28
Jan
Persistent Organic Pollutants like Organochlorine Pesticides Pose Health Risk to Rare Giant Panda Subspecies
(Beyond Pesticides, January 28, 2021) Persistent organic pollutants (POPs)—including banned pesticides—present a health risk to the endangered Qinling Panda (Ailuropoda melanoleuca qinlingensis), the rarest subspecies of giant pandas, according to a new Chinese study published in Environmental Pollution. Organochlorine compounds (OCs), such as organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), are well-known persistent organic pollutants. They were banned by the Stockholm Convention treaty in 2001 and are primary pollutants of concern (UNEP, 2009) because of their persistence, toxicity, and adverse effects on environmental and biological health. These pollutants have a global distribution, with evaporation and precipitation facilitating long-range atmospheric transport, deposition, and bioaccumulation of hazardous chemicals in the environment. The U.S. was a signatory to the treaty, but U.S. Senate never ratified it, relegating U.S. officials to observer status.
Although various studies demonstrate the volatile, toxic nature of POPs, much less research evaluates the impact POPs have on biodiversity over time. The globe is currently going through the Holocene Extinction, Earth’s 6th mass extinction, with one million species of plants and animals at risk. With the increasing rate of biodiversity loss, advocates say it is essential for government agencies to research how previous and ongoing use of POPs can impact present-day species. Likewise, collaborative, global monitoring of POPs can help leaders identify the effect on vulnerable species of the chemicals’ long-range transport and the most effective unified global strategy.
Researchers note, “We provide data for health risk assessment that can guide the identification of priority congeners [different forms of the same chemical structure] and recommend a long-term monitoring plan. This study proposes an approach to ecotoxicological threats whereby giant pandas may be used as sentinel species for other threatened or endangered mammals. By highlighting the risks of long-distance transmission of pollutants, the study emphasizes the importance of transboundary cooperation to safeguard biodiversity.”
Researchers in the study assessed organochlorine compound (OC) concentrations by analyzing the distribution of OCs from various sources within the habitat and research center of the Qinling panda. The sources include soil, bamboo, and feces that researchers examined for concentrations of 32 PCBs and 22 OCPs congeners (chemical compounds related to each other by origin, structure, or function). Some OCP compounds encompass widely banned chemicals: dichlorodiphenyltrichloroethane and metabolites (DDTs), hexachlorocyclohexanes (HCHs), methoxychlor, mirex, HCB, and cyclodienes (cis- and trans-chlordane, isodrin, endosulfan, aldrin, dieldrin, endrin, heptachlor).
This study demonstrates that Quinling Panda species are generally exposed to moderate levels of OC pollution. Higher levels of OCs are present in captive pandas relative to wild pandas. The authors identify PCB and OCP residues as coming from atmospheric transportation. At the same time, the study identifies PCBs as a cancer risk to the pandas, in fact the most notable toxicant with the highest carcinogenic risk index of PCB 126 (the most potent highly toxic industrial byproduct that incites numerous adverse physiological effects).
Long-range atmospheric transport and condensation are significant contributors to the global contamination of environmental pollutants like POPs. Most concerning are the persistent properties of POPs that allow these substances to remain in the environment long after use. Some of these long-lived chemicals include regionally banned pesticides that are all highly toxic to humans and animals: DDT, heptachlor, and lindane. These pesticides cause a range of adverse effects, from respiratory issues, nervous system disorders, and birth deformities, to various common and uncommon cancers. Although some, but not all, manufacturing and use of specific POPs have declined in the U.S., POPs remain a global issue, as much of the developing world still reports usage. Continued manufacturing and use of POPs increase the probability of long-range transport of these chemicals and their deposition across the globe via precipitation.
Currently, POPs are present in “pristine” polar regions and remote areas seemingly void of pollution inputs. Arctic snowmelt threatens to re-release POPs entrapped in ice, further contributing to the transport of these toxic chemicals and passive pesticide exposure globally. The glacial melting caused by the climate crisis will only add to water source contamination. The release of volatile POPs will enter waterways at the same concentration levels as before ice entrapment, even after several decades. Pesticide contamination is already an issue in the United States. Results from a United States Geological Survey’s (USGS) study demonstrate that pesticides and their degradates are widespread in U.S. streams and groundwater. Furthermore, a recent study discovered the presence of DDT metabolite (DDE’) residues in black women in Chicago who consume more glasses of tap water per day.
Exposure concerns about POPs exposure are increasing significantly, especially for adults and children who are more vulnerable to their toxic effects. Moreover, many contaminants are subject to regulatory standards that do not fully evaluate disease implications associated with exposure associated with global transport and releases associated with the climate crisis. Advocates say that addressing the manufacturing and use of pesticides is essential to mitigate risks from chemical exposure to toxic pesticides.
Overall, a combination of long-range atmospheric transport, local climate, topography, and human activity contributes to organochlorine compound accumulation in the Qinling panda habitat. Furthermore, regions at high latitudes and near cities tend to accumulate greater concentrations of OCs than other chemicals in the same area.
Uniquely, the Qinling Panda is primarily a captive species. Past research demonstrates they experience routine exposure to OCs from their bamboo diet, due to atmospheric deposition of environmental contaminants from air pollution into soils. Study researchers suggest OCs may be accumulating in panda tissue as OC concentrations are slightly lower in giant panda feces than in bamboo. Accumulation of these toxic chemicals in tissue can have long-term, severe health consequences that remain latent for years (i.e., cancer, endocrine disruption). Scientists say it is essential to understand how long-banned chemicals impact giant pandas’ health, especially because many endangered mammals are also in captivity. Giant pandas can serve as a sentinel species for threatened/endangered mammal health regarding chemical exposure.
Study researchers conclude, “We demonstrated that health risk assessments are important for prioritizing congeners of pollutants in Qinling… However, further studies should focus on more refined assessments of daily intake and improvements of exposure parameters. Hence, regular monitoring is needed to ensure that dangerous increases in these pollutants do not go unnoticed. In light of the long-distance transport of pollutants, our study provides an additional strand of evidence for the necessity of trans-boundary, and indeed global, actions to deliver conservation of biodiversity. [These include] such coordinated and cooperative approaches to conservation are urgent, and raise important questions as to how people can achieve the necessary cooperation.”
Lack of adequate persistent pesticide regulations highlights the need for better policies on pesticide production and use. Better pesticide policies are especially relevant when a toxic pesticide banned or highly restricted for use in the U.S. is still in production and exported to other countries.
A switch from chemical-intensive agriculture to regenerative organic agriculture can significantly reduce the threat of the climate crisis. Organic agriculture eliminates toxic, petroleum-based pesticide and synthetic fertilizer use, builds soil health, and sequesters carbon. The Intergovernmental Panel on Climate Change (IPCC) finds that agriculture, forestry, and other land use contributes about 23% of total net anthropogenic emissions of greenhouse gases. However, organic production reduces greenhouse gas emissions and sequesters ambient carbon in the soil. Learn about how we can sequester more than 100% of current annual CO2 emissions by switching to organic management practices by reading Regenerative Organic Agriculture and Climate Change: A Down-to-Earth Solution to Global Warming. For more information about organic food production, visit Beyond Pesticides’ Keep Organic Strong webpage. Learn more about the adverse health and environmental effects chemical-intensive farming poses for various crops and how eating organic produce reduces pesticide exposure.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Environmental Pollution
Hey. Thanks for making me aware of primary pollutants of concern. I will share this post as much as I can.
February 4th, 2021 at 7:58 am