Highlights and Discussion:
In the summer of 2003 water samples from the Rideau River, Mosquito Creek and Sawmill Creek were collected by Ottawa City staff, and analysed for pesticides at the University of Guelph. Samples were obtained at three occasions of wet and three occasions of dry weather.
Pesticides were detected at least once in every location sampled.
Pesticides were detected in 63% (27/43) of the samples.
The four pesticides detected (herbicides mecoprop (MCPP), dicamba, and 2,4-D, and the insecticide diazinon) are four of the top five pesticides used by lawn care applicators. None of the pesticides that are used only for agricultural purposes were detected.
Phenoxy herbicides (weedkillers) were present in 60% (26/43) of the samples.
CHO comment: This is of concern, not only because of the herbicide contamination, but because phenoxy herbicides are, by nature of the way they are synthesised, inevitably contaminated with chlorinated dioxins. These persistent, bioaccumulative toxic substances are linked to cancers, and to reproductive, immunological and neurological problems.
The organophosphate insecticide diazinon was present in 26% (11/43) of the samples, and at levels above the water quality objective for protection of aquatic species (0.08 ppb) in 12% (5/43) of the samples. Samples obtained downstream of Emerald Links golf course, during dry weather, was very contaminated (up to 0.2 ppb diazinon). This contamination had spread along the rest of Mosquito Creek.
The insecticide diazinon, used for grubs, was at levels harmful to aquatic species in both creeks. The species at risk include mosquito predators, that would protect people from West Nile virus.
The drinking water standard (set in 1986) is 20 ppb 250 x the standard for aquatic species! Ottawa's drinking water is monitored occasionally through the Ontario MoE (using cruder testing, for the 20 ppb standard) and is apparently free of pesticides. That test would not have detected diazinon in any of the samples found to be contaminated by the University of Guelph.
Diazinon inhibits an enzyme in the nervous system, AchE. Some people in Ottawa are severely disabled, with very low enzyme levels that do not improve. There is a forty-fold variability in people's ability to rid the body of this nerve poison. Chronic exposure to pesticides in the environment and drinking water could contribute to keeping susceptible people sick.
Background Resources, Information
February 2004 City of Ottawa Pesticide Reduction Report
Pesticide Concentrations in the Don and Humber River Watersheds (1998-2000), 2002.
Struger J, Fletcher T, Martos P, Ripley B, Gris G. http://www.ene.gov.on.ca/envision/techdocs/4335e.pdf
Landscaping chemicals (herbicides 2,4-D, mecoprop and dicamba, and the insecticide diazinon) were detected with similar frequency, in similar concentrations in Toronto.
Health Canada Drinking Water Guideline Documents
(Diazinon and other documents accessible from page)
Canadian Water Guidelines
Water Legislation in Ontario
Drinking Water Quality Standards in Ontario Are They Tough?
Discussion of lower standards compared to other jurisdictions