[back] Chlorine

Finnish Study Links Chlorinated Water to Cancer

By Thelma MacAdam

The majority of municipal water systems in Canada use chlorine to disinfect drinking water. However the carcinogenic and mutagenic compounds found in chlorinated drinking water have raised concerns over the potential long term health effects of water chlorinations and chlorination by-products.

The latest study, Drinking Water Mutagenicity and Gastrointestinal and Urinary Tract Cancers; an Ecological Study in Finland is reported in the American Journal of Public Health, August 1994. This study was done on 56 Finnish municipalities and is the largest long term study ever done.

Objectives: The purpose of this study was to investigate the relationship between exposure to mutagenic drinking water and cancers of the gastrointestinal and urinary tract.

Reported results: Statistically significant exposure-response association was observed between exposure to chlorinated water and incidence of bladder, kidney and stomach cancers. In an ordinary municipality using chlorinated surface water, this exposure would indicate a relative risk of 1.2 for bladder cancer and 1.2 to 1.4 for kidney cancer compared with municipalities where nonmutagenic drinking water was consumed.