Study: Pesticides May Increase Risk of Some Cancers as Much as Smoking

Pesticides may lead to as many cancers as cigarettes, a well-known carcinogen, according to new research.¹

The authors of the new report, published in the journal Frontiers in Cancer Control and Society, explored how pesticide use in agricultural hotspots contributes to cancer rates in the communities around those settings.¹

Pesticides were most strongly associated with leukemia, non-Hodgkin’s lymphoma, and bladder cancer.¹

“We were not focusing on specific compounds, but [instead] looking at the big picture,” Isain Zapata, PhD, researcher at Rocky Vista University and author of the new paper, told Health.

The study highlighted the fact that pesticides are inescapable for many Americans, and experts said it should be a reminder of how our farming practices affect our health and well-being.

“Pediatric cancer rates, cancer rates in younger adults, and cancer rates in certain ethnic/racial groups are increasing,” Lauren Petrick, PhD, professor in the Department of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai, who was not involved with the new study, told Health. “While we don’t know if these increased rates are due to environmental factors alone or in combination with genetic differences, we do know that where you live matters. For example, studies repeatedly show that living close to pesticide use is linked to increased risk of pediatric and adult leukemia.”

Though the study suggests the risk of cancers related to pesticide use may be highest in or around farming communities, it also emphasizes the widespread use of pesticides and the reality that they affect the health and well-being of everyone in the United States—regardless of their socioeconomic status.

Despite the fact that pesticide use has been linked to cancers as well as problems with the nervous system, skin, eyes, and endocrine system,² it’s an essential tool for producing enough food to feed the world’s population. “There is no alternative,” Zapata said. “If we’re going to continue having the produce that we need, we need to use [pesticides].”

While the authors ultimately concluded that pesticides may contribute to as many cancers as smoking, it’s important to make the distinction between the function of smoking and that of pesticides in terms of public health, Zapata said. “Smoking was not benefiting anything [in our society], but agriculture feeds us,” he explained.

How Pesticides Influence Cancer Rates

Zapata and his team decided to conduct the research to learn more about the ways in which pesticides affect not just agricultural workers, but the population more broadly. They conducted what is known as an ecological study, or a study in which scientists ask a question regarding a whole population.³

For the report, the researchers looked at data on pesticide use and cancer rates across the US. The team looked at how a variety of different pesticides are used. Zapata said looking at data this way can be more helpful than thinking about pesticide use in terms of one particular product that has been linked to negative health effects, since pesticides are used in conjunction with other pesticides. “We’re not really thinking about what is the most noxious compound,” he explained. All told, his team reviewed the usage of 69 different pesticides. Data on pesticide use came from the United States Geological Survey.¹

The researchers found that pesticide use is associated with increased rates of leukemia, non-Hodgkin’s lymphoma, as well as cancers of the bladder, lung, colon, and pancreas. The team was able to contextualize just how widespread the impact of pesticide use is by comparing it to a carcinogen most people are aware of: “Pesticides have a significant effect on increasing cancer risk for all the cancer types evaluated…in a way that is only matched by smoking prevalence,” the authors wrote. The data on cancer incidence rates came from the National Institutes of Health (NIH) and the Centers for Disease Control (CDC) State Cancer Profiles database.¹

The study authors found that the region most affected by pesticide use—in terms of cancer rates—was the Midwest, which is responsible for much of the country’s agricultural output.¹

Before this research, experts already knew that pesticides could be dangerous: Glyphosate, sold as Roundup, was classified as a probable carcinogen by the International Agency for Research on Cancer, and other agents, including parathion, diazinon, tetrachlorvinphos, and malathion, had shown “some evidence of carcinogenicity,” the study authors wrote.¹

One of the strengths of the study was that the authors looked at confounding variables—such as smoking rates, socioeconomic disadvantages, and more—when they assessed cancer rates to try to explain what the true burden of cancers related to pesticide use might be.¹

But the study was also limited: The team did not have uniform data sets from all U.S. counties. It’s also crucial to understand that the research did not prove a causal relationship: The study authors did not conclude that pesticide use definitely causes cancer rates similar to those caused by smoking.¹

What Future Research Needs to Explore to Determine the Relationship Between Pesticides and Cancer

Though it’s easy to understand the ways in which agricultural workers are exposed to pesticides, it may be harder to conceptualize the ways in which people who do not work in agriculture—or who live and work miles away from agricultural settings—are exposed at levels that may affect cancer risk.

Weather can influence exposure, and some levels of pesticides can remain on food that gets sold at the supermarket, Zapata said. Though organic food may be, on the whole, healthier, there is still some risk involved in eating organic food: “We think organic food is ‘clean,’ but it’s not necessarily ‘clean,’” Zapata said.

Though the news is alarming, it’s important to put it into perspective: A wide variety of things contribute to cancer risk—such as age, alcohol use, diet, chronic inflammation, diet, obesity, sunlight, and more.⁴ Experts said the takeaway from this research is that we need more research.

Since we can’t grow the amount of food needed to feed the population without pesticides, the answer to reducing this problem could be to invest in the development of application techniques that give agricultural workers more control when using pesticides so as not to expose so many people to them, Zapata said. “We need more efficient ways of using these chemicals, but before that, we need to understand how much we are using and enhance our monitoring of [pesticide use],” he explained.

We also need continued research on the effects of pesticides. “Studies in human populations are now emerging, strengthening the evidence linking pesticides to cancers, and supporting the need for regulation to reduce human exposure to pesticides,” Petrick said.