Pesticides May Raise Your Risk of Cancer as Much as Smoking

• Environmental pesticide exposure due to industrial agriculture potentially increases cancer risk to a degree similar to smoking.
• In a new study, researchers correlated cancer rates in geographic regions based on pesticide usage.
• The study does not demonstrate causation. More research is needed to understand how environmental pesticides affect cancer risk.

Is pesticide exposure as bad for you as smoking in terms of cancer risk?

Potentially, yes, claims a new scientific study.

The research, published in the journal Frontiers in Cancer Control and Society , found a strong association between the presence of environmental pesticides and several cancers, including leukemia , non-Hodgkin’s lymphoma , bladder, lung, and pancreatic cancer.

The authors used population and geographic data from sources, including the CDC, Department of Agriculture, and US Geological Survey, to investigate the correlation between rates of these cancers and pesticide usage in various regions across the United States.

This type of study, known as an ecological study, is used to identify broad trends but does not demonstrate a causal link, which the study authors readily admit.

The trends identified between pesticides and cancer risk are akin to those you would typically see with smoking .

“We found that every cancer is affected. So, everything is affected by pesticides. And it is very similar to what you see in smoking. If you increase how much you smoke, you increase your risk for every cancer, even when some of those are more affected than others. And that is exactly what happened here,” Isain Zapata, PhD, an Assistant Professor of Research and Statistics at the Rocky Vista University and Senior Author of the study, told Healthline.

Loren Lipworth, ScD, a Professor of Medicine and Associate Director of the Division of Epidemiology at Vanderbilt University Medical Center who wasn’t affiliated with the research, told Healthline that, due to its design, we need to be cautious about interpreting this study’s findings.

“The conclusions that can be drawn from this type of study are that there may be some etiologic clues, there may be some signals of associations between various types of cancer and pesticide use patterns at this large ecologic population level, but in terms of individual-level data, the study does not provide that,” she said.

Mapping the potential link between pesticides and cancer

The study is the first comprehensive examination of the effects of pesticides on cancer risk across large geographic regions and populations in the United States.

Researchers used reporting data for sixty-nine different pesticides to create geographic regions. Essentially, they carved out areas of the US used for agriculture based on reported pesticide usage.

For example, the Midwest, the country’s leading region for corn production, has the highest presence of environmental pesticides. Meanwhile, the Great Plains region, from northern Texas to North Dakota, has the least.

Once the authors established these geographic regions, they then looked at rates of cancer in these areas.

They hypothesize that cancer risk is likely tied to the amount of pesticide use and different kinds of agricultural production since pesticide usage also varies based on activity. For example, California, the nation’s largest vegetable producer, would likely have different cancer outcomes than the Midwest, where corn is the predominant crop.

Zapata told Healthline that this methodology gives a more holistic impression of how exposure can occur, noting that individuals are rarely ever exposed to a single pesticide but rather a “cocktail” of different contaminants in the real world.

“You’re going to be exposed to the pesticides that might be floating around from the farms that are close to where you live. There might be industrial residues that are unique to the agricultural activity of that area,” he said.

Specific pesticide outcomes

Sixty-nine nationally reported pesticides were included in the study. Individually, many were linked to different cancer outcomes.

• Atrazine is used to control grasses. The study found that it was consistently a top contributor for increased risk of all cancers and colon cancers.
• Glyphosate is commercially available as a weed killer named Roundup and is associated with an increased risk of all cancers, colon cancer, and pancreatic cancer.
• Dicamba is commonly used in corn and soybean agriculture. It was linked to an increased risk of colon cancer and pancreatic cancer.
• Dimethomorph is a fungicide. It was identified in regions with a high risk of leukemia and non-Hodgkin’s lymphoma.

Despite these findings, Zapata told Healthline that the goal of their study is not to stop pesticide usage.

“We aren’t trying to tell the Midwest, OK, you cannot grow corn anymore,” he said.

“We need to eat. We need to have products derived from agriculture. And to have the efficiency that we need to be economically sustainable, we need to use those chemicals. So it becomes a cost-benefit, risk-benefit approach,” said Zapata.

Strengths and weaknesses of the study

The study authors controlled for major confounding factors, including smoking, socioeconomic factors, and the area of agricultural land. However, when using population data, not all confounding factors can be accounted for.

To be clear, even in a region with high rates of cancer and pesticide usage, the study’s nature doesn’t allow one to be attributed to the other. It does, however, provide a signal that more research is needed.

“There’s no causal inference that can be drawn between individuals or a group of people’s actual pesticide exposure and their individual cancer risk,” said Lipworth.

The study doesn’t differentiate between groups of people, such as farm workers who may have direct exposure to pesticides, and members of the surrounding community whose exposure could vary based on proximity and other factors.

“It’s really important that we have person-level exposure assessment. There are people who are occupationally exposed, and there are farmers, but in the same area, there are people living with farmers who are exposed in a different way. So, personal level exposure assessment is really critical for us to understand this type of scientific association,” said Lipworth.

The bottom line

A national population study has found a broad association between environmental pesticide usage and various forms of cancer.

Across different US geographic regions, sixty-nine different pesticides were associated with increased risk of colon, pancreatic, lung, and other cancers.

The design of the study only shows association, not causation. More research is needed to better understand how environmental pesticide exposure affects cancer risk on a personal level.