Exposure to a Major Pesticide Is Linked to Three Generations of Disease

Pesticides have the power to inflict biological harm; not just in those unfortunate enough to be exposed to large amounts of them—but in their children and children's children, too.

Brian Merchant

Brian Merchant

Image: Messina, John / Wikimedia

Science has demonstrated time and again why we need to be careful about the kind of pesticides we spray on our crops. Most famously, in the 1960s, researchers discovered that the potent DDT was linked to cancer and other health hazards. Now, new research reminds us again of pesticides' power to inflict biological harm; not just in those unfortunate enough to be exposed to large amounts of them—but in their children and children's children, too. 

Washington State University scientists have found, once again, that a mammal's exposure to certain pesticides may increase susceptibility to disease for generations to come. Including, perhaps, us humans.

Michael Skinner, a WSU professor, examined the once-widely used pesticide methoxychlor—known commercially as Chemform or Moxie—which was considered a safer replacement for DDT in the US until banned in 2003. It was heavily used in the 1970s, and is still sprayed worldwide today. Its effects, apparently, will be seen for quite some time.

"What your great-grandmother was exposed to during pregnancy, like the pesticide methoxychlor, may promote a dramatic increase in your susceptibility to develop disease, and you will pass this on to your grandchildren in the absence of any continued exposures," Skinner, founder of WSU's Center for Reproductive Biology, said in a statement. His study is "the first to show that a majority of transgenerational disease traits can be transmitted primarily through the female line."

In high concentrations, it's a neurotoxin, and while it has been linked by at least one study to leukemia, it's not considered a carcinogen.

However, the Environmental Protection Agency has found "methoxychlor to potentially cause central nervous system depression, diarrhea, and damage to liver, kidney and heart tissue from short-term exposures at levels above the MCL." It considers the chemical toxic. 

The WSU researchers exposed gestating rats to the pesticide, and, according to the university, they "saw increases in the incidence of kidney disease, ovary disease and obesity in offspring spanning three generations. The incidence of multiple diseases increased in the third generation or 'great-grandchildren.' The researchers say the pesticide may be affecting how genes are turned on and off in the progeny of an exposed animal, even though its DNA and gene sequences remain unchanged."

Meet "transgenerational epigenetic inheritance," or a trait passed down your family line that makes you more likely to contract a serious disease. Skinner and his team have found a number of "environmental toxicants" that seem to spur the phenomenon, including DDT, plastics, and fungicides.

"Many environmental chemicals like DDT will do similar things," Skinner told me in an email, "so we are finding most major classes of exposures promote transgenerational disease. So we need to be more aware of our ancestors exposures and how it may effect our health, even now we are not exposed."

Got that? This latest research confirms the previous findings: Exposure to toxic stuff in the environment today can haunt the bodies of those not yet born. If you ingested too much pesticide, your grandchildren could be at greater risk for kidney or ovary disease. 

It's another reminder that nature draws an almost unfathomably complex web, and reckless pluckings at its fiber can alter its organisms' physiologies even well into the future. As such, Skinner says we should begin cataloging these epigenetic biomarkers, and watching these traits that increase the likelihood of future disease.

"Knowing this is part of disease development suggests epigenetic biomarkers may be used in the future to diagnose exposure and disease before it develops," he told me, "so therapeutics and life style changes may prevent disease from developing, thus preventative medicine."

And please, let's use those pesticides responsibly, for once.