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Does pesticide exposure affect the sense of smell?

Researchers recently studied whether pesticide exposure affected farmers’ sense of smell. The results were published in the journal Environmental Health Perspectives.


Global pesticide use since 1990 has almost doubled from 2.29 tons to 4.09 tons. The Americas are the second highest user of pesticides, accounting for 29.4% of pesticides used. Pesticides are a necessary evil in modern agriculture, but pesticide exposure is an inevitable side effect for agricultural workers and consumers.

Researchers at Michigan State University in the United States recently completed a review of data from the United States Agricultural Health Study (AHS) on the effects of pesticide exposure on farmers’ sense of smell. The results were published in the journal Environmental Health Perspectives.

The study reviewed data from questionnaires completed by 11,232 farmers in the states of North Carolina and Iowa in the United States. The questionnaire was first given between 1993-1997 and asked farmers about their use of pesticides, including any history of high pesticide exposure events (HPEEs). Follow-up questionnaires were completed every five to six years, giving researchers 20 years of data.

Farmers were considered to have had a high pesticide exposure event if they had large amounts of pesticide in contact with their skin or had breathed or swallowed pesticide. They also gave information on the amount of time between the HPEE and washing their skin and clothes.

The first and second follow-up questionnaires received information on additional HPEEs and removal of pesticide residue. The third follow-up questionnaire asked whether the farmers had experienced any loss of the sense of smell. If so, they provided information on how long they’d experienced the olfactory loss and any other symptoms they’d experienced.

Farmers with a history of pesticide exposure had a 49% higher likelihood of an impaired sense of smell 

A total of 10.6% of the farmers that had HPEEs experienced a loss of smell. Researchers determined that farmers with a history of pesticide exposure were 49% more likely to experience olfactory impairment. The more time between pesticide exposure and washing, the more likely farmers were to experience a loss of smell.

Because the study data was self-reported, there are possible limitations which could lead to misclassification of loss of smell, underestimating the time period when smell loss was first noticed, and determining what was a high pesticide exposure event. Other limitations included olfactory impairment questions were only asked in the third questionnaire, farmers were exposed to multiple pesticides, and only 61% of participants completed the most recent questionnaire.

Pesticide exposure can be dangerous for anyone, especially farmers that are more frequently exposed. The study results emphasize the importance of using precautions when using pesticides and promptly washing with soap and water if the user spills on their skin or clothing.

Written by Rebecca K. Blankenship, B.Sc.


  1. Shrestha S, Kamel F, Umbach D et al. High Pesticide Exposure Events and Olfactory Impairment among U.S. Farmers. Environ Health Perspect. 2019;127(1):017005. doi:10.1289/ehp3713
  2. Group E. EWG’s 2019 Shopper’s Guide to Pesticides in Produce™. Published 2019. Accessed March 30, 2019.
  3. Published 2019. Accessed March 30, 2019.
Rebecca Blankenship BSc
Rebecca Blankenship BSc
Rebecca Blankenship is a freelance technical writer. She reviews, edits, and authors internal quality documentation required for regulatory compliance. She has twenty years experience in industrial pharma/medical device quality management systems and an honors BSc in chemistry. She is a natural born rule follower and enjoys applying this strength to help others be audit ready to meet regulatory requirements. She also loves learning about the latest scientific discoveries while writing for Medical News Bulletin. Her free time is spent as a full-time mom, encouraging can-do attitudes and cooperation in her three children.


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