Open AccessA case–control study of breast cancer risk and ambient exposure to pesticides
Author(s) -
Carrie Tayour,
Beate Ritz,
Bryan Langholz,
Paul K. Mills,
Anna H. Wu,
John P. Wilson,
Kaveh Shahabi,
Myles Cockburn
Publication year - 2019
Publication title -
environmental epidemiology
Language(s) - English
Resource type - Journals
ISSN - 2474-7882
DOI - 10.1097/ee9.0000000000000070
Subject(s) - chlorpyrifos , pesticide , breast cancer , environmental health , medicine , population , exposure assessment , cancer , risk assessment , toxicology , case control study , biology , ecology , computer security , computer science
Background: While the estrogenic properties of certain pesticides have been established, associations between pesticide exposure and risk of breast cancer have been inconsistently observed. We investigated the relation between pesticide exposure and breast cancer risk using methods capable of objectively assessing exposure to specific pesticides occurring decades before diagnosis. Methods: A case–control study was conducted to evaluate the risk of postmenopausal breast cancer associated with historic pesticide exposure in California’s Central Valley, the most agriculturally productive region in the United States where pesticide drift poses a major source of nonoccupational exposure. Residential and occupational histories were linked to commercial pesticide reports and land use data to determine exposure to specific chemicals. Cases (N = 155) were recruited from a population-based cancer registry, and controls (N = 150) were obtained from tax assessor and Medicare list mailings. Results: There was no association between breast cancer and exposure to a selected group of organochlorine pesticides thought to have synergistic endocrine-disrupting potential; however, breast cancer was three times as likely to occur among women exposed to chlorpyrifos compared with those not exposed, after adjusting for exposure to other pesticides including organochlorines (OR = 3.22; 95% CI = 1.38, 7.53). Conclusions: Organophosphate pesticides, such as chlorpyrifos, have rarely been evaluated in studies of breast cancer risk. Additional research is needed to confirm these findings and to better understand the underlying mechanisms given that chlorpyrifos has been detected in local air monitoring at levels of concern for residents living in the agricultural regions where it is used.