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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
screening for reproductive / developmental toxicity
Remarks:
based on test type (migrated information)
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
1993-12-03 to 1994-08-26
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study is classified as reliable without restrictions because it was conducted according to OECD 421 guidelines and was GLP compliant.
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report Date:
1995

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)
Deviations:
no
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): The test material was composed of equal amounts of Neodene 6 alpha olefin (component A), hexene-1 Gulftene 6 (component B), and alpha olefin C6 1-hexene (component C).
- Substance type: C6 alpha olefin
- Physical state: Clear, colourless liquid
- Analytical purity: Approximately 99%
- Lot/batch No.: 20202-45-1049 (component A), CBN0044 (component B), and 300-974 (component C)
- Expiration date of the lot/batch: December, 1994 (component A), others not provided
- Storage condition of test material: Under nitrogen at room temperature

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Inc., Portage, Michigan
- Age at study initiation: (P) x males were 6 weeks old and females were 8 weeks old; F1 not treated
- Weight at study initiation: (P) Males: 195 to 242 grams; Females: 163 to 219 grams; F1 not treated
- Fasting period before study: No
- Housing: Individually except during mating
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: 11 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 23 °C
- Humidity (%): 35 to 65%
- Air changes (per hr): 10 to 12
- Photoperiod (hrs dark / hrs light): 12 hours dark/ 12 hours light

IN-LIFE DATES: From: 1994-02-11 To: 1994-05

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: After stirring the blended test material for 15 minutes, a specified amount of test material was added to a flask with half of the corn oil. The flasks were capped and inverted several times, then the remaining corn oil was added and the procedure repeated. The solution was then stirred for 15 minutes. Fresh preparations were made bi-weekly.

VEHICLE
- Concentration in vehicle: 0, 20, 100, or 200 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg
- Lot/batch no. (if required): APR0695A, Oct0494A, Jun2695A, and Dec2194A
Details on mating procedure:
- M/F ratio per cage: 1 to 1
- Length of cohabitation: 15 days
- Proof of pregnancy: Vaginal plug or sperm in vaginal smear referred to as day 0 of pregnancy
- After 10 days of unsuccessful pairing replacement of first male by another male with proven fertility for a maximum of 5 days.
- Further matings after two unsuccessful attempts: No
- After successful mating each pregnant female was caged (how): Individual boxes containing nesting materials
- Any other deviations from standard protocol: None
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Homogeneity of the dose formulation was checked from upper, middle, and lower layers of 20 and 200 mg/mL samples. The dose formulation was found to be homogeneous. The stability of the dose formulation was tested on 20 and 200 mg/mL samples stored in the fridge for 3, 8, or 15 days. The samples were found to be stable for at least 15 days. Verification of the 0, 20, 100, and 200 mg/mL dose formulations prepared during week 1, 3, 5, 7, and 9 were conducted. All dose formulations were found to be within 10% of the nominal concentration.
Duration of treatment / exposure:
Males: 44 days starting 28 days prior to mating
Females: 41 to 55 days starting 14 days prior to mating through lactation day 4
Frequency of treatment:
Daily
Details on study schedule:
F1 animals were not mated
Doses / concentrations
Remarks:
Doses / Concentrations:
100, 500, or 1000 mg/kg/day
Basis:
actual ingested
5.0 mL/kg of dose formulations of 20, 100, or 200 mg/mL were used
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: A non-reproductive dose range finding study
Positive control:
None

Examinations

Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: No

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once daily, mortality was checked twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: Weekly in males; weekly in females prior to mating, then on gestational days 0, 7, 14, and 20 and lactation days 1 and 4

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No
Oestrous cyclicity (parental animals):
Not examined
Sperm parameters (parental animals):
Parameters examined in P male parental generations: Testis weight and epididymis weight and histopathology
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


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 after 43 days of dosing.
- Maternal animals: All surviving animals on day 4 of lactation or in females that failed to deliver, 25 days after evidence of mating detected.

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

HISTOPATHOLOGY / ORGAN WEIGHTS: The brain and ovaries were weighed in females. The ovaries, lungs, liver, kidneys, sciatic nerve, and gross lesions were examined histologically. The brain, testes, and epididymides were weighed in males. The testes, epididymides, accessory sex organs, liver, kidneys, sciatic nerve, and gross lesions were examined histologically.
Postmortem examinations (offspring):
SACRIFICE: All F1 animals were sacrificed on lactation day 4.
- These animals were subjected to postmortem examinations macroscopic examination as follows:

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

Statistics:
A one-way ANOVA followed by Dunnett's test or a chi-square test
Reproductive indices:
Fertility, gestation, parturition, and lactation
Offspring viability indices:
Live and dead pups, number of litters with live offspring, mean live litter size, male to female ratio, and the number of survivors

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
no effects observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Other effects:
not specified

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): There were no clinical signs or mortality.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS): There were no treatment-related changes in body weight.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS): Reproductive performance was not affected.

ORGAN WEIGHTS (PARENTAL ANIMALS): There was a slight, but significant, decrease in absolute epididymal weight at all concentrations. The relative epididymal to brain weight was only significantly decreased in the low dose group. In addition, there was no dose response; therefore, the significance of this data is not clear.

GROSS PATHOLOGY (PARENTAL ANIMALS): Pitted kidneys were observed at necropsy for 2 of 12 mid-dose males (500 mg/kg/day) and 3 of 12 high-dose males (1000 mg/kg/day).

HISTOPATHOLOGY (PARENTAL ANIMALS): There was a dose-related increase in large hyaline droplets in the proximal converted tubule.

Effect levels (P0)

Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: lack of reproductive, developmental, or systemic effects

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
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 were no effects on viability.


CLINICAL SIGNS (OFFSPRING): There were no clinical signs of toxicity in the offspring.


BODY WEIGHT (OFFSPRING): There were no changes in body weight.



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


Effect levels (F1)

Dose descriptor:
NOAEL
Generation:
F1
Effect level:
1 000 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: lack of developmental effects

Overall reproductive toxicity

Reproductive effects observed:
not specified

Any other information on results incl. tables

The presence of large hyaline drops noted in the kidneys of paternal males suggests hydrocarbon nephropathy, which is a toxicological effect specific to male rats and is not considered a biologically relevant endpoint in humans. Therefore, this endpoint is excluded in determining the NOAEL. Although the absolute epididymides weight was significantly decreased in parental males; the change was within 10% of the control, there was no dose response, there was no effects noted microscopically, and there were no effects on fertility. Therefore, this is not considered to be toxicologically significant.

Applicant's summary and conclusion

Conclusions:
The NOAEL for systemic, reproductive, and developmental toxicity was reported as 1000 mg/kg/day, which excluded the hydrocarbon nephropathy noted in males.
Executive summary:

In this screening for reproductive/developmental toxicity study, 1 -hexene was administered via gavage to twelve Sprague-Dawley rats/sex/dose at doses of 0, 100, 500, or 1000 mg/kg/day. The test material was composed of equal amounts of Neodene 6 alpha olefin, hexene-1 Gulftene 6, and alpha olefin C6 1 -hexene, which were obtained from different sources. Males were treated for 44 days beginning 28 days prior to mating and females were treated for 41 to 55 days beginning 14 days prior to mating through lactation day 4.

No reproductive or developmental effects were observed. There was a slight, but significant, decrease in absolute epididymal weight at all concentrations. The relative epididymal to brain weight was only significantly decreased in the low-dose group. Although the absolute epididymides weight was significantly decreased in parental males; the change was within 10% of the control, there was no dose response, there was no effects noted microscopically, and there were no effects on fertility. Therefore, this is not considered to be toxicologically significant. Pitted kidneys were observed at necropsy for 2 of 12 mid-dose males and 3 of 12 high-dose males. The predominant microscopic finding in males was the presence of large hyaline droplets in the proximal convoluted tubule that was dose related. These findings suggest hydrocarbon nephropathy, which is a toxicological effect specific to male rats and is not considered relevant to humans. There was no LOAEL for this study. The NOAEL for systemic, reproductive, and developmental toxicity was 1000 mg/kg/day, which excluded the hydrocarbon nephropathy in males.

This study received a Klimisch score of 1 and is classified as reliable without restrictions because it was conducted according to OECD 421 guidelines and was GLP compliant.