Nitromethane

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

circa 1973

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

publication

Title:

Etude toxicologique experimentale de quelques Nitroparaffines. 4. Etude du nitromethane. (English translation by Dr. PJ Baker Jr., IMC Chemical Group, Inc.)

Author:

Dequidt J, Vasseur P and Potencier

Year:

1973

Bibliographic source:

Bull Soc Pharm Lille, 1973, 29-35

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

Rats were exposed to 500, 2500 or 13,000 ppm nitromethane for six hours. At the lower concentrations, rats were exposed multiple days. Rats were exposed for 4 days to 2500 ppm and for three weeks to 500 ppm. Methemoglobin levels in the blood and test material concentration in liver, lung, heart and kidney were determined.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Nitromethane

EC Number:

200-876-6

EC Name:

Nitromethane

Cas Number:

75-52-5

Molecular formula:

CH3NO2

IUPAC Name:

nitromethane

Details on test material:

No additional information available.

Test animals

Species:

rat

Strain:

Wistar

Sex:

not specified

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

not specified

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

6 h

Remarks on duration:

depending upon the concentrations, rats were exposed for 1 day to 3 weeks

Concentrations:

500 ppm (1.25 mg/L) (3 weeks), 2500 ppm(6.25 mg/L) (4 exposures) and 13,000 ppm (32.5 mg/L) (single exposure)

No. of animals per sex per dose:

1 at 13,000 ppm 8 - 10 rats were used for each concentration
4 at 2500 ppm
15 at 500 ppm

Control animals:

not specified

Results and discussion

Effect levels

Key result

Sex:

not specified

Dose descriptor:

LC100

Effect level:

13 000 ppm

Based on:

test mat.

Exp. duration:

6 h

Remarks on result:

other: equivalent to 33 mg/L

Mortality:

See below

Clinical signs:

other: See below

Body weight:

See below

Gross pathology:

See below

Other findings:

No additional information available.

Any other information on results incl. tables

In the first experiment, rats exposed to 13,000 ppm nitromethane (33 mg/L) died after 6 hours. In the second experiment, rats were exposed to 2,500 ppm (6.3 mg/L), 6 hours/day for 4 consecutive days. The animals died after the 4th day. In these animals no trace of methaemoglobin in the blood was observed. There was no NM in any of the organs. The nitrite ion content was considered to be high. All animals exposed to 500 ppm (1.27 mg/L) 6 hours/day for 3 weeks survived until termination. The animals appeared normal after these 15 inhalation sessions. At the end of the exposure period, the animals were sacrificed. There was no evidence of NM except in the liver (0.27 g/100g) and then only in the acute experiment with 13,000 ppm in the atmosphere. Based on these studies NM does not appear to cause methaemaglobinemia, or if so very feeble activity, also testified to by the elevated concentrations and the minimal quantity of nitrites found in the organs. The amount of MetHb found after exposure to these materials was < 1% for nitromethane. Nitromethane was detected only in the liver of the rat exposed to 13,000 ppm.

Applicant's summary and conclusion

Conclusions:

The acute LC100 following a single 6 hour exposure is 13,000 ppm.

Executive summary:

The acute toxicity of nitromethane was examined. Rats were exposed to 500 ppm (1.25 mg/L) (3 weeks), 2500 ppm (6.24 mg/L) (4 days) or 13,000 ppm (32.4 mg/L) (single exposure). In the first experiment, the only rat exposed to 13,000 ppm nitromethane (32.4 mg/L) died after 6 hours. In the second experiment, 4 rats were exposed to 2,500 ppm (6.24 mg/L), 6 hours/day for 4 consecutive days. The animals died after the 4th day. All 15 animals exposed to 500 ppm (1.25 mg/L) 6 hours/day for 3 weeks survived until termination. The amount of MetHb found after exposure to these materials was <1% for nitromethane. Nitromethane was detected only in the liver of the rat exposed to 13,000 ppm.