As growers still wait for the final decision on whether certain neonicotinoid seed treatments will be banned in Canada, many are still scratching their heads about how the proposed ban came about.
As it happens, the re-evaluation of pesticides is a legal requirement and it was during a periodic routine re-evaluation that the Pest Management Regulatory Agency (PMRA) discovered new information about neonics. The concern over possible consequences to human health and the environment eventually led to the proposal to ban them.
The federal legislation that governs these products is the Pest Control Products Act (PCPA), overseeing pesticide registration and re-evaluations, according to Pratisara Bajracharya, Manitoba Agriculture’s pesticide minor use and regulatory specialist.
Speaking to the Manitoba Agronomist’s Conference earlier this winter she explained that under the PCPA, every product is re-evaluated every 15 years.
“It ensures that the current standards for environment safety and human health is preserved or are met, and it incorporates any new information that may be available since the product was registered or last re-evaluated,” Bajracharya said.
“These re-evaluations take into account those factors and make necessary changes on pesticide product labels.”
There are six steps to the re-evaluation process and it’s not speedy. The first four phases involve collecting information, scientific assessment, a decision proposal and update assessment and can take up to four years to complete. The last two stages, final decision and implementation, can take an additional two to three years.
“As soon as PMRA comes out with a decision, there’s still product in the market so it doesn’t automatically vanish,” says Bajracharya. “In order to allow that product to gradually be phased out, PMRA normally allows two to three years from the time the final decision is made to when the product is actually allowed to be used for the last time in Canada.”
Reviewing the science
At the information collection stage, PMRA contacts various stakeholders to gather any new information about the product or its use. Probably the most important step is the science assessment, which looks at the data, including existing scientific literature from other jurisdictions and regulatory agencies.
“A few examples of risk assessment could be dietary risk — so residue in food — or a risk from any concentration of the pesticide being found in drinking water, or in environmental situations where it may be doing a pollinator assessment or an aquatic invertebrate assessment like we saw in the case of neonicotinoids,” says Bajracharya.
The proposed decision stage takes all this data and if a problem has been identified, will propose changes to mitigate the risk, such as additional label requirements or discontinuation of a product. As an example, PMRA came out with a proposed decision to discontinue or phase out the neonic insecticide imidacloprod (often used as a seed treatment) due to a threat to pollinators and aquatic insects. A 90-day public consultation period follows the publishing of the proposed decision.
“At this stage when consultation is happening on a final document, you can only comment with significant scientific data,” says Bajracharya. “At this stage, if you do not like PMRA’s decision they probably won’t listen to you unless you have solid scientific information to support your claim.”
Neonics under the microscope
Over the past years, three different neonic products commonly used in Manitoba and Canada have been proposed for discontinuation: imidacloprid, thiamethoxam and clothianidin, and another, acetamiprid is currently being re-evaluated.
“With neonicotinoid re-evaluations, it began with imidacloprid, it was a cyclical re-evaluation and started as a pollinator issue. But with more study, it was found that seed treatments were perhaps safe if used according to the label direction and with proper mitigation measures in place, but that was not the case for foliar applications,” says Bajracharya. “However, another risk was identified. PMRA said it was finding imidacloprid at concentrations that were toxic to aquatic invertebrates.”
That triggered special reviews for clothianidin and thiamethoxam specifically for aquatic invertebrate assessments.
The 15-year-cycle re-evaluations are mandated by PMRA but special reviews only happen when a particular risk is identified in an OECD country or through PMRA’s other evaluations, so this is how special reviews for clothianidin and thiamethoxam were initiated.
The imidacloprid re-evaluation was largely based upon data from Eastern Canada, and the concern at the time was that the use patterns in Eastern versus Western Canada were different and for different crops.
“We use more seed treatments in our crops versus more foliar applications in the East,” said Bajracharya. “So, there were concerns that all of these neonicotinoid products may be discontinued or proposed to be discontinued.”
In 2017 and 2018 the Province of Manitoba conducted a water quality monitoring program and submitted the data to PMRA.
“We were finding that there were detections for neonics but not an alarming level of incidences from what PMRA was proposing as thresholds,” said Bajracharya.
Despite the new data, PMRA’s proposal continues to be discontinuation of neonics.
“PMRA has said that it does not think that the risks to aquatic invertebrate posed by the neonicotinoid insecticides at the current level at which they’re being detected in water is acceptable,” said Bajracharya. “Unfortunately, 2017 and 2018 were dry years in Manitoba and all across the Prairies, so PMRA felt like it did not adequately represent the environmental conditions in the Prairies and honestly, when you’re talking about Prairies, there aren’t a lot of risk mitigation measures, and the mitigation measures that exist, we don’t really know if they work at this point. So, these are some of the reasons why (neonics are) currently being proposed to be discontinued.”