04
Oct
Pesticides in Sediment Contribute to Secondary Source of Chemical Pollution in Aquatic Environments
(Beyond Pesticides, October 4, 2022) A study published in Environmental Pollution finds pyrethroid insecticides contribute to a secondary source of contamination in water resources. Various pyrethroids, including bifenthrin, are detectable in urban catch basins (storm drains) that collect runoff water before draining into the open environment. There is a lack of information regarding the pesticides’ presence in urban catch basins. However, pesticide contamination in water resources is historically commonplace and widespread throughout U.S. rivers and streams, with at least five different pesticides present in 90 percent of water samples. Moreover, thousands of tons of pesticides not only enter waterways (e.g., rivers, streams, lakes, oceans) around the U.S. through urban catch basins but agricultural and nonagricultural sources as well, contaminating essential drinking water sources, such as surface water and groundwater. Reports like these are essential for determining appropriate regulatory action to protect the human, animal, and environmental health from chemical toxicant contamination, especially if chemical contamination is highly detectable. The study notes, “The high detection frequency of bifenthrin and overall pyrethroid concentrations, especially for particle-bound residues, suggest that underground urban catch basins constitute an important secondary source for extended and widespread contamination of downstream surface waters by pesticides such as pyrethroids in urban regions.”
Many urban areas contain underground catch basins responsible for collecting runoff for drainage into waterways. However, pesticides contaminate runoff in these catch basins, implicating a secondary source of contamination in aquatic environments. Thus, the researchers gathered several water samples from urban underground catch basins throughout various U.S. California regions. The samples emphasize the occurrence and profile of pyrethroid insecticides during the spring, summer, and fall). Overall, the study finds that 98 percent of water samples contained detectable levels of pyrethroids. Of the individual pyrethroids, bifenthrin is the most detectable pyrethroid occurring in 97 percent of water samples, while the pyrethroid fenpropathrin is the non-detectable in samples. In addition to the highest detection frequency, bifenthrin also elicits severe toxicity to sensitive aquatic invertebrates in 89 percent of samples. However, during time frames when pesticide inputs decrease, all pyrethroid residues remain suspended in catch water basin soils, contributing to a secondary source of aquatic ecosystem contamination.
Synthetic pyrethroids are toxicologically similar derivatives of naturally occurring pyrethrins, which have dramatically shorter half-lives and extreme sensitivity to light, heat, and moisture. These insecticides can irritate the eyes, skin, and airways, causing high acute toxicity symptoms (e.g., asthma, incoordination, tremors, and convulsions) depending on the chemical formula. However, these chemicals also have links to chronic health problems from developmental and endocrine disruption adversely affecting reproduction and sexual development to immune system dysfunction and increased chances of cancers. Moreover, synthetic pyrethroids are extremely toxic to aquatic organisms, including crustaceans, fish, and macro/microorganisms responsible for ecosystem function and services. While synthetic pyrethroids pose significant dangers to the environment and human health, there is growing evidence that “inert” ingredients are causing just as much harm or more harm than the active ingredients in pesticide products. Toxic pesticide products can remain in the environment for months, years, and even decades. As the number of pesticides in waterways increases, it has detrimental impacts on aquatic ecosystem health, especially as some chemicals 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 the surface or groundwater. Additionally, disease vector pests like ticks and mosquitos are developing resistance to chemical treatments, prompting the augmented use of chemical control methods, including the addition of toxic synergists like piperonyl butoxide (PBO), known to cause and exacerbate adverse health effects from exposure.
The study highlights how pervasive pyrethroids are in waterways and how these chemicals contribute to secondary chemical pollution through sediments. Pyrethroids are hydrophobic (do not mix with water) and accumulate in soils/sediments in aquatic environments. Soils/sediments can have anaerobic conditions lacking oxygen and slowing the degradation rate of pyrethroids, prolonging their persistence in the ecosystem. Thus, high levels of pyrethroid contamination impair invertebrate communities within sediments. However, this study is not the first to highlight the pervasiveness of pesticide compounds in ecological resources. Previous reports demonstrate the pervasiveness of pesticides, including pyrethroids, in urban watersheds and other waterways and resources from agricultural, household, and community insecticide treatments and pet spray runoff. Moreover, the ubiquity and persistence of certain compounds make it difficult to limit the number of toxicants that enter waterways. Many of the most commonly used pesticides in the U.S. are detectable in both surface and groundwater, which serve as drinking water sources for half of the U.S. population, raising another issue of deficient waterway monitoring and regulations that allow pesticides to accumulate in waterways.
The study concludes, “To improve understanding of pesticide behaviors in urban catch basins and USDSs [underground storm drains systems], further research should characterize runoff before and after it passes through a catch basin, the hydraulic retention of both water and solids in catch basins, and release of water and suspended solids from catch basins into the rest of the USDS. Efforts to design catch basins with reduced contaminant accumulation potential, and pest management practices to prevent the transport of pesticide residues from entering USDSs and catch basins, should be further explored.”
Beyond Pesticides has long advocated for healthier and more environmentally friendly pest management practices to protect the environment and wildlife, particularly water resources. Therefore, toxic pesticides should be phased out and eliminated to protect the nation’s and world’s waterways and reduce the number of pesticides that make their way into your drinking water. Additionally, Beyond Pesticides has long advocated for regulations that consider potential synergistic and additive threats, to ecosystems and organisms, from admixtures of pesticides — whether in formulated products or “de facto” in the environment. However, advocating for local and state pesticide reform policies can protect you and your family from pesticide-contaminated water. Furthermore, organic/regenerative systems conserve water, nurture fertility, reduce surface runoff and erosion, reduce the need for nutrient input, and eliminate the toxic chemicals that threaten many aspects of human and ecosystem life, including water resources. 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.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Environmental Pollution
