Non-polymer PFAS can build up in blood protein of animals, and is not always removed quickly. This means that predators eating PFAS-contaminated food will have higher levels in their bloodstream, and concentrations can increase up the food chain. Studies suggest that build up of PFAS is similar to those of other Persistent Organic Pollutants such as DDT.PFAS are estimated to be settling in arctic regions at rates of tens to hundreds of kilograms per year (25-850kg per year), depending on the specific PFAS chemical in question. Certain PFAS are released as gases to the environment and are blown a long way by wind and air currents in the atmosphere,. These gas PFAS will over time degrade to more persistent chemicals like PFOS and PFOA. This may be one reason why PFAS of environmental concern have been found in remote regions such as the Arctic as well as near PFAS production sitesPFAS including PFOS and PFOA have been found in air samples around Europe. The chemicals are found in small quantities, but appear in almost all samples tested. PFAS enters the atmosphere both from factories and the air inside our homes. PFAS is found in treated waste water from industrial and domestic sources and has been found in both rivers and groundwater. Conventional drinking water processes will not remove PFAS.PFAS-coated clothes that are thrown away will often end up either incinerated or in landfill. Unless incinerated at very high temperatures (>1000oC), fluorinated polymers could release more harmful PFAS during burning. PFAS of environmental concern have also been found in landfill leachate. Non-polymer PFAS are used in the production of fluorinated polymers. The manufacture of stain-resistant finishes generally releases these PFASs into the environment, both by air and water emissions. They are very hard to remove during water treatment. Workers in textiles factories are some of the population most exposed to these potentially harmful chemicals. Small quantities of PFAS will be removed during wash and wear of products containing PFAS. This includes fluorinated polymers used on stain-resistant coatings, and non-polymers that remain on clothes after production (Lassen et al. 2015).Most UK waste still ends up in landfill, and this includes PFAS-containing products. Studies have shown that the liquid coming from landfills (known as leachate) often contain non-polymer PFAS chemicals. In the USA the total quantities were estimated at 563-638 kg in 2013. To properly break down PFAS chemicals high temperature (1000oC or more) incineration is recommended. Incineration of municipal waste does not necessarily reach these temperatures (min temp. required is 850oC), and the incomplete breakdown could release non-polymer PFAS.Wash and wear of clothing that contains PFAS-based stain-resistant or water repellent finishes release PFAS to the environment. Coatings are thought to lose effectiveness after 20-30 washes. This can include non-polymer PFAS, remnant from production or as a break-down product of side-chain polymers (Lassen et al. 2015). The manufacture of stain-resistant finishes releases PFAS into the environment, both by air and water emissions. PFAS are very hard to remove during water treatment. Industrial emissions are estimated to be the biggest source of these chemicals to the environment.

The Problem with PFAS in Pesticides

Pesticides, already products of concern for the environment, can also contain per- and poly-fluoroalkyl substances (PFAS), also products of great concern. PFAS have been connected with a wide range of adverse environmental and human health impacts and recent research in America has found PFAS in pesticides to be yet another direct route of PFAS into the environment. With their known environmental impacts, alongside their alarming persistence, should this be allowed to continue?

Much of our agriculture today is intensive and relies heavily on manufactured chemicals (insecticides, fungicides and herbicides) to control pest species and increase yield. However, their use negatively impacts the insects underpinning vital ecosystem services like crop pollination. Organisms are often exposed to more than one stressor at a time, and the interactive effects of such stressors may be underestimated.i


PFAS addition as an ‘inert ingredient’.

Within agrochemical products, there are two broad groups of chemicals: ‘active’ ingredients, responsible for the actual pest control, and ‘inert’ ingredients or co-formulants, which help the formulation work and are widely assumed to be ‘non-toxic’. Research that tested the effects of these ‘inert’ ingredients found that they caused mortality in bees through multiple exposure routes, acted synergistically with other stressors and caused colony-level effects.i Perhaps they are not so ‘inert’ after all.

PFAS, also known as ‘forever chemicals’ because of their extreme persistence in the environment, are synthetic chemicals frequently used in a variety of consumer and industrial products. They are also commonly used as a surfactant, which helps a product mix and spray or spread more effectively. An example of this use in pesticides is shown by recent research from the United States Department of Agriculture (USDA).ii Having detected PFAS in plants grown in their research laboratory greenhouse, the USDA carried out further analysis for PFAS in the potting soil, water, fertilizer, insecticides and other plants. They found the source of PFAS contamination to be the insecticides used on the soil, which did not have PFAS as ‘active ingredients’. The results therefore suggest that a previously unknown route of PFAS to the environment is through ‘inert’ pesticide ingredients. An alternative source could be PFAS leaching from plastic storage barrels into the insecticides,iii however the types of PFAS compounds found differed from those used in plastic containers.iv


PFAS as ‘active substances’ in pesticides

Alarmingly, PFAS can also be found as ‘active ingredients’ in some pesticides. Active substances that fulfil the PFAS definition are commonly characterised by the presence of one or more CF3-group(s) in their molecular structure.xii Fluorinated pesticides are those that contain one or more fluorine atoms in their molecular structure. Note that not all fluorinated pesticides will be defined as a PFAS.

Adding fluorine to pesticides improves their most “favourable properties”: quick action, prolonged residual activity, high selectivity and specificity without altering their potency and intended biological activity.vii However, their high affinity to bioaccumulate in living organisms is of great concern. For example, a study found a correlation between the bioaccumulation of fluorinated pesticides in honeybees, alongside other types of pesticides, and events of mass mortality of honeybee colonies in Italy.v There have also been examples of bioaccumulation in fish and

Fluorinated pesticides have increased in use in the last two decades and they are steadily becoming an established product in modern agriculture.vii Many fluorinated pesticides are now frequently featured in the top-selling pesticides, and their use is expected to increase in the foreseeable Concerningly, this growing trend has not been accompanied by a comprehensive testing and regulatory framework that addresses their environmental fate or safety profile.

The Pesticide Usage Survey Team of Fera Science Ltd conducts pesticide usage surveys across the UK in various situations (arable, vegetable, amenity).vii Of the fifty most extensively used active substances for arable crops, fourteen were fluorinated and applied to the equivalent of nearly 13 million hectares of UK fields in 2020.viii Using the same criteria, Fera measured nine fluorinated pesticides used on vegetable crop fields in 2021. Nineteen fluorinated active substances are in use in the UK’s amenity sector.ix

Although it is well documented that PFAS are present throughout the environment, much remains to be discovered about PFAS exposure from a contaminated food chain. However, it is already well-established that crops take up PFAS, which can then be ingested by livestock intended for human consumption, or directly by humans.x

The potential of any pesticide to be an environmental pollutant is influenced by attributes that often seem “ideal”: their persistence, stability and ecotoxicological effects mean there is great potential to inflict ecosystem damage.xi For example, Epoxiconazole, which was the UK’s seventh most-used active substance on arable crops in 2020, before being banned in late 2021, has proven endocrine disruption effects in human cell lines,vii with a high long-term risk to herbivorous birds when used on cereals.xii


What action is being taken?

The US Environmental Protection Agency (EPA) is removing twelve chemicals identified as PFAS from the current list of inert ingredients approved for use in pesticide products,xiii to better protect human health and the environment. The PFAS restriction proposal recently published by the European Chemical Agency (ECHA) has an option to exempt PFAS used as active ingredients in plant protection products, as these products and their uses are covered under separate EU regulations (EC. 1107/2009).xiv

However, it doesn’t consider the use of PFAS as co-formulants or so-called ‘inert ingredients’. It is also unclear whether the predominant concern for ECHA‘s PFAS restriction proposal – persistence – is adequately taken into account in these separate regulations. In the UK it remains to be seen whether the UK Government’s ‘upcoming’ PFAS Regulatory Management Options Analysis (RMOA) will take the opportunity to address this potentially critical but largely unknown source of PFAS.xv


What can we do?

Fidra will ensure that PFAS presence in pesticides is included in discussions with policymakers. Suppliers and users of pesticides need to ensure that the products they use do not contain active PFAS ingredients and to question whether PFAS is present as an ‘inert ingredient’. In addition, there is a need to move to greater transparency of formulation ingredients. To enable this policymakers need to develop a register of all ‘inert ingredients’ on the market and to ensure that these ingredients are subject to the same regulatory tests as the ‘active’ ingredient.

If you are a member of the public, please write to your local representative to express your concerns over the contamination of our environment by these persistent and toxic chemicals. If you use pesticides in your garden or allotment, we urge you to stop immediately due to the risk from the unlisted ‘inert ingredients’ that may be in them.


References and Links

[i] Siviter, H. et al. (2021) “Agrochemicals interact synergistically to increase Bee Mortality,” Nature, 596(7872), pp. 389–392. Available at:
[ii] Lasee, S. et al. (2022) “Targeted analysis and total oxidizable precursor assay of several insecticides for pfas,” Journal of Hazardous Materials Letters, 3, p. 100067. Available at:
[v] Martinello, M. et al. (2019) “A survey from 2015 to 2019 to investigate the occurrence of pesticide residues in dead honeybees and other matrices related to honeybee mortality incidents in Italy,” Diversity, 12(1), p. 15. Available at:
[vi] Alexandrino, P. et al. (2021) Atlas of the microbial degradation of fluorinated pesticides, Critical Reviews in Biotechnology, DOI: 10.1080/07388551.2021.1977234
[viii] Note: multiple active substances may be used within one pesticide formulation, therefore e.g the same area treated being counted twice (12,859, 803 hectares)
[ix] Amenity sector = local authorities, highways, railways, contractors, golf courses, lawn care and other sectors (invasive weeds, sports turf, turf growers, water companies and “other responders” to the questionnaire).
[x] Navarro, I. et al. (2017) “Uptake of perfluoroalkyl substances and halogenated flame retardants by crop plants grown in biosolids-amended soils,” Environmental Research, 152, pp. 199–206. Available at:
[xi] Alexandrino, D.A.M. et al. (2022) “Revisiting pesticide pollution: The case of fluorinated pesticides,” Environmental Pollution, 292, p. 118315. Available at:
[xii] “Peer Review of the pesticide risk assessment for the active substance EPOXICONAZOLE in light of confirmatory data submitted” (2015) EFSA Journal, 13(6). Available at:
[xiv] ANNEX XV Restriction Report – Per and polyfluoroalkyl substances (PFAS). Version 1. Date of publication: 07.02.2023. Page 74.



Tags: , , , , , , , , , ,