smiles notation (if other than submission substance): See attached
- Structural formula attached as image file (if other than submission substance): see attached
Name of test material (as cited in study report): β-Myrcene
- Name of test material (as cited in study report): β-myrcene
- Source: Sigma Chemical Co., St. Louis, MO
- Analytical purity: 95% (by methanol extraction and HPLC purification)

Test animals

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

Administration / exposure

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

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0 mg/kg bw
Basis:
actual ingested

Doses / concentrations 2

Remarks:

Doses / Concentrations:
100 mg/kg bw
Basis:
actual ingested

Doses / concentrations 3

Remarks:

Doses / Concentrations:
300 mg/kg bw
Basis:
actual ingested

Doses / concentrations 4

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

Examinations

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

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

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 / performance (P0)

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Details on results (P0)

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

Effect levels (P0)

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

Results: F1 generation

General toxicity (F1)

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

Details on results (F1)

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.

Effect levels (F1)

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

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

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).

Applicant's summary and conclusion

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.