2-chloropyridine

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

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 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

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
- Stability under test conditions: Stability data indicates an 8-day shelf life
- 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 6 weeks
- Weight at study initiation: 79-94 g (males) and 70-86 g (females) at arrival
- Housing: 1/cage by sex and dose group in suspended polypropylene cages with stainless steel grid tops
- Diet (e.g. ad libitum): Rat and Mouse No. 1 Expanded SQC Diet (Special Diets Services Limited, 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 oral 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.

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 Week 4, triplicate samples of dosing formulation (1 mL) were taken immediately after preparation and stored in the dark at ambient temperature prior to analysis at Inveresk.

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

Once/day, 7 days/week

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 2, 10, or 45 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

5/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

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once during the pre-treatment week and weekly thereafter.

BODY WEIGHT: Yes
- Time schedule for examinations: Twice during the week prior to commencement of dosing, and then daily from the start of dosing.

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: Monitored by visual inspection of the water bottles on a weekly basis.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: During pre-trial and after approximately 4 weeks of dosing.
- Dose groups that were examined: All control and high-dose animals.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: During Week 4.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: During Week 4.

URINALYSIS: Yes

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: Once during the pre-treatment week (Week -1) and weekly thereafter
- Dose groups that were examined: All animals

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Statistics:

"F-max" test, ANOVA, Student's t-test, Fisher's Exact Probability, and Kruskal-Wallis ANOVA were used.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Behaviour (functional findings):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY: No premature deaths at any dose level. At 45 mg/kg bw/day, subdued behaviour was observed in all animals on the first day of treatment. Other findings noted at the onset of treatment at this level included, but were not limited to, subdued behaviour, piloerection, irregular/slow respiration, clear discharge around eyes and partially closed eyes. The onset of all these signs generally occurred 2 hours after the dose and remained until the end of the working day when the last examination was made. In addition, at the 45 mg/kg bw/day level, salivation was evident in 5/5 males and 4/5 females, with staining around the mouth/muzzle in 4/5 males and 2/5 females.

BODY WEIGHT AND WEIGHT GAIN: At 45 mg/kg bw/d, weight loss was evident in all animals after one dose. From Day 2 of treatment, weight gain in both sexes was essentially comparable to that of the controls throughout the remainder of the study.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): At 45 mg/kg bw/d, there was a notable reduction in food consumption over Days 0to 4 of treatment in males and females; consumption thereafter was essentially similar to that of controls.

HAEMATOLOGY: A slight, statistically significant decrease in haemoglobin was noted in both sexes receiving 45 mg/kg bw/day. A marginal, but dose-related decrease in mean cell haemoglobin concentration in females attained statistical significance at 10 and 45 mg/kg bw/day. Red cell morphology generally demonstrated moderate to marked polychromasia, but in males treated at 45 mg/kg bw/day, marked polychromasia was seen in all animals.

CLINICAL CHEMISTRY: At 45 mg/kg bw/day, there was a statistically significant increase in total bilirubin and calcium in males. Increased total protein, albumin, and cholesterol levels achieved statistical significance in both sexes treated at 45 mg/kg bw/day and in males treated at 10 mg/kg bw/day.

NEUROBEHAVIOUR: Slight increases in piloerection (2/5 males and 2/5 females) and altered gait (4/5 males and 3/5 females) treated at 45 mg/kg bw/day. Slightly increased alertness was also observed in the arena especially in males at this level, but the opposite was true for the cage side observations. A slight, statistically significant increase was noted in the incidences of rearing in males treated at 45 mg/kg bw/day during Week 4 of the study and also a slight decrease in latency and a slight increase in number of sectors traversed.

ORGAN WEIGHTS: At 45 mg/kg bw/day, there was a statistically significant increase in liver weights in males and females and, at 10 mg/kg bw/day, an increase in liver weights was noted in females.

HISTOPATHOLOGY: NON-NEOPLASTIC: Centrilobular hypertrophy was noted in 1/5 males treated with 10 mg/kg bw/d and 4/5 males and 4/5 females treated with 45 mg/kg bw/d.

Effect levels

Dose descriptor:

NOEL

Effect level:

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

Sex:

male/female

Basis for effect level:

other: Based on increases in plasma levels of total bilirubin, albumin, and cholesterol, as well as an increase in centrilobular hypertrophy and increased liver weight at 10 and 45 mg/kg bw/day.

Target system / organ toxicity

Critical effects observed:

not specified