Firefighters face a greater risk of developing cancer because of an "alarmingly high" level of dangerous chemicals carried on their clothing, researchers have found.
In the first study of its kind, experts at the University of Central Lancashire (UCLan) discovered firefighters were more likely to absorb cancerous gases through their skin rather than inhaling them.
"Dangerously high levels of harmful chemicals" remain on their protective gear following exposure to smoke, according to the research, published in the Scientific Reports journal.
The Government has been urged to take action after it was reported the cancer death rate among firefighters aged 75 or under was up to three times higher than in the general population.
The Fire Brigades Union (FBU) described the findings as "shocking" and said it believed firefighters' kits were not being cleaned properly.
Anna Stec, professor of fire chemistry and toxicity at UCLan, said: "We have found that contaminated clothing and equipment is causing firefighters to be exposed to alarmingly high amounts of dangerous chemicals, which puts them at a greater risk of cancer.
"If this level of toxic exposure was found in the US or Canada, Government would immediately put measures in place to monitor the health of firefighters and address this.
"The UK must do more to tackle the growing issue of cancer in firefighters."
The risk of developing cancer among UK firefighters because of skin absorption of toxic chemicals is as high as 350 times above the level that would prompt government intervention in the US, according to UCLan.
The university said firefighting remained an "unregulated occupation in the UK in terms of long-term health protection", unlike other jobs such as hairdressing.
Exposure to toxic gases and the effect on the long-term health of firefighters are not officially monitored in the UK, despite cancer deaths in firefighters growing steadily since the 1970s, it added.
In contrast, certain cancers are recognised as "occupational diseases" among firefighters in Canada and the US and the number of fire toxins they are exposed to is measured.
For the study, researchers collected samples from firefighters' skin and protective equipment at two UK fire stations and examined them for cancerous gases created during a blaze, known as polycyclic aromatic hydrocarbons (PAHs).
Researchers found that the methods used to clean firefighters' protective clothing and equipment were not effectively carried out, meaning the length of time that skin was exposed to fire toxins increased.
Former firefighter Sean Starbuck, national officer with the FBU, said: "We believe this is happening because firefighters kits aren't being cleaned properly or regularly enough.
"There is such a low awareness of what contaminants are and of the dangers they pose to human health.
"It appears that some employers have been paying lip service to this critical issue instead of listening and putting measures in place to ensure kit is cleaned properly."
More from UK
The Home Office said individual fire services were responsible for ensuring firefighters were appropriately equipped and trained to undertake their role safely.
The National Fire Chiefs Council is leading a review of the "complex and emerging issue", it added.