13
May
Literature Review Documents Enhanced Toxicity of Chemical Mixtures in Aquatic Organisms with PFAS Exposure
(Beyond Pesticides, May 13, 2026) Published in Toxics, a review finds that per- and polyfluoroalkyl substances (PFAS) can heighten the risks to exposed organisms from environmental contaminants. Mixtures of these compounds can negatively impact the nervous, cardiovascular, immune, and reproductive systems, particularly in aquatic organisms, and threaten overall biodiversity. The review highlights synergistic effects (greater in combination) observed in mixtures, such as PFAS with pesticides and microplastics, that can cause enhanced oxidative stress, neurotoxicity, developmental defects, and reproductive dysfunction, among others.
“The objectives were to evaluate the toxicological effects of mixtures of the selected contaminants with PFAS on aquatic organisms to better understand biological responses in animals,†the study authors explain. “Based on our review, data suggest that PFAS can modify the toxicity of co-occurring pollutants.â€
Background
PFAS were first created in the 1930s and have since been used in many industries and in the production of many products. The multitude of PFAS sources and exposure routes leads to widespread contamination of the environment and organisms. PFAS in agriculture represents a large source, as PFAS can be pesticide active ingredients, used in the plastic containers that pesticides are stored in, and as surfactants in pesticide products. Additionally, PFAS are used in many other plastic storage containers and food packaging, personal care products, nonstick cookware, cleaning supplies, treated clothing, firefighting foam, and machinery and equipment used in manufacturing—all of which contaminate food, water, soil, and the air. (See additional coverage on PFAS here.)
A previous Daily News piece, entitled “Science on ‘Forever Chemicals’ (PFAS) as Pesticide Ingredients and Contaminants Documented,†shows how and to what extent PFAS can be introduced into pesticide products, and how this impacts health and the environment. The findings are gleaned from public records requests to state and federal agencies in the U. S. and Canada, as well as from publicly accessible databases discussed in the commentary “Forever Pesticides: A Growing Source of PFAS Contamination in the Environment.†The classification of PFAS is also of concern, as the number of PFAS in the U.S. heavily depends on the U.S. Environmental Protection Agency (EPA) definition, based on “case-by-case†rulemakings and agency actions. The broad definition of PFAS as a compound with at least “one fully fluorinated carbon†has been adopted by many states and other authorities.
EPA continues to ignore the widely accepted definition of PFAS, supported by scientists, through the Organization for Economic Cooperation and Development (OECD). EPA’s current scientific definition of PFAS, also known as “forever chemicals†due to their persistence, is at odds with the prevalent scientific thinking of scientists worldwide who have challenged the agency’s position and its resulting risk assessments. (See Artificially Narrow EPA Definition of PFAS Mischaracterizes Widespread Threat to Health and Environment.)
Widespread Use of PFAS and Resulting Chemical Mixtures
EPA continues to register PFAS pesticides, including the latest instance with the active ingredient tetflupyrolimet (TFP) that was declared as an “emergency.†This emergency, however, is caused by weed resistance, which is a recurring and predictable event. By definition, a chronic and routine problem does not qualify as an emergency. As shared in Beyond Pesticides’ comments, the allowance of this emergency use of an unregistered pesticide is not warranted, given the serious concern about the hazards of this herbicide and the lack of a full registration review subject to public comment. According to public health advocates, a wide body of science on the effects of PFAS supports the removal of all PFAS from production, not the approval of a PFAS for emergency use, particularly for a compound that is not registered with EPA for any current uses.
Beyond Pesticides has also commented on the increasing number of PFAS pesticide active ingredients proposed for use over the last year. The latest pesticide proposed for EPA registration, epyrifenacil (agricultural weed killer), joins cyclobutrifluram (soil fungicide/nematicide), isocycloseram (household and agricultural insecticide), diflufenican (lawn and agricultural weed killer), and trifludimoxazin (agricultural weed killer), making a total of five PFAS pesticide proposals in 2025 that have been associated with national and worldwide contamination of food, land, and water. Two of these, cyclobutrifluram and isocycloseram, have been approved as of last fall.
Exposure to PFAS does not occur in isolation, as many compounds are continuously encountered in complex mixtures where the combined effects can differ substantially from those predicted by examining each substance individually. In humans, these compounds can accumulate, referred to as “Body Burden,†which encompasses numerous chemicals. (See Daily News here.)
Literature Review Methodology and Results
In the current review, researchers from the U.S. and Brazil performed a literature search for scientific literature published between 2010 and 2025 involving aquatic organisms, such as fish, algae, and microorganisms, with combined exposure to PFAS and other contaminants. “Many studies to date have analyzed the biological impacts of PFAS on invertebrates and vertebrates, such as algae, fish, rodents, and humans,†the authors report. They continue: “Several PFAS, including perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), are reported to bioaccumulate within species and can contribute to a wide range of biological and physiological effects (i.e., altered metabolism, endocrine disruption, oxidative stress, reproduction disruption).â€
Additional results include:
- Chlorpyrifos and the PFAS perfluorohexanoic acid (PFHxA) exhibit synergistic effects by increasing reactive oxygen species (ROS) and upregulating neurotoxicity-related genes in zebrafish.
- PFOA and atrazine show synergy as the mixture increases the presence of malformations and oxidative stress. These compounds also cause decreased embryo hatchability in zebrafish. (See research here.)
- PFAS combined with microplastics also intensifies oxidative stress, as well as other developmental and reproductive effects.
- Zebrafish with coexposure to chlorpyrifos and PFAS experience neurotoxicity and oxidative stress.
In summary, the researchers say: “The coexistence of PFAS and other contaminants in environmental matrices is a reality, raising concerns about ecological and health risks. In vivo and in vitro studies in several aquatic organisms indicate that co-exposure can exacerbate toxicity, leading to a higher incidence of malformations, inhibition of hatching, increased oxidative stress, and alterations in metabolism and gene expression.†This review highlights the complexities of the interactions between PFAS and other environmental contaminants, further supporting the need to eliminate the use of these chemicals.
Previous Research
As shared in additional comments to EPA regarding PFAS contamination (see here and here), there is a wide body of science highlighting the adverse effects of these compounds on human and environmental health. Additionally, of serious concern are the many PFAS known to break down in the environment to other compounds such as trifluoroacetic acid (TFA), which is noted as one of the most pervasive PFAS water contaminants in the world and is the most extensively studied ultrashort-chain perfluoroalkyl acid (PFAA).
PFAS residues are pervasive in food and drinking water, with over six million U.S. residents regularly exposed to drinking water with PFAS levels above the EPA health advisory of 70 ng/L. PFAS are detectable in almost all of the U.S. population—disproportionately afflicting people of color communities—and have implications for human health. From epigenetic to immunotoxic effects, there is a wide range of health implications with PFAS exposure. Because of their ubiquitous use and exposure, studies report that PFAS compounds are detectable in infants, children, and pregnant women. Like other legacy chemicals, the effects of PFAS endure through generations—pregnant women can readily transfer compounds to the developing fetus through the placenta.
The detection of any level of PFAS is cause for concern. From widespread presence in farm fields and sewage sludge (biosolids) to contaminated water bodies throughout the U.S., PFAS have made their way into the environment and human bodies. PFAS are even present in remote environments like the Arctic, Antarctica, and Eastern European Tibetan Plateau. Numerous studies document exposure to endocrine-disrupting pesticides (EDPs), including PFAS, leading to dysfunction of the body’s endocrine system as well as additional health effects, such as cancer, brain and nervous system disorders, immune system disorders, diabetes, learning/developmental impacts, and sexual and reproductive dysfunction.
PFAS contamination is much more pervasive than previously assumed, polluting storage and transportation containers, food and water resources, and other chemical products. Not only is the public exposed to PFAS, but cumulative exposure is higher among workers, including those who work in factories that manufacture products with PFAS, and workers who use them regularly. As science continues to emerge on the enhanced effects of PFAS when combined with other contaminants, protecting health and the environment becomes increasingly important.
The Organic Solution
To avoid the use of these harmful chemicals, Beyond Pesticides recommends choosing certified organic products whenever possible. Through the Eating with a Conscience database, you can select from over 90 different common crops you regularly consume and learn about the organic difference from their conventional, chemical-intensive counterparts. See Buying Organic Products (on a budget!) and Grow Your Own Organic Food for more information.
As EPA continues to fail in its statutory duty to adequately protect the health of the environment and all organisms within it, as extensively covered by Beyond Pesticides, the call to truly safeguard ecosystems and public health with the elimination of PFAS and pesticides takes on a greater urgency. We must instead facilitate a widespread conversion to organic practices.
The holistic, systems-based organic solution for land management and agriculture offers numerous health and environmental benefits. Learn more about how to take action and have your voice heard on governmental efforts that are harmful to the environment and public and worker health, increase overall pesticide use, and undermine the advancement of organic, sustainable, and regenerative practices and policies with Action of the Week.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source:
Valle, E. et al. (2026) Do Perfluorinated Chemicals Enhance the Toxicity of Other Contaminants in Aquatic Organisms? A Review, Toxics. Available at: https://www.mdpi.com/2305-6304/14/5/373.
