17
Jul
Unregulated, “Shocking” and Destructive Levels of Pesticide Mixtures Found in Waterways
(Beyond Pesticides, July 17, 2020) Researchers have discovered that the rivers and creeks that discharge into the lagoon of the Great Barrier Reef are riddled with mixtures of pesticides. The University of Queensland team expected to find some such mixtures in their sampling, but was shocked to find that 99.8% of their samples contained up to 20 different pesticides. Michael Warne, PhD, lead researcher and associate professor at the University of Queensland’s School of Earth and Environmental Sciences, says, “The issue with having mixtures of pesticides is that as the number of pesticides increases the impact to aquatic ecosystems generally increases.” Beyond Pesticides has covered waterway pesticide contamination in Europe and the U.S. The organization has long advocated for protective federal regulation that considers potential synergistic and additive threats, to ecosystems and organisms, from admixtures of pesticides — whether in formulated products, or “de facto” in the environment, as this study addresses.
The Great Barrier Reef (GBR) Lagoon is the open water of the Coral sea that lies between the reef and the Queensland, Australia coast. The GBR is the world’s largest coral reef system, comprising more than 2,900 individual reefs and 900 islands, and extending across an area of approximately 133,000 square miles. It was designated a UNESCO (United Nations Educational, Scientific and Cultural Organization) World Heritage site in 1981 because of its unique and rich habitat and biodiversity.
UNESCO says of it, “The latitudinal and cross-shelf diversity, combined with diversity through the depths of the water column, encompasses a globally unique array of ecological communities, habitats and species. This diversity of species and habitats, and their interconnectivity, make the GBR one of the richest and most complex natural ecosystems on earth. There are over 1,500 species of fish, about 400 species of coral, 4,000 species of mollusk, and some 240 species of birds, plus a great diversity of sponges, anemones, marine worms, crustaceans, and other species.”
During the 2011–2015 period, the researchers gathered 2,600 samples from 15 waterways that discharge into the lagoon of the Great Barrier Reef. The samples were analyzed for between 21 and 47 pesticides, and 80% contained quantifiable mixtures of 2–20 pesticide compounds. Of the samples with multiple pesticides, 82% of the pesticides identified are compounds that exhibit more than two modes of action; a mode of action is how a chemical causes physiological disruption in target, or other, organisms. Both numbers of pesticides and modes of action vary spatially and are greatly influenced by nearby land use, with waterways that drain areas of sugar cane cultivation evidencing the greatest number of pesticides.
The Special Report on Global Warming of 1.5 °C, produced in 2018 by the Intergovernmental Panel on Climate Change (IPCC), identifies tropical coral reefs as among the most vulnerable ecosystems in the world. The now-fragile GBR system is already subject to a variety of assaults, including mass bleaching events caused by warming ocean temperatures, and threats to the very foundation of the reefs from ocean acidification. The framework of coral reefs depends on calcium-carbonate-secreting organisms; such basic (in the pH sense) structures fare poorly in an increasingly acidic environment. As noted in a 2019 paper, “The Great Barrier Reef: Vulnerabilities and solutions in the face of ocean acidification,” “Loss of coral cover, whether due to OA [ocean acidification], warming or other pressures on the reef, will lead to a shift in fish communities from species that prefer coral habitats toward species which are successful outside reef settings, with associated potential changes to important reef fisheries. Coral reefs also provide coastal protection from storms and support livelihoods and economic activities such as reef-associated tourism and recreation.”
The discovery of such intensive penetration of pesticides in the GBR Lagoon adds to the chronicling of damage being wrought on these marine wonderlands. In March 2020 coverage of a report by the Australian government that showed that agricultural pesticides are severely damaging the Great Barrier Reef, Beyond Pesticides also noted that, with the other hand, the government had given sugar cane growers an extension on the use of a weed killer, Diuron, which EPA classifies as a likely human carcinogen. The sugar cane industry was given eight years in which to find an alternative way to deal with target weeds, but failed to do so. This herbicide, according to World Wildlife Fund Australia, is frequently found in streams that discharge around the GBR, and causes 75% of the pollution that is likely “poisoning the health of seagrass and coral, further contributing to the current heavy die-off of hundreds of turtles and dugong. . . . We call on the federal government to move swiftly to ban this chemical.”
Dr. Warne says of his study, “This work strongly supports the inclusion of the pesticide reduction target in the Reef 2050 Water Quality Improvement Plan which aims to protect at least 99 per cent of aquatic organisms at the mouths of rivers from the adverse effects of all pesticides.” (The plan “seeks to improve the quality of water flowing from the catchments adjacent to the Great Barrier Reef.”) He indicates that working with land managers, sharing information, and helping them improve their pesticide management practices may be the best way forward, given these results.
His team is partnering with James Cook University and others on Project Bluewater (a project of the Great Barrier Reef Foundation) to reduce the runoff of pesticides into the Great Barrier Reef Lagoon through the adoption of improved sugar cane farming practices. The project currently works with 70 sugar cane farmers in two areas to improve pesticide management and application, upgrade equipment, reduce pesticide use, and switch to use of “lower-risk” pesticides. Dr. Warner reports, “We have found the farmers involved to be very eager to engage with the science — they have embraced the challenge and are making significant steps toward improvement.”
Such pesticide mixtures are found in U.S. waterways, as well. The Environmental Protection Agency (EPA) is primarily responsible for regulating pesticides in the U.S. It regulates point source pollution of surface waters through permitting processes authorized by the Clean Water Act. (That said, EPA recently rolled back protections, stripping them from roughly one of every five stream miles, more than half of the nation’s wetlands, and many other kinds of waterways). The U.S. Geological Survey (USGS), through its National Water-Quality Assessment (NAWQA) studies, “assesses the occurrence and behavior of pesticides in streams, lakes, and groundwater and the potential for pesticides to contaminate our drinking-water supplies or harm aquatic ecosystems.” February 2020 USGS reporting on a collaborative sampling project (conducted with EPA) for pesticides in waterways detected 141 pesticides in seven Midwest streams, and 73 in seven streams in the Southeast.
Neither USGS studies nor EPA’s aquatic risk assessments investigate the synergistic or additive risks of mixtures of pesticide chemicals. As is typical, EPA assessments focus on the presence of discrete pesticide compounds and their potential toxicity to organisms, but not on any additional risks due to the “medleys” of compounds present in waterways. This negligence likely results in an underestimation — and allowing — of potential hazards to aquatic wildlife. Among the deficiencies in monitoring and regulation of pesticides in waterways are these, as NAWQA has acknowledged (as of 2011), “Current standards and guidelines do not completely eliminate risks posed by pesticides in waterways because: (i) values are not established for many pesticides; (ii) mixtures and breakdown products are not considered; (iii) the effects of seasonal exposure to high concentrations have not been evaluated; and, (iv) some types of potential effects, such as endocrine disruption and unique responses of sensitive individuals, have not yet been assessed.”
Healthy waterways, whether those feeding the GBR Lagoon, or those draining Midwest U.S. agricultural fields, or major rivers that discharge into the world’s oceans (think the Mississippi, Nile, Ganges, or Yangtze), are fundamental to healthy terrestrial and marine ecosystems, as well as to human health. Whatever pesticides make their way into waterways, from either point or non-point sources, end up in those rivers, in lakes and oceans, and in groundwater — from which half the U.S. population derives it drinking water. The majority of the most commonly used pesticides in the U.S. have been detected in both surface and groundwaters.
It is imperative that pesticide use be phased out and ultimately, eliminated, and alternative practices, such as organic, regenerative agriculture, adopted to protect the nation’s and world’s precious waterways. Creating and nurturing living, healthy soils — the foundation of organic/regenerative systems — conserves water, nurtures fertility, reduces surface runoff and erosion, reduces the need for nutrient input, and critically, eliminates the toxic chemicals that threaten so many aspects of human and ecosystem life, including water resources. Learn more about these nontoxic, protective approaches here.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
