In a first-of-its-kind study – undertaken in the agricultural heartland of the United States – researchers found that being exposed to multiple common pesticides significantly increases childhood cancer risks compared with exposures to just one pesticide, suggesting that children are more at risk to the substances’ harmful effects than was thought.
The authors say they are the first to examine the link between exposures to multiple widely used pesticides and the most common childhood cancers, reports The Guardian.
Most research considers pesticides’ toxicity on an individual basis, and the substances are regulated as if exposures occur in isolation from one another.
But people are exposed to multiple pesticides in water, produce, meat, fish and processed foods. In agricultural communities, children can be even further exposed to multiple pesticides in water, air and dust, and in the home.
The study found that exposure to a 10% mixture increased brain cancer rates by 36%, leukaemia rates by 23% and overall paediatric cancer rates by 30% in Nebraska. The cancers are among the most common in the state, and may help explain their prevalence, said Jabeen Taiba, a lead author with the University of Nebraska medical centre.
“As individuals, we aren’t just exposed to one chemical, but a mixture, so if you are just studying one chemical alone, then you are not able to capture the exposures – it gives you limited information,” Taiba told The Guardian.
The study investigated cancer data from 2 500 paediatric cases across 22 years in Nebraska, the nation’s agricultural heartland. It holds America’s second highest childhood cancer rates, in part due to widespread use of multiple pesticides.
Of the 32 pesticides researchers examined, the most potent mixes included herbicides like dicamba, glyphosate and paraquat – controversial products that are each sprayed on tens of millions of acres of farmland nationally.
The pesticides have drawn intense scrutiny for their toxicity, and are prohibited in many other countries, but US regulators have resisted calls for bans. Pesticides are especially dangerous for children because they are smaller than adults and their bodies are still developing, so health risks can be considerable at a smaller exposure level.
The greatest risk is for farm workers and people living in agricultural communities, but children’s exposure in food presents an underestimated danger, Taiba said.
“We are exposed to multiple pesticides through water and food, so this is not just a problem for the agricultural communities,” she said.
Although the problem’s solution lies in changes in regulatory structure, which will take into account the toxicity of exposure to multiple substances, people can take steps to protect themselves, and Taiba recommends buying organic foods when possible.
Pesticide pollution of water sources in some communities is also common, and people could research levels in their water, then buy water filtration systems that are effective at removing the substances, the authors suggested, recommending reverse osmosis and granular activated-carbon systems as among the best solutions.
In agricultural communities, adults who work around pesticides should leave their work clothes and shoes outdoors, Taiba added.
Previous research has found pesticides tracked or brought into the home are a significant exposure source for children.
Study details
Exploring the joint association between agrichemical mixtures and paediatric cancer
Jabeen Taiba, Cheryl Beseler, Muhammad Zahid et al.
Published in GeoHealth on 12 February 2025
Abstract
Nebraska’s age-adjusted incidence rates for childhood cancers are among the highest in the US. Previous studies indicated associations between agrichemical exposures (atrazine and nitrates) and paediatric cancer rate, assuming single pollutant exposure. We evaluated the joint association between the agricultural mixture and paediatric cancer. Agrichemical exposures at a county scale were quantified using the USGS Pesticide National Synthesis Project for frequently applied pesticides from 1992 to 2014 in 93 Nebraska counties. Outcomes were quantified using pediatric cancer diagnosed among children <20 years of age (1992–2014) from the Nebraska cancer registry. We adjusted for social vulnerability factors such as race, income, employment, and access to care. The associations between 32 agrichemicals and cancer subtypes were assessed using the Generalised Weighted Quantile Sum Regression (gWQS) model. The model was fit assuming a Poisson distribution and using the paediatric population as an offset-term and social vulnerability factors as covariates. We observed a statistically significant positive association between the 32 agrichemicals and overall pediatric cancer and subtypes. The strength of associations was slightly stronger among brain and CNS cancers (β = 0.36, CI = 0.14, 0.57) compared to overall cancer (β = 0.30, CI = 0.16, 0.44) and leukaemia (β = 0.23, CI = 0.09, 0.38). Dicamba, glyphosate, paraquat, quizalofop, triasulfuron, and tefluthrin largely contributed to the joint association. These findings may explain the joint associations of the agrichemical mixture on childhood cancer. Alternative biomarker-based approaches to measuring human exposure are worth investigating for chemicals of concern, particularly in counties with high agrichemical and cancer rates.
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