2,5-bis-isocyanatomethyl-bicyclo[2.2.1]heptane

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:

August 28, 1990 - August 12, 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This study meets the standards of the EC-method and was conducted according to GLP principles. However, deviations from the test guideline were noted, which affect the reliability of the study.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: The Japanese Guidelines for Screening Toxicity Testings of Chemicals (1986)

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

no full histopathology was done

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2,5-bis-isocyanatomethyl-bicyclo[2.2.1]heptane

EC Number:

411-280-2

EC Name:

2,5-bis-isocyanatomethyl-bicyclo[2.2.1]heptane

Cas Number:

74091-64-8

Molecular formula:

C11H14N2O2

IUPAC Name:

(1R,2R,4R,5R)-2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane; (1R,2S,4R,5S)-2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane; (1S,2R,4S,5R)-2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane; (1S,2S,4S,5S)-2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane; bis((1r,2R,4s,6S)-2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane); bis((1s,2R,4r,6S)-2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane)

Details on test material:

- Name of test material (as cited in study report): NBDI (BCHI is used in the tables)
- Physical state: liquid

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 Japan
- Age at study initiation: At the start of the exposure, the rats are 5 weeks old.
- Weight at study initiation: males: 157-188, females: 123-151
- Housing: Two rats of the same sex were housed in a polycarbonate cage with hard wood chip bedding
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5-7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-25 °C
- Humidity (%): 40-70%
- Air changes (per hr): 12 changes/hour
- Photoperiod (hrs dark / hrs light): 12/12 hours

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

olive oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
The test substance solutions were prepared by dissolving the test substance in the vehicle (olive oil) at desired concentrations using an ultra high speed homogenizer. The test substance solutions were prepared once a week and stored in the refridgerator until just before use. The stability of the test substance solutions for 7 days after preparation was confirmed by chemical analysis.

VEHICLE
- Amount of vehicle (if gavage): 1.0 ml per 100 g body weight in all rats

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The stability of the test substance solutions for 7 days after preparation was confirmed by chemical analysis. No results included in the report.

Duration of treatment / exposure:

28 days

Frequency of treatment:

Once a day in the morning

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

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

Doses / concentrations 2

Dose / conc.:

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

Doses / concentrations 3

Dose / conc.:

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

No. of animals per sex per dose:

Main study:
0 and 500 mg/kg bw/day : 12 (6 for 14-day recovery)
15 and 100 mg/kg bw/day: 6
Additional study:
0, 2, 10 mg/kg bw/day: 6 females
2 mg/kg bw/day: 6 female
10 mg/kg bw/day: 6 female

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: A 1-week preliminary study was performed at the doses of 60, 500 and 700 mg/kg bw/day. It was found that the substance produced toxic effects on animals of the 500 and 700 mg/kg bw/day dose groups. Suppressed body weight gains, thickening of the forestomach and decreased spleen weight.
- Rationale for animal assignment (if not random): so that the body weights in each group became almost the same
- Rationale for selecting satellite groups: to evaluate recovery. Satelite animals in the control and the top dose group
- Post-exposure recovery period in satellite groups: 14 days

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: No data

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least once daily, and with palpation once a week

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

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

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data:No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: just before necropsy
- Anaesthetic used for blood collection: Yes (pentobarbital)
- Animals fasted: No data
- How many animals: all
- Parameters were examined: erytrocyte count, Leucocyte count, platelet count, hemoglobin concentration, hematocrit, leucocyte count differential, reticulocyte count, prothrombin time, activated partial thromboplastin time, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: just before necropsy
- Animals fasted: No data
- How many animals: all
- Parameters were examined: total protein, albumin, A/G ratio, Glucose, triglyceride, total cholesterol, urea nitrogen, creatinine, calcium, inorganic phosphorus, GOT(AST), GTP(ALT, gamma-GTP, ALP, sodium, potassium, chloride.

URINALYSIS: Yes
- Time schedule for collection of urine: two days before necropsy
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data
- Parameters were examined: pH, occult blood, protein, glucose, ketone bodies, bilirubin, urobilinogen

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes , brain, pituitary, eyes(with Hardian glands), lungs, stomach, thyroids (with parathyroids), heart, liver, spleen, kidneys, adrenals, urinary bladder and bone marrow (femur), testes or ovaries. Of all organs removed at the end of treatment, the heart, liver, kidneys, adrenals, spleen and stomach from rats of both sexes of the control and high dose group and the kidneys from 1 male rat of the low dose group, were examined microscopically. The OECD guideline states that full histopathology should be done.

Statistics:

Barlett's test.
Anova and dunnett's multiplerange test or Kruskal-Wallis and Dunnet's type rank sum test.
Armitage's chi2test was used for urunary paper tests

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Almost all rats of both sexes of the 500 mg/kg bw/day dose group had salivation after administration continuously after 5 days of treatment (reversible). Although related to the substance, it was only slight and readily improved, disappearing after discontinuation. Some male rats also had soft faeces, reduced spontaneous movement and rales. These symptoms were transient and seemed to be slight.

Mortality:

no mortality observed

Description (incidence):

No death occurred during the periods of treatment and recovery.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weight gains were suppressed in male rats of the 500 mg/kg bw/day dose group during treatment and recovery (up to 13% on day 7 and day 28).

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Decreased in rats of both sexes of the high dose group early in treatment, returned to normal or tended to increase thereafter, and thus considered only slight.

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Starting at the 15 mg/kg bw/day dose group, the hematocrit values decreased in the female animals:
At 15 mg/kg bw/day: 5% decrease compared to control
At 100 mg/kg bw/day: 4.8% decrease compared to control
At 500 mg/kg bw/day: 6.4% decrease compared to control
These changes, although statistically significant, are not considered toxicologically relevant, since the decrease is not dose-dependent and only minor. The author of the report considers the effects to be related to the substance.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

At highest dose, increase in GPT in rats of both sexes, increase in GOT in males, decrease in glucose and increase in A/G ratio in female rats.

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Presence of occult blood in male rats of high dose group and decreased protein in female rats of the high dose dose group. These effecst were not considered to be toxicologically relevant.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant observations:
Female rats of 500 mg/kg bw/day dose group showed an increase of absolute (12%) and relative (7%) liver weights as well as a reduction in relative (14%) and absolute (18%) ovary weight, and decreased relative and absolute adrenal weight. The latter was also seen in the low dose groups (small change and not dose related). Male rats of 500 mg/kg bw/day dose group showed a statistically significant but very slight decrease in absolute liver weight only (2%).

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

In female rats of the high dose group, deposition of glycogen in the liver (6/6) was seen.

Effect levels

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Based on an increase of liver weights and a reduction in ovary weights in the females and a suppression of body weight gain in males at 500 mg/kg bw/day.

Target system / organ toxicity

1

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

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

System:

hepatobiliary

Organ:

liver

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

2

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

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

System:

female reproductive system

Organ:

ovary

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Any other information on results incl. tables

In the additional study with 0, 2 and 10 mg/kg bw/day dose groups, no mortality, no clinical signs, no effect on bodyweight and food consumption, neither on haematological parameters, organ weight and macroscopic examination were observed.

Based on the main study, the effects on organ weights at the highest dose tested and the decrease in body weight gain are considered toxicologically relevant. As all other effects, clinical signs, haematological and biochemical effects, are considered not relevant, the NOAEL is considered to be 100 mg/kg bw/day. Note: no microscopic examination of several organs was performed, therefore the organ weight effects although sometimes slight, are considered relevant.

Applicant's summary and conclusion

Conclusions:

In a sub-acute oral study in rats a NOAEL (systemic effects) of 100 mg/kg bw/day was established based on an increase of liver weights and a reduction in ovary weights in the females and a suppression of body weight gain in males at 500 mg/kg bw/day.