Low neonic levels found in Alta. water bodies

Survey data comes as the Pest Management Regulatory Agency studies the possibility of banning neonic use in Canada

Recent surveys show neonicotinoids have been detected in Alberta water bodies, though their risk of impacting aquatic invertebrates is considered low.

The data, shared by Alberta Agriculture during FarmTech on Jan. 29, found neonics ranged in concentrations of 2.5 nanograms per litre to 125.9 nanograms per litre at 61 of the 102 sample sites in 2018.

Concentrations were detected more frequently during the spring and there were more detections in irrigation bodies and tile drains. They weren’t found as often in rivers, reservoirs and wetlands, though they were more frequent in streams.

The levels overall are considered low, said Shaun Cook, an agri-environmental specialist with Alberta Agriculture.

Cook, who presented the findings, said surveyors detected neonics only 25 percent of the time when they visited the sites.

He said levels never exceeded acute concentrations, which would pose immediate and detrimental effects to aquatic wildlife.

As well, he said levels rarely exceeded chronic concentrations, and such levels weren’t reoccurring. Chronic levels could affect aquatic ecosystems if concentrations remained persistent.

“We’ve characterized this as not indicating a high level of risk to aquatic invertebrates in Alberta,” Cook said in an interview following his presentation.

“We recognize the use of neonics is ubiquitous in agriculture areas, but we very infrequently find them,” Cook said.

“When we do find them, it’s early in the season. At that time of year, aquatic invertebrates are likely not as active in their life cycle as they would be later on.”

Cook has submitted the data to the Pest Management Regulatory Agency, which is currently reviewing the possibility of banning thiamethoxam and clothianidin, citing environmental risk to aquatic invertebrates.

Many agronomists and farmers have said the ban would cause the use of insecticides to increase, which would be more harmful to beneficial insects and the environment.

“The PMRA’s proposed decision, which was released in November 2016, is what really precipitated our action on this portfolio,” Cook said, noting there was little data on prairie waterways that the agency could use at the time.

Other data points, compiled by the Environmental Monitoring Working Group, found concentrations in water across the Prairies were low when they were detected, which was infrequent.

That data has also been submitted to the PMRA, Cook said.

While the agency is only looking at their impact on water species, concerns have been raised about the effect of neonics on bees.

The insecticides have been linked to bee deaths and pollinator decline, though beekeepers appear split on phasing them out. Some worry producers will go back to using foliar sprays, while others say neonics are hurting colonies.

Survey findings per water body:

  • Rivers had the lowest neonic concentrations among flowing water bodies sampled. Neonics were detected in 12.2 percent or 18/148 of river samples, but were detected at least once in each of the seven rivers.
  • Streams: Among all flowing surface water bodies sampled, streams had the highest sample frequency of neonic detection (33 percent or 61/183 samples). Streams also had the highest incidence rate of exceeding chronic concentrations (1.6 per cent of samples).
  • Irrigation: Of all water bodies sampled, irrigation had the highest proportion of sites having levels of neonics at least once during the 2018 sampling season (90.5 per cent or 19/21 sites). Their prevalence, however, was lower than streams.
  • Reservoirs: Of the 15 samples collected from eight reservoirs, only one sample had a positive detection of thiamethoxam, and no other neonic pesticides were detected.
  • Wetlands: Of the 49 samples from 18 wetlands, neonics were each detected in 10.2 percent or 5/49 of the samples. The province says aquatic life concerns are minimal because wetlands are able to largely filter neonics.
  • Tile drains had the highest probability of detection of all water bodies sampled, with 43.2 percent or 16/37 of samples testing positive.

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