Authorities analyzed water samples over two years for pesticide concentration. In summers 2008 and 2009 (before and after the ban took effect), staff from Ontario Ministry of Environment and five conservation authorities conducted water quality monitoring studies of ten urban streams and creeks. They tested them for up to 105 pesticides and breakdown products. Results show in 2009 concentrations of the three most popular cosmetic pesticides dropped by more than 80 per cent: 2,4D reduced by 86 per cent followed by dicamba (82 per cent) and MCPP (2-methyl-4-chlorophenoxyacetic acid; 78 per cent).

"The sort of thing we were hoping would happen: that kids would be protected, that water would be protected, that urban streams would be protected is happening, and it is very gratifying," stated Gideon Forman, Executive Director for the Canadian Association of Physicians for the Environment.

More than 250 pesticide products are banned for sale in Ontario, and over 95 pesticide ingredients are banned for cosmetic uses. Exceptions exist for public health or safety, natural resources, golf courses, sports fields, specialty turf, trees, agriculture, forestry and public works projects.