You need to be exposed to asbestos just once to find yourself at risk for developing mesothelioma.
And new research suggests the mesothelioma risk created by that single exposure actually grows over time.
Appearing in the May 19 edition of the journal Thorax, the findings indicate that the risk for pleural mesothelioma keeps rising for 45 years after exposure, at which point it finally stops increasing.
Unfortunately, the risk for the other form of mesothelioma — peritoneal mesothelioma — does not appear to stop climbing at all. It just keeps elevating, the researchers indicated.
What happens after the risk for pleural mesothelioma finally plateaus is not clear. The researchers said they do not know if the risk remains flat or begins to decline a number of years further down the road.
The reason for the head-scratching is that the researchers lacked good information about the fates of asbestos-exposed individuals still alive 50 years after their initial encounter with the toxic mineral.
Mesothelioma Onsets Sooner in Men
They did note, though, that it takes longer for mesothelioma to onset in women than it does in men.
But, man or woman, the researchers said the more exposed you are to asbestos, the shorter the time it takes for mesothelioma to show up inside you.
The researchers, who all hail from several universities in Australia, wrote that they think they know why this is so.
Apparently, your body is able to purge at least some of the asbestos fibers you inhale or swallow. So, the less asbestos trapped in your lungs or intestines, the longer it takes for mesothelioma to onset.
And if you had only one or a few exposures to asbestos, the quantity of asbestos that gets purged won’t be replenished the way it would be if you were exposed to asbestos many times over many years.
Mesothelioma Risk in 22,000 Workers
To reach their conclusions about asbestos exposure, the researchers reviewed eight studies done earlier by others who examined the effects of asbestos on various types of workers.
The workers included World War II gas-mask fabricators, mill hands from a textile plant, and people who either were employed by or lived near an asbestos company.
All together the studies covered more than 22,000 adults. Of that number, nearly 5,800 were women.
Among the total population of asbestos-exposed subjects, pleural mesothelioma struck 542 men and 165 women. Peritoneal mesothelioma devastated 133 men and 32 women.
Half of the men and women who developed pleural mesothelioma were exposed to asbestos for more than 3.75 years, and half were exposed to asbestos for fewer than 3.75 years.
Just over 38 years was the median length of time that lapsed from first exposure to the onset of pleural mesothelioma.
The researchers found that mesothelioma risk was greater for individuals who had been exposed to the crocidolite type of asbestos.
The insights gleaned by the researchers as they poured over the past studies were eye-opening, they indicated.
But further investigation is needed to unearth answers to more questions about asbestos exposure.