(Beyond Pesticides, September 14, 2016) According to a recent study by the U.S. Geological Survey (USGS), high concentrations of dioxins and furans have been detected in tree swallow eggs collected near several sites around the Great Lakes. Other chemicals detected include polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), which were at background levels. The study is part of efforts to clean up a toxic chemical legacy around the Great Lakes, and the researchers believe their results are critical to regulators to assess “bird or animal deformity or reproductive problems”
The study, “Concentrations and spatial patterns of organic contaminants in tree swallow (Tachycineta bicolor) eggs at United States and binational Great Lakes Areas of Concern, 2010—2015,” used tree swallows to quantify current exposure to organic contaminants across all five Great Lakes including 59 sites within 27 Areas of Concern (AOCs) and 10 nearby locations. The Great Lakes Areas of Concern refers to a U.S.-Canada Great Lakes Water Quality Agreement (Annex 1 of the 2012 Protocol) that defines AOCs as “geographic areas designated by the Parties where significant impairment of beneficial uses has occurred as a result of human activities at the local level.” An AOC is a location that has experienced environmental degradation, and includes several water bodies in New York, Ohio, Michigan, Wisconsin and others.
Tree swallows in this study were sampled across the Great Lakes basin in 2010 through 2015 where concentrations of organic contaminants in the eggs were quantified and compared with background and reproductive effect thresholds in order to provide a system-wide assessment of current exposure. The contaminants, including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (dioxins), polychlorinated dibenzofurans (furans), polybrominated diphenyl ethers (PBDEs), and a suite of 26 pesticides (including chlordane, heptachlor and mirex), were selected because they are listed by the AOCs as contaminants of concern, tend to persist in the environment, and are known or suspected to cause reproductive issues.
While many of the contaminants tested in the study are at or below average background exposure, including PCBs and PBDEs, concentrations of polychlorinated dibenzo-p-dioxin and furan (PCDD-F) at the Saginaw River and Bay and Midland, Michigan exceed set benchmarks associated with reproductive effects (hatching effects). The researchers note that their findings “can be used by States and the U.S. Environmental Protection Agency (EPA) to assess ongoing restoration activities intended to reduce wildlife exposures to these contaminants, which can cause deformities or reproductive problems.”
This ongoing biomonitoring work is part of The Great Lakes Restoration Initiative, which was launched in 2010 to accelerate efforts to protect and restore the Great Lakes- largest system of fresh surface water in the world. According to the initiative, federal agencies will continue to strategically target the biggest threats to the Great Lakes ecosystem and accelerate progress toward long-term goals for this important ecosystem. Actions include, cleaning up Great Lakes Areas of Concern, preventing and controlling invasive species, reducing nutrient runoff that contributes to harmful/nuisance algal blooms, and restoring habitat to protect native species.
Legacy chemicals like dioxins and PCBs, longed banned in the U.S., continue to plague wildlife and even humans. In addition to the birds in this study, river otters in the Midwest have also been found to still be contaminated with these substances. Another study attributed to DDT the reproductive problems plaguing endangered condors in California, as a result of the birds’ feeding on contaminated sea lions. A recent study by researchers at Drexel University, which looked at PCB, DDT and other persistent organic pollutants, report that higher levels of some of these compounds during pregnancy are associated with autism spectrum disorder (ASD) and intellectual disability (ID). Dioxins, PCBs and other organochlorines are categorized as persistent organic pollutants (POPs) because they persist for long periods of time in the environment, eventually making their way up food chains, accumulating in the fatty tissues and animals and humans. Their legacy of poisoning the environment has been well documented, despite being banned for decades. Recent studies have linked these POPs to hormonal disturbances, abnormal sperm development, cancer, diabetes, obesity and environmental contamination.
Efforts to halt the pollution of the Great Lakes and other waterways has been a focus in the region for many years. Toxicants like lindane, dioxin, PCB, and microcystin, have also been detected as pollutants in the Great Lakes. In 2015, two Michigan Representatives introduced the Great Lakes Assurance Program Verification Act (HR 3120) in an effort to halt the pollution of the Great Lakes from agricultural run-off, which causes dangerous algae blooms and it a major threat to ecosystems in the region . Scientists had been tracking algal blooms in the Great Lakes for years and have recommended region-wide monitoring and a change in farm management practices. In 2014, residents of Toledo, Ohio were advised to stop using tap water after a local water treatment plant found toxic substances in dangerous quantities in the water. 500,000 residents were instructed not to drink the water, brush teeth or prepare food with the water, or give it to pets. The contamination resulted from continuously growing algal blooms on Lake Erie, Ohio’s northern water source.
Beyond Pesticides tracks the scientific literature related to pesticide exposure through the Pesticide Induced Diseases Database (PIDD). For more information on the impacts of pesticides, past and present, on human and environmental health, visit our PIDD page.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.