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Neonicotinoid Pesticides

Topics: Contaminants and Hazards

Neonicotinoids (also referred to as “neonics”) are insecticides derived from nicotine. They act by binding strongly to nicotinic acetycholine receptors in the central nervous system of insects, causing overstimulation of their nerve cells, paralysis and death. Neonicotinoids are highly water-soluble, persistent in the environment and systemic - the pesticides migrate into all parts of treated plants.

Although their principal use is in agriculture for seed and soil treatment and on plant foliage; they may be used in home yards and gardens, golf courses, and for flea and tick treatments on dogs and cats. Introduced in Canada in the 1990s, the three neonicotinoids currently approved for agricultural use in Canada, imidacloprid, clothianidin, and thiamethoxam, are being re-evaluated for continued registration. (Health Canada, 2017)  Acetamiprid and thiacloprid are approved for specific purposes only.  

Public awareness of the hazards of neonicotinoids is from publicized concerns about deaths and colony collapse disorder of honey bees and other pollinator insects. While there is evidence of environmental exposure to neonicotinoids, there is scientific controversy as to whether there are potential health risks to the public from exposure to neonicotinoids and their metabolites.

  • Neonicotinoids insecticide residues have been detected in wetlands, surface water and agricultural soil in Canadian studies, such as those undertaken in Ontario (Schaafsma et al., 2015) and Saskatchewan (Main et al., 2014).
  • Neonicotinoid residues cannot be washed off of fruit or vegetables. A  U.S. study found all commonly eaten fruits and vegetables (other than nectarine and tomato) had positive detections for at least one neonicotinoid, with imidacloprid having the highest detection rate (Chen et al., 2014).  In Japan, although the public is frequently exposed to neonicotinoid residues from consuming fruits and vegetables, the calculated daily intake of each neonicotinoid was low (under 1% of the acceptable daily intake). (Harada et al., 2016)
  • Transferable residues of neonicotinoids have been demonstrated in dogs given a flea treatment containing the active ingredient imidacloprid. Glove samples were collected after petting the dogs for 5 minutes. Residues were measurable in gloves up to four weeks after the flea application, indicating potential exposure to family members. (Craig et al., 2005)
  • A systematic review of four general population studies suggested a link between chronic neonicotinoid exposure and different adverse developmental or neurological outcomes. (Cimino et al, 2017). For example, frequent maternal use of flea medications containing imidacloprid on pets was associated with a higher risk of children developing autism spectrum disorder from prenatal exposure. (Keil et al, 2014)
  • The scientific opinion from the European Food Safety Authority concluded that both imidiacloprid and acetamiprid may affect neuronal development and function, but further scientific study is warranted. (EFSA, 2014)  According to Health Canada, the amount of neonicotinoids in the environment is well below any level of concern for human health. (Health Canada, 2016)

Selected External References

  • Update on the neonicotinoid pesticides (Health Canada, 2017)
    This document offers some background on use of neonicotinoids and concerns of effects on pollinators, including honeybees. A human health risk assessment for imidacloprid did not identify human health concerns from any exposure route when used according to current label standards. After consideration of potential toxicity and exposure, including sensitive populations it was concluded that human health risks were within acceptable limits. 
     
  • Neonicotinoids (European Commission, 2017)
    This document provides facts on neonicotinoids and information about actions taken by the European Commission to protect honeybees, including restrictions of 3 commonly used neonicotinoids on plant protection products and treated seeds.
     
  • Case Study: Neonicotinoids (Public Health Ontario, 2015)
    This case study describes the risks to bees from use of neonicotinoids, and provides information on regulation, ecosystem considerations and on food security, with consideration of residual concentrations of neonicotinoids in fruits and vegetables.

Peer-reviewed Publications

Last updatedJun 05, 2018