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 history of PFASs highlights how chemical risk assessment can fail- says expert

Professor Phillippe Grandjean calls for new methods of risk assessment to ensure PFAS replacements are evaluated properly before use.

Evidence that PFAS chemicals PFOA and PFOS are toxic to the immune (reticuloendothelial) system has existed since the 1970s, but this evidence was not made publicly available until 2000, and is still not necessarily taken into account in risk assessment. Findings of some early company-led studies indicating the immunity of workers might be affected by PFOA were never published after apparent disagreements over the wording of the conclusions.

It has taken decades for action to be taken. Both PFOA and PFOS are now restricted by international regulation due to concerns for the environment and human health. PFOS was added to the Stockholm convention of Persistent Organic Pollutants in 2009, while PFOA will be restricted under the European chemicals legislation REACH by 2020. Both chemicals continue to be used in certain specialised applications, and PFOA can still be used to make products outwith the European Union (see Regulations).

Safe unless proven unsafe?

Professor Grandjean has highlighted how chemical risk is often assessed on the assumption that industrial chemicals are “inert, or safe, unless proven otherwise”. It can take decades for scientific evidence to lead to intervention on a policy level.

PFOA and PFOS have been phased out of many textile uses, and the most common PFAS-based stain resistant coatings now use short-chain PFAS as alternatives to PFOA and PFOS (read more about the difference on our Background pages). These compounds have a similar chemistry, but have not been as well studied yet. Just like the chemicals they are replacing, they don’t break down in the environment, and have already been found in the environment. New evidence for their toxicity is emerging.

Professor Grandjean calls for any alternatives, whether PFAS-based or not, to be scrutinised before their widespread use. We see this as a sensible approach!

Read more about this:
Chemical Watch: Prior scrutiny needed for PFAS substitutes, expert says

The original article (open access): Delayed discovery, dissemination, and decisions on intervention in environmental health: a case study on immunotoxicity of perfluorinated alkylate substances