Toxic "forever chemicals" can take hundreds of years to break down in the environment, making them a concern for scientists for decades. These substances are found in cookware and clothing and are turning up all over the place. Researchers warn that common pesticides are the source of some of the toxins. A review paper published in Environmental Pollution states that 70% of all pesticides introduced into the global market from 2015 to 2020 contained these chemicals. The surge in their use has not fully understood their impact on the environment and human health.

The chemicals that are scientifically known as perfluoroalkyl and polyfluoroalkyl substances, or PFASs, are a subset of so-called fluorinated chemicals. Such chemicals are useful in repelling grease and water. They don't biodegrade easily. Efforts to limit the use of PFASs are complicated by differing technical definitions of which chemicals are technically PFASs and pose a risk to people and the environment. Many chemicals in the rest of the world are not classified the same way as in the US.

Pesticides made from fluorinated chemicals, commonly referred to as fluorinated pesticides, can be incredible molecules that meet a lot of the challenges that exist in agriculture, according to a study co-author. We should be aware that they can have a huge impact on the environment and on our own health.


It's a question of stability or persistence.

Consumer products have been made with fluoroinated chemicals since the 1940's. The Environmental Protection Agency began investigating the chemicals in the 1990s after scientists realized that they were still in the water. Low levels of PFASs are found in nearly every US resident. These chemicals have been linked to a number of diseases and even increased susceptibility to COVID-19. Congress is considering several bills to restrict their use in food containers and cookware and to require the EPA to take comprehensive action to prevent PFAS pollution. The EPA has published a strategic plan to address the crisis. Pesticides are not included in the laws that have already been adopted.

The use of florinated pesticides first appeared in the 1930s, but only in the past decade has it grown so much. Improvements in manufacturing processes and the end of patents have led to the rise.

Karen Reardon is a spokeswoman for the pesticide industry group Responsible Industry for a Sound Environment. Crops can be sprayed less often if pesticides stay stable.

Reardon and others call it stability. Half-lives range from a few days to 2.5 years for top-selling pesticides, according to data compiled by the team. The EPA defines a pollutant as having a half-life of 60 days or more if it is a persistent pollutant. Kyla Bennett is the science director of the nonprofit environmental advocacy organization Public Employees for Environmental Responsibility. For a reason, it is called a forever chemical.


Is a PFAS a thing?

Bifenthrin is one of the most popular pesticides. It is the main ingredient in more than 600 pesticides used on crops. It is used to control pests in the city. There is not much known about its effects on human health, and the EPA has classified it as a human carcinogen. The EPA concluded in a 2020 human health risk assessment that diet exposure and risk estimates are not of concern for the existing uses of bifenthrin. In the last few years, some fruits and vegetables have exceeded the EPA's safety levels. Bifenthrin is an oily substance, so extra scrubbing is required.

Bifenthrin has a half-life of 97 to 345 days in the soil. It can persist in surface waters where it harms beneficial insects that provide food for fish, birds and wildlife. Maria de Ftima Carvalho, a co-author of the new paper, said that the carbon and fluorine configuration is stable and will be persistent in the environment.

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Bifenthrin is one of more than 200 active pesticide ingredients that would be recognized as a PFAS by the latest Organization for Economic Co-operation and Development definition and is banned for most agricultural uses in the European Union. Efforts to understand and regulate chemical use are complicated by differing definitions. Some experts disagree with the EPA's definition of compounds that are less likely to accumulate in the food chain and are potentially less toxic. Rolf Halden is the director of the Biodesign Center for Environmental Health Engineering at Arizona State University. A chemistry has no known biodegradation mechanism. Signing up for a lifetime of exposure around the world is what you are doing.

Robert Daguillard wrote in an e-mail to Scientific American that the EPA's definition was intended to identify the most likely to present risk to human health and the environment. The definition has been adjusted and we are currently looking at the differences between the EPA and OECD definitions to see if the definition should be changed to capture more substances.


The EPA allows at least three active pesticide ingredients to be used. Some of the others that the EPA qualifies as a PFAS have been banned in the US but are still being used in some countries. There are new pesticides on the market in China. Nathan Donley is an environmental health science director at the Center for Biological Diversity. Donley says that on paper, they look like they break down within a reasonable time period. There is a pesticide molecule that can break down into a complex molecule. What those products are doing in the environment isn't followed up with. Wendy Heiger- Bernays is a clinical professor of environmental health at the Boston University School of Public Health.

The EPA has a process for assessing the environmental risks of pesticides. While the EPA looks at initial breakdown products, it doesn't follow the pesticide degradation process, which can take decades or centuries to complete, according to Donley. What happens in the environment doesn't always correlate with what happens in the lab. Donley doesn't expect the EPA to do all the study needed to get definitive answers, but they need to account for the uncertainty. People and the environment should get the benefit of the doubt.

pesticides undergo a rigorous scientific assessment process prior to registration, regardless of the evolving definition of a PFAS, according to an e-mail from the EPA.

Bennett, who worked at the EPA for more than a decade, points out that the data the agency use to evaluate pesticide safety are almost entirely provided by manufacturers. According to her, the EPA staff does not have enough information to do their job correctly. The issues have been brought to light by recent reporting. Bennett points out that the EPA's pesticide determinations are made solely by the agency. When asked about Bennett's claims, the EPA didn't say anything.

The EPA and others tell us that the newer pesticides are better than the older ones. That may be true in some respects. Even though these don't technically meet the definition of the EPA, they meet the definition of the rest of the world.


Some people prefer to focus on the pesticides that the EPA has labeled as PFASs. Graham Peaslee is a professor of physics at the University of Notre Dame. Heiger- Bernays doesn't worry about the potential for human harm from pesticides. She emphasizes that she is not apesticide advocate and that there can be legitimate uses for these chemicals. She says the problem is to figure out what those limited, legitimate uses are.

It is not known whether the EPA will take action on fluorinated pesticides that meet its definition. As EPA continues to refine the testing process, as regulatory work matures, and as the Agency learns more from its partnerships across the country, it will adjust the definition of PFAS to reflect the information gathered through this process. All available regulatory and non-regulatory tools will be used to address the issue.

Those words are not comforting for some. A lot of us are not sure. Donley says they don't know much. It will take a few years, or even a few decades, to really grasp what is going to happen with all these new pesticides.