The toxicity literature for chlorine has been comprehensively summarized elsewhere (ACGIH,
1996a; USEPA, 1994a; WHO, 1996; WHO, 2000). According to the latest review by WHO
(2000) related to drinking water, “evidence from these [discussed elsewhere in its report]
animal and human studies suggest that chlorine, hypochlorite solutions, chloramine, and
chlorine dioxide themselves probably do not contribute to the development of cancer or any
toxic effects.” The following briefly describes the chlorine data determined to be particularly
germane to the estimation of the health safety and risk from exposures to chlorine for
swimmers in residential and commercial pools.
3.1.1 Skin Contact
No human or laboratory animal studies were located regarding dermal exposures to chlorine.
However, limited human experiences suggest that chlorine may be capable of causing “itching”
at concentrations much greater than 10 ppm (a case report of a skin patch test of an individual
who was exposed to 400 to 600 ppm of sodium hypochlorite and who was shown to have skin
irritation as a result; a report of an occupational exposure to sodium hypochlorite
(concentration unspecified) causing dermatitis; and a secondary reference stating that 5%-10%
available chlorine is allegedly classified in Europe as an "irritant" whereas <5% does not
require classification as to irritancy). This information has not been confirmed. Because
some microbes present in pool water are known to be stimuli for itching, it is unclear what, if
any, role chlorine might have in this phenomenon.