It has been 26 years since the UK Government finally removed leaded petrol from sale. So why are MPs, peers, academics and activists still calling for routine health screenings to check for exposure?
Publishing an open letter in February, 50 signatories — including university researchers and lawmakers — demanded that Health Secretary Wes Streeting put an end to ‘dangerous complacency’ over lead pollution. According to campaign advocates, millions of Britons may be inadvertently and unknowingly ingesting this highly potent neurotoxin with serious implications.
When an outright ban on leaded petrol was introduced in January 2000 one of the main catalysts was the risk to children. Successive studies have shown early years exposure to this dangerous heavy metal can trigger a lifelong reduction in IQ levels, stunted growth, and hearing loss.
Accumulating in the body over time, there are also grave implications for pregnant women who can pass the material from skeleton to unborn child via the placenta. As lead builds up in a person of any age it begins to impact all internal organs, but its effects on the nervous system are particularly profound. Mimicking vital minerals like potassium and calcium, it wreaks havoc on natural processes, causing cell death, seizures and loss of consciousness.
But despite the dangers, across the world’s most advanced economies the UK is an outlier with no system in place to monitor lead poisoning in the general population. Only when someone is displaying symptoms and has proven risk of exposure will tests for lead poisoning be conducted. It’s a policy that becomes all the more worrying when you consider Imperial College London’s 2021 research into lead particles in the capital’s atmosphere.
Two decades after leaded petrol went off-sale, concentrations of the metal in London’s air had fallen. However, the troposphere was still found to be ‘highly lead-enriched compared with natural background levels’. And up to 40% of these ‘leaded particles’ were attributed to petroleum, suggesting a significant legacy impact long after regulatory changes are rolled out.
‘We’ve been working on environmental lead for some time,’ says Dominik Weiss, Professor of Environmental Geochemistry at Imperial’s Department of Earth Science & Engineering. ‘We use a tool called isotope ratios, kind of like colours, to determine sources. Each type of source has a different colour, so it’s possible to identify where molecules have come from — the process is a speciality of our lab.
‘To be honest, this all began as a side study, but we were really interested in where the lead was coming from. In the end, the only way to explain its colour was that it originated in gasoline,’ he continues. ‘So basically lead is sticking around for a very long time. From an environmental perspective, it’s a bit like [the insecticide] DDT — it was banned in the 1980s and so it’s out of sight and out of mind, but still very much there. And the question of how long the impact will be is one we don’t really have an answer to.’
For Weiss, the situation points to a lack of understanding around the whole of life impacts of hazardous materials, and an abject failure to learn from past mistakes. Lead is one example with a very long history predating modern science. Pfas, or forever chemicals, is another comparable but much more contemporaneous crisis. As are microplastics. All reflect the same doomed approach — use now, then figure out the consequences.
Even with a major public outcry — as happened with leaded gasoline — the response from policymakers is often to target a specific source. But petrol aside, lead production, we are told, is actually on the rise, largely driven by manufacturing use cases. ‘We have less insight into what is happening within the industrial ecosystem: lead is very much there and probably escaping,’ says Weiss.
‘I think lead exposure is still a very big problem. In the past, we associated it with gasoline, but now it’s very much part of the energy industry and batteries. Not necessarily EVs, but most cars have a starter battery which is lead-acid and low speed vehicles — like buggies — run on these too,” explains Dr Mengli Chen, Research Fellow at the Tropical Marine Science Institute, National University of Singapore.
‘The industry is quite big, and during their lifecycle these batteries are recycled over and over. Technically 100% goes through this process, but in reality there are leaks, often due to imperfect supply chains and processes,’ she continues. ‘Because the lead is so bound to the energy sector, environmental contamination is still quite messy, and still with us. This is a big reason why it is being found in air pollution over a quarter of a century later. Once it’s in the environment, lead just multi-fuses and diffuses.’
Other members of the team point to different concerns arising from the research. Although open to some subjectiveness, the analysis of air quality in London identified wood burning as a potential source of lead found in PM10 particulate matter. In turn, it’s possible to hypothesise that this stems from the heavy metal’s use in paint, despite prohibition dating back to the early-1960s. Regulations were then updated again in 1992, at which point the sale of lead-based paint in Britain was effectively banned.
‘In [the] 2020 data, we found that the lead in PM10 is mostly coming from wood burning, we suspect people in London were burning furniture, and lead has historically been used in paint to prevent corrosion. It’s also linked to some of the road dust, but in London it seems like it is coming from that type of wood burning,’ says Ian Chen, Research Associate at the Imperial College School of Public Health.
‘In terms of life cycle assessment, and air quality monitoring, lead is something we continue monitoring and use to remind ourselves of what is in the air, how much is there, then implement a similar approach to soil and water, and understand the environmental fate of this pollutant. So probably more investment is needed in this area,’ he adds.
A more recent follow up analysis went beyond PM10, which accounts for anything smaller than 10 micrometres and is usually traced to dust, construction activity, wildfires and exhaust fumes. Anja Tremper, Research Fellow in the School of Public Health at Imperial College, tells us about an investigation into smaller fine particulates — anything under than 2.5 micrometres — which also supports the theory. At this size, materials find it easier to penetrate deep into the lungs, pass through the blood-air barrier and eventually reach major organs.
‘There was also a follow up study we did… not just in PM10 but in smaller sized fractions — PM2.5 — and there you could see the lead was definitely associated with wood burning. In coarser particles that’s where there are links to tyre and road wear dust, and general dust. So there seems to be different sources,’ says Tremper. “I’ve also read that small airplanes are still allowed to fly with leaded fuel. I know that in America there are communities that are very concerned, near smaller airfields, where a lot of these smaller planes are used. But I’m not sure if that’s an issue in London.’
Air travel is a key talking point when we reach Dr Ashley Mills, a Research Fellow at NIHR Applied Research Collaboration Kent, Surrey, and Sussex (ARC KSS). Speaking on video call, he begins by explaining how lead is ingested into the bloodstream and why this particular form of air pollution is subject to significant seasonal differences.
‘Lead gets into the body in a number of ways, one is through the lungs. So in summer months, when the soil dries out, then you get dust in the air, and lead suspended in the air,’ he tells us. ‘That can then be tracked into houses and becomes trapped in the home. Children playing in the dirt can also disturb those particles and then ingest lead. So the boundary between air and other forms of ingestion changes with the time of year.
‘The Imperial study is most likely talking about resuspension of lead from petrol. There will also still be some from unleaded fuel as there is a small amount [of lead] allowed, tiny quantities, but most of these findings will be legacy depositions that have stayed at surface level — in a similar way to how you find deposits from old lead mines,’ Mills continues, before reiterating Tremper’s point. ‘In terms of aviation, deposition is a particular issue around aerodromes.’
According to Mills, small piston and propeller powered planes continue to run on avgas. Although considered low lead, this fuel still contains up to 0.6 grams of the metal per litre, meaning around 10 tonnes of lead are emitted into the UK atmosphere each year. This then falls back to Earth, leading to lead deposits. As aircraft engines work hardest during takeoff and landing, emissions are highest close to aerodromes, meaning traces of lead are also most concentrated in these locations.
‘The evidence for this is extremely robust. In the US they routinely test the public for lead. In Michigan they looked at the blood of 1 million children, so an enormous piece of research, and identified a direct dose response linked to aerodromes. The closer you were to the aerodrome, the more lead was in the blood,’ says Mills. ‘And this was true at some distance — up to four kilometres from the runway centroid still presented impact from lead exposure. So it was a really significant finding.’
‘The EU put a sunset date of May 2025 on leaded aviation gasoline, then they gave a company — well, multiple companies, including Shell — a sort of grace period of seven years to phase it out completely,’ says Tim Pye of the LEAPP [Lead Exposure and Poisoning Prevention] Alliance. ‘In America the FAA has a target of 2030 to remove lead from aviation fuel. But the UK has no plans in place at the moment.
‘I mean, the most common form of lead exposure is still from old paint, maybe lead pipes. But this can be an indoor air quality issue when dust is also involved. Like a child playing on the floor or coming inside after playing in the soil, although that’s more about ingestion than inhalation,’he continues. ‘But when you look at all these cases you could almost say everyone is being exposed to some lead all of the time.’
It’s a big statement, and one that isn’t made any less troubling when you consider where this story began: the campaign lobbying Downing Street to catch up with other governments by introducing routine tests for lead in people’s blood. But, perhaps more importantly, the key takeaway is surely that we urgently need to adopt a more conservative approach towards what we are willing to put into the atmosphere and environment, or risk inflicting more avoidable lasting damage.
Image: Martti Salmi
More on lead pollution:
Societal lead poisoning, rural grouse hunting and the fall of Rome