08
Jul
Chemicals, including Pesticides, in Wastewater Discharge Contaminate Oysters in Pacific Northwest
(Beyond Pesticides, July 08, 2021) A Portland State University (PSU) study finds oysters of varying distances from wastewater discharge pipes along the Oregon and Washington state coast contain low levels of chemical contaminants. Although wastewater treatment facilities clean water draining from sinks and toilets, the process does not adequately remove all contaminants. The process can leave behind pharmaceutical drugs and personal care products (e. g., shampoos, make-up, deodorant) residues in treated water. PSU has already found that pesticides from the forestry industry threaten clams, mussels, oysters (bivalves) along the Oregon coast. Marine ecosystem pollution is difficult to track and measure, and pesticide regulations can invoke variations in water quality requirements through discrepancies in buffer zones and application concentrations. The combined presence of pesticides, medicine, and personal care products in aquatic environments has direct implications for species and ecosystem health and indirect consequences for human well-being. Therefore, studies like this can help government and health officials develop strategies to reduce the number of chemicals entering aquatic ecosystems, with researchers noting officials can “better understand whether contaminant exposure affects oyster condition.”
Researchers wanted to evaluate how proximity to wastewater facilities affects variations in aquatic pollution. Thus, scientists transplanted one-week-old Pacific oysters along the Oregon and Washington coastline, placing oysters near wastewater facilities (unapproved for oyster growing) and oyster aquaculture sites (approved for growing oysters). The researchers collected and analyzed contaminant uptake and oyster condition nine- and 12-months following transplantation.
Spring-time oyster samples, nearest wastewater sites, contain two pharmaceuticals: miconazole (a common antifungal medication) and virginiamycin (a common-use veterinary antibiotic medication). Additionally, researchers find four alkylphenols compounds (industrial chemicals used to make detergents, cleaner, and pesticide products) present in summertime oyster samples at both aquaculture and wastewater sites: 4-nonylphenol (NP), 4-tert-octylphenol (OP), and 4-nonylphenol mono- (NP1EO) and diethoxylates (NP2EO). Although chemical detection frequency is highest in oysters near wastewater facilities, contaminant concentration remains the same across all sample sites. Even in areas where shellfish populations are scarce, oysters still experience chemical exposure from wastewater contaminant uptake. Proximity to wastewater sites determines overall oyster health/condition, as oysters near aquaculture sites have better health conditions.
Chemical contamination is widespread in U.S. rivers and streams, with at least five or more different pesticides present in 90 percent of water samples. Moreover, research finds millions of people already consume drinking water contaminated with pesticides or pesticide compounds from groundwater sheds. Thousands of tons of pesticides and other chemicals enter rivers and streams from agricultural (i.e., crop care, livestock) and nonagricultural sources (i.e., wastewater discharge, landfills). These chemicals contaminate essential aquatic ecosystems, such as watersheds consisting of surface water (e.g., lakes, streams, reservoirs, and wetlands) and groundwater. Although communities around the nation are required to treat their wastewater under the Clean Water Act, the wastewater treatment process does not remove all chemical contaminants, even during high-level treatment processes. The ubiquity of certain compounds makes it difficult to extract all pollutants from the water, which can persist in the water for long periods. Often, wastewater facilities will discharge this “clean” wastewater into nearby water sources. However, the combined impact of contaminated wastewater and chemicals already in waterways has detrimental impacts on aquatic ecosystem health. Moreover, some compounds work synergistically (together) with others to increase the severity of the effect. In addition to adverse health effects on marine organisms, these chemicals harm terrestrial organisms relying on surface or groundwater. Many of these chemicals cause endocrine disruption, reproductive defects, neurotoxicity, and cancer in humans and animals, while being highly toxic to aquatic species.
Wastewater has long been a source of exposure to pesticides, industrial chemicals, pharmaceuticals, personal care products, and household chemicals. Attempts to reduce wastewater discharge include recycling water for agricultural irrigation. However, similar to discharged wastewater, recycled wastewater presents a risk to human health and the environment from contaminants. Many states use treated wastewater from human sources (e.g., toilets, sinks, baths) or industrial activity (e.g., fracking) to irrigate organic and non-organic crops, compensating for excessive water use. Even if treated produced water bypasses agriculture use, oil and gas companies dispose of produced water in waterways or ground pits (wastewater disposal wells).
Although this study finds that chemical concentrations present in oysters remain under federally established guidelines, aquatic environments continuously encounter environmental pollutants and toxic compounds. These contaminants are known to have harmful biological consequences on both aquatic and terrestrial organisms. The report, “Human Health and Ocean Pollution,” finds that the combination of nonpoint source chemical contamination from microplastics and pesticide runoff can have an adverse synergistic effect on species’ health and ecosystem. Additionally, coastal and offshore aquaculture (farming of aquatic organisms) presents a new, looming threat to marine health. Bivalves like oysters are excellent indicator species, signaling environmental contamination through their sedimentary, filter-feeding diet. However, continuous pesticide inputs into waterways along Oregon and Washington’s coastal zone endanger these species in downstream rivers and estuaries (river mouths). The use of pharmaceuticals, like antibiotics and antifungals treatments, and pesticides in local marine ecosystems (e.g., insecticides to control sea lice in farmed salmon) results in coastal habitat loss and genetic health risks like pest resistance among wild marine organisms. The four alkylphenols compounds within the study, for example, are present in items of everyday use: detergents, cosmetics, soaps, and cleaners, as well as forestry pesticides, which already pose a threat to coastal shellfish health. Furthermore, chemical bioaccumulation can increase exposure levels as some contaminant compounds have a higher tendency to accumulate in plants. These residues can impact vulnerable populations like pregnant women or developing children.
All aquatic environments are essential to human health and well-being, feeding billions, supporting millions of jobs, and supplying medicinal materials. However, marine species biodiversity is rapidly declining due to overfishing, global warming, pathogens, and pollution. This biodiversity loss results in changes in marine and terrestrial ecosystem function and reduces ecosystem services. The study determines that oyster condition—although better—has the most variation at non-wastewater sites. The difference in oyster conditions indicates the need to understand the role that the ecosystem plays in the irregular distribution of chemical pollutant exposure. Therefore, this study highlights the need to identify nonpoint pollution sources readily contaminating aquatic ecosystems to establish regulations that mitigate adverse effects. The study researchers conclude, “We recommend that future studies expanding on this work use oysters as bioindicators but increase replication at the site level, measure additional environmental covariates to characterize the role of environmental variability in PPCP [pharmaceutical and personal care products] occurrence and oyster health, include measurements at multiple biological levels, and analyze multiple matrices (tissue, water, sediment) for more analytes.”
Chemical contamination is ubiquitous in terrestrial and marine environments. Therefore, indicator species, like bivalves, can act as sentinel species for chemical contamination, detecting risk to humans by exhibiting signs of environmental threat sooner than humans in the same environment. Unless more is done to address chemical pollution, humans will also continue to see similar declines in general health, fitness, and well-being. For more information about pesticide contamination in water, see the Threatened Waters program page and Beyond Pesticides’ article Pesticides in My Drinking Water? Individual Precautionary Measures and Community Action, where Beyond Pesticides states: “This problem requires individual precautionary measures and preventive, community-based action to protect [individual and public health] and ultimately, stop ongoing pesticide use that ends up in drinking water from numerous agricultural, public land, and home and garden use. Beyond Pesticides urges a solution that keeps pesticides out of the water, rather than trying to clean them up after they enter our waterways and drinking water supply.”
Beyond Pesticides has long advocated for healthier and more environmentally friendly pest management practices to protect the environment and wildlife, particularly water resources. Therefore, pesticide use should be phased out and ultimately eliminated to protect the nation’s and world’s waterways and reduce the number of pesticides that make their way into drinking water. Additionally, Beyond Pesticides has long advocated for federal regulation that considers potential synergistic and additive threats to ecosystems and organisms from admixtures of pesticides.
Replacing pesticides with organic regenerative systems conserves water, nurtures soil fertility, reduces surface runoff and erosion, and reduces the need for nutrient input (i.e., fertilizers). Most critically, organic systems eliminate the use of toxic chemicals that threaten so many aspects of human and ecosystem life, including water resources. Learn more about the hazards pesticides pose to wildlife and what you can do through Beyond Pesticides’ wildlife program page.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
