Toxins that may have long-term health implications for the survivors of the Grenfell Tower fire, and thousands of people who live and work nearby, have been identified in the preliminary findings of a study led by one of the world’s leading toxicology experts, the Guardian can reveal.

Early results of the study by Prof Anna Stec prompted her to privately urge Public Health England (PHE), the Department of Health, the police and Kensington and Chelsea council to organise a range of tests to ensure any potential health risks can be properly assessed.

In briefings to senior health agency staff, Stec said she had found “huge concentrations” of potential carcinogens in the dust and soil around the tower in west London, and in burned debris that had fallen from the tower.

High levels of hydrogen cyanide were also present in the soil she analysed.

She suggested that health authorities should consider taking samples of blood and saliva from survivors, firefighters and local residents to monitor any damage to their DNA.

PHE has decided not to take such action until Stec’s full report is published, likely to be early next year – 18 months after the fire that killed 72 people.

The Guardian understands that PHE’s decision has caused widespread concern among other health agencies that support a mass health surveillance programme, and a PR campaign to raise awareness of the potential risks.

Stec is an expert in fire chemistry and toxicology and runs a team at the University of Central Lancashire. She was recently appointed as an expert witness to the Grenfell Tower fire inquiry.

She began an independent study late last year after hearing the concerns of survivors who have long feared hidden health consequences from the devastating blaze.

While PHE has monitored the air quality around the tower and repeatedly said it has found nothing to cause concern, Stec has focused on soil, dust and residue and has taken samples from eight sites up to a mile away.

Stec said she was trying to identify any potential health risks to survivors and firefighters. “I have taken a high number of samples from a number of locations in the area – some were taken close to Grenfell Tower, others were taken from almost a mile away,” she said.

“As a result of this work, I already have datasets that indicate a number of toxins that have not yet been measured by PHE, who have already looked into air quality.

“I think my research will show there are a number of added toxicants that need to be measured, but it’s important to emphasise that this work has not yet been completed – and we still need to carry out a lot of analysis before we can be completely sure of the implications. The findings will need to be validated before they are published.”

Q&A What are PAHs? Show Hide There are plenty of natural sources of polycyclic aromatic hydrocarbons, or PAHs. The chemicals form in coal and crude oil and are released into the air from exhaust pipes and industries that burn fossil fuels, but also residential and other building fires. Once airborne, the contaminants float around and settle on buildings, vehicles and the ground. In soil, PAHs can persist for years and even decades. The compounds can be harmful if breathed in, ingested, or if they come into contact with the skin. in 2018, Prof Anna Stec and others at the University of Central Lancashire looked at PAH exposure among UK firefighters, a group believed to have higher rates of cancer than the general population. Tests on swabs from the firefighters’ skin, clothing, breathing equipment and vehicles revealed PAH levels high enough to cause a ‘marked elevated risk’ of cancer. The most potent PAHs include benzo(a)pyrene, or BaP, and 3-methylcholanthrene, or 3-MCA. Once inside the body, the compounds spread around and build up in fatty tissues and organs. Long-term exposure has been linked to coughs, chest pain and poor lung function as well as dermatitis and a depressed immune system. Some PAHs, including BaP, can cause cancer by binding to DNA to produce what are called ‘adducts’. The main effect is to disable the normal repair mechanisms that prevent dangerous mutations in cells. Without them, mutations accumulate until they turn into cancers. Harmful BaP-DNA adducts can cross the placenta and potentially affect the health and development of unborn children.



Earlier this year, Stec briefed the health authorities leading the Grenfell recovery effort, explaining that she was analysing soil and residue samples, not just air quality, and that she was looking for particles that were much smaller than those assessed by PHE.

In a briefing note circulated to senior staff on 8 February, Stec said further analysis was needed of soil and dust within the tower andother evacuated buildings before residents returned.

Stec said the so-called “Grenfell cough” reported by survivors after the fire “seems indicative of elevated levels of atmospheric contaminants”, and that she had assessed the levels of polycyclic aromatic hydrocarbons (PAH), a group of chemicals produced following fires that can cause health problems, and are considered potentially carcinogenic.

In the briefing note, Stec said her early results indicated “high levels of PAH in the surrounding soil”. She warned officials that the biggest threat to survivors and residents was likely to come from absorption of toxic material via the skin, not from smoke inhalation. Black soot from the fire, for instance, was highly likely to be contaminated with asbestos, which is known to have been present in the tower.

Sources have told the Guardian that Stec had sounded “very worried” when she set out her early findings, and was frustrated PHE did not appear receptive to her concerns.

“Public Health England has looked at air quality and Prof Stec has been looking at the soil, which are two different things,” one source said. “If Stec’s findings are proved right, we are looking at potentially large-scale contamination of a site up to a mile away from the tower, with potential long-term health implications that are significant.”

The source added: “There is a feeling that PHE has been too complacent about this. It would be better for everyone if PHE did its own tests, rather than waiting for Prof Stec’s final report to be published. If there is a problem, the survivors and residents should be told. And if there isn’t a problem, they need to be told.”

PHE said it was aware that Stec had carried out “some soil research” and that it would “take the results into consideration” after the research had been published. The body said it had commissioned “independent air quality monitoring around the Grenfell Tower site that has shown the risk to people’s physical health from air pollution and chemical hazards to be consistently low”.

A PHE spokesperson added: “Contaminants found in soils can come from a variety of sources and depend in large part on the historical use of the land, for example past industrial use or ash from coal fires, therefore it would be difficult to link it directly with the Grenfell Tower fire.

“When Grenfell Tower burned the plume rose vertically before dispersing at a high level with minimal local deposition. Debris from the fire, such as charred insulating foam which did deposit locally was cleared up by the council in the days following the fire and advice was provided to residents on the clear-up of remaining dust.”

PHE said saliva, blood and urine samples were not “recommended as a means to determine individual exposure from a certain time period or event.”

However, concern over the long-term health impact of the fire has led to two announcements in recent weeks. Last month, the Grenfell coroner, Dr Fiona Wilcox, demanded long term health screening for those exposed to potentially hazardous smoke from the fire. She said it was of real concern that this was not already in place for firefighters and survivors from the tower. And earlier this week, NHS England announced it would be screening survivors for the effects of smoke inhalation.