You cannot smell, see, or taste these chemicals, but they are everywhere and are highly toxic to humans.

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People perceive risk largely by what we can see, smell and taste. These senses serve us well when there are perceptible dangers to our health and the environment.

We can see and smell raw sewage and therefore it is perceived as a risk to human and environmental health. Scientists’ growing concern about the presence of antibiotic-resistant bacteria in sewers confirmed its true risk. The Environment Agency also reports that pollution from sewage discharge is the leading cause of poor river quality in England.

However, there are serious chemical threats called perfluoroalkyl and polyfluoroalkyl substances (PFAS) that we cannot detect because they are colorless and odorless. High levels of exposure to these toxic chemicals, now found in our drinking water and natural ecosystems, can cause a range of adverse health effects in humans and wildlife. These include increased risk of certain cancers, kidney disease, cholesterol, reproductive and developmental impairment, and decreased vaccine response.

People cannot see, smell, or taste PFAS in our water. Yet they pose a serious global threat. The real risk of PFAS is high, but in my experience as a scientist working on environmental pollution, many people are unaware of it.

What is PFAS?

First developed in the 1940s, PFAS is a large group of more than 4,000 synthetic chemicals. Their properties, commonly known as “forever chemicals” make them water and oil repellent and highly resistant to chemical and thermal degradation.

As such, they are ingredients found in various everyday products and are therefore ubiquitous. Non-stick pans, waterproof raincoats, flame-retardant sofas and carpets, food packaging, makeup and countless more products contain these chemicals.

But PFAS can remain in the environment for hundreds or thousands of years. Studies estimate that, on average, it takes more than 1000 years for the chemical concentration of some PFASs to decrease by 50% in soil.

PFAS exposure

Because of their persistence, PFAS has steadily accumulated in drinking water supplies and oceans worldwide. This can happen because contaminated water seeps into groundwater from landfills. PFAS in household items can also be washed into rivers and oceans through sewage systems.

A garbage truck unloads waste at a landfill.

In 2019, at least one PFAS was detected in 60% of public groundwater wells and 20% of private groundwater wells used as drinking water sources in the eastern United States. And in the UK, the Environment Agency analyzed 470 freshwater sites between 2014 and 2019 and found PFAS contamination in 97% of them.

Freshwater pollutants then accumulate in plants and animals, where they can be transferred to humans by ingestion.

In the city of Charleston, South Carolina, scientists recorded 11 PFAS concentrations in six fish species. Levels of the most abundant chemical recorded in each species – perfluorooctane sulfonate – exceeded wildlife conservation guidelines in 83% of all fish examined. Therefore, consumption of wild fish poses a serious health problem for the local population.

here to stay

It is likely that most people in the world have been exposed to PFAS. For example, in 2012 it was estimated that more than 97% of Americans had detectable levels of PFAS in their blood.

However, unlike most other chemical pollutants, PFAS can continually cycle through hydrological processes and be released into the atmosphere. For example, scientists have recorded PFAS concentrations in rainwater almost all over the world. This means that contamination can be largely irreversible.

PFAS dispersed by the water cycle has been allowed to pollute remote corners of the planet and negatively impact wildlife. In Antarctica, one type of PFAS – perfluorobutanoic acid – increased more than 200 times in snow between 1957 and 2015.

Researchers have also found high concentrations of PFAS in Arctic algae. Algae are an important food source for zooplankton; Up the food chain, they feed on fish and shrimp, then seals, and finally predators such as polar bears. A study of East Greenland polar bears revealed that PFAS contamination can disrupt the polar bear’s hormone system and negatively affect reproduction.

Two polar bear cubs eating fish.

For many people, current PFAS exposure levels are unlikely to be high enough to warrant serious concern. However, exposure is likely to be much higher in some occupations, including firefighting and chemical manufacturing and processing. People who have contaminated drinking water or food sources will also be a risk.

Science and even Hollywood have warned us of the global chemical threat posed by PFAS. Yet most of us do not perceive them as a threat.

This may be because PFAS is an “invisible” threat that is not as obvious as sewage or plastic pollution. But these toxic chemicals have accumulated in many of our water supplies and are now interfering with natural ecosystems. Governments, scientists and the media should improve their communications regarding the risks associated with PFAS.

This article has been republished under a Creative Commons license from The Conversation. Read the original article.



Patrick Byrne receives funding from the Natural Environment Research Council.

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