Water Disinfectants & disinfectant by-products
3.2 Chlorine by-products toxicology
The different groups of chlorine by-products have different toxicity. They can particularly affect the liver and kidney of laboratory rats and mice:
- The toxicity of the trihalomethanes (THMs) in laboratory animals is higher when administered with corn oil than with water. Chloroform is not considered to be genotoxic and induces cancers only at high doses after tissues have been damaged. The other THMs appear to be weakly genotoxic. At high doses, some induce tumours of the liver and kidney and others of the large intestine, when administered in corn oil.
- The haloacetic acids (HAAs) produce a range of effects in rodents including tumours of the liver and reproductive and neurological effects, but only at very high doses. They are only weakly genotoxic but this does not appear to be how they cause tumours.
- Chloral hydrate has been shown to potentially induce liver tumours and other health effects in laboratory rodents but only at very high doses. Some of the other halogenated aldehydes and ketones are highly genotoxic possibly carcinogenic and one, chloroacetaldehyde has induced liver tumours in laboratory animals.
- The haloacetonitriles have not been well studied. Some are mutagenic, but may not induce tumours.
- MX is a very potent mutagen in bacteria and also appears to cause some tumours in laboratory rats.