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Abstract
No systematic reviews are available on data from humans on cancer risk from exposure to permethrin, a widely used insecticide for which some animal studies have reported positive findings based on mechanisms that may not be relevant to humans. We identified potentially relevant articles through a search of electronic databases which included all studies of pesticide exposure and human cancer. A total of 18 articles were selected, including six identified from the list of references of other articles. Most articles were based on analyzes of the Agriculture Health Study (AHS); they provided no evidence of an increased risk of cancers of colon, rectum, pancreas, lung, melanoma, female breast, prostate, urinary bladder, as well as non-Hodgkin lymphoma (including its main subtypes), and leukemia. An increased risk of multiple myeloma was reported among AHS members with the highest tertile of estimated permethrin exposure (odds ratio 5.01; 95% confidence interval 2.41–10.42; p for trend <0.01). A subsequent analysis with a larger number of cases found a less pronounced association between permethrin exposure and risk of multiple myeloma; no exposed cases were reported in a separate study. Two case–control studies of childhood leukemia reported an association with biological markers of permethrin metabolites; in another study self-reported exposure to permethrin was associated with risk in children below 1 year of age, but not in older children. In conclusion, permethrin exposure does not seem to entail a risk of cancer in humans. Results on multiple myeloma and childhood leukemia are weak and inconsistent, and require replication in independent populations.
Acknowledgements
The authors gratefully acknowledge the review comments provided by four external reviewers selected by the Editor and anonymous to the authors. These comments helped improve the manuscript.
Declaration of interest
The professional association of the authors is shown on the cover sheet. The review was conducted in response to a request to PB from Dr Thomas Osimitz of Science Strategies (SS; http://www.sciencestrategies.com/) acting as an intermediary for the Permethrin Data Group II (PDGII) Steering Committee/Joint Venture operating under the auspices of the Household and Commercial Products Association (HCPA; https://www.thehcpa.org). Members of the PDG II include AMVAC, Bayer CropScience, FMC, GhardaChemicals Ltd. LG Lifesciences, Meghmani Organics Ltd, MGK Co, and UPI, companies that produce and/or market Permethrin. The authors were compensated via a consultancy contract with SS funded by PDGII. The planning and conduct of the review and preparation of the paper were independent professional activities of the authors. A draft of the paper was provided to SS/PDGII for technical review. The SS/PDGII, in turn, requested a technical review of the paper by Dr. Samuel Cohen, University of Nebraska Medical Center, comments which were provided to Paolo Boffetta. The conclusions in the paper are the views of the authors and are not necessarily the views of SS or PDGII. Neither of the authors during the past 5 years has appeared in any legal/regulatory proceedings related to the contents of the paper nor have they been engaged to appear in such proceedings in the future.
Supplemental material
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