A new study by scientists at the University of Portsmouth and the UK’s Marine Conservation Society (MCS) has found alarming levels of ‘forever chemicals’ discharged through sewage into a highly protected marine area.
The chemicals, known as per- and polyfluoroalkyl substances – or PFAS for short – are a group of more than 4,700 synthetic substances that are resistant to grease, oil, water and heat.
PFAS have been used in a variety of household products since the 1940s, including cleaning products, paints, firefighting foam and stain- and water-resistant coatings for fabrics. Some are also used in non-stick coatings for cookware and food packaging.
There are many different types of PFAS but they all possess an immensely strong carbon-fluorine bond, meaning they do not break down easily and can persist in the environment for decades.
Studies have estimated that some PFAS polymers may have a half-life (the time it takes a chemical to degrade by 50 per cent) of more than 40 years in water – and a staggering 1,000 years in soil, hence their reputation as ‘forever chemicals’.
Furthermore, some PFAS chemicals are known to degrade into other PFAS chemicals, which are just as persistent.
Blood tests have shown that PFAS accumulate in humans and animals. Although research into the cumulative effects is still limited, exposure to some types of PFAS is known to cause serious adverse effects.
They enter the water system through simple day-to-day activities such as the use of cosmetics and cleaning products, and washing the clothes and utensils in which the PFAS are present – most of the water from which finds its way into the UK sewage system.
Untreated sewage contains a cocktail of harmful contaminants in the form of bacteria, viruses, chemicals and microplastics, but water companies are not required to monitor the level of contaminants found in storm overflows, which discharge excess rainwater and sewage into rivers and seas when a sewer system is at risk of flooding.
In 2023, over 3.6 million hours of sewage discharge were recorded from storm overflows in England alone, showing the extent of the problem.
The new research focused on Langstone Harbour in Hampshire, UK, a Site of Special Scientific Interest (SSSI) and a Special Area of Conservation (SAC) which is home to harbour seals and numerous species of birds.
A team from the University of Portsmouth’s Institute of Marine Sciences collected seawater samples before and after sewage discharges from a local wastewater treatment plant – which services over 400,000 people – and found that PFAS concentrations ‘increased significantly’ after sewage discharges.
The findings of the study, published in the online journal Chemosphere, showed eight different PFAS compounds were detected following the discharge, compared to just one detectable compound beforehand.
In addition, two banned substances, perfluorooctane sulfonate (PFOS, formerly used in fabric water and stain repellants) and perfluorooctanoic acid (PFOA, an industrial surfactant), were found at levels exceeding environmental quality standards.
‘Given how much we now know about the extent to which sewage gets discharged into our rivers and seas, it is worrying to see these contaminants elevated in a coastal environment which could take decades to break down,’ said project lead, Professor Alex Ford from the University’s School of the Environment and Life Sciences. ‘Unfortunately, it is unsurprising that these toxic compounds are detectable in our whales and dolphins.’
Alarming levels of PFAS found in seaweed
Samples from the study also found that the amount of one particular PFAS called Perfluorobutanoic acid (PFBA, which was formerly used for manufacturing photographic film) in seaweed was more than 6,000 times higher than the amount found in the surrounding water.
‘These seaweeds could potentially be acting as a reservoir for these forever chemicals around our coasts,’ said Ford. ‘High concentrations of PFAS compounds in macroalgae might be harmful for marine life which graze on seaweeds and as a result provide a trophic link up the food chain.
‘Toxicity studies in the laboratory and human epidemiological studies of those drinking PFAS contaminated water have highlighted these chemical compounds can impact the immune, nervous and reproductive systems as well as being carcinogenic and cause birth defects.
‘It is important that we get these chemicals banned as we are still seeing the impacts of persistent chemical contaminants – like PCBs – impacting wildlife which were banned decades ago which is why it is so important we act faster.’
Professor Ford has previously shown that small shrimp-like crustaceans called amphipods, which graze on seaweeds in Langstone Harbour have low sperm counts. Research has also found that long-term exposure to PFOS in amphipods inhibits reproduction and increases the chance of infection by disease and parasites.
The scientists say that further research is needed to understand the long-term effects of PFAS on marine food chains and to develop effective strategies for reducing their presence in the environment.
‘These findings underscore the need for an urgent ban on PFAS from all uses where there are alternatives,’ said Dr Francesca Ginley, Chemicals Policy and Advocacy Manager at the Marine Conservation Society and one of the study’s co-authors. ‘PFAS are found in water and wildlife around the globe, from plankton to polar bears. These chemicals will impact us and the environment for generations to come.
‘We need the UK Government to properly protect our environment from this preventable pollution.’
MCS is inviting people to join the March for Clean Water, which takes place in London on 3 November, to demand the government acts urgently to ‘end the poisoning’ of the UK’s seas, rivers, and lakes.
The paper, ‘Insights into PFAS contaminants before and after sewage discharges into a marine protected harbour’, is published under a creative commons licence in the online journal Chemosphere, part of ScienceDirect
