Endocrine-disrupting pesticide exposure linked to increased testicular cancer risk
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Prenatal proximity to certain commonly used pesticides appeared to increase testicular cancer risk later in life, according to study results.
The findings, presented at the virtual American Association for Cancer Research Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved, showed acephate, in particular, appeared associated with increased testicular cancer risk among Hispanic residents of California.
“Testicular cancer rates have been rising for decades and are rising especially quickly among Hispanics in the United States,” Scott J. Swartz, an MD candidate in University of California Berkeley-UCSF Joint Medical Program, told Healio. “There is ample evidence in the scientific literature to suggest that exposure to endocrine-disrupting chemicals in the womb puts an individual at greater risk for testicular cancer later in life. Given that Hispanics are disproportionately exposed to many endocrine-disrupting pesticides in California, we were interested in investigating the potential effects of nearby endocrine-disrupting pesticide application on testicular cancer among Hispanics in California.”
Swartz and colleagues conducted a registry-based case-control study of 381 California-born men who had been diagnosed with testicular germ cell tumors (336 nonseminomas and 41 seminomas) between the ages of 15 and 19 years. They compared cases, diagnosed between 1997 and 2011, with 762 otherwise healthy controls matched for birth year and race/ethnicity.
The researchers used the California’s Pesticide Use Reporting database to assess the agricultural application of 22 endocrine-disrupting pesticides for an area within a 3-km radius of participants’ birth address during the year before birth.
The statistical analysis included 15 high-volume endocrine-disrupting pesticides to which 50 or more participants potentially had been exposed. Researchers accounted for the timing of pesticide application, histologic subtype, race/ethnicity, birth year and neighborhood socioeconomic status.
Nearly half (48%) of cases and 45% of controls resided within 3 km of an endocrine-disrupting pesticide application during the year before birth.
The population attributable risk for high levels of acephate was 5.4% among Hispanics, and less than 1% before 1990 vs. 10% after 1990 for the overall cohort. Among non-Hispanics, the population attributable risk was 4.8% for carbaryl and 2.5% for copper sulfate.
Nearby applications of 13 of the 15 endocrine-disrupting pesticides were greater among Hispanics compared with non-Hispanics (median total application, 29 kg vs. 11 kg) and, for all but one of the 15 pesticides, among participants born after vs. before 1990 (median total application, 54 kg vs. 13 kg).
An analysis of individual endocrine-disrupting pesticides showed an increased risk for testicular germ cell tumors associated with exposure to acephate (OR = 1.1; 95% CI, 1-1.2), with an OR of 1.3 (95% CI, 1-1.7) for continuous and binary exposures.
When the researchers stratified the analysis by ethnicity, they found the risk remained elevated for acephate among 614 Hispanics participants (OR for continuous exposure model = 1.1; 95% CI, 1-1.2) and, among 504 non-Hispanic participants, for carbaryl (OR = 1.2; 95% CI, 1-1.3) and copper sulfate (OR = 1.1, 95% CI, 1-1.3).
“The connection between acephate and testicular cancer was particularly strong among Hispanics, suggesting that increasing endocrine-disrupting pesticide application and exposure could be a possible driver of increasing testicular cancer rates,” Swartz said.
Although researchers reported no differences by reporting period for pesticide use and the timing of pesticide application (preconception and trimesters), the risk appeared to be higher for nonseminomas and among participants with high neighborhood socioeconomic status.
“It was surprising to find that only one endocrine-disrupting pesticide showed a consistent signal of increased testicular cancer risk among Hispanics, while multiple endocrine-disrupting pesticides showed certain subgroup-specific increases in risk among non-Hispanics,” Swartz said. “Otherwise, it was not surprising that most pesticides did not show a significant increase in testicular cancer risk, given the fact that our estimation of nearby endocrine-disrupting pesticide application was likely imperfect. Although this was, of course, the best we could do given that we were attempting to retrospectively assess exposure over decades.
“Future research should include prospective studies that investigate the relationship between testicular cancer and endocrine-disrupting pesticides, so the latter can be assessed more accurately,” Swartz added. “Specifically, acephate’s effects on reproductive health should be investigated more thoroughly in both humans and animals.”
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Swartz SJ, et al. Abstract PO-125. Presented at: American Association for Cancer Research Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved (virtual); Oct. 2-4, 2020.
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