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. 

Chloramine in Water Supplies Poses Hazards to Plants and Fish
According to the 21st Century Gardener (March/April, 1993) in an article entitled "Municipal Water Purification, A Potential Crisis For Growers", in Matsqui, an urban municipality in British Columbia, it was reported that local growers noticed a dramatic increase in the pH of the water which was shortly followed by a rapid deterioration in plant health. These problems began to show up after the municipality added ammonium to the water supply to create chloramines, which stay in the water for a long period of time. 
In 1989 two massive fish kills occurred when chloramine-treated water accidentally got into Fergus Creek, one of the most important fish-bearing streams in the Lower Mainland in BC. With these fish kills, coupled with the rapid decline in plant health when watered with chloramine-treated water, it is quite obvious that any water that kills fish and plants, also has the potential to be very detrimental to human health. 
Canadian communities investigating options to chlorine for treating drinking water supplies must thoroughly examine safe alternatives such as ozone (not to be confused with smog). It is valuable to note that chloramine has been banned in Germany for over 30 years. 

Parasites in Water

In 1993 the worst outbreak of a water born disease in modern US history occurred in Milwaukee, Wisconsin. Severe bouts of watery diarrhea struck an estimated 403,000 people. In unhealthy human hosts the illness proved unrelenting and often fatal. More than 100 people are estimated to have died from contracting cryptosporidium parasite. Normally healthy people were sick an average of nine days. 
The same parasite was reported in 1991 to be present in our three watersheds in the Greater Vancouver Regional District's quality control Annual Report. during the public meetings held to assess opinions on a number of water treatment options, there was no mention of cryptosporidium being in our water supply. 
Miranda Holmes of the Save the Georgia Straight Alliance, who has championed a biological filtration and ozone water-treatment system that kills cryptosporidium said, "They never talked about crypto. They always talked about Giardia. For them to have known since 1991 that this problem existed and to not have brought it up as part of the debate on treating water is an absolute scandal." 
At present the Greater Vancouver Regional District (GVRD) is planning to build up to 40 more rechlorination plants throughout Vancouver's Lower Mainland for water treatment; unfortunately the cryptosporidium is highly resistant to chlorine. Why would the GVRD spend millions building these stations when this parasite might be a dangerous problem? It is known that ozone is an effective treatment for cryptosporidium, perhaps there are others. There needs to be further investigation into possible solutions; let's not make a hasty decision to rechlorinate water supplies when it won't do an adequate job in eradicating resistant parasites.