Pesticides as big a cancer risk as smoking, study finds

Pesticides may cause cancer on a level equivalent to smoking cigarettes, a new study has found.

The widespread use of pesticides may lead to hundreds of thousands of additional cancer cases in major corn-producing states like Iowa, Illinois, Indiana, Missouri and Ohio — even for Americans who don’t work on farms, according to findings published Thursday in Frontiers in Cancer Control and Society.

Scientists and public health professionals have long been concerned about links between pesticides and cancer. 

In February, scientists from the Endocrine Society and the International Pollutants Elimination Network raised concerns that there was no safe level of exposure to many common pesticides.

The insect-killing chemicals have been linked to lung cancer, pancreatic cancer, colon cancer and leukemia (blood cancers) in both children and adults. One particularly common pesticide, glyphosate — better known by its trade name, Roundup — is viewed by the World Health Organization as potentially cancer-causing, which has caused a movement among farmworkers and public health campaigners for federal public health officials to ban it.

Even with glyphosate left out, many other pesticides also have links to cancer.

But all this research, the Frontiers authors argued Thursday, has tended to focus on specific pesticides, regions or cohorts of the population (like farm workers) — which obscures the fact that pesticides are used across the country, and that those exposed to any of them tend to be exposed to many of them, creating a greater compound risk.

“In the real world, it is not likely that people are exposed to a single pesticide, but more to a cocktail of pesticides within their region,” coauthor Isain Zapata of Rocky Vista University said in a statement.

The researchers cautioned about a “publication bias” as researchers focused on more well-known or controversial pesticides — like glyphosate — to the expense of less well-known ones that could be equally damaging.

“We cannot assume that less published associations for a particular pesticide and cancer imply these do not exist,” they wrote.

Thursday’s study, by contrast, bills itself as the first-ever population-level study of cancer impacts from all pesticides. 

The researchers found a difference of 154,000 cancer cases per year, adjusted for population, between the area with the lowest pesticide use — the Great Plains — and that with the highest, the corn belt of the inner Midwest, where hundreds of millions of pounds of glyphosate are applied each year across millions of acres of Roundup Ready corn. 

Beyond that area, Florida, with its large agricultural industry, has elevated cases of bladder cancer and blood cancers that appear to correlate with its use of pesticides, the researchers found.

When it came to individual cancers, pesticide use seemed to have the strongest association with blood cancers like leukemia or non-Hodgkin lymphoma.

Half again as many cases of the latter appeared to be “caused by pesticides compared to smoking,” the researchers wrote.

They suggested that in the future, pesticide exposure risk might be a factor homebuyers evaluate alongside more prosaic concerns like school quality and the job market. 

If new homebuyers had to be notified that their potential purchase lay in an area of heightened pesticide use, “then public awareness of this issue would rise, garnering the attention that this issue calls for,” they wrote.

Finally, they called for public health officials to approach the question of whether pesticides are safe with “more skepticism.”

In a statement, Zapata said that this study had made him think of the heavy burden of farmers who expose themselves to dangerous chemicals to feed the country.

“Every time I go to the supermarket to buy food, I think of a farmer who was part of making that product,” he said. “These people often put themselves at risk for my convenience.”

That realization, he added, “definitely has had an impact on how I feel when that forgotten tomato in the fridge goes bad and I have to put it in the trash.”