Dodecene

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type (migrated information)

Type of information:

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

Adequacy of study:

key study

Study period:

2002-06-11 to 2002-10-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

This study is classified as reliable without restrictions because the study was compliant with GLPs set forth by OECD [ENV/MC/CHEM(98)17, and the study design was based on OECD guideline 422. The study is well documented and scientifically acceptable.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

yes

Remarks:

No urinalysis was conducted.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Alkenes, C6-

EC Number:

271-208-9

EC Name:

Alkenes, C6-

Cas Number:

68526-52-3

IUPAC Name:

hex-3-ene

Details on test material:

This substance is very similar with regard to health endpoints to the substance being registered.
- Name of test material (as cited in study report): C6-Olefin/Hexene
- Substance type: Alkene C6
- Physical state: Liquid
- Analytical purity: 85.31%
- Impurities (identity and concentrations): Water (0.0065%), C4 and lights (0.12%), C5 hydrocarbon (13.06%), and C7 hydrocarbon (1.52%)
- Lot/batch No.: None provided
- Stability under test conditions: The compound is stable under the test conditions.
- Storage condition of test material: In a non-flammable cabinet at ambient conditions.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Portage, Michigan and Raleigh, North Carolina
- Age at study initiation: (P) approximately 11 wks
- Weight at study initiation: (P) Males: 237 to 296 grams; Females: 170 to 226 grams; weights were obtained on the day after receipt
- Housing: Individually except during mating
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: 17 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 to 26
- Humidity (%): 41% to 53%
- Air changes (per hr): 10 to 15
- Photoperiod (hrs dark / hrs light): 12 hours dark/12 hours light

IN-LIFE DATES: From:2002-06-11 To:2002-08-08

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: A specific amount of test compound was weighed into a precalibrated beaker. A sufficient amount of corn oil was added to the beaker to achieve the desired concentration and the solution was stirred for 30 minutes. The dose formulations were prepared twice during the first week and weekly thereafter. Dose solutions were stirred continuously prior to and during dosing.


VEHICLE
- Justification for use and choice of vehicle (if other than water): None provided.
- Concentration in vehicle: 0, 20, 100, or 200 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg
- Lot/batch no. (if required): RE1547
- Purity: Not reported

Details on mating procedure:

- M/F ratio per cage: One to one
- Length of cohabitation: 14 days
- Proof of pregnancy: Vaginal plug or sperm in vaginal smear referred to as day 0 of pregnancy
- After 14 days of unsuccessful pairing the mating phase was concluded.
- After successful mating each pregnant female was caged (how): Individual plastic boxes with nesting material on gestational day 18

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The test solution was determined to be homogeneous and stable for at least 14 days. The first, third, fifth, seventh, and final dose preparation were tested for concentration verification. The concentrations were found to be within acceptable ranges and were within 15% of the nominal concentration.

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

Daily

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 100, 500, or 1000 mg/kg/day
Basis:
nominal conc.

No. of animals per sex per dose:

Twelve animals per sex per dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The doses were selected to produce a graded response, but there was no rationale as to why these specific doses were selected.
- Rationale for animal assignment (if not random): Animals were randomly assigned based on body weights.

Positive control:

None

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Once daily
- Cage side observations checked for overt signs of toxicity.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Weekly and on day of sacrifice

BODY WEIGHT: Yes
- Time schedule for examinations:Days 0, 3, 7, 12, 16, 20, 23, 27, 30, and at sacrifice (day 34 for males and 38 for females).

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

WATER CONSUMPTION: No

OTHER: Haematology and clinical chemistry were conducted on blood collected at sacrifice as part of the short-term toxicity phase. An abbreviated functional battery observational test was conducted prior to study initiation and weekly thereafter as part of the short-term toxicity phase. Motor actiNity was also tested.

Oestrous cyclicity (parental animals):

Not determined

Sperm parameters (parental animals):

Not determined

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, presence of gross anomalies, weight gain

GROSS EXAMINATION OF DEAD PUPS:
yes, for external and internal abnormalities; 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 on day 34.
- Maternal animals: All surviving animals were sacrificed on lactational day 4.

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations including the cervical, thoracic, and abdominal viscera.

HISTOPATHOLOGY / ORGAN WEIGHTS
The tissues indicated in Table 1 were prepared for microscopic examination and weighed, respectively. However, histopathology was not routinely performed on the females in the reproduction phase of the study and was performed on the females in the short-term toxicity phase of the study.

Postmortem examinations (offspring):

SACRIFICE
- The F1 offspring were sacrificed at 4 days of age.

HISTOPATHOLOGY / ORGAN WEIGHTS: Histopathology and organ weights were not obtained on the offspring.

Statistics:

A one-way analysis of variance followed by Tukey-Kramel test or Dunnett's test was used on continuous data. Organ weight data was first checked for homogeneity with Levene's test. Non-parametric organ weight was analyzed using a Kruskal-Wallis followed by Dunn's test. Categorical data was analyzed using Fischer's exact test or RxC chi-square test followed

Reproductive indices:

Mating index, female fertility index, gestation index, deliveries with stillborn pups and with all stillborn pups, implantation sites, and corpora lutena

Offspring viability indices:

Live birth index, pups dying in the first 4 days of birth, viability index (pups surviving to day 4), live pups per litter, and pup weight

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

not examined

Food consumption and compound intake (if feeding study):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS): Four of the females had occasional salivation after dosing. There were no other treatment-related clinical signs and there was no treatment-related effect on mortality.


BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS):There was no treatment-related effect on body weight.


REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS): There were no treatment-related effects on reproductive performance.


ORGAN WEIGHTS (PARENTAL ANIMALS): Absolute kidney weight was increased in all groups of males and relative kidney weights were increased in the 500 and 1000 mg/kg/day groups. The increase in kidney weight is related to hydrocarbon nephropathy, which is specific for male rats and is not considered to be toxicologically significant. There were no other changes related to treatment.


GROSS PATHOLOGY (PARENTAL ANIMALS): There were no treatment-related changes in gross pathology.


HISTOPATHOLOGY (PARENTAL ANIMALS): The only histopathology changes related to treatment were associated with the hydrocarbon nephropathy in males. This is not considered toxicologically significant because the effect is specific to male rats.

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: overall effects

Results: F1 generation

General toxicity (F1)

Clinical signs:

not examined

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

VIABILITY (OFFSPRING): There was a statistically-significant decrease in the viability index in 500-mg/kg/day pups. This is not considered treatment-related as there was no dose response and the high-dose had a viability index comparable to the control.


CLINICAL SIGNS (OFFSPRING): There were no treatment-related effects.


BODY WEIGHT (OFFSPRING): There were no treatement-related effects.


GROSS PATHOLOGY (OFFSPRING): There were no treatment-related effects.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Based on the lack of significant adverse clinical effects, the systemic toxicity and reproductive toxicity NOAEL for C6 alkenes is 1000 mg/kg/day.

Executive summary:

Justification for Read Across

Several criteria justify the use of the read across approach to fill data gaps for single carbon number isomerised olefin substances using multiple carbon number isomerised olefin substance analogues. Studies indicate that changing the carbon number, the location of the double bond, or adding branching does not measurably alter the effects on mammalian health endpoints. There is a consistent toxicity potency pattern for isomerised olefins with a range of carbon numbers and they are considered to have minimal acute toxicity potential. Genotoxicity studies indicate that these materials are not mutagenic. No adverse systemic toxicity was observed in a 90-day repeated oral dose study in which rats were exposed to alkenes, C20-24. The toxicological profile of multiple carbon number isomerised olefins alkenes described above indicates a low hazard potential for human health. Since multiple carbon number isomerised olefins, alkenes is comprised of a mixture of single carbon number isomerised olefins, no significant toxicological differences are expected between the two categories of substance and read across between these two categories can be justified.

The potential reproductive/developmental effects of C6 alkenes, following oral administration were assessed in male and female rats. The test conditions complied with guideline requirements, and the statistical methods used were appropriate.

 

C6 alkenes dissolved in corn oil were administered via oral gavage to F0 male and female Sprague-Dawley rats at dose levels of 100, 500 and 1000 mg/kg/day for at least 4 weeks. For the reproduction phase of the study, males and females were mated after 14 days of treatment. Mating was allowed for 14 days if no evidence of pregnancy. Treatment continued until sacrifice with males sacrificed on day 34 and females sacrificed on lactation day 4.

 

There was no mortality observed in either male or female rats at any of the doses tested in the oral toxicity study. Besides post-dosing salivation at 1000 mg/kg, no significant signs of clinical toxicity were observed at any dose level. Functional observational evaluations revealed no significant differences between the treatment and control animals. Mean body weight, body weight gain, food consumption, haematology and clinical chemistry parameters were comparable to controls at all dose levels. Organ weight and gross necroscopy evaluations revealed no significant adverse effects subsequent to oral treatment with C6 alkenes.

 

There was no mortality or adverse signs of toxicity observed at any dose level in the reproductive/developmental toxicity screening study. F0 mating, fertility indices, mean gestation lengths, mean number of pups delivered, F1 live birth index, F1 viability index, F1 pups per litter, and F1 pup sex ratios were comparable between control and treatment groups.

 

Gross necroscopy of F0 females and F1 pups revealed no significant treatment-related findings. Organ weight determinations in F0 rats did not reveal any significant difference between treatment and control animals.

 

Based on the lack of significant adverse clinical effects, the systemic toxicity and reproductive toxicity NOAEL for C6 alkenes is 1000 mg/kg.

 

This study received a Klimisch score of 1 and is classified as reliable without restrictions because the study was compliant with GLPs set forth by OECD [ENV/MC/CHEM(98)17, and the study design was based on OECD guideline 422. This study will influence the DNEL.