Discovering that a persistent cough or constantly feeling out of breath are symptoms of mesothelioma cancer is of course, not only devastating news to the victim, their family and friends, it is almost always a total shock and “the last thing anyone would have expected.”

Not least when a victim realizes that innocently “playing with asbestos dust” as a child living in a street near an asbestos-using factory or starting a working life as a young man in the same factory was almost certain to be the cause of their mesothelioma many decades later.

Significant advances in asbestos awareness and to understanding the development of asbestos-related disease have been made, not least in the body’s response to the behaviour of fibre dust particles, yet it is still an area of ongoing research to determine levels of risk to different individuals.

The passage of time that elapses from an initial and sustained period of exposure to asbestos and the emergence of mesothelioma or asbestosis symptoms is known to be between 15 to 50 years or more. Previous studies have investigated the relative risk of different types of asbestos fibres and their subsequent effects over time. Whereas, toxic risk level was once measured against different asbestos fibre types, new studies offer a more negative conclusion.

Risk is still at the same high level or even increases

New medical research, which included 862 mesothelioma cases from more than 22,000 individual exposures across patient groups in Europe and as far afield as Australia, suggest that the risk of developing mesothelioma cancer following an initial exposure never reduces, regardless of life expectancy. While it has always been known that the risk of mesothelioma increases as time continues since a first exposure, even after nearly half a century, the risk of developing the disease is still at the same high level or even increases.

According to the new study, nearly 45 per cent of pleural mesothelioma cases and more than 50 per cent of peritoneal mesothelioma cases were diagnosed at least 40 years after a first exposure, with the risk continuing to increase. Even after 50 years, there were still over 13 per cent and 23 per cent of pleural and peritoneal cases recorded. It was also found that the rate and risk of pleural mesothelioma actually intensified until 45 years following first exposure and then appeared to advance but at a slower pace.

Assumptions made over exposure risk level were originally based upon observations of the most dangerous asbestos types – blue “crocidolite” and brown “amosite” – which were used to manufacture insulation or fireproofing materials. Consequently, they were banned in the mid 1980s, with the exception of white “chrysotile”. The reason was largely due to the difference in the fibres.

Longer and thinner fibres more likely to cause tumours

The structure of white chrysotile fibres are curly, or “serpentine”. They are longer, thinner and found to be more flexible than the insoluble rigid, needle fibres of ‘amphibole’ brown and blue asbestos. Longer and thinner fibres are much more likely to cause tumours than short fibres, and to be the cause of cancer and fibrosis.

Inhaled chrysotile fibre particles were also less likely to be permanently embedded in the lung linings and more able to be “broken down”, resulting in a higher number to be expelled over a shorter period of time. Consequently, white chrysotile asbestos was designated “low risk.” White asbestos continued to be used for at least another ten years, mostly in the materials manufactured for the building industry, such as interior wallboard, textured surface coatings, roof sheeting and boiler / pipe linings.

Today, chrysotile has been confirmed as a Class 1 carcinogenic substance without a confirmed threshold level below which exposure to ‘pure’ chrysotile could be deemed ‘safe’ for human health.

The latest research conclusions may also reinforce current understanding as to why the number of mesothelioma patients continues to remained steady despite each passing year, even though asbestos use reduced significantly from the late 1970s / early 1980s onwards.

The incidence rate of mesothelioma in the UK has steadily risen to being one of the world’s highest, with a four-fold increase just in the last thirty years, according to The Office of National Statistics and at least 2,000 cases continue to be diagnosed every year (Health and Safety Executive).