19
Nov
Study Highlights Correlation Between Pesticide Exposure and Prostate Cancer in Men in the U.S.
(Beyond Pesticides, November 19, 2024) Researchers at Stanford University recently published a study in Cancer, an international interdisciplinary journal of the American Cancer Society (ACS), that reveals a correlation for numerous pesticides with increased prostate cancer occurrence and associated death. The study finds that exposure to 22 pesticides is positively associated with prostate cancer. The 22 pesticides include 2,4â€D, acephate, azoxystrobin, bifenthrin, carbaryl, chloropicrin, cloransulamâ€methyl, cyhalothrinâ€lambda, diflufenzopyr, diuron, glyphosate, hexazinone, linuron, methyl parathion, pendimethalin, propiconazole, sulfosate, thiamethoxam, thifensulfuron, tribenuron methyl, trifloxystrobin, and trifluralin. (See more on 2,4-D and cancer prevalence here and here.)
As prostate cancer is a leading national health concern, the authors investigate agricultural pesticide exposure and compared it to prostate cancer incidence and mortality across counties in the contiguous U.S. “The 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 researchers postulate.
In comparing countyâ€level associations of 295 pesticides and prostate cancer reports, the authors were able to conduct an environmentâ€wide association study (EWAS) to determine any statistically significant links. “We acquired annual estimated total usage data (kg per county) for all pesticides reported and applied to agricultural crops grown in the United States from 1997 to 2006 from the National Waterâ€Quality Assessment Project through the U.S. Geological Survey Pesticide National Synthesis Project,†the researchers note. “We selected these years to allow for lagâ€time between exposure and prostate cancer outcomes.â€
The prostate cancer incidence and mortality rates were acquired for the timeframes of 2011–2015 and 2016–2020 from the U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, and the National Cancer Institute. This data is U.S.â€wide, countyâ€level, and age-adjusted. The final data is compiled from 3,107 counties within the 48 states. Two cohorts were created based on the pesticide data for 1997–2001 and 2002–2006 and were then compared to cohorts for the prostate cancer data. Of the 295 pesticides that are analyzed, the authors focus on those that are available in both cohorts and that appear in at least 35 counties.
To further explain their methodology, the researchers say, “We used linear regression models examining 5â€year cumulative pesticide use separately for each of the 295 individual pesticides measured in 1997–2001 and ageâ€adjusted prostate cancer incidence rates from 2011–2015 (discovery cohort). We conducted parallel analyses for pesticide use in 2002–2006 among the same 295 pesticides and prostate cancer incidence rates in 2016–2020 (replication cohort).â€
As a result, the discovery cohort with the 2011–2015 data shows 953,204 prostate cancer diagnoses and 140,086 deaths, while the replication cohort from 2016–2020 increased to 1,063,671 diagnoses and 156,687 deaths.
Statistical analyses reveal exposure to the 22 pesticides is positively associated with prostate cancer incidence in both cohorts. “The 22 candidate pesticides identified by this EWAS approach include pesticides previously reported to be associated with the incidence of prostate cancer: 2,4â€D, linuron, and carbaryl… Of the 19 candidate pesticides not previously reported as associated with the incidence of prostate cancer, many have been evaluated by the EPA [Environmental Protection Agency] for their potential carcinogenic effects, although not explicitly in relation to prostate cancer, with seven of these pesticides classified as possible human carcinogens,†the researchers report. They continue, “[F]our of these candidate pesticides [cloransulamâ€methyl, diflufenzopyr, thiamethoxam, and trifluralin] were associated with prostate cancer mortality, highlighting their potential relevance to the development of clinically significant prostate cancer.â€
In the results connecting four pesticides to an increase in death from prostate cancer, further investigation into these classes of pesticides is needed. Three of the pesticides are herbicides, but come from different classes—trifluralin (dinitroaniline), cloransulamâ€methyl (triazolopyrimidine), and diflufenzopyr (arylâ€carboxylates)—while thiamethoxam is a neonicotinoid insecticide. Of these, EPA considers only trifluralin as a possible human carcinogen. The other three are considered not likely to be carcinogenic or have evidence of non-carcinogenicity. Advocates are calling for EPA to fully evaluate all chemicals regarding endocrine disruption, carcinogenicity, and other long-term effects, as many currently registered pesticides lack chronic epidemiological studies.
There are many studies (see here and here) connecting pesticides with an increased prostate cancer risk. Beyond Pesticides has also highlighted this link through Daily News coverage over the last 10+ years here, here, and here. The correlation between pesticide exposure and endocrine disruption is also heavily documented. As reported in 2017, alterations in gene expression, such as with oxidative stress and endocrine disruption, can occur after contact with pesticides. One study finds that these DNA changes and “subsequent gene inactivation has been consistently associated with prostate cancer.†(See additional coverage here and here.)
ACS estimates that prostate cancer incidence in the U.S. for 2024 will include 299,010 new cases and 35,250 deaths. They also note that about 1 in 8 men will be diagnosed with prostate cancer, as it is the most common cancer among men in the U.S., second to skin cancer. Regarding cancer deaths in U.S. men, prostate cancer ranks second, with lung cancer being first. This translates to 1 in every 44 men dying from prostate cancer, which is lower than in past decades as early detection and treatment options have increased. ACS also finds that globally prostate cancer is the most diagnosed cancer type in men for 66% of the world (118 countries).
With the high prevalence of prostate cancer, and many other cancers, within the U.S. and worldwide, contributing factors such as pesticide use and exposure from drift need to be addressed. As the study authors conclude, “Public health efforts to reduce the burden of prostate cancer should consider pesticides as environmental exposures that may contribute to the incidence of, and mortality related to, prostate cancer.†Beyond Pesticides has not only called for more extensive testing but the adoption of alternative practices and products that eliminate toxic pesticide use to safeguard human health and the environment.
In organic land management, the reliance on petrochemical pesticides and synthetic fertilizers is removed. Instead, least-toxic alternatives are used to effectively manage insects, rodents, and weeds without exposing any organisms or the environment to harmful chemicals. You can make The Safer Choice to avoid hazardous home, garden, community, and food use pesticides and eat with a conscience.
Choosing organic food rejects hazardous agricultural practices, mitigates climate change, protects farmworkers and farm families, and promotes healthy systems. Whether buying organic products or growing your own organic food, you can support the organic solution. Become a member of Beyond Pesticides today and sign up for Action of the Week and Weekly News Updates delivered right to your inbox!   Â
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source:
Soerensen, S. et al. (2024) Pesticides and prostate cancer incidence and mortality: An environment-wide association study, Cancer. Available at: https://acsjournals.onlinelibrary.wiley.com/doi/10.1002/cncr.35572.
