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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

P/vP: Based on screening level criteria, persistence of 1-nitroethane cannot be ruled out. Thus, the test substance is assumed to meet the criteria for persistence since data is not available to conclude otherwise.

B/vB: The test substance does not meet the criteria of B and vB. The substance has a low potential to bioaccumulate because of its low log Pow value (0.16 at 22°C). 

T: The 48-hour LC50 for Brachydanio rerio was 880 mg/L.

The 24-hour EC50 for freshwater invertebrate (Daphnia magna) was > 21.9 mg/L.

The 21 d NOEC on reproduction of D. magna was 2.44 mg/L

The 72-hour ErC50 (based on growth rate) for freshwater algae (P. subcapitata) was determined to be 17.4 mg/L, while the NOEC was 7.11 mg/L.

Since these aquatic toxicity endpoints are far greater than the 0.1 mg/L threshold for toxicity (T), the test substance is not T.

For mammalian toxicity endpoints:

Nitroethane (NE) was tested in three Ames studies with negative results in each with and without metabolic activation. NE was also evaluated in the in vitro Chinese hamster ovary cell/hypoxanthine-guanine-phosphoribosyl transferase (CHO/HGPRT) forward gene mutation assay. The concentrations ranged from 0 (solvent control) to 751 µg/ml (10mM) in the absence and presence of S9. NE was non-mutagenic when evaluated in the absence or presence of S9 metabolic activation.

The mutagenic potential of NE was evaluated in the in vivo mouse micronucleus test. NE did not cause a significant increase in the numbers of polychromatic erythrocytes with micronuclei when compared to corresponding negative control groups of mice.

Short-term in vivo and in vitro tests do not indicate that NE has the potential to be genotoxic.

Male and female Long-Evans rats were exposed by inhalation to vapors of NE at either 100 ppm or 200 ppm, seven hours per day, five days per week for two years. There was no significant difference in the non-neoplastic or neoplastic pathology related to exposure to NE.

There are no reproductive/developmental studies for NE. However, there is a OECD 422 guideline study for a similar molecule 1-nitropropane. In the high-exposure group, the mean number of pups born live and the mean number of pups on day 1 and 4 postpartum were less than controls. Differences were not statistically significant but values were outside the historical control range. The toxicological significance of this finding is equivocal, there were no apparent effects on any other reproductive parameter, nor were there corroborating findings at gross or histopathological examination. These results suggest that the reduced litter size in animals exposed to 100 ppm 1-nitropropane was secondary to maternal toxicity and/or stress from nasal irritation.

Thus, based on the available data, NE is neither classified as carcinogen, nor as mutagen, repro toxicant, T-R48, nor Xn-R48.