medwireNews: A US study has revealed a significant association between 22 pesticides and increased incidence of prostate cancer.
Four of these pesticides were also significantly associated with increased prostate cancer mortality, “highlighting their potential relevance to the development of clinically significant [disease],” say the researchers in Cancer.
They explain that “[t]he geographic variation in prostate cancer incidence and mortality suggests that regional environmental factors, such as pesticide exposure, may contribute to the development of prostate cancer.”
The investigators conducted a large-scale environment‐wide association study looking at the annual use of 295 distinct pesticides and prostate cancer across counties in the contiguous USA. They analyzed the data in two cohorts: “1997–2001 pesticide use with 2011–2015 outcomes (discovery) and 2002–2006 use with 2016–2020 outcomes (replication).”
Twenty-two pesticides were found to be significantly associated with an increased incidence of prostate cancer in both the discovery and replication cohorts. These included herbicides such as glyphosate and diuron, fungicides such as propiconazole, insecticides such as methyl parathion, and the all‐purpose soil fumigant chloropicrin. Of note, 19 of the identified pesticides had not previously been reported to be associated with prostate cancer incidence.
In the replication cohort, each standard deviation increase in log-transformed pesticide use (in kg per county) corresponded to increases in age-adjusted incidence of prostate cancer per 100,000 individuals ranging from 2.43 for the insecticide bifenthrin to 7.11 for propiconazole.
Additionally, four pesticides – the herbicides cloransulam‐methyl, diflufenzopyr, and trifluralin, and the insecticide thiamethoxam – were significantly associated with prostate cancer mortality in both cohorts.
The team highlights that only trifluralin is classed by the US Environmental Protection Agency “as a ‘possible human carcinogen,’ whereas the other three are considered ‘not likely to be carcinogenic’ or have evidence of ‘noncarcinogenicity’.”
Simon John Christoph Soerensen and colleagues, from Stanford University in California, USA, acknowledge the limitations of the study, such as the “ecological study design, potential unmeasured confounding, and lack of individual‐level exposure data.”
But they nevertheless believe that the results “underscore the need for continued research into the relations among these specific pesticides and prostate cancer incidence and into the potential public health relevance of pesticide exposures and cancer incidence more generally.”
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