Bromoform

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Date of first dose 06 March 1980. Date of last dose 04 June 1980.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1989

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

The study was essentially similar to the OCED 408 guideline; however, a number of endpoints specified in the guideline were not investigated such as haematology, clinical chemistry, ophthalmology and functional observations.
 

Deviations:

not applicable

GLP compliance:

yes

Remarks:

Only the pathology specimens, experimental data, study documents, and preliminary draft report were audited.

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Bromoform

EC Number:

200-854-6

EC Name:

Bromoform

Cas Number:

75-25-2

Molecular formula:

CHBr3

IUPAC Name:

tribromomethane

Test material form:

liquid

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories (Portage, MI, and Kingston, NY);
- Females (if applicable) nulliparous and non-pregnant: not stated
- Age at study initiation: 7- 8 weeks (when placed on the study)
- Weight at study initiation: Not stated.
- Fasting period before study: Not stated.
- Housing: five rats per cage in polycarbonate cages
- Bedding: Aspen Bed hardwood chips studies (American Excelsior, Baltimore, MD) or Beta Chips hardwood chips (Agway, Inc., Syracuse,NY) when Aspen Bed were not available.
- Diet (e.g. ad libitum): NIH 07 Rat and Mouse Ration (Zeigler Bros., Inc., Gardners, PA); available ad libitum.
- Water (e.g. ad libitum): ad libitum
- Acclimation period: Rats were observed for 22 days prior to the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 -26 °C
- Humidity (%): 44 - 78%
- Air changes (per hr): 12
- Photoperiod (hrs dark / hrs light): fluorescent light 12hrs per day

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Test substance and corn oil were mixed to give the desired concentrations. Dose mixture stability studies were performed by gas chromatography of methanol extracts. The test substance 2% (w/v) in corn oil was found to be stable when stored at room temperature for up to 7 days. For the study dose mixtures were stored at 0°C ±5°C for no longer than 14 days.

Analysis of dose mixtures was conducted periodically at the study laboratory by gas chromatography after extraction with methanol containing 0.1 mg/ml n-amyl alcohol as an internal standard. The results of analysis of dose mixtures indicated that two test solutions were out of specification at 73% (target = 10 mg/mL) and 162.5% (target = 2.4 mg/mL).

For samples within the target specification the measured concentration range was 91.7% and 98% of target.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

Five dats per week.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

12 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

25 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

50 mg/kg bw/day (nominal)

Doses / concentrations 5

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 6

Dose / conc.:

200 mg/kg bw/day (nominal)

No. of animals per sex per dose:

Five males and five females per dose.

Control animals:

yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: twice daily
-
BODY WEIGHT: wbody wieght was measured at study initiation and once a week thereafter.


OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

IMMUNOLOGY: No

Sacrifice and pathology:

GROSS PATHOLOGY: Necropsy performed on all animals. During necropsy, all organs and tissues were examined for grossly visible lesions.

HISTOPATHOLOGY: the following tissues examined histologically for vehicle control and high dose groups: adrenal glands, brain, colon, oesophagus, eyes (if grossly abnormal), gross lesions and tis- sue masses, heart, kidneys, liver, lungs and bronchi, mammary gland, mandibular lymph nodes, pancreas, parathyroid glands, pituitary gland, prostate, testes or ovaries/uterus, salivary glands, skin, small intestine, spinal cord (if neurologic signs present), spleen, sternebrae, stomach, thymus, thyroid gland, trachea, and urinary bladder.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

All males that received 100 or 200 mg/kg and all females receiving 200 mg/kg were lethargic.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

All males that received 100 or 200 mg/kg and all females receiving 200 mg/kg were lethargic.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Hepatocellular vacuolisation was observed in most male rats (10/10 at 200 mg/kg, 8/10 at 100 mg/kg, 8/10 at 50 mg/kg, 5/10 at 25 mg/kg 6/10 at 12 mg/kg and 3/10 in vehicle controls. This liver lesion which was not seen in females was characterised by the presence of well-demarcated vacuoles in the cytoplasm of hepatocytes; larger vacuoles crowded the nuclei towards the periphery of the cells.

Histopathological findings: neoplastic:

no effects observed

Effect levels

1

Key result

Dose descriptor:

NOAEL

Remarks:

A NOAEL or other dose descriptor was not included in study report and is determined from a separate analysis of the data.

Effect level:

12 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: non-neoplastic

2

Key result

Dose descriptor:

NOAEL

Remarks:

A NOAEL or other dose descriptor was not included in study report and is determined from a separate analysis of the data.

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

clinical signs

Target system / organ toxicity

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

12 mg/kg bw/day (nominal)

System:

hepatobiliary

Organ:

liver

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

Applicant's summary and conclusion

Conclusions:

Administration of the test substance 5-days per week for 13 weeks resulted in a LOEL of 12 mg/kg for male animals based on hepatocellular vacuolisation. In females the LOEL was 200 mg/kg based on lethargy observed in the animals.

Executive summary:

Introduction

The effects of oral ingestion of the test substance in feed were assessed in a 90-Day oral gavage study using male and female F344/N rats. The method was essentially similar to OECD Guideline 408: Repeated Dose 90-Day Oral Toxicity Study in Rodents; however, a number of endpoints specified in the guideline were not investigated such as heamatology, clinical chemistry, ophthalmology and functional observations.

 

Method

Rats (10 males and 10 females per group) were treated with test substance administered orally by gavage in corn oil 5 days per week for 13 weeks. Test substance doses were: 0, 12, 25, 50, 100 or 200 mg/kg/ bw. 

Animals were observed two times per day. Individual animal weights were recorded once per week. At the end of the 13-week studies, survivors were killed. Complete necropsies were performed on all animals.

Results

Mortality: No animals died on the study.

Clinical signs: Lethargy was noticed in all males that received 100 or 200 mg/kg/bw and all females receiving 200 mg/kg.

Histopathological Findings: Hepatocellular vacuolisation was observed in most male rats (10/10 at 200 mg/kg, 8/10 at 100 mg/kg, 8/10 at 50 mg/kg, 5/10 at 25 mg/kg 6/10 at 12 mg/kg and 3/10 in vehicle controls. This liver lesion which was not seen in females was characterised by the presence of well-demarcated vacuoles in the cytoplasm of hepatocytes; larger vacuoles crowded the nuclei towards the periphery of the cells.

Conclusion

Administration of the test substance 5-days per week for 13 weeks resulted in a LOEL of 12 mg/kg/bw for male animals based on hepatocellular vacuolisation. In females the LOEL was 200 mg/kg/bw based on lethargy observed in the animals.