NRDC to EPA: Red Flags on Imidacloprid Health Risks

A young boy kissing his pet dog on the head.
Credit: iStock

Imidacloprid is one of the most popular and widespread insecticides in the U.S. The neonicotinoid or “neonic” pesticides are used to treat soil, seeds and foliage to control sucking insects such as rice hoppers, aphids, thrips, whiteflies, turf insects, soil insects and some beetles. Imidacloprid kills insects by debilitating their central nervous system. It mimics nicotine and binds to nicotinic acetylcholine receptors, blocking the receptor and thereby preventing nerve cell transmission, leading to paralysis and death in insects. In humans these receptors are found in neuromuscular junctions and the central nervous system.

In November 2017 NRDC comments to U.S. EPA raised the following human health concerns:

Imidacloprid residue on baby and children’s foods

Imidacloprid is most commonly used on the following crops: rice, cereal, corn, potatoes, vegetables, sugar beets, fruit, cotton, hops and turf.  New and disturbing evidence shows that imidacloprid is making its way into our food supply. According to the Pesticide Action Network publicly searchable database, “What’s On My Food”, using data aggregated from public sources including the USDA PDP 2012 data, imidacloprid was detected in the following baby foods and common children’s foods: baby food—applesauce (0.3% of samples); baby food—pears (13.6% of samples); bananas (1.8% of samples); apples (20% of samples); cherries (14% of samples); and grapes (48% of samples). Moreover, the pesticide’s systemic nature means it cannot just be washed off the surface of these foods prior to consumption. (See U.S. FDA 2015 report)

Imidacloprid exposure from residential uses

Imidacloprid is approved for a wide range of residential uses that lead to exposures to vulnerable populations, including women of reproductive age, infants, and toddlers. It is permitted to be used on ornamental turf and plants, residential lawns and gardens, pets (spot-on treatments and collars), bed bugs, crack-and-crevice treatments, and on wood as a preservative and termiticide.

Imidacloprid poisoning incident data gathered by the EPA between 1992 and mid-2009 documents over 22 thousand minor poisoning incidents in people from residential uses (received through FOIA public records request HQ-RIN-1475-09 to Jennifer Sass). Most people were exposed from applying imidacloprid products to lawns and gardens, or by playing with pets that had recently been treated for fleas and ticks with imidacloprid-containing products. Reported adverse effects included skin irritation and rashes, numbing and tingling on fingers and lips, facial numbness and swelling, lethargy and nausea.

Over the same time EPA documented over 4 hundred deaths of domestic animals, mainly dogs and cats treated with flea and tick products.

A study by NIH-funded researchers from the Universities of UNC Chapel Hill and UC Davis reported that frequent exposure (self-reported by parents) to imidacloprid applied as flea and tick treatments for pets (Advantage by Bayer) during pregnancy was associated with an up to four-fold elevated risk of Autism Spectrum Disorder (OR 2.0, 95% CI 1.0-3.9) in prenatally-exposed children.

Imidacloprid in water

A study by the U.S. Geological Survey found widespread neonic contamination of streams across the country. At least one neonic pesticide was detected in half the samples collected, with imidacloprid being the most frequently detected contaminant (37% of samples). Interestingly, while the concentration of two neonic pesticides—clothianidin and thiamethoxam—were higher in agriculture areas, imidacloprid concentrations were higher in denser urban areas within the watershed. This suggests that its urban uses in lawns and gardens, and parks and public spaces are having a measurable impact on watershed contamination, including sources of tap water. Unfortunately, EPA has not established a mandatory drinking water limit (Maximum Contaminant Level, MCL) for imidacloprid or any of the other neonic pesticides. 

Imidacloprid treated seeds

Imidacloprid is also used as a seed treatment—a use that NRDC opposed because the value to farmers of these costly and environmentally-damaging seed treatments is increasingly shown to be negligible or marginal at best. Worse, the toxic soil residues from neonic seeds may make pest control even more difficult by disrupting biological control systems.

Pesticide Use Map - Imidacloprid


EPA Failed to Address Risks to Children under FQPA

Under pesticide law, the Food Quality Protection Act (FQPA) requires that EPA make an affirmative determination that there is reasonable certainty of no harm from use of a pesticide in accordance with its label, and it must make this finding considering aggregate and cumulative exposures to infants and children. By law, EPA must not allow the pesticide residue on food if it finds a pesticide residue would not be safe.

In Conclusion

NRDC makes the following recommendations, based on the scientific record detailed in our comments:

  • Consistent with the available evidence, EPA should apply an FQPA factor of at least 10X to account for the evidence of developmental neurotoxicity, including the more severe and even deadly effects in the offspring compared to the less severe maternal effects.
  • EPA should classify imidacloprid as an endocrine disruptor, consistent with the affirmative evidence of biologically relevant adverse effects from the EDSP Tier 1 tests.
  • EPA should re-do its cancer assessment of imidacloprid to address the evidence of cancer risks, including significant elevate risks of rare and deadly cancers, from guideline studies.
  • EPA should cancel all pet collar uses because of the excessive risks they pose to children; risks would be calculated to be even higher if EPA applied the legally-mandated default 10X FQPA factor.

The warning against false negatives—calling something safe when it is harmful—is echoed by EPA statistician Herbert Lacayo in a recently surfaced internal EPA memo on glyphosate cancer risks. In his 1985 memo dismissing Monsanto’s pleas to ignore cancer evidence in rodents treated with glyphosate, Dr. Lacayo wrote, “Our viewpoint is one of protecting the public health when we see suspicious data. It is not our job to protect registrants from false positives.”

In summary, EPA is in the business of protecting the public, not agrochemical company profits. The EPA pesticide office must not lose its way.

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