Pesticide Exposure in the Urban Environment

Pesticides are chemicals developed to prevent or destroy unwanted species including insects (insecticides) and weeds (herbicides).  Organochlorines and organophosphates, developed prior to the 1960s, are being replaced over time with pyrethroids and neonicotinoids which are considered to be less toxic alternatives.

Pesticides are not only applied to the many stages of crop growth and harvest, they also may be used to control commercial, household, and animal infestations (including bed bugs, fleas and ticks). There are many environmental health concerns about chronic exposure to pesticides due to their widespread use and evidence of health risks.

• Maternal exposure during pregnancy to residential pesticides (particularly indoor insecticides, but also herbicides) has been associated with childhood leukemia. (Chen et al. 2015)
• Childhood brain tumours, particularly gliomas, have been associated with prenatal indoor exposure to insecticides and pet flea/tick treatment. (Van Maele-Fabry et al. 2016)
• A large study of Canadians 6 to 79 years of age found that over 90% of participants had organophosphate metabolites (dialkyl phosphates) detected in their urine; for pyrethroid metabolites, the detection rate was 99.8%. Fruit, vegetables and nuts were positively associated with these pesticide metabolites. (Ye et al. 2015).
• Over a one year period, pyrethroid metabolites were detected in children by spot urine sampling, Predictors were diet, residential use of pyrethroid insecticides (gardening activities and treatment for head lice) and season. (Lu et al. 2009)

Many provinces and municipalities have enacted a ban on cosmetic use of pesticides for improving the appearance of lawns and gardens because of such health concerns about pesticides. For a summary of provincial regulations concerning banned cosmetic pesticides see: Canadian Association of Physicians for the Environment (2016). Under these restrictions, exposures to pesticides in the urban environment may be reduced, but not eliminated, since other sources of exposure remain, including conventionally-grown produce that often contains pesticide residues.  

NCCEH Resources

• Review of Field Tests on Bed Bug Control Technologies  (2015)
  This evidence review describes field tests and emerging technologies for bed bug control, including a summary of end-use pesticides, including different types of pyrethroids and pyrethrins.
   
• Increasing Use of Pyrethroids in Canadian Households: Should We Be Concerned? (2013)
  This peer-reviewed article describes the increasing use of pyrethroids, particularly for bed bug control but also for crop farming, that has resulted in residues detected in homes, child care centers and food. The safety of these pesticides is questionable without further study of possible health effects from chronic exposure.
   
• Public Health Considerations on Cosmetic Use of Pesticides in BC (2013)
  This document by the NCCEH and the Environmental Health Service at BCCDC outlines typical lawn and garden pesticide ingredients, and the toxicology and epidemiology of specific pesticides. The positive effects as well as unintended consequences of bans on cosmetic pesticides are considered.
   
• Reducing Residential Indoor Exposure to Pesticides: a Toolkit for Practitioners (2011)
  This guidance document provides information on alternatives to pesticides, safe pesticide use and ways to reduce take-home and track-in exposures from the transfer of pesticides from outside to inside the home.
   
• Does Eating Organic Food Reduce Pesticide Exposures and Health Risks? (2010)
  This evidence review describes differences between organically vs. conventionally-grown food, the presence of synthetic pesticide residues in food, biomonitoring of pesticide exposures in children according to type of diet, and considerations of nutritional quality and other factors.  There was no scientific information on whether or not an organic diet provides greater health benefits, along with a reduction in pesticides.
   
• Residential pesticides and childhood leukemia: a systematic review and meta-analysis (2010)
  This peer-reviewed article found that residential exposures during pregnancy to insecticides and herbicides were positively associated with childhood leukemia as was exposure to insecticides during childhood.

Selected External Resources

• Pesticides and Pest Management Fact Sheets and Other Resources (Health Canada, 2017) Included in the fact sheets is information on healthy lawns, homeowner guidelines for pesticide use and pesticides in food. Information notes include an update on neonicotinoid pesticides and bee health.
   
• Changes in Acid Herbicide Concentrations in Urban Streams after a Cosmetic Pesticides Ban (Todd and Struger, 2014)
  This peer-reviewed study compared surface water concentrations of the herbicides 2,4-D, dicamba and mecoprop before and after an Ontario cosmetic pesticides ban and found that concentrations in a majority of the streams did decrease significantly, most likely related to reduced urban use.
   
• Children’s Exposures to Pyrethroid Insecticides at Home: A Review of Data Collected in Published Exposure Measurement Studies Conducted in the United States (Morgan, 2012)
  This review examines children’s exposure to pyrethroids in the home environment.  Seven different pyrethroids were detected. The majority of the children were likely exposed to one or several pyrethroids from food, dust or on surfaces at their residence.
   
• Pesticide exposure in children. Policy statement. American Academy of Pediatrics. (Roberts and Karr, 2012). This position paper describes acute toxicity of pesticides and epidemiological evidence of associations between early life exposures to pesticides and pediatric cancers, decreased cognitive function, and behavioral problems. (Note the May 2013 erratum.)

This list is not intended to be exhaustive. Omission of a resource does not preclude it from having value.