(Beyond Pesticides, January 16, 2007) A proposal is underway within New Jersey’s Department of Agriculture (DOA) to lift a 20-year ban on the use of Dimilin (diflubenzuron) for gypsy moth suppression. The State’s DOA is proposing to amend its regulations (N.J.A.C. 2:23) to permit the synthetic chemical pesticide to be aerially sprayed over forested residential areas (estimated to be 50,000 acres) in 14 counties where egg mass counts are over 4,000 per acre. In addition, the Department of Environmental Protection’s (DEP) Division of Parks and Forestry may propose using Dimilin in state park areas where the egg masses are 4,000 per acre or more — potentially treating up to an additional 28,000 acres.The New Jersey Environmental Federation (NJEF) has taken action to stop the plan. In a letter co-signed by an additional 25 organizations to the Commissioners of DEP and DOA, they state, “While gypsy moth is a nuisance pest and can contribute to oak tree mortality, it is not a human health threat, nor a disease vector. We believe that given the potential harm to human health and biodiversity by the chemical pesticide Dimilin, the Departments should err on the side of caution and stand by their regulations that have been in effect for more than twenty years.”
NJEF will be meeting with the governor’s staff this coming week to request intervention. “New Jersey ‘s governor should affirm the 20 year ban on aerial spraying of toxic pesticides over homes, schools and parks, not reverse it. The human and ecological risks of chemical pesticides are not worth the temporary relief they give from insect problems like gypsy moth,” says Jane Nogaki, NJEF’s pesticide program coordinator.
Concerns over this proposal arise from the potential effects on human health and biodiversity from the product Dimilin and its active ingredient diflubenzuron, as well as the aerial method of application. Diflubenzuron, a haloaromatic substituted urea (chlorinated diphenyl compound), acts as a chemical growth regulator that inhibits chitin formation in invertebrates, including, but not limited to, gypsy moth caterpillars. Diflubenzuron has also been shown to affect vertebrate species.
Non-target effects of diflubenzuron include adverse environmental effects on freshwater and estuarine marine invertebrates, requiring a 150-foot buffer to waterways, and the human risk from its metabolite, PCA (p-chloroaniline), a class B2 carcinogen (probable human carcinogen).
Dimilin, an endocrine disruptor, causes reduced testosterone production in birds. In humans, it could cause methemoglobinemia, also known as blue baby syndrome. It persists at toxic levels for up to four months, which makes it more likely to affect non-target organisms and expose humans in and near the spray area through drift and runoff.
Aerial spraying poses its own risks from drift and the inherent danger of low flying aircraft. The proposed DOA aerial spray areas are all in forested residential areas, and inevitably direct human exposure occurs. New Jersey public policy has generally not supported aerial application of broad-spectrum pesticides over residential areas except in extreme circumstances like the threat of West Nile virus from mosquitoes. DEP’s own pesticide regulations ban aerial spraying of broad-spectrum pesticides for non-agricultural purposes. An exemption can be made for agricultural, health or environmental emergencies (N.J.A.C.7:30-10 (t).1.). DOA will likely be applying for that exemption.
Since l985, DOA and DEP have used only Bt, a biological pesticide with no known mammalian toxicity, as the pesticide of choice for gypsy moth suppression. DOA’s regulations explicitly state that DOA “select the most efficacious non-chemical insecticide (Bacillus thuringiensis).” However, now there is a claim that gypsy moths have become resistant to Bt, a common occurrence with pesticides.
Without human intervention, gypsy moth populations rise and fall in cycles, and are subject to collapse due to a naturally occurring fungus. Due to two years of very dry springs, this fungus has not been adequate to suppress the moths. Spraying, however, has a questionable impact on the gypsy moth cycle. In fact, some scientists believe spraying may actually prolong this cycle.