Bromomethane

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Materials and methods

Test guideline

Guideline:

EPA OPP 81-1 (Acute Oral Toxicity)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Bromomethane

EC Number:

200-813-2

EC Name:

Bromomethane

Cas Number:

74-83-9

Molecular formula:

CH3Br

IUPAC Name:

bromomethane

Test animals

Species:

rat

Sex:

male/female

Administration / exposure

Details on oral exposure:

Comparative Phase
Three groups of five male and five female rats were administered single doses of the microencapsulated Methyl Bromide preparation at dose levels of 80, 120 and 160 mg/kg.
Observations included mortality, body weights and food consumption. After 14 days, necropsy was performed on all rats, major organs were examined and a microscopic examination was carried out on tissues from animals in the comparative phase only.

Results and discussion

Effect levels

Effect levels 1

Dose descriptor:

LD50

Effect level:

104 mg/kg bw

Remarks on result:

other: liquid Methyl Bromide

Effect levels 2

Dose descriptor:

LD50

Effect level:

133 mg/kg bw

Remarks on result:

other: microencapsulated Methyl Bromide

Clinical signs:

other: Clinical Observations: Several clinical signs observed were limited to those animals that died. Hypoactivity was observed for essentially all animals that died. Ataxia was noted for 23 animals that died. Laboured respiration and hypothermia were observ

Gross pathology:

Necropsy:
Gastric abnormalities were observed for 34/35 rats that died during the study. 16 rats from the liquid Methyl Bromide group and 14 from the microencapsulated group had reddened mucosal lining of the stomach. The glandular portion of the stomach was oedematous for 22 animals and the stomach was distended for 5 animals that died. Intestinal abnormalities including dark red or red fluid contents in the intestine were observed for eight dead animals. Clear fluid contents in the thoracic cavity were noted for 4 animals. Dark red kidneys were observed for 26 rats that died. 8 rats had a haemorrhagic thymus gland. Enlarged mesenteric lymph nodes were noted for 2 rats in the liquid Methyl Bromide group.

Gastric abnormalities in the liquid Methyl Bromide group (12 animals) and in the microencapsulated group (13 animals) that survived to day 14 were as follows. The stomach was attached by adhesions to the liver, spleen, abdominal and/or thoracic wall, diaphragm and/or caecum. White material was adhered to the mucosal lining of the nonglandular portion of the stomach for 6 rats in the liquid group and 7 rats in the microencapsulated group. 4 rats had a necrotic area on the liver.

Other findings:

Microscopic examinations:
Of the rats that died, haemorrhages in the glandular mucosa of the stomach were observed in 12 rats in the liquid group and 6 rats in the microencapsulated group. Submucosal oedema in the forestomach was noted for 8 rats in the liquid group and 9 in the microencapsulated group. One rat also had cytoplasmic vacuolation of the gastric submucosa.

Of the rats that survived to 14 days, squamous cell hyperplasia in the stomach was noted for 11 animals in the liquid group and 11 animals in the microencapsulated group. Ulceration, primarily in the nonglandular portion of the forestomach, was observed in 8 animals in the liquid group and 11 animals in the microencapsulated group. Other, less common gastric lesions included granulomatous inflammation, lymphomoplasmactic cell infiltration, chronic active inflammation and granulocyte infiltration.

Applicant's summary and conclusion

Conclusions:

The oral LD50 of liquid Methyl Bromide in rats was 104 mg/kg. The oral LD50 of microencapsulated Methyl Bromide in rats was 133mg/kg. In accordance with the provisions of Council Directive 67/548/EEC, classification as “toxic if swallowed” is required.