Short and ultra-short chain PFAS compounds: a growing concern for health and the environment.
- PFAS make up a group of more than 4,700 man-made chemicals, the two best known of which are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). They are part of endocrine disruptors of chemical origin.
- Faced with the health and environmental risks that PFAS cause, those with a long chain, that is to say with more than 8 carbon atoms, have been gradually replaced by PFAS with a short or ultra-short chain.
- But a new study shows that these short or ultra-short chain PFAS are even more present in our environments and organisms than their long-chain counterparts, raising fears of harmful effects for health and the environment.
Non-stick pan coatings, food packaging, waterproof textiles… Per- and polyfluoroalkyl substances (PFAS) are present in many everyday objects. Their main characteristic is their resistance to degradation, which has earned them the nickname “forever chemicals”.
Smaller versions but just as disturbing
Faced with the accumulation of PFAS in soils, sediments and living organisms, and the discovery of their endocrine disrupting effects, the manufacture and use of these substances have been regulated over the past two decades. As a result, researchers created smaller versions of these compounds, with fewer than 8 carbon atoms in their structure. These new substances, known as short-chain or ultra-short-chain PFAS, were supposed to be less hazardous to health while preserving some of the useful properties of longer PFAS. However, a recent study published in ACS Environmental Science & Technology reveals disturbing data.
In more than 300 dust, drinking water, serum, and urine samples collected from 81 people and their homes in the United States between August and December 2020, 39 PFAS were detected (on 47 targeted), including ultra-short and short chain compounds.
Ultra-short PFAS: possible contamination by tap water
“Overall, PFAAs [acides perfluoroalkyles, ndlr] ultra-short-chain and short-chain totals contributed a greater share to the total serum PFAA concentration (69%), demonstrating that the levels of shorter-chain alternatives accumulated in the blood exceed those of the shorter-chain PFAAs long existing”, detail the researchers in the report. “Although short-chain PFAAs have shorter half-lives in humans than long-chain PFAAs, these compounds are not effectively removed in water treatment processes, which can result in continued exposure by tap water consumption”, they add.
The scientists say this is the first report of significant correlations between concentrations of ultra-short- and short-chain PFAAs found in drinking water and blood samples collected from a general population. According to them, the high abundance of ultra-short-chain and short-chain PFAAs in drinking water from municipal sources constitutes “a potential environmental health concern that should be considered when assessing the risk of PFAS exposure in the general population”. They add that they also found a “significant positive relationship between TFA concentrations [acide trifluoroacétique, ndlr] in the dust and those in the serum“, what “indicates that dust absorption could also be an important exposure route for this compound”.
Further research is now necessary to better assess the effects of these substances on health and the environment. Especially since according to one Public Health France study published in 2019, 100% of the French population is affected by PFAS.
What is an endocrine disruptor?
Endocrine disruptors began to attract the attention of researchers as early as the 1950s, “but it’s the matter of distillbene [un médicament hormonal qui a entraîné une forme rare de cancer gynécologique chez des adolescentes et de jeunes adultes, ndlr] which, in the 1970s, made the subject explode on the scientific and media scene, even though the term endocrine disruptor was not yet used”, reminds Inserm.
Today, scientists know that endocrine disruptors can:
– modify the natural production of natural hormones (estrogens, testosterone) by interfering with their synthesis, transport, or excretion mechanisms;
– mimic the action of these hormones by replacing them in the biological mechanisms they control;
– prevent the action of these hormones by attaching to the receptors with which they usually interact.
“This results in a certain number of potential consequences for the body, specific to each endocrine disruptor: alteration of reproductive functions, malformation of the reproductive organs, development of tumors, disruption of the functioning of the thyroid, the development of the nervous system and cognitive development.”, specify the Inserm experts.
Concerning PFAS, the latest knowledge on the subject indicates that they have an effect on the immune system in children (less good response to vaccines) but without it being possible to say whether exposure increases the frequency of diseases, that they cause a small reduction in birth weight, higher cholesterol levels and can disrupt liver function. In addition, PFOA is classified by the IARC (International Agency for Research on Cancer) in group 2B of “substances possibly carcinogenic to humans”.
