2-chloropyridine

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented, according to accepted guidelines

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-chloropyridine

EC Number:

203-646-3

EC Name:

2-chloropyridine

Cas Number:

109-09-1

Molecular formula:

C5H4ClN

IUPAC Name:

2-chloropyridine

Details on test material:

- Name of test material (as cited in study report): Pyridine, 2-Chloro
- Physical state: Colourless liquid
- Analytical purity: 99.7%
- Lot/batch No.: 2RC328562
- Expiration date of the lot/batch: 07 April 2004
- Storage condition of test material: Stored in the dark at ambient room temperature

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 (UK) Limited, Margate, Kent, England
- Age at study initiation: Approximately 8 weeks
- Weight at study initiation: 144-171 g (males) and 103-128 g (females) on arrival
- Housing: 2/cage initially in polypropylene cages with stainless steel grid bottoms. A few days prior to mating, males were transferred to individual grid-bottomed cages of similar design. Mated females were transferred to individual solid bottomed cages.
- Diet (e.g. ad libitum): Rat and Mouse Breeder Diet No. 3 SQC (Special Diets Services Ltd., Stepfield, Witham, Essex) ad libitum
- Water (e.g. ad libitum): Domestic mains water ad libitum
- Acclimation period: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ºC ± 2 ºC
- Humidity (%): 50% ± 15%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 hours:12 hours

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

maize oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Prepared by adding appropriate weighed quantities of test item to measured volumes of a vehicle (maize oil) and mixing by manual inversion and sonication until visibly homogenous.

Details on mating procedure:

- M/F ratio per cage: 1:1 within the same treatment group
- Length of cohabitation: Maximum of 7 consecutive nights
- Proof of pregnancy: vaginal plug/sperm in vaginal smear referred to as day 0 of gestation

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples of dosing formulations were analysed with regard to concentration and homogeneity. From Day 1 formulations and during Weeks 3 and 6, triplicate samples of dosing formulation (1 mL) were taken immediately after preparation and stored at 4 ºC prior to analysis at Inveresk.

Duration of treatment / exposure:

Males = at least 4 weeks.
Females = treated until termination, commencing 2 weeks prior to mating, then through mating until termination after Day 4 of lactation.

Frequency of treatment:

Once/day, 7 days/week

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 3, 15, or 60 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

10/sex/group

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Doses were selected following evaluation of existing toxicological data.

Positive control:

Not required.

Examinations

Parental animals: Observations and examinations:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Every day

BODY WEIGHT: Yes
- Time schedule for examinations: Once during the week prior to the commencement of dosing and once weekly up until Day 10 of the study, and then daily thereafter until termination (males). Once during the week prior to the commencement of dosing and weekly up until day 10 of the study, and then daily thereafter (females). On the day of detection of a positive mating sign (Day 0 of gestation) weights were recorded, followed by Days 7, 14, and 20 of gestation, and then Days 1 and 4 of lactation (where Day 0 = the day of parturition).

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): Yes
- Time schedule for examinations: Visual inspection of the water bottles on a weekly basis throughout the study.

Oestrous cyclicity (parental animals):

Not examined.

Sperm parameters (parental animals):

Not examined.

Litter observations:

The females were allowed to litter normally. The day on which parturition commenced was designated Day 0 of lactation. The number of live pups born and the number found dead in each litter was recorded as soon as possible after completion of parturition. The live pups were sexed, counted, examined for the presence of milk in the stomach and for any externally visible abnormalities daily until Day 4 of lactation.

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals following 4 weeks of treatment.
- Maternal animals: All surviving animals between Day 4 and Day 7 of lactation.

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

HISTOPATHOLOGY / ORGAN WEIGHTS: Conducted on control and high-dose animals only.

Postmortem examinations (offspring):

Pups were examined for externally visible abnormalities.

Statistics:

ANOVA, Kruskal-Wallis, analysis of covariance, and Disher's Eact Probability test were used.

Reproductive indices:

Reproductive indices that were examined included fertility index (males and females), gestation index, birth index, live birth index, and viability index.

Offspring viability indices:

Viability = Number of live pups on Day 4 of lactation ÷ Number of live pups on Day 0 of lactation.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

not examined

Other effects:

not examined

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): At 60 mg/kg bw/day, signs were noted on the first day of dosing in all/most animals. These findings included subdued behaviour, and/or slow respiration. Other findings noted in both sexes included salivation, clear discharge around eyes, wet discharge around the nose, staining of the coat, piloerection, and decreased faeces. In addition, in females, hunched posture, reduced activity, eyes partially closed, and rolling gait were noted. At 15 mg/kg bw/day, salivation was noted in 3/10 females.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS): At 60 mg/kg bw/ayd, there was a notable reduction in weight gain in both sexes following the first week of treatment. There was a marginal decrease in weight gain mid-gestation.

ORGAN WEIGHTS (PARENTAL ANIMALS): A statistically significant, dose-related increase in liver weights in both sexes was noted at 15 and 60 mg/kg bw/d.

GROSS PATHOLOGY (PARENTAL ANIMALS): Enlarged liver was noted in 3/10 males at 15 mg/kg bw/day and in 10/10 males at 60 mg/kg bw/day. The livers for these animals were not examined histologically.

OTHER FINDINGS (PARENTAL ANIMALS): Decreased food consumption was evident at 60 mg/kg bw/day following one week of treatment and was considered to be associated with the decreased faecal output noted in all animals.

Effect levels (P0)

1

Dose descriptor:

NOAEL

Effect level:

3 mg/kg bw/day (actual dose received)

Sex:

male

Basis for effect level:

other: Based on statistically significant dose-related increases in liver weight at 15 and 60 mg/kg bw/day and an increase only in relative liver weights at 3 mg/kg bw/day.

2

Dose descriptor:

NOEL

Effect level:

3 mg/kg bw/day (actual dose received)

Sex:

female

Basis for effect level:

other: Based on statistically significant dose-related increases in liver weights at 15 and 60 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:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

VIABILITY (OFFSPRING): A slight decrease in pup survival was noted at 60 mg/kg bw/day; however, this decrease in survival was noted by the study authors to be mainly due to the loss of 2 litters.

Effect levels (F1)

Dose descriptor:

NOEL

Generation:

F1

Effect level:

15 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: Based on a slight decrease in pup survival at the high-dose of 60 mg/kg bw/day.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

The NOAELs were 3 and 15 mg/kg bw/day in male and female parents and pups, respectively, following oral (gavage) administration of 2 -CP.