We know summer is on its way when seasonally fresh strawberries appear in the supermarket. Who can resist the cream of the fruit crop adding its burst of juicy sweetness to smoothies, desserts and cocktails? But this week came a warning from scientists that whichever way you prefer to eat your strawberries — plain, with cream or otherwise — there is a strong chance they will also come with an unwanted trace of PFAS (per- and polyfluoroalkyl substances), those ominous-sounding “forever chemicals” that can remain in our bodies for years, and in the environment for centuries.
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In 2022 more than 3,300 food samples were tested for pesticides by the government’s expert committee on pesticide residues in food. Of the 120 strawberry samples tested, 95 per cent were found to have at least one PFAS present. And according to new analysis of the committee’s report by the campaign group Pesticide Action Network (PAN), grapes (61 per cent of samples), cherries (56 per cent), spinach (42 per cent), tomatoes (38 per cent) and peaches (38 per cent) also contained worrying levels of the toxins. Could it be that in aiming for our five a day we are unwittingly consuming toxins that may harm our health?
PFAS were discovered in 1938 by a chemist working for DuPont. They are invisible to the naked eye, virtually indestructible and almost impossible to avoid. They seep insidiously into our homes, our drinking water, soil and consequently the food we eat — and therefore into our bodies too. You will find them everywhere, from food packaging and shampoo bottles to non-stick cooking pans and stain-resistant sofas and rugs, and in clothing, shoes and accessories.
“PFAS are man-made, non-biodegradable chemicals created by fusing carbon and fluorine atoms that have been leeched from industrial production in factories since about the 1970s,” says Alex Ruani, researcher in nutrition science at University College London and chief science educator at the Health Sciences Academy. “They are persistent because the body cannot chemically destroy them or neutralise them.”
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In terms of fruit and vegetables it is the juiciest and tastiest varieties that are primed to be PFAS carriers. “Freshly grown foods that absorb the most water, like strawberries and grapes, are the most likely to have the greatest PFAS content,” Ruani says. According to PAN, there are 25 pesticides containing PFAS, but washing them off won’t necessarily help much, partly because our tap water also contains these chemicals. “In the UK the government advice is always to wash or peel fruit and vegetables to remove pesticide residues,” says Dr David Megson, reader in chemistry and environmental forensics at Manchester Metropolitan University. “But these PFAS chemicals make a very good job of sticking to stuff.”
Buying organic is one option for reducing exposure to many agricultural chemicals, but this doesn’t necessarily reduce the intake of PFAS, which are mostly absorbed from land and water, whether organically farmed or not. A study published last year in the journal Environmental Research indicated that organic vegetables may have lower amounts of PFAS, but they are not completely free from the chemicals. Even growing your own or sticking to seasonal eating doesn’t remove the risk. “When a garden or greenhouse is in or near an industrial area, PFAS concentration in produce is higher,” Ruani says. “Sad to say there’s probably no garden or patch of land entirely free from PFAS and, seasonal or not, these persistent chemicals will make their way into our food.”
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Concerns about the toxins centre on research showing a correlation between long-term exposure to PFAS and an increased risk of health issues and certain diseases including cancer, high cholesterol, kidney and thyroid problems, reduced fertility and repressed immunity. “These potentially carcinogenic molecules accumulate in blood, cells and tissue,” Ruani says. “There’s evidence they are even passed on to our children during pregnancy and can affect learning and behaviour in young people.” Research published as long ago as 2007 in the journal Environmental Health Perspectives estimated that 99 per cent of people have PFOA (perfluorooctanoic acid) — considered one of the most harmful of the PFAS — in their bodies. “They have been traced in glacial water and rainforests, basically everywhere in our environment,” Ruani says. “And the worrying thing is, we don’t yet know the full consequences on our health and longevity.”
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Not that the advice is to avoid fruit and vegetables shown to contain PFAS. “These chemicals are certainly not desirable in the food system, but we have a well-regulated food supply and the amounts in food are considered a safe and not dangerous level of exposure,” says Dr Duane Mellor, a registered dietician and senior teaching fellow at Aston University. “No single food is likely to expose you to toxic levels of PFAS and, as far as we know, the benefits of consuming more fruit, veg and wholegrains in terms of cancer and disease prevention will offset some of the risks associated with consuming them via the food chain.”
Ruani says there are benefits to eating strawberries and other summer fruits — and we shouldn’t stop doing so. “They are packed with precious polyphenols, vitamins and fibre, so the benefits of eating them far outweigh any kind of PFAS risks.” But there are steps we can take to reduce chemical exposure when eating fruit and veg:
Salad, spinach and rocket
It’s convenient but ready-to-eat bagged salad may contain more than a colourful array of leaves. In the government’s tests, 7 per cent of 97 lettuce samples contained traces of PFAS. Spinach containing multiple pesticide residues has increased from 57 per cent in 2019 to 73 per cent in 2022, according to PAN.
With any leaves, health chiefs recommend removing any loose soil before storing vegetables, and washing all herbs and salads that will be eaten raw thoroughly unless they have been pre-prepared and are specifically labelled “ready to eat”.
Even so, ready-washed salads come with other risks. Researchers at the University of Leicester found that the moist environment in a bag of washed salad with damp, partially bruised leaves, combined with nutrients leeching out, provides the perfect breeding ground for bacteria including salmonella — which increased 2,400-fold in their five-day trial. They have also been linked with outbreaks of E. coli. “It is always better to prepare and wash your own salad leaves rather than to purchase ready-bagged,” Mellor says.
Potatoes
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Although they featured relatively low down in the government survey, with only 2 per cent of 145 potato samples containing PFAS, according to PAN, a hectare of non-organic potatoes in the UK is treated with agricultural pesticides an average of 22 times. Although not sprayed directly, potatoes can absorb the pesticides and germs in the soil. “It is advisable to wash and scrub potatoes before consuming them,” Megson says.
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Grapes
Research carried out by PAN in 2022 showed that grapes from 13 countries, including South Africa, Brazil and India, contained multiple chemical residues on their surface, with 84 per cent of samples containing at least one of 47 different “active substances” including 31 fungicides used to prevent rotting during storage.
Fungicides can partially be removed by washing the fruit thoroughly. However, grapes were also found to have absorbed other systemic pesticides, making them more difficult to remove. European grape growers, including those in Spain, France and Italy, are moving away from pesticides, PAN says.
Apples
Although only 2 per cent of 96 samples tested contained traces of PFAS, according to PAN, the number of apples containing multiple pesticide residues increased from 44 per cent in 2018 to 72 per cent in 2022. “Apple skins do contain useful sources of fibre, but always wash them before eating,” Ruani says. Washing fruit and vegetables will remove some pesticides but has little effect on PFAS levels.
Citrus fruit
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Grapefruit, mandarins and satsumas were at the top of PAN’s latest “Dirty Dozen” list of UK produce that contains the highest levels of pesticide residues. Although most of these are in the peel, PAN says that some citrus fruit pesticides are “systemic”, meaning they are contained within the flesh and pith. Handling citrus fruit can lead to dermal absorption, ie through the skin. “Avoid using non-organic peel and zest where possible,” Ruani says.
Drinking water
Last year a report from the Royal Society of Chemistry revealed that more than a third of water supplies tested in England and Wales contained PFAS. “I would like to be confident that the water I am drinking poses a low risk and the RSC have proposed sensible steps to allow this to happen,” says Megson, who was part of the RSC report team. “An interactive map allows consumers to see what PFA levels are like near them.” To access the map visit rsc.org.
Non-stick pans
Throw away any of these that have been hanging around in your cupboards for years — they likely contain higher levels of materials that may contain PFAS. “Teflon and other non-stick coating used to be made using PFOA,” Ruani says. “This use has been phased out and replaced with shorter-chain PFAS. The best type to opt for are stainless steel, ceramic and cast-iron pots and pans.”
Food packaging
We are not just talking ready meals and ultra-processed foods but disposable snack and sandwich bags and one-use cutlery items. “PFAS were historically used in the coating of food packaging and wrapping in order to make it resistant to grease or water,” Ruani says. “While the more damaging longer-carbon-chain PFOA has been phased out in the UK and Europe, it has been replaced with shorter-chain PFAS products which are an improvement but not PFAS-free.” Opt for PFAS-free compostable greaseproof paper for baking.
Anything described as stain-resistant
This includes sofas, rugs, jackets, hiking boots and moisture-resistant sports performance fabric, all of which usually contain PFAS. You can’t avoid everything and will want to stay dry on a long walk or run — but be strategic about buying too many of these products.
