New cancer links claimed
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Scientists in the US have linked 22 pesticides to prostate cancer, raising fresh concerns for farmers.
A recent US study has identified pesticides consistently linked to the incidence of prostate cancer across counties, with four pesticides also associated with prostate cancer mortality. The findings, published in the journal CANCER by the American Cancer Society, bring new insight into the impact of agricultural pesticide exposure on health outcomes, specifically prostate cancer.
Researchers used county-level data across two timeframes, correlating pesticide use from 1997–2001 and 2002–2006 with prostate cancer cases diagnosed 10 to 18 years later.
This approach considers prostate cancer's typically slow growth, allowing researchers to observe a lag between pesticide exposure and cancer incidence.
In both timeframes, three of the 22 pesticides identified had previously been associated with prostate cancer, including the herbicide 2,4-D, which has seen widespread application in the United States and Australia since the 1960s.
Additionally, 19 pesticides with no former links to prostate cancer were identified in this study, comprising 10 herbicides, several fungicides, insecticides, and one soil fumigant.
Notably, four pesticides showed associations not only with increased prostate cancer incidence but also with prostate cancer mortality.
These include three herbicides (trifluralin, cloransulam-methyl, and diflufenzopyr) and one insecticide (thiamethoxam).
While trifluralin is currently approved for use in Australia, the other two herbicides are not sanctioned for use.
Cloransulam-methyl, for instance, remains unauthorised in the Australian market.
“This research demonstrates the importance of studying environmental exposures, such as pesticide use, to potentially explain some of the geographic variation we observe in prostate cancer incidence and deaths across the United States,” said lead author Dr Simon John Christoph Soerensen of Stanford University.
According to Dr Soerensen, the findings can help guide further studies on risk factors and health policies aimed at reducing prostate cancer rates.
But some experts remain cautious about interpreting these findings.
Professor Oliver Jones of RMIT University has commented on the limitations of associating pesticide use with cancer incidence.
“The evidence in this paper is quite weak for several reasons,” said Jones.
“The authors don’t actually say that pesticides cause prostate cancer, just that they found 22 pesticides statistically associated with it.”
Jones cautioned that statistical correlations alone are insufficient to confirm a causal link, especially without detailed individual exposure data and direct experiments to validate findings.
Professor Adrian Esterman from the University of South Australia also acknowledged the study's limitations, noting that the use of county-level data may not accurately represent individual exposures.
He stressed that while the study's findings could inform future research and public health policy, causation has not been established and that additional studies are necessary to clarify the relationship between pesticides and prostate cancer.
The study, which advocates for continued research into pesticide-related health risks, highlights the complexities in examining environmental influences on disease.