(Beyond Pesticides, February 29, 2008) The National Park Service (NPS) recently released a report documenting airborne pesticides. The report of the Western Airborne Contaminants Assessment Project (WACAP), with data collected from 2002 to 2007, found high concentrations of “numerous” airborne contaminants, including current and former use pesticides. Contamination is widespread throughout twenty parks throughout the western United States and Alaska, exceeding consumption levels for humans and wildlife in some areas.
According to the report, the contaminants of second and third “highest concern” are “Dieldrin – an acutely toxic insecticide banned from use in the U.S. since 1987 that decreases the effectiveness of the immune system” and “DDT – an insecticide banned in the U.S. since 1972 that reduces reproductive success.”
NPS also reported that Dieldrin and DDT levels exceeded the threshold for recreational fishermen in several parks, and Dieldrin levels exceeded that for subsistence fishermen in all but Olympic National Park. Fish-eating birds are also at risk in some parks. While NPS could not establish a correlation between contaminant levels and fish reproductive effects due to small sample size, two parks produced individual “intersex” fish. However, NPS stated, “This condition is commonly associated with exposure to certain contaminants (e.g., dieldrin and DDT) that mimic the hormone estrogen.”
NPS reported that the sources of this extensive contamination are widespread, both locally and globally. It announced, “Evidence suggests that the contaminants found in this study are carried in air masses from sources as far away as Europe and Asia, and as near as the local country. According to Landers, the presence of contaminants in snow is well-correlated with the proximity of each park to agricultural areas, pointing to these areas as probable major sources of these contaminants. In Alaska Parks, with little nearby agriculture in the region, there are very low concentrations of most current-use compounds. However, concentrations of historic-use chemicals in Alaska systems are similar to those in other parks sampled, suggesting greater influence from global atmospheric transport.”
According to report co-author Michael Kent, “Contaminants are everywhere. You can’t get more remote than these northern parts of Alaska and the high Rockies.” They have also not been reduced with the bans of DDT and dieldrin; newer chemicals are persisting in measurable quantities. University of Washington researcher Daniel Jaffe said, “We replaced [DDT and dieldrin] with pesticides with much shorter lifetimes in the environment. But in places like the Central Valley of California, we are applying many, many tons of these every year. We now know they can move substantial distances.”