Nitric acid

Endpoint summary

Additional information

Read accross with nitrates, as defined in the read-accross sodium and potassium nitrates are the nitrates with most structural similarities with nitric acid.

Nitric acid:

Under the conditions of the bacterial reverse mutation assay realized by BASF in 1989 (similar to OECD 471), nitric acid was not mutagenic.

Potassium nitrate:

From the studies of Prival & al, 1991 and Ishidate & al, 1984, potassium nitrate (similar to OECD 471), potassium nitrate was not mutagenic.

From the study of Ishidate & al, 1984, potassium nitrate does not cause chromosome aberration.

Under the conditions of the tests realized according to OECD 476 in 2010 in Notox, potassium nitrate was not mutagenic in mouse lymphoma L5178Y test system.

All studies performed on potassium nitrates provide negative results and thus it can be concluded that this substance does not cause genetic toxicity.

Sodium nitrate:

In vitro studies on sodium nitrate

Sodium nitrate is not mutagenic in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100, TA 92 and TA 94 with and without metabolic activation. No chromosomal aberrations or micronuclei were induced (not indicated whether metabolic activation was used). However, a chromosome aberration study in CHO cells did show positive effects without metabolic activation. Therefore, a new study was performed, and in this reliable OECD 473 guideline chromosome aberration study sodium nitrate did not show genotoxicity in human lymphocytes with or without metabolic activation. Several less reliable in vitro studies supported this conclusion.

In vivo study on sodium nitrate

An in vivo chromosomal aberration and micronucleus test was negative. No unscheduled DNA synthesis was demonstrated in an UDS test. No sperm abnormalities or effect on rate of spermatogenesis were induced. Sodium nitrate was not mutagenic in a heritable translocation test. In a chromosome aberration/micronucleus study in rats and mice, no increase in chromosome aberrations were found when animals were treated twice. However, an increase in aberrant metaphases was observed in rats that were treated for 2 weeks with a 24 hour sampling. Such a repeated dosing and long sampling time is not according requirements, and as studies with acute dosing do not show positive findings with regard to chromosome aberrations this positive finding is considered not reliable. However, in the micronucleus study with the mice with a short sampling time (6 hours), two acute doses resulted already in an induction of micronuclei.

Based on all genotoxicity studies present, together with the findings that sodium nitrate does not induce tumor formation at high doses (see carcinogenicity section), it is concluded that sodium nitrate is not genotoxic.

From the available study on nitric acid and the numerous studies in potassium and sodium nitrates, nitric acid is not expected to be genotoxic.

Justification for selection of genetic toxicity endpoint
An Ames test is available on the substance. Chromosome aberration on the read-across substances sodium nitrate and potassium nitrate. A mouse lymphoma on the read-across substance potassium nitrate.

Short description of key information:
AMES test: Negative on nitric acid (one test similar to OECD471), negative sodium nitrate (two tests similar to OECD 471)and negative on potassium nitrate (one test similar to OECD 471)
Chromosome aberration: No data on nitric acid - Negative on sodium nitrate from new test realized according to OECD 473- Negative on potassium nitrate (one test similar to OECD 473)
Gene mutation: No data on nitric acid - No data on sodium nitrate - Negative on potassium nitrate (One test realized according to OECD 476)
The read-across rationale can be found in the category approach document attached in Section 13.
In vivo data: Data available on sodium nitrate- see discussion

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

From the results obtained on nitric acid, sodium and potassium nitrates and due to their structural similarities with nitric acid, it is possible to conclude that nitric acid is not expected to cause genetic toxicity and thus should not be classified according to the CLP Regulation.