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Imidacloprid Uncertainty

UPDATE:  The consultation period has been extended. Interested parties are encouraged to provide comments and suggestions by 23 March 2017.

Unless you’ve been hiding under a rock, you have probably heard by now that Health Canada’s Pest Management Regulatory Agency (PMRA) is proposing to phase out all agricultural uses of imidacloprid over three to five years.

The proposed phase out comes as a result of a re-evaluation of imidacloprid by the PMRA, which reviewed scientific information provided by pesticide manufacturers, provinces and Environment and Climate Change Canada, as well as published scientific information.

As part of its re-evalution, the PMRA stated that in aquatic environments in Canada, imidacloprid is being measured at levels that are harmful to aquatic insects.

“…the levels of the pesticide being found in waterways and aquatic environments are harmful to aquatic insects, such as mayflies and midges, which are food sources for fish, birds and other animals,” states the re-evalution document. “These insects are an important part of the ecosystem, including as a food source for fish, birds and other animals. Based on currently available information, the continued high volume use of imidacloprid in agricultural areas is not sustainable.”

Imidacloprid was first registered in Canada for use on Colorado potato beetle, in 1995. According to Craig Hunter, research and crop protection specialist with the Ontario Fruit and Vegetable Growers’ Association, the Ontario and Quebec growers at that time had lost the use of every other registered insecticide to control Colorado potato beetle due to resistance.

“Imidacloprid was a new insecticide and the first in the class of neonicotinoids known to be effective and registered already in the U.S.,” says Hunter. “Because of the severe problem in Canada, the registration was put through the system and it was approved for use for Canadian growers.” Since then a number of other crops have been added to the label.

One of the major benefits of imidacloprid is the multiplicity of pests it controls with one application. “If the product is no longer available for use on potatoes, then I expect one, two, three, even four other insecticides might be needed, and maybe even multiple applications of other insecticides might be needed through the season to do the same job that this one does,” says Hunter, adding that could bring up a new problem – insecticide resistance. “Most new modern pesticides that have come out in the last 20 years tend to be very specific to one or two insects or one family of insects. Because they’re more specific in the way they work, they become more prone to resistance.”

In the last 15 years, imidacloprid has become the most widely used insecticide in the world. Indeed, the spectrum of activity and the number of crops it can be used on has exceeded any other pesticide. Looking to the future, Hunter says he doesn’t see another big family of new insecticides coming along that’s going to do the same job. “It’s going to take several of these newer ones because they are so specific.”

So what is it that’s driving the PMRA to make this proposal? According to Hunter, the PMRA has taken laboratory experimental data and determined toxicity in a pristine laboratory environment, and then paired that number with field monitoring data. “Some of the data shows that the levels were approaching levels of concern,” says Hunter. “However, there is other data that was done in the field that would suggest that the toxicity numbers calculated in the lab experiments are 10- to 100-fold less sensitive in the real environment than what the lab numbers would say.”

Which would mean that none of the data from field observations would indicate an imminent threat of toxicity. Hunter says there was also no data from the field to show monitoring of the bugs themselves to see if there was any negative affect taking place.

“Somewhere along the line there has to be a very frank and open discussion between the scientists who’ve done work in the lab and the scientists who’ve done work in the field to come back with a more realistic toxicity number. There is no hard data anywhere that anyone has shown that this is causing actual harm. What we’ve got is potential harm or suspected potential harm. That’s a big difference.”

The PMRA is inviting the public to submit comments on the proposed re-evaluation decision for imidacloprid including proposals that may refine the risk assessment and risk management. Deadline to do that is Feb. 21, 2017. Once the PMRA considers the comments and any information are received during the public consultation period, it will publish a final decision.

Let’s hope their decision is based on fact and common sense.

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