Alarming research on pesticide warrants curbs on its use

Even if you’ve never heard of imidacloprid, there’s a good chance the world’s most-used neonicotinoid pesticide is lurking somewhere in your home. Or on your dog. Or maybe even in your groundwater or drinking-water supplies.

This insecticide, widely used for decades on fruits, vegetables and many other crops, has triggered growing concerns over its well-documented role in the dramatic declines of birds, bees, butterflies and other insects across the globe. But despite its presence in many household bug sprays and flea-control products, the human health risks of this dangerous pesticide have managed to fly largely under the regulatory radar here in California. Until now.

With imidacloprid being discovered in groundwater and drinking-water supplies across the state, state regulators — and legislators — finally are paying closer attention to recent scientific research revealing troubling links between the insecticide and a wide range of human health concerns, including cognitive and reproductive harms that start in the womb.

The best-trusted independent science — meaning research other than studies conducted by the makers of the pesticide themselves — leaves no question that California’s leaders should take decisive protective action. The need is urgent: A review by California’s Office of Environmental Health Hazard Assessment of the most recently published research indicates that imidacloprid can cause health harms at thresholds significantly lower than what the state considers acceptable exposures.

That research is worrisome.

Published studies by independent researchers have discovered links between imidacloprid and elevated risks of autism spectrum disorders and congenital heart defects, and a threefold increased risk of major brain defects at birth. Research also links the pesticide to memory loss and tremors.

What makes these findings of harm even more concerning is that given imidacloprid’s extensive use in both household and agricultural products, its toxic footprint is continuing to expand. That disconcerting reality was highlighted last year when the California Department of Pesticide Regulation discovered 15 groundwater wells in Fresno, Santa Barbara and Tulare counties tainted with high concentrations of neonicotinoids like imidacloprid. 

Equally concerning is that imidacloprid and its neonic cousins now have been detected in 92% of urban water samples in Southern California, 58% in urban areas of Northern California and 94% in agricultural areas.

For all these reasons, responsible state legislators are leading a push to better protect Californians from imidacloprid.

Assembly Bill 2146, which passed its first legislative committee hearing last month, would ban residential outdoor use of neonicotinoid pesticides such as Imidacloprid.

The bill follows the lead of similar legislation in Maine and New Jersey.

Because of the evidence that agricultural uses of pesticide products containing imidacloprid that are approved by California regulators have polluted groundwater, the state’s Pesticide Contamination Prevention Act requires that the Department of Pesticide Regulation reassess all registered agricultural uses for products containing imidacloprid.

That review, which includes a hearing on May 17, could even result in cancellation of imidacloprid.

Short of that, state regulators must follow the cues of recent research and take meaningful steps to better protect people and wildlife from the unacceptably high risks posed by imidacloprid.

At minimum, those steps must include limiting residential use of imidacloprid and creating a more protective standard — based squarely on the latest independent science — for what’s considered to be acceptable levels of exposure to the pesticide.