The link between working with asbestos and mesothelioma – case closed?
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Category: Science blog January 20, 2014 6 comments
Highly magnified scanning electron micrograph (SEM) of asbestos – image from Wikimedia Commons
We’ve come a long way since asbestos was heavily used in the building industry and shipyards. Thanks in part to research published by Professor Julian Peto, regulations were put in place to free workers from exposure to this deadly substance.
But the epidemic of mesothelioma, a type of cancer predominantly caused by asbestos, is still very much a reality today, as Kelly Wickens knows only too well.
Kelly lost her grandfather, Terry, to mesothelioma because of the many years he spent working with asbestos in the local shipyard.
But that wasn’t the end of the impact this substance would have on Kelly’s life. In 2013 she also lost her mum to the disease, who was exposed to the asbestos Terry brought home from work clinging to his overalls.
Kelly’s grandfather started working in the shipyard in 1956, just six years before her mother was born and four years before the link between mesothelioma and asbestos was first reported.
Asbestos is a naturally occurring mineral that’s mined and processed into a useable powdery product.
Asbestos (brown) in the lung – image from Flickr
It’s made of very fine fibres, which makes it good for insulation. But breathing these fibres into the lungs allows access to the neighbouring tissue that covers the lungs (called the pleura), where the fibres damage cells.
This sparks the development of the cancer mesothelioma.
Some restrictions on asbestos exposure were put in place in the 1960s to protect workers in asbestos factories, where the mineral was processed. The so-called ‘safe’ levels were based on a study in 1966 by the British Occupational Hygiene Society (BOHS).
But the ‘safe’ level didn’t adequately protect workers from the potentially deadly substance. And it didn’t protect those, like Terry, who worked with asbestos outside the factories.
Asbestos continued to be used heavily in industry until well into the 1970s, with little recognition of its dangers. The turning point came when Professor Peto started to look more closely at the risks.
Professor Peto studied the patterns of lung cancer and mesothelioma in asbestos workers in the 1970s, looking at how it causes cancer, in whom and when.
In 1978, his research, published in The Lancet and funded by the forefather of Cancer Research UK, would prove to be a game changer in asbestos legislation.
Asbestos – there is no safe level – image from Wikimedia Commons
Spurred on by concerns about the continued occupational use, he began investigating whether there truly was a safe level of asbestos exposure.
Over a decade after the ‘safe’ level was set, Professor Peto began analysing information from the same group of asbestos exposed workers used in the BOHS report.
Professor Peto could also now study the effects of an extra 10 years of exposure to asbestos in that same group of workers. And, importantly, he also included information about men from the same factory who had retired or died – information that was missing from the initial BOHS study.
By including data about those who had died, and their causes of death, he was able to build a more realistic picture of the impact of asbestos on health.
Professor Peto pointed to some other flaws in the original study. One key problem was the way the researchers had predicted the effect of asbestos exposure, by looking at how many workers, who had been exposed to asbestos for 10 years or more, had crackly-sounding lungs.
Professor Peto argued that crackly-sounding lungs, also known as crepitations, may never end up being a sign of mesothelioma or any form of health issue, so they’re not useful for predicting the effects of asbestos.
Professor Peto also pointed out that there was no evidence for a safe level. If the fibres were there at all, they could still be breathed in and potentially cause health problems. His analysis showed that 5-10 per cent of men exposed to asbestos within the ‘safe’ levels for 50 years (a typical working life span) would die of an asbestos-induced disease – a terrifying prospect.
In his paper, Professor Peto suggested three possibilities for what could be done next. Two of them were variations of ‘wait and see what happens over the next 15 years to asbestos workers’. But the third was to use the results of his study to make decisions to improve working conditions, by accepting that there was no safe level of asbestos exposure.
This study, along with other research, led to stricter industrial regulations, and in 1985 the importation and use of blue and brown asbestos (the types of asbestos strongly linked to mesothelioma) were banned. But this came too late to save Kelly’s grandfather.
Kelly with her mum and nan
Terry worked at the shipyard until 1989. Kelly told us about his time there: “The asbestos came in paper bags that would split, covering him in the powder that he’d then bring home on his overalls.
And when he worked down in the hold of the ships, he and his friends would sit on the bales of asbestos to have their breaks.”
Unfortunately, there are many other families with similar stories. And because mesothelioma is a disease that can take over 40 years to develop, the long and painful legacy of asbestos use is still being felt today.
In the 1990s, Professor Peto was one of the first people to predict that we were heading for an epidemic of mesothelioma.
He warned that people at risk, largely construction and building maintenance workers, should be made aware and take precautions to monitor their health.
We’re still witnessing the full impact of asbestos exposure. Around 2,500 people are diagnosed with mesothelioma every year – around seven every day. That figure is set to rise to a peak by 2020 in the UK .
This means many more families will battle with this disease, as Kelly’s did.
When Kelly’s grandfather was diagnosed with mesothelioma, it was too late for him to have any treatment and he died two years later at the age of 75.
Kelly told us about what this meant to her mum. “She was very much a daddy’s girl, and was devastated when granddad died. It was such a strange feeling to know that granddad’s little girl was going to have the same fate as him.”
Kelly’s mum with her grandkids
“Mum was diagnosed with mesothelioma in April 2012. She had a very painful operation and chemotherapy. She felt really rotten for a week after each of the chemotherapy treatments, but was fortunate enough to not lose her hair. She was so proud cancer didn’t take her hair.”
Chemotherapy held the cancer at bay for a while, but more tumours grew, and radiotherapy and other types of treatments couldn’t hold it back indefinitely.
Kelly’s mother had a CT scan, which showed the cancer had spread to her brain. Kelly said: “That’s the one place I prayed it wouldn’t go. We were told that chemotherapy was no longer an option. So mum had radiotherapy on her brain.
“But then she got really poorly. The doctor came to see us and said that mum wouldn’t be coming home. Our lives just stopped still. We stayed by mum’s side as she hung on to her life for three more days.
“We told her that she didn’t need to fight anymore – that she had been amazing. My brother and I said everything we wanted to say to her and finally, when it was just her and my nan, she passed away.”
“I feel like I have a massive hole inside me. Mum and I were best friends. She was supposed to be there always, to see her grandkids grow up. To see my brother get married and have kids. But I feel blessed in a strange way that I had some time to enjoy life with her after her diagnosis.
“She could have been taken without warning and we may not have had the opportunity to say and do the things we had always wanted to.”
Many more families will be afflicted by this disease over the coming years.
Stories like Kelly’s highlight the immense importance of research into the causes of cancer. The legacy of Professor Peto’s research means that in the future fewer people will experience what her family has had to go through.
But the distress and disease caused by asbestos isn’t yet over.
Researchers are still working out the risks posed by asbestos today. Numerous buildings, built before regulations became tighter, still contain asbestos.
And other events such as the 9-11 terrorist attack in New York City created extra exposure on the eastern US seaboard, the impact of which won’t be known for quite some time.
So the case against asbestos isn’t yet closed. There’s much more we can and should do to help patients with mesothelioma now, and those who develop the disease as we ride out the epidemic.
With continued research we hope to make a difference to families like Kelly’s.
Sarah Hazell (senior science communications officer) and Indi Ghangrekar (health information officer)
With special thanks to Kelly and her nan for telling us about their family’s cancer journey.
Reference
Peto J. (1978). The Hygiene Standard for Chrysotile Asbestos, The Lancet, 311 (8062) 484-489. DOI: 10.1016/S0140-6736(78)90145-9
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