By Dr. Colin Michie FRCPCH
In 2025, we will accumulate in our bodies many man-made molecules. Some of these we shall keep for most of our lives. One particular group of fluorine compounds, the PFAS family, persists in our environment and can only be eliminated very slowly. PFOS, one of these, may affect our health and that of our children.
Fluoride atoms built into carbon chains were manufactured as super-detergents for the fire-protection of fabrics in 1949. These compounds, the PFAS family, were also used to coat metal, leather, paper and carpets. As foams, they effectively extinguish fires caused by liquids; they are valuable as a fire-resistant hydraulic fluid for aircraft.
Molecular globalisation of PFAS took place rapidly: they have no taste or smell. By the 1970s, they were found in samples from babies and blood donors on every continent. The compounds are particularly concentrated in protein-rich areas of the body – the blood, liver and kidneys. PFAS move in dusts and water; they are in the soils, lakes and seas; they have been identified in children living in the Arctic. PFAS accumulate in food chains, from low levels in plankton, fungi and plants to high levels in apex predators such as dolphins. We probably take in most PFOS from drinking water.
Regulations in the 1990s reduced PFOS production specifically; it was banned in 2009 and later listed by the Stockholm Convention, a landmark global treaty designed to protect human health and the environment from the harms caused by persistent organic pollutants. Methods have been developed to clean PFOS out of drinking water using charcoal and biochar that can bind them. PFOS has been replaced with alternative PFAS molecules for most purposes as recommended in the Stockholm Convention.
Our bodies have robust methods of removing toxins because our metabolisms and diets routinely deliver harmful molecules. Microbes in our bowel work alongside the liver to prevent the absorption of some toxins and the breakdown of others into harmless components. Some toxins are made fat soluble in the liver then passed into the bile and eliminated in the stool. Some are oxidised, made soluble in water then removed in urine, stool or sweat. Smaller toxins may be lost through breathing. Because PFOS sticks to many proteins, elimination is slow. It can take over five years to eliminate half of the PFOS molecules in our body. During this time, more PFOS is likely to be absorbed, so these have been called “forever chemicals”.
What does PFOS do to us? Their exact effects are difficult to calculate. One powerful reason for this is that all humans, plants and animals have been exposed to PFOS for over 50 years. We cannot compare ourselves with anyone who has not met PFOS. No magic treatment has been found for PFOS; no theriac cure will remove or inactivate these molecules which biological processes have problems removing. PFOS has been associated with disruption of the endocrine system, in particular causing low testosterone levels in both sexes and an increased risk of thyroid disease. It is tempting to make rising global infertility in humans and other species the responsibility of PFOS, but this cannot be stated with certainty.
PFOS has been classified as possibly carcinogenic. A related compound, PFOA, banned in 2020, has been defined as carcinogenic. PFOS may in some situations influence immune systems. For instance, children born to parents exposed to PFOS in the Faroe Islands showed reduced vaccine responses to routine tetanus and diphtheria vaccination. A large American study has reported an association between levels of the PFAS family of chemicals and coronary heart disease.
Children are particularly vulnerable to environmental toxins such as PFOS. Developing from a foetus into adulthood, they have times when their hormones or brains are more susceptible. They may be exposed to higher levels of toxins as they take in more water, food and air per kilogram than an adult. Research suggests that wider umbrella approaches should measure their risks from several toxins at the same time – an “exposome” to these hazards. For instance, tiny particles of plastic are also widely prevalent in our environments, along with molecules such as plasticisers, all of which can also be found in the placenta.
Our powers may be limited, but we should consider the safety of our own environments. Digital apps, such as Yuka, help us check the shopping: What is used in the manufacture and packaging of the food, drink, cosmetics and household products we purchase? How safe is our drinking water and air? Industrial pollutants such as PFOS have changed our world. Their health impacts cannot be accurately estimated yet, particularly in the most vulnerable group in our communities, our children.
Dr. Colin Michie specializes in paediatrics, nutrition, and immunology. Michie has worked in the UK, southern Africa and Gaza as a paediatrician and educator and was the associate Academic Dean for the American University of the Caribbean Medical School in Sint Maarten a few years ago.
Useful resources:
Stockholm convention on Persistent Organic Pollutants: https://pops.int
Environmental toxicology and Children: tps://pmc.ncbi.nlm.nih.gov/articles/PMC7121289/
