By Marcia Anderson
During a visit to the New Jersey Raptor Trust, a wild bird rehabilitation center, I became aware of recurring and confirmed regional chlordane poisonings in our local bird populations. This prompted my investigation into its cause. Songbirds and raptors in suburban areas of New Jersey, New York and surrounding states have been found dead and dying of chlordane poisoning every summer, for over 14 years. The gruesome event occurs like clockwork every June and July.
Why? The New Jersey Department of Environmental Protection Fish and Wildlife and the New York State Department of Environmental Conservation tested soils from some local golf courses and found that wildlife poisoning still occurs where there was a substantial effort to control beetle grub populations with organochlorine pesticides for more than 30 years, from the 1950s to the 1980s. This resulted in turf contamination by the very persistent and commonly used organic pollutant (POP) chlordane. While environmental problems have lessened, they have far from disappeared.
Chlordane was introduced in the United States in 1947 as both an insecticide and an herbicide to control lawn, garden, and commercial pests and weeds in turfgrass. In 1979 restrictions were imposed on the use of chlordane because of its potential human carcinogenicity. It was banned for home, garden and agricultural uses in 1983 – 30 years ago. Chlordane products were allowed for restricted underground termite control for an additional five years until suspended in 1988. The ban of a toxic chemical does not immediately eliminate it from the environment, and chlordane poisoning of birds is still common.
Chlordane is environmentally persistent, and once applied, much of it still remains unaltered in the environment. Residues remain in soils, sediment and biota at levels sufficient to cause death in some bird species. Evaporation is the major route of removal from the top soil layer where chlordane slowly volatilizes into the atmosphere. Sunlight can also break down small amounts of chlordane. Chlordane rapidly binds to clay and soil particles making it highly immobile within soil layers. Chlordane does not chemically degrade and is not subject to biodegradation in soils. Perhaps the only good news is that chlordane has a low potential for groundwater contamination, because it is insoluble in water.
How chlordane is re-exposed:
Many bird mortalities were discovered when the New Jersey Fish &Wildlife Department was testing what they thought was an outbreak of avian West Nile Virus. They discovered that the deaths were attributed to high chlordane concentrations in already resistant insects. Concentrations of chlordane were high in Scarab, June, and Oriental beetles and highest in adult Japanese beetles from suburban area golf courses.
Spring emergence of grubs and adult beetles directly coincides with summer peaks in bird mortality. Songbirds were exposed to chlordane through the ingestion of soil invertebrates, including the aforementioned beetle grubs. In spring, beetle grubs are eaten by grackles, robins, starlings, and crows. By June, emerging adult beetles are eaten by kestrels, blue jays and house sparrows.
The timing of raptor deaths, such as Cooper’s hawk mortalities, coincides closely with the July peak in songbird mortalities, as hawks often feed on smaller songbirds debilitated by the chlordane. Chlordane and its breakdown products are lipophilic, meaning that it bioaccumulates in fatty tissues. Chlordane also affects the nervous system by blocking important chemical signals and enzymes that result in overstimulation and death.
About the Author: Marcia is the bed bug and vector management specialist for the Pesticides Program in Edison. She has a BS in Biology from Monmouth, second degree in Environmental Design-Landscape Architecture from Rutgers, Masters in Instruction and Curriculum from Kean, and is a PhD in Environmental Management candidate from Montclair – specializing in Integrated Pest Management and Environmental Communications. Prior to EPA, and concurrently, she has been a professor of Earth and Environmental Studies, Geology and Oceanography at Kean University for 14 years.