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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.
- Potential human exposures to neonicotinoid insecticides: A review (Zhang et al, 2018)
This review of articles on exposure and biomonitoring for neonicotinoids published prior to 2017 confirmed the likelihood of human exposure to neonicotinoids, given that they are ubiquitous and have long half-lives.
- Neonicotinoid Residues in Fruits and Vegetables: An Integrated Dietary Exposure Assessment Approach. (Lu et al., 2018)
This cross-sectional study analyzed residues of seven neonicotinoids in fruit and vegetable samples collected from U.S. and Chinese studies. Imidacloprid and thiamethoxam were detected in over one half of the samples. The authors concluded that neonicotinoids have become part of the dietary staple, with possible health implications for individuals.
- Catching Up with Popular Pesticides: More Human Health Studies Are Needed on Neonicotinoids (Seltenrich, 2017)
This science selection article emphasizes the widespread use of neonicotinoids and the concern that these insecticides can have adverse effects on mammals at sublethal doses, which suggests there is the potential for human health effects.
- Human exposure to neonicotinoid insecticides and the evaluation of their potential toxicity: An overview (Han et al., 2017)
This narrative review refers to studies on human neonicotinoid exposure levels and health effects, and provides an evaluation of the potential toxicity of neonicotinoids on humans.
- Effects of Neonicotinoid Pesticide Exposure on Human Health: A Systematic Review (Cimino et al., 2017)
This systematic review included studies up to 2015 on the human health effects of acute and chronic neonicotinoid exposure. Elevated odds ratios for birth anomalies including tetralogy of Fallot and anencephaly, as well as autism spectrum disorder and memory loss/finger tremor were shown in four studies related to chronic exposure.
- Relationship between Urinary N-Desmethyl-Acetamiprid and Typical Symptoms including Neurological Findings: A Prevalence Case-Control Study. (Marlo et al., 2015)
In this small case-control study, cases exhibiting a number of neo-nicotinic symptoms, including postural finger tremor, recent memory loss, headache and electrocardiographic findings, had the neonicotinoid, acetamiprid, more frequently detected in their urine.
This list is not intended to be exhaustive. Omission of a resource does not preclude it from having value.
|Last updated||Jun 05, 2018|