Quebec flood: hidden consequences

By Olga Speranskaya, PhD, Toxic chemicals specialist

Rising water levels of the Ottawa River and heavy rains affected thousands of homes in Quebec. Many of them were severely damaged by the water.
Seasonal flooding happens every year, but this year reports showed water inside the houses and garage spaces. Experts warn that such extreme weather events could become more frequent due to global warming.
However there are concerns over a flood consequence that have not been discussed much. A study published in the Journal of Public Health (Oxford, UK) in 2004, concludes “that chemical material may contaminate homes and that in some cases flooding may lead to mobilization of dangerous chemicals from storage or remobilization of chemicals already in the environment, e.g. pesticides.”
Environmentalists warn that flooding water may bring toxic chemicals into affected houses and backyards from the nearby farm lands. Water will eventually leave the place, but what about these toxins? How can people clear their houses to be sure there are no health safety concerns when we even do not know what chemicals are used on all of these farms?
“Glyphosate is the mostly widely used herbicide in the world. Likewise, 2,4-D herbicide is in hundreds of products. Undoubtedly, both would be used by farmers in Quebec,” says Kathleen Cooper, senior researcher with the Canadian Environmental Law Association.
Nearly one third of samples tested by the Canadian Food Inspection Agency contain detectable residues of glyphosate. In 2015 the International Agency for Research on Cancer (IARC) classified glyphosate as a probable human carcinogen. Many researchers consider glyphosate to be an endocrine disrupting chemical. According to Pesticide Action Network report on Glyphosate of 2016, “Exposure to glyphosate-based herbicides, even at very low doses, may result in reproductive problems including miscarriages, pre-term deliveries, low birth weights, and birth defects”.
Health Canada states that 2,4-D herbicide is not a carcinogen and that products containing 2,4-D are acceptable for continued registration. However IARC classified 2,4-D as “possibly carcinogenic to humans”. According to the Natural Resources Defense Council, “There’s a growing body of scientific evidence that the chemical poses a danger to both human health and the environment.”
The use of 2,4-D herbicide on lawns was banned in Quebec in 2006. “Quebec’s decision was legitimately based on a precautionary approach, says Cooper. “It followed the advice of public health authorities who noted that scientific uncertainty and greater vulnerability of certain groups to pesticides justified a prudent, precautionary response.”

However the use of 2,4-D herbicide on farms, industrial areas, and pastures continues. The National Pesticide Information Centre (NPIC) notes that people may be exposed if “2,4-D gets on the skin, or if a person breathes it in, or eats or smokes afterwards without washing hands.

2,4-D and glyphosate are not the only herbicides used in Canada. “There are no published data about the amount of pesticides used, nor available data on total usage and whatever exists resides at the provincial level, says Cooper. The only information we have are total sales data that must be reported annually to the Pest Management Regulatory Agency (PMRA). It is impossible to know what total sales data means in terms of where individual pesticides are used, on what crops, etc. Published results are also typically a few years out of date.”
To reduce pesticide exposure during floods or heavy rains that produce surface water runoff farmers “follow certain farm practices to help reduce the movement of pesticides through surface water runoff”, according to the Ontario Ministry of Agriculture, Food and Rural Affairs. Guidelines for managing pesticide spills are available on the Ministry’s website.
However avoiding water runoffs during heavy rains and floods like those happened this year is nearly impossible. Information sharing on what chemicals are used on the farms, their health effects and protective measures will help people better clean up their houses in case of water damage.

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