(Beyond Pesticides, December 7, 2023) A new review published in Ecotoxicology reiterates what past studies have repeatedly stated: the herbicide paraquat (PQ) has profound adverse effects on wildlife at environmentally relevant concentrations. Moreover, these adverse effects span beyond the wilderness, as exposure to this highly toxic herbicide also impacts the health of people working with this chemical (e.g., pesticide applicators) or living adjacent to areas of chemical use.
Current data gaps regarding the effects of environmentally relevant concentrations and exposure times, population- or ecosystem-level effects, and biomagnification potential contribute to the uncertainty of predicting risk from environmental PQ exposure. Furthermore, Beyond Pesticides has previously pointed out deficiencies in the U.S. Environmental Protection Agencyâ€™s (EPA) ecological risk assessments for paraquat, highlighting failures to perform complete evaluations of the impacts of pesticides on threatened and endangered species. All this occurs amidÂ documented threats to biodiversityÂ from the combined effects of pesticides and climate change.Â
The review investigated paraquat in the environment, the chemicalâ€™s toxicity to nontarget species, and significant data gaps. Overall, the long-term risks of environmental PQ contamination for human and ecological communities can be challenging since the potential chronic effects from extended use are nearly unstudied. Most concerning is that PQ is immobile in soil and remarkably hydrophilic (remaining in water columns and sediment), thus having a long environmental half-life with nonselective toxicity. Although the review highlights that nontarget plants are most at risk from environmentally relevant concentrations of PQ, vertebrates, and invertebrates still receive nonselective toxicity mainly through oxidative stress, with the review noting that PQ has one of the highest acute toxicity values among all herbicides.
Paraquat is the most acutely dangerous herbicide on the market. As EPA readilyÂ admits, â€śOne small sip [of paraquat] can be fatal, and there is no antidote.â€ť Importantly, in addition to its high acute toxicity, it also presents a range of chronic concerns, including cancer, damage to the reproductive system and organs like the kidney and liver, and most notably, Parkinsonâ€™s disease (PD). Standing out among the wide range of impacts that makes clear that this chemical poses unreasonable risks are its neurotoxic effects. Inhalation of low dosesÂ can disrupt oneâ€™s sense of smell, andÂ past research has foundÂ the chemical can cause damage to the lungs of farmers who apply it. Data is increasingly showing thatÂ cumulative exposures over oneâ€™s life increase the risk of developing Parkinsonâ€™s disease, and other factorsÂ such as genetics and exposure to other chemicals further elevate the threat. Recent studies have even found thatÂ oneâ€™s zip codeÂ and proximity to paraquatâ€™s use in farm fields is likely playing a role in an individualâ€™s Parkinsonâ€™s Disease risk. Strong links to this chronic condition are incredibly concerning, givenÂ emerging evidence of a Parkinsonâ€™s pandemic, predicting that rates of the disease will double between now and 2040.
Agricultural land is subject to chemical-intensive farming that uses toxic pesticides to manage pests (e.g., weeds, insects, fungi) on animal feed crops. In the Center For Biological Diversity (CBD) report No Refuge U.S. Fish and Wildlife Service (FWS) data demonstrate a 34 percent increase in the number of acres to which agricultural pesticides were applied to wildlife refuges from 2016-2018, encompassing 363,000 acres of refuge land treated with 350,000 pounds of pesticides. Furthermore, the data reveals an increase in the aerial spraying of pesticides by 35 percent. Lastly, wildlife refuges have experienced a 70 percent higher level of dangerous pesticide inputs, including a 100 percent increase in paraquat. The chemical poses hazards to birds and bees and is prone to leaching into groundwater, disrupting the stability of aquatic ecosystems. The impact of pesticides on wildlifeâ€”including mammals, bees and other pollinators, fish and other marine organisms, birds, and the biota within the soilâ€”is extensive. A plethora ofÂ studies documentÂ how exposure to toxic chemicals causes reproductive, neurological, renal, hepatic, endocrine disruptive, and developmental anomalies, as well as cancers, in a wide range of species. Despite statutory language in place to protect wildlife from harm, such as the Endangered Species Act (ESA) of 1973, a 2013Â reportÂ by the National Academy of Sciences detected shortcomings in EPAâ€™s evaluation and analysis of pesticides on endangered species, with the agencyÂ regularly disregardingÂ the ESAâ€™s requirement to confer with federal wildlife agencies on how to take precaution to protect threatened and endangered species from pesticide harms. Therefore, EPA and other federal government agencies, including FWS, reformed the pesticide review process to meet the pesticide approval requirements for the ESA.Â
This review notes that the high use of PQ over the years without proper research on environmental effects offers much uncertainty regarding the benefits and harm to ecosystem health and function. In addition to health and environmental risks from using paraquat, there are growing legal troubles for its primary manufacturer, Syngenta, a Switzerland-based company purchased by the Chinese National Chemical Corporation (ChemChina) in 2016.Â Mounting lawsuits against Syngenta/ChemChinaÂ were consolidated andÂ are set to begin jury trials next yearÂ for farmworkers and other individuals who worked with paraquat and are now suffering from Parkinsonâ€™s disease.Â Plaintiffs in the suit claimÂ â€śthat manufacturers and sellers of paraquat deliberately concealed the dangers of paraquat for at least four decades, hid evidence of its dangers from government safety agencies, and knowingly unleashed a product they knew caused Parkinsonâ€™s Disease on the public.â€ť Therefore, advocates are uncertain how far the EPA will go in restricting paraquat and underline that more public pressure is needed for the EPA to act meaningfully.
This review concludes, â€śThe discrepancy between the known and the unknown of PQ toxicity (i.e., effects on certain taxonomic groups, habitats, and ecosystem services; biomagnification potential; role in the development of Parkinsonâ€™s disease in humans, etc.) despite being commercially available for over 60 years should serve as a call for scientists and regulators to be more aware of novel chemicals that are being synthesized and then introduced into the environment, especially in light of accelerating trends of chemical production. It has been estimated that we have already far exceeded the safe planetary boundaries for novel chemicals and that we, therefore, have surpassed the planetâ€™s threshold to be safely handle these new chemicals. It is clear there is an urgent need for enhanced regulation and testing of chemicals as well as better engineering and regulatory controls to limit the introduction of hazardous chemicals into the environment. This is particularly important for herbicides like PQ, which are purposefully applied to the land and then unintentionally introduced to the biosphere, including human populations.â€ť
Comment from Beyond Pesticides. The use of pesticides should be phased out and ultimately eliminated toÂ protect global wildlifeÂ and reduce the number of dangerous pesticides exposed to all species, whether residing in wildlife refuges or urban spaces. Additionally, Beyond Pesticides has long fought against pesticide use, advocating for federal regulations that consider all potential impacts of pesticides on ecosystems and organisms. Current regulations fail to consider the environment holistically, thus creating a blind spot that limits our ability to adopt widespread change that improves ecosystem health. It is vital to understand how pesticide use can increase biodiversity loss, especially since the globe is currently going through theÂ Holocene Extinction, Earthâ€™s 6th mass extinction, with one million species of plants and animals at risk of extinction. However, advocating for local and state pesticide reform policies and the adoption of organic land management can protect wildlife from pesticide contamination. For more information on pesticide impacts on wildlife, visit Beyond Pesticidesâ€™Â wildlife page.Â
Furthermore,Â buying,Â growing, and supporting organic can help eliminate the extensive use of pesticides in the ecosystem. Organic agriculture has manyÂ healthÂ andÂ environmentalÂ benefits, which can eliminate the need for chemical-intensive agricultural practices. For more information on how organic is the right choice for all individuals, see the Beyond Pesticides webpage,Â Health Benefits of Organic Agriculture.Â Â
All unattributed positions and opinions in this piece are those of Beyond Pesticides.