Are Pesticides the New Smoking?

Pesticides have transformed modern agriculture by boosting production yields and helping alleviate food insecurity amid rapid global population growth. However, from a public health perspective, exposure to pesticides has been linked to numerous harmful effects, including neurologic disorders like Parkinson’s disease, weakened immune function, and an increased risk for cancer.

Pesticide exposure has been associated with cancers such as colorectal cancer, lung cancer, leukemia (in children and adults), lymphoma, and pancreatic cancer. But these studies primarily have focused on specific groups of individuals with known exposure to certain pesticides or cancer types, thus offering a limited perspective.

A comprehensive assessment of how pesticide use affects cancer risk across a broader population has yet to be conducted.

A recent population-level study aimed to address this gap by evaluating cancer risks in the US population using a model that accounts for pesticide use and adjusts for various factors. The goal was to identify regional disparities in exposure and contribute to the development of public health policies that protect populations from potential harm.

Calculating Cancer Risk

Researchers developed a model using several data sources to estimate the additional cancer risk from agricultural pesticide use. Key data included:

• Pesticide use data from the US Geological Survey in 2019, which covered 69 agricultural pesticides across 3143 counties
• Cancer incidence rates per 100,000 people, which were collected between 2015 and 2019 by the National Institutes of Health and the Centers for Disease Control and Prevention; these data covered various cancers, including bladder, colorectal, leukemia, lung, non-Hodgkin lymphoma, and pancreatic cancers
• Covariates, including smoking prevalence, the Social Vulnerability Index, agricultural land use, and total US population in 2019

Pesticide use profile patterns were developed using latent class analysis, a statistical method used to identify homogeneous subgroups within a heterogeneous population. A generalized linear model then estimated how these pesticide use patterns and the covariates affected cancer incidence.

The model highlighted regions with the highest and lowest “additional” cancer risks linked to pesticide exposure, calculating the estimated increase in cancer cases per year that resulted from variations in agricultural pesticide use.

Midwest Most Affected

While this model doesn’t establish causality or assess individual risk, it reveals regional trends in the association between pesticide use patterns and cancer incidence from a population-based perspective.

The Midwest, known for its high corn production, emerged as the region most affected by pesticide use. Compared with regions with the lowest risk, the Midwest faced an additional 154,541 cancer cases annually across all types. For colorectal and pancreatic cancers, the yearly increases were 20,927 and 3835 cases, respectively. Similar trends were observed for leukemia and non-Hodgkin lymphoma.

Pesticides vs Smoking

The researchers also estimated the additional cancer risk related to smoking, using the same model. They found that pesticides contributed to a higher risk for cancer than smoking in several cases.

The most significant difference was observed with non-Hodgkin lymphoma, where pesticides were linked to 154.1% more cases than smoking. For all cancers combined, as well as bladder cancer and leukemia, the increases were moderate: 18.7%, 19.3%, and 21.0%, respectively.

This result highlights the importance of considering pesticide exposure alongside smoking when studying cancer risks.

Expanding Scope of Research

Some limitations of this study should be noted. Certain counties lacked complete data, and there was heterogeneity in the size and population of the counties studied. The research also did not account for seasonal and migrant workers, who are likely to be heavily exposed. In addition, the data used in the study were not independently validated, and they could not be used to assess individual risk.

The effect of pesticides on human health is a vast and critical field of research, often focusing on a limited range of pesticides or specific cancers. This study stands out by taking a broader, more holistic approach, aiming to highlight regional inequalities and identify less-studied pesticides that could be future research priorities.

Given the significant public health impact, the authors encouraged the authorities to share these findings with the most vulnerable communities to raise awareness.

This story was translated from JIM using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.