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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 nitromethane 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 (-.024 at 22°C). 

T: The 48-hour LC50 for Brachydanio rerio was 455.3 mg/L.

The 24-hour EC50 for freshwater invertebrate (Daphnia magna) was >103 mg/L.

The 72-hour ErC50 (based on growth rate) for freshwater algae was determined to be >102 mg/L.

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

For mammalian endpoints, No mutagenic activity of nitromethane (NM) was observed in the Ames test at 23,732 ppm (118.7 mg/L) NM with or without S9 mix, approximately one half of a saturated atmosphere. Toxicity was noted in some strains at 47,465 ppm NM. NM was negative in the CHO Chromosomal Aberration Test with and without metabolic activation at doses as high as 4980 micrograms/ml. NM was negative in the SHE micronucleus assay. In the Syrian hamster embryo cell transformation assay, NM produced positive results.somal Aberration Test with and without metabolic activation at doses as high as 4980 micrograms/ml. NM was negative in the SHE micronucleus assay. In the Syrian hamster embryo cell transformation assay, NM produced positive results. Inin vivostudies, NM was negative in the mouse bone marrow micronucleus assay at ip doses as high as 1830 mg/kg or following 13 weeks exposure at concentrations as high as 1,500 ppm. In the Drosophila Basc test, NM was negative at 125mM, a dose very close to the LD50. 

The carcinogenic potential of NM was examined in an NTP inhalation study with Fischer 344 rats and B6C3 F1 mice. Groups of 50 male and 50 female rats were exposed to 0, 94, 188, or 375 ppm NM, 6 hours per day, 5 days per week and similar groups mice were exposed to 0, 188, 375 or 750 ppm NM, 6 hours/day, 5 days/week for 103 weeks.  The findings were: clear evidence of carcinogenic activity of NM in female F344/N rats based on increased incidences of mammary gland fibroadenomas and carcinomas and in female B6C3F1 mice, based on increased incidences of liver neoplasms (primarily adenomas) and harderian gland adenomas and carcinomas. Increased incidences of alveolar/bronchiolar adenomas and carcinomas in male and female mice exposed to NM were also considered to be treatment related. 

Long-Evans rats were exposed to vapors of NM at either 100 ppm or 200 ppm. The animals were exposed seven hours per day, five days per week for two years. No significant differences in the non-neoplastic or neoplastic pathology related to exposure to NM.

Based on an NTP study, NM can cause cancer in laboratory animals. Therefore NM is classified as a catagory 2 carcinogen according to GHS.