Early exposure to glyphosate and other common pesticides may increase the likelihood that a child will develop an autism spectrum disorder, according to a study published last month in the British Medical Journal (BMJ).
Previous research has suggested that common agricultural pesticides can affect brain development, and environmental exposures during early brain development are suspected to increase risk for autism spectrum disorders in children. However, research examining the link between real-world exposure and autism is rare.
For this study, scientists at the University of California searched registry records to identify 2,961 patients diagnosed with autism spectrum disorders, including 445 who also had an intellectual disability. To establish a control group, they identified 35,370 patients of the same age and sex without autism.
Patients in both groups were born between 1998 and 2010 in California’s Central Valley, a major agricultural area. The majority – 80% — were male.
The research team used data from California’s Pesticide Use Registry to assess prenatal exposure to glyphosate and 10 other widely-used pesticides suspected of having toxic effects on the brain.
The analysis suggested moderate increases in the risk for autism among children exposed to several pesticides (including glyphosate, chlorpyrifos, diazinon, malathion, permethrin, bifenthrin and methyl-bromide) before birth and during the first year of life.
The strongest association was seen among those diagnosed with both an autism spectrum disorder and an intellectual disability. Prenatal exposure to glyphosate, the active ingredient in Monsanto Roundup, appeared to increase the risk for autism by 30%. Permethrin had the greatest association, increasing the risk of autism with intellectual disability by just under 50%.
Because the study was observational, it could not establish a causal link between pesticide exposure and autism spectrum disorders. However, the study is the largest ever conducted on this subject, and backs up previous research.
While the authors acknowledged a need for further investigation into the underlying mechanisms in the development of autism, they asserted their findings “support the need to avoid prenatal and infant exposure to pesticides to protect early brain development.”
Glyphosate is by far the most popular weed killer in the world.
Unfortunately, this is not the first study to link glyphosate exposure to harmful health effects. In fact, the World Health Organization’s International Agency for Research on Cancer (IARC) declared the pesticide a probable human carcinogen in March 2015, after an independent review linked occupational glyphosate exposure to an increased risk of cancer, especially non-Hodgkin’s lymphoma and its various subtypes.
Monsanto, which developed glyphosate and began marketing Roundup in the 1970s, vehemently denied that the weed killer has any link to cancer. It also pursued an aggressive campaign to discredit the IARC review, commissioning many of the studies that contradicted the group’s findings.
Bayer AG completed its acquisition of Monsanto earlier this year. The company currently faces more than 13,000 Monsanto Roundup lawsuits that allege exposure to glyphosate caused non-Hodgkin’s lymphoma or other cancer. Among other things, these lawsuits claim Monsanto manipulated scientific research and unduly influenced regulators to conceal glyphosate’s health risks from the public.
Just last week, a jury in the U.S. District Court, Northern of California, awarded $80 million in compensatory and punitive damages to a home gardener who used Roundup for nearly 30 years before learning he had non-Hodgkin’s lymphoma. The jury determined that glyphosate was a “substantial factor” in the plaintiff’s cancer and that Monsanto had acted with “malice and oppression” in failing to warn consumers about its potential health effects.
The first trial of a Monsanto Roundup lawsuit concluded last August, when a jury in San Francisco Superior Court ordered Bayer to pay $289 million to another plaintiff with non-Hodgkin’s lymphoma. However, the judge overseeing that case ultimately reduced the verdict to $78 million, after finding that punitive damages were excessive.