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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
circa 1973
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was not conducted according to guideline/s and GLP but the report contains sufficient data for interpretation of study results

Data source

Reference
Reference Type:
publication
Title:
Etude toxicologique experimentale de quelques nitroparaffines.
Author:
Dequidt J, Vasseur P and Potencier, J.
Year:
1973
Bibliographic source:
Bull Soc Pharm Lille, 1973, 29-35. English translation by Dr. PJ Baker Jr., IMC Chemical Group, Inc.

Materials and methods

Principles of method if other than guideline:
Groups of rats were exposed for 6 or 7 hours to various concentrations of nitroethane for varying number of days. At 13,000 ppm (40.6 mg/L), rats were exposed for a single 6 or 7 hour period. At 2200 ppm rats (6.8 mg/L) were exposed for 6 hours for 5 exposures. At 200 and 550 ppm (0.625 and 1.55 mg/L, respectively), rats were exposed for 6 hours for 12 days.Rats were exposed to 200, 550, 2200 or 13,000 ppm nitroethane for six hours. At the lower concentrations, rats were exposed multiple days. Rats were exposed for 4 days to 2200 ppm and for three weeks to 200 or 550 ppm. Methemoglobin levels in the blood and test material concentration in liver, lung, heart and kidney were determined.
GLP compliance:
no
Test type:
other: rats were exposed for 6 or 7 hours for various number of exposures
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
No additional information available.

Test animals

Species:
rat
Strain:
Wistar
Sex:
not specified
Details on test animals and environmental conditions:
Wistar rats with a mean weight of 250 g were used. Animals were fed a diet devoid of nitrites.

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
air
Details on inhalation exposure:
Groups of 8-10 rats were exposed for 6-7 hours in inhalation chambers.
Analytical verification of test atmosphere concentrations:
yes
Remarks:
gas chromatographic analysis
Duration of exposure:
6 - 7 h
Concentrations:
13,000 ppm for 6 or 7 hours for a single exposure2200 ppm for 6 hours for 5 exposures550 ppm for 6 hours for 12 exposures200 ppm for 6 hours for 12 exposures
No. of animals per sex per dose:
8-10 rats/group
Control animals:
not specified
Details on study design:
Groups of 8-10 rats were exposed for 6-7 hours in inhalation chambers for a single - twelve exposures. After the last exposure, blood methemoglobin levels and NO2 levels in selected tissues were measured.
Statistics:
Mean levels of blood methemoglobin and NO2 levels in selected tissues were calculated.

Results and discussion

Effect levels
Key result
Sex:
not specified
Dose descriptor:
LC50
Effect level:
> 19.8 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
6 h
Remarks on result:
other: Rats survived repeated exposure to 2200 ppm (6.7 mg/L) for 6 hours/day for 5 days. The LC100 is 13'000 ppm following a six hour exposure to nitroethane.
Mortality:
See below.
Clinical signs:
See below.
Body weight:
See below.
Gross pathology:
See below.
Other findings:
See below

Any other information on results incl. tables

Experiment 1: Rats were exposed to 13,000 ppm nitroethane for several hours. The rats died 6 -7 hours during the inhalation exposure. The methemoglobin level of 2.8% was lower than that recorded for the nitropropanes, either 1 -NP or 2 -NP. Similarly with nitrite ion concentration. NE was found in the liver (0.8 mg) as well as in the lungs (0.1 ml).

Experiment 2: Animals placed in an atmosphere of 2200 ppm (6.8 mg/L) of nitroethane survived numerous 6-hour inhalation sessions. Nonmetabolized nitroethane in the liver was 0.1 mg/100 g. Since no noticeable effects were observed in rats exposed to 2200 ppm, groups of rats were exposed to lower concentrations for longer periods of time.

Experiment 3: Groups of rats were exposed to 550 ppm (1.55 mg/L) for 6 hours/day for 12 exposures. There was no methemoglobin noted in the blood and only traces of nitrites in the organs.

Experiment 4: Groups of rats were exposed to 200 ppm (0.625 mg/L) for 6 hours/day for 12 exposures. Similar to the results in experiment 3, there was no methemoglobin noted in the blood and only traces of nitrites in the organs.

Table 1 Effects following nitroethane exposure via inhalation

                  Level of NO2, ug/100 g tissue
 Exposure Conc., ppm  Number of exposures  Duration, hours  Methemoglobin, %  Heart  Lungs  Kidney  Spleen
 13,000  1  6 -7  2.84  930  192  255  700
 2,200  5  6  0  171  14  55  121
 550  12  6  0  236  60  trace  trace
 200  12  6  0  trace  trace  trace  trace

Applicant's summary and conclusion

Interpretation of results:
Category 4 based on GHS criteria
Remarks:
Migrated information
Conclusions:
The LC50 of nitroethane is calculated to be 6025 ppm.
Executive summary:

The acute toxicity of nitroethane was examined following a single exposure to 13'000 ppm and repeated exposure to lower concentrations. Under the conditions of this study, the LC100 is 13'000 ppm following a six hour exposure to nitroethane.  All rats exposed to 2200 ppm of nitroethane for 6 hours/day for 5 days survived (LC0). This study was conducted before guidelines and GLP, but sufficient data is available for interpretation of results. Normalizing the LC0 value for a 4 hour exposure, this is equivalent to a LC50 of 6025 ppm/4 hr (2200*301/2/ 41/2). According to the CLP/GHS legislation, nitroethane can be classified as Category 4 for acute toxicity via the inhalation route.