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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Toxicological information


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Description of key information

Key value for chemical safety assessment

Justification for classification or non-classification

No classification for carcinogenicity is proposed for selenous acid since according to ATSDR (2003) “there is no evidence to support a causal association between selenium compounds and cancer in humans. In fact, some epidemiological and experimental evidence suggests that selenium exposure under certain conditions may contribute to a reduction in cancer risk. The chemopreventive potential of supplemental selenium is currently under research. "

Additional information

Only supportive data are available on carcinogenicity of selenous acid (Soullier, 1981). According to the expert judgement of ATSDR (2003) no carcinogenic effect was observed in this study: the total carcinogenic challenge (initiator + promoter) used in these experiments was considerably higher than in previous studies. Even with this increased challenge, the selenium supplement (8 ppm H2SeO3) had a significant inhibitory effect on a colonic carcinogenesis.


ATSDR (2003). Agency for toxic substances and disease registry. Toxicological profile for selenium. U.S. Department of Health and Human Services, Public Health Services, Atlanta, Georgia.