Chlorination for
drinking water forms various disinfection byproducts (
DBPs). Some
DBPs are probably linked to human
cancer (e.g., bladder,
colorectal cancers) and other chronic and sub-chronic effects. This emphasizes the need to understand and characterize
DBPs in
drinking water and possible risks to human health. In this study, occurrences of
DBPs throughout Canada were investigated.
Trihalomethanes (THMs) were observed to be highest in Manitoba followed by Nova Scotia and Saskatchewan, while haloacetic
acids were highest in Nova Scotia followed by Newfoundland and Labrador. Based on the characterization of
DBPs, risk of
cancer from exposure to THMs was predicted using ingestion, inhalation and dermal contact pathways of exposure. In Canada, approximately 700
cancer cases may be caused by exposure to THMs in
drinking water. Medical expenses associated with these
cancer incidents are estimated at some $140 million/year. Expense may be highest in Ontario (∼$47 million/year) followed by Quebec (∼$25 million/year) due to a greater population base. This paper suggests improvements in water treatment, source protection and disinfection processes, and caution in the use of alternative
disinfectants to reduce
DBPs. Finally, elements are provided to mitigate risks and reduce cost estimates in future studies.