Chlorpyrifos: Why Edmontonians Should be Concerned About its Use

Chlorpyrifos is a neurotoxin that inhibits proper nerve functioning. It is used to kill insects by paralysing the insect’s essential muscles like those used for breathing. Of course it doesn’t just impact insects as many health studies have proven. The chemical is linked to severe birth defects, brain damage, developmental delays and behavioural problems in humans. Its use correlates with increased incidence of cancer and it has caused deaths. Some of the largest lawsuits around any pesticide are related to chlorpyrifos. $23.5 million was awarded in 2010 to one US family in a lawsuit after their children were permanently harmed. New York State also sued Dow Chemical, the company that makes the chemical, for $2 million for saying chlorpyrifos is safe. Currently, seven US state attorney generals have charged the Environmental Protection Agency with violating federal law by failing to issue required safety findings on chlorpyrifos. Meanwhile, in Canada, when Health Canada’s Pest Management Regulatory Agency was audited in 2015, this pesticide was specifically mentioned as not being re-evaluated as required by law.

Besides being dangerous there is evidence that chlorpyrifos does not work. Edmonton uses chlorpyrifos to kill mosquito larva but the chemical also kills mosquito predators like dragonflies, bats, and birds.  Mosquito populations rise due to their inevitable resistance and lack of predators. This is why Winnipeg sold their stock of the chemical to Edmonton. Edmonton’s website states that chlorpyrifos is applied in areas where dragonflies do not lay eggs but entomologists say local species of dragonflies do lay eggs in temporary water bodies and in grass where the city applies it. One study from 2016 also shows that chlorpyrifos is harmful to 97% of endangered species in the US including honeybees. This pesticide is very persistent and has been found in Arctic ice dating back to 1972. This means it drifts for very long distances, and hangs around for a very long time.

Why, then, is Edmonton the only municipality in Canada to continue to use chlorpyrifos for mosquitoes? (A number of documents prove this to be the case, including a document sent to Pesticide-Free Edmonton from Health Canada.) Edmonton keeps one form of the chemical, Dursban, in reserve in case of an “emergency,” and city staff say they no longer spray it. However, the city continues to use another form of the chemical called Pyrate—and it does so against federal regulations as chlorpyrifos is only to be used in “public health programs” such as during an outbreak of West Nile virus.

We have had only one case of West Nile Virus in our region in ten years, and the Centre for Disease Control states that only 1% of people diagnosed develop a serious illness. Edmonton’s chief medical officer of health agrees that there is not a public health reason for using this chemical. Yet after Pesticide-Free Edmonton filed a report of misuse of this chemical to the Pest Management Regulatory Agency, information that the use of chlorpyrifos must be limited to public health programs vanished from Health Canada’s website.

What is even more disconcerting is that the city of Edmonton has failed to notify the public it is spraying chlorpyrifos in the form of Pyrate. The city has further contravened federal regulations by spraying this chemical inside our city’s boundaries when Health Canada states that “these uses will be limited to temporary pools in outlying areas of municipalities.” The city has also said in a letter shared with surrounding counties the city sprays in that this pesticide is “safe”—which is what Dow was sued for saying. This chemical is being used in our city and we are not even notified of its use, let alone where it has been applied.

We believe that the citizens of Edmonton have a right to expect that regulations be followed. We also believe that public health professionals should be involved in the policies that determine how pesticides are used, and that the city and the province should be educating the public on the very real risks associated with pesticides. The city of Edmonton should stop using chlorpyrifos immediately, and create policy to prevent abuse of pesticides in the future.

Sheryl McCumsey – Environment and Ecosystem Health


Comments 4

  • Sheryl;

    Very important information here. I recall, as a very young person, (circa 1960) in Whitehorse, the DND would spray for mosquitoes in the residential areas of the Hillcrest base.

    There would be a truck driving around with a DDT fog being sent into the air. What I remember most was that there were a number of children, myself included, riding bicycles through the fog for enjoyment.

    57 years later, I cannot say what effects this may have had, but I would be somewhat surprised if there were no neurological effects.

    I am generally healthy at this time, but I do feel some of the symptoms of aging.

    On a side note, I am wondering if you have any information regarding the use of iron chelate on the sports fields in Edmonton this past summer for the purpose of “weed” control.


  • Pat, I lived in Whitehorse 1980 – 1987 and worked in the (variously named) Dep’t of Municipal Affairs which was responsible for mosquito control throughout Yukon. As far as I recall, the seasonal employee had carefully researched what was to be used. It was a granular larvicide applied by hand or from helicopter to pools of standing water. Sorry, I have no idea of the name of the chemical. I don’t recall any fogging.

    • I am curious about the research a “seasonal employee” does. Generally it would seem the kind of research going on is calling suppliers for the most “effective” pesticide that does not include the safest or best alternative over the long term. There are currently 1904 peer reviewed studies on the acute toxicity of this insecticide. I wonder why it takes so long for us to learn. In this case there is no doubt how persistent and harmful this is. This is not the only reason no one else is currently using it for mosquitoes- it is also because it impacts all the predators to the mosquito and mosquitoes become resistant. Everyone I talk to is incredulous that Edmonton uses this. What does this tell you? How and who decides what should be sprayed where and when? We do not have malaria in Canada. A “granular larvicide” could have been Dursban which contains chlorpyrifos. I am glad that no one else is still using this for this in Canada- this pesticide was about to be banned entirely before Trump was elected. Now it will remain on the market since Dow chemical has very good representation in the White House. Canada collaborates with the US EPA- we will follow their lead.

      Sorry Pat – I haven’t had a chance to research the iron chelate as of yet. I can tell you that the focus is wrong. Killing dandelions is the wrong focus. Today we have many serious issues to deal with and dandelions should be last on our list. The city will spend $3 million to address this- this will kill clover – a natural nitrogen fixer for grass. If you wipe out something that is a free positive impact I would say you have the wrong focus on how to address any concerns. It seems in North America we blindly succumb to corporate brain washing about a yellow flower. I can think of many better ways to spend $3 million dollars. Creating healthy turf is not about spraying pesticides. This is like thinking taking drugs will make you healthy. We need to change the direction of our thought……….what we have been doing clearly does not work.

  • Mark, as you noticed, this fogging was done in the early 1960s by dnd in the residential area know as Hillcrest. I am sure that things have changed since then.

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