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

(Group 3)

VOL.: 52 (1991) (p. 159)

Calcium hypochlorite
: 7778-54-3

Calcium hypochlorite, dibasic
CAS No.: 12394-14-8

Calcium hypochlorite dihydrate
: 22464-76-2

Lithium hypochlorite
: 13840-33-0

Potassium hypochlorite
: 7778-66-7

Sodium hypochlorite
: 7681-52-9

Sodium hypochlorite heptahydrate
: 6431-03-9

Sodium hypochlorite hydrate (2:5)
: 55248-17-4

Sodium hypochlorite pentahydrate
: 10022-70-5

Calcium sodium hypochorite
: 53053-57-9

5. Summary of Data Reported and Evaluation

5.1 Exposure data

The principal hypochlorite salts produced commercially are calcium, sodium and lithium hypochlorites. Calcium hypochlorite (solid or aqueous solution) is widely used for disinfection in swimming pools and in industrial applications and for pulp and textile bleaching. Sodium hypochlorite (aqueous solution) is used as a household laundry bleach, in commercial laundering, in pulp and paper manufacture, in industrial chemical synthesis and in the disinfection of drinking-water. Lithium hypochlorite (solid) is used in swimming pools for disinfection and in household detergents.

Hypochlorite salts (principally sodium hypochlorite) are used to disinfect drinking-water at many small treatment works. In the disinfection of drinking-water and wastewater, addition of hypochlorite salts and of chlorine gas gives the same chlorine species in solution - i.e., an equilibrium mixture of mainly hypochlorous acid and hypochlorite anion. In this way, much of the general population is exposed to hypochlorite via chlorinated drinking-water (see the monograph on Chlorinated drinking-water).

5.2 Experimental carcinogenicity data

Sodium hypochlorite was tested for carcinogenicity in a two-year study in male and female B6C3F1 mice and Fischer 344 rats by oral administration in drinking-water, in limited studies in female Sencar mice and in female ddN mice by skin application. Sodium hypochlorite was also tested for promoting effects in female Sencar mice following initiation with 7,12-dimethylbenz[a]anthracene and in female ddN mice following initiation with 4-nitroquinoline 1-oxide. Sodium hypochlorite administered in the drinking-water did not increase the proportion of rats or mice with tumours. Sodium hypochlorite applied to the skin of Sencar mice or ddN mice did not produce skin tumours. No skin promoting effect was observed in the study with 7,12-dimethylbenz[a]anthracene, whereas some effect was seen in the study with 4-nitroquinoline 1-oxide.

Drinking-water containing 100 mg/l chlorine was tested for carcinogenicity in a multigeneration study in male and female BDII rats. No increase in the incidence of tumours was seen in treated animals relative to controls through six generations.

5.3 Human carcinogenicity data

No data were available to the Working Group.

5.4 Other relevant data

Sodium hypochlorite induced genotoxic effects in bacteria. In single studies, chromosomal aberrations were observed in cultured mammalian cells, whereas sister chromatid exchange but no chromosomal aberration was seen in cultured human cells. In a single study, micronuclei were induced in newt larvae. In mice, no induction of micronuclei, aneuploidy or chromosomal aberrations was observed in bone marrow, but abnormal sperm morphology was seen after administration of sodium hypochlorite.

5.5 Evaluation

There is inadequate evidence for the carcinogenicity of hypochlorite salts in experimental animals.

No data were available from studies in humans on the carcinogenicity of hypochlorite salts.

Overall evaluation

Hypochlorite salts are not classifiable as to their carcinogenicity to humans (Group 3).

Synonyms for Calcium hypochlorite

Synonyms for Calcium hypochlorite, dibasic

Synonym for Calcium hypochlorite dihydrate

Synonyms for Lithium hypochlorite

Synonyms for Potassium hypochlorite

Synonyms for Sodium hypochlorite Synonym for Sodium hypochlorite hydrate (2:5) Synonym for Sodium hypochlorite heptahydrate Synonym for sodium hypochlorite pentahydrate Synonym for Calcium sodium hypochorite

Last updated: 17 November 1997

    See Also:
       Toxicological Abbreviations