2-fluoro-6-trifluoromethylpyridine

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

428-100-3

EC Name:

-

Cas Number:

94239-04-0

Molecular formula:

C6H3NF4

IUPAC Name:

2-fluoro-6-(trifluoromethyl)pyridine

Details on test material:

- Purity: 99.8%

Specific details on test material used for the study:

Substance ID: F6TF
Purity: 99.56%

Test animals

Species:

rat

Strain:

other: Sprague Dawley (SD) strain ( SPF grade)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 5 weeks
- Weight at study initiation: 141-112 g for the males and 133-118 g for the females
- Housing: 2 rats for each cage were housed in suspended metal. cages (L32 X W28 X H20 cm) with stainless steel mesh at the front and floors
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-25°C
- Humidity (%): 30-70%
- Air changes (per hr): 10-20 times/hour
- Photoperiod (hrs dark / hrs light): illumination: 150-300 Lux, 12 hours of light and 12 hours of dark

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

PREPARATION OF TEST SUBSTANCE FORMULATION: For the treated groups, the test substance was mixed with a part of the basal diet in a beaker, and the mixture was put into the rest of basal diet for further mixing by mixer for 20 minutes, then put into stainless steel barrel with lid.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

Daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

500 mg/kg diet

Doses / concentrations 2

Dose / conc.:

2 500 mg/kg diet

Doses / concentrations 3

Dose / conc.:

12 500 mg/kg diet

No. of animals per sex per dose:

16/sex at 0 and 12500 mg/kg (for which 6/sex served as recovery animals)
10/sex at 500 and 2500 mg/kg

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure recovery period in satellite groups: 2 weeks

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: once daily for mortality and moribundity

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Clinical examinations were performed daily

BODY WEIGHT: Yes
- Time schedule for examinations: Weekly

FOOD CONSUMPTION: Yes/No
- Time schedule for examinations: Weekly

FOOD EFFICIENCY: Yes
- The quantity of food given was weighed at day 6, and the quantity of food that remained was weighed at day 7, weekly. Then food consumption and food efficiency were calculated. Food efficiency was calculated as the amount of food consumed per unit of body weight gain. Overall calculations were also performed for 1-13 weeks and 1-15 weeks. Achieved intake of test substance was calculated, based on the food consumption, body weight of each animal and target concentration of each group.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Study week 13 and Study week 15 (recovery)
- Anaesthetic used for blood collection: Yes
- Animals fasted: Yes
- How many animals: All animals
- Parameters checked in table No. 1 were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Study week 13 and Study week 15 (recovery)
- Animals fasted: Yes
- How many animals: All animals
- Parameters checked in table No. 2 were examined.

URINALYSIS: Yes
- Time schedule for collection of urine: Study week 13 and Study week 15 (recovery)
- Parameters checked in table No. 2 were examined.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table No. 3)
HISTOPATHOLOGY: Yes (see table No. 3)

After 13 weeks (end of treatment phase) and 15 weeks (end of 2-week recovery phase), detailed necropsy was performed on all animals. Histopathological examination was performed on animals in the control and high (12500 mg/kg) dose groups.

Statistics:

Bodyweight, food consumption, food efficiency, haematology, blood chemistry, mean organ weights and organ weight to bodyweight ratio were analyzed by Bartlett's for homogeneity of variance. The data with homogeneity pattern of variance (p>0.05) were compared using One-way Analysis of Variance (ANOVA); The data with heterogeneous pattern of variance (p≤0.05) were compared using the Kruskal-Wallis test. If result of Analysis of Variance test was significant differences (p≤0.05) between each treated group and control group, and using Dunnett's test; otherwise, end test. If result of the Kruskal-Wallis test was significant differences (p≤0.05), then using Dunnett's no parameter test, or else end test. The data of urinalysis was analyzed by Mann-Whitney U-test.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weight of male and female rats in the 12500 mg/kg diet group was lower than that of the control group during treatment period, and the gross mean body weight gain in 1-13 weeks decreased 7.6% for the female and 7.3% for the male rats, but no showed statistically significant difference (P>0.05).
The body weight gain of male and female rats was high in the recovery observation group (in the 12500 mg/kg diet group) compared with control group from 13 to 15 week, and the body weight gain were 33% for the female and 55% for the male rats more than this control group

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Amounts of food consumed of every treated group were compared with those of the control group the mean intakes were lower from week 1 to week 13 for male and female rats in 12500 mg/kg diet group, and statistical significance was seen (p≤0.01). The mean intakes were also lower compared with those of the control group from week 13 to week 15 for male and female rats in recovery observation group (in the 12500 mg/kg diet groups).

Food efficiency:

no effects observed

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Test results of the males and females in the 12500 mg/kg diet group were higher or lower compared with the control group. However, they were not considered treatment related, since the change was slight and was in normal value ranges. Each index of male and female rats in recovery observation group (in the 12500 mg/kg diet groups) was also in normal value ranges.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

TP, ALB, GLB, CHO and GGT were high for male and female rats and T-BIL was high for males in high dose groups compared with the control group and showed statistically significant differences (p≤0.05 or p≤0.01). There were dose-related changes and over normal value ranges, so these findings were attributable to the treatment. However, male and female rats of other dose groups did not shown changes related to treatment. Each index of male and female rats in recovery observation group (in the 12500 mg kg diet group) had decreased difference than those values of control group.

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Absolute and relative weights of liver and kidney for male and female rats in the 12500 mg/kg diet group were higher, and showed statistically significant differences (p < 0.05 or p < 0.01) compared with the control groups. They were over normal value ranges and there were dose-related changes that were considered to be attributable to the test substance. At the end of the recovery observation period, differences were lower, indicating a recovery trend. High dose group others index and absolute weights and relative weights of liver and kidney in the middle dose group male rats were also higher and showed statistically significant differences (p≤0.05 or p≤0.01) compared with the control group; however, these values were within the normal range and were not considered to be attributable to toxicity effect of the test substance. The test results for male and female rats in lower dose groups did not display abnormity changes compared with the control group.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Testes atrophy was found in one male rat in the 12500 mg/kg diet group. The results of autopsy of other dose group rats did not show abnormality changes.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Renal tubule basophilic change, thymus local abscess for 1 case, respectively, and 2 cases of renal mineral deposit were found in the control group; 2 cases of renal mineral deposit and testis tubular denaturalization were found in the high dose group.

Histopathological findings: neoplastic:

no effects observed

Effect levels

Key result

Dose descriptor:

NOEL

Effect level:

2 500 mg/kg diet

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

food consumption and compound intake

gross pathology

haematology

histopathology: non-neoplastic

organ weights and organ / body weight ratios

Remarks on result:

other: This NOEL corresponds to 218.8 and 246.9 for males and females, respectively

Applicant's summary and conclusion

Conclusions:

13 Week Rat Male NOEL = 2500 mg/kg diet (corresponds to 218.8 mg/kg bw/day)
13 Week Rat Female NOEL = 2500 mg/kg/day (corresponds to 246.9 mg/kg bw/day)

Executive summary:

A 13 week oral toxicity study was carried out in male and female Sprague Dawley rats by feeding a diet containing 0, 500, 2500, 12500 mg/kg diet, with an additional recovery observation group (0 and 12500 mg/kg diet) according to the guideline OECD 408. Animals were observed for clinical symptoms of toxicity, and the body weight and food consumption were weighed periodically during the treatment. Laboratory examinations including organ weight measurement, autopsy, urinalysis, histopathological, haematological, and blood biochemistry examinations were carried out after 13weeks of treatment and the end of the 2-week recovery period. The group mean food efficiency and group mean chemical intake were calculated.

 

During the treatment period no mortality or clinical signs were observed. Male and female rats showed low-grade decreases in body weight gain at 12500 mg/kg during treatment period (7.3% and 7.6%, respectively from 1-13 weeks), but none showed statistically significant differences (P>0.05). The body weight gain of male and female rats at 12500 mg/kg increased compared to controls during the recovery period. Statistically significant decreases in food consumption of male and female rats were observed at 12500 mg/kg from 1-13 weeks. Food consumption of male and female rats was also lower at 12500 mg/kg during recovery. Food efficiency of male and female rats was higher (not statistically significant) at 12500 mg/kg from 1-13 weeks. Food efficiency of male and female rats was also somewhat high during recovery at 12500 mg/kg. Urine, haematology and blood coagulation examination not show treatment-related changes at any dose. Blood chemistry examination results showed statistically significant increase of TP, ALB, GLB and CHO in male and female rats, and increased T-BIL in male rats at 12500 mg/kg. Increased absolute and relative liver and kidney weights were observed in male and female rats at 12500 mg/kg. Differences in these values decreased during the recovery period. No treatment-related changes were observed in histopathological examinations. Based on the above findings, the no-observed-effect-level (NOEL) for the test substance in the 13 week toxicity study in SD was 2500 mg/kg diet (218:8±16.8 mg/kg/day for males and 246.9±18.0 mg/kg/day for females).