International Agency for Research on Cancer (IARC) - Summaries & Evaluations

(Group 3)

For definition of Groups, see Preamble Evaluation.

VOL.: 52 (1991) (p. 145)

Sodium chlorite
: 7758-192

Sodium chlorite trihydrate
: 49658-21-1

5. Summary of Data Reported and Evaluation

5.1 Exposure data

Sodium chlorite is the only chlorite salt produced commercially in significant quantities. It is used mainly for the generation of chlorine dioxide in situ for bleaching textiles, in pulp and paper processing, and for disinfection. Sodium chlorite is used in a small number of water treatment plants to generate chlorine dioxide; this may result in low residual concentrations of chlorite in drinking-water.

No information was available on occupational exposures to sodium chlorite.

5.2 Experimental carcinogenicity data

Sodium chlorite was tested for carcinogenicity in male and female B6C3F1 mice and Fischer 344 rats by oral administration in the drinking-water and in a limited study by skin application in female Sencar mice. It was further tested for promoting effects in female Sencar mice by skin application following a single application of 7,12-dimethylbenz[a]anthracene. Oral administration of sodium chlorite to mice was associated with a marginal increase in the incidence of lung tumours in treated males. In the study in rats, no significant increase in tumour incidence at any site was seen in treated animals. Skin tumours did not occur in Sencar mice following skin application of sodium chlorite. In the initiation/promotion study, sodium chlorite had a marginal promoting effect.

5.3 Human carcinogenicity data

No data were available to the Working Group.

5.4 Other relevant data

Sodium chlorite has been shown to produce haemolytic anaemia in several animal species at concentrations in drinking-water of 100 mg/l or higher. No sign of such effects was seen in humans at much lower doses.

Minimal adverse reproductive effects were observed in rats and mice given sodium chlorite in the drinking-water at concentrations of 100 mg/l or higher.

Single studies indicated that sodium chlorite induced mutations in bacteria and chromosomal aberrations in cultured mammalian cells. In mice treated in vivo, conflicting results were obtained with regard to the induction of micronuclei, while a single study showed no induction of aneuploidy, chromosomal aberrations or abnormal sperm morphology.

5.5 Evaluation

There is inadequate evidence for the carcinogenicity of sodium chlorite in experimental animals.

No data were available from studies in humans on the carcinogenicity of sodium chlorite.

Overall evaluation

Sodium chlorite is not classifiable as to its carcinogenicity to humans (Group 3).

For definition of the italicized terms, see Preamble Evaluation.

Synonyms for Sodium chlorite

Synonym for Sodium chlorite trihydrate

Last updated: 17 November 1997

    See Also:
       Toxicological Abbreviations
       Sodium chlorite (ICSC)