Exposure to asbestos in certain occupations places patients at risk for mesothelioma. At most risk are workers in the field of insulation, fireproofing, plumbing, pipe fitting, plastering, cement production, shipyard construction, boiler making and the automotive brake and clutch industry. Environmental hazards such as joint compound, transite siding, gunnite, roof, floor and ceiling tiles, wall plasters and insulation all pose a threat to patients.
Other rare causes are irradiation of the chest wall, intrapleural thorium dioxide and inhalation of fibrous silicate.
There may be a viral connection to mesothelioma. The Simian Virus 40 (SV40) may be a cofactor in the development of mesothelioma.
Additionally, others living with asbestos workers are at risk of developing this disease. It is thought that exposed workers bring home fibers of asbestos in their clothing and hair which in turn expose their families. Mandatory showering before leaving the workplace is felt to decrease this risk.
People who were involved in the cleanup of the rubble after the World Trade Center buildings were attacked on 9/11 are also thought to be at high risk for the disease, as are those who lived, worked or attended school nearby, and possibly those who were in the vicinity only on the day of the attack. Anyone who falls into any of these categories should regularly consult with medical professionals due to their high risk of developing mesiothelioma or other severe respiratory problems.
Exposure to asbestos is the greatest risk factor for the development of mesothelioma, causing 80% of all cases, but it can also occur in the absence of exposure. Heavy concentrations and longer duration of exposure results in a greater risk for the disease, but shorter exposure times have also caused the disease. Men and women seem to be affected equally, but since more men work with asbestos, they have a higher incidence. Smoking AND asbestos exposure greatly multiplies the risk of developing lung cancer, but does not seem to increase the risk of developing mesothelioma compared to the disease rate among non-smokers exposed to asbestos.
The U.S. Occupational Safety and Health Administration (OSHA) is responsible for setting the limits of asbestos exposure. Those who work with asbestos must wear equipment that reduces the risk of exposure. Workers should shower and change clothes at work to avoid bringing asbestos home with them, since family members have been known to contract the disease in this way.
Thankfully, mesothelioma is extremely rare, with about 2000-3000 cases diagnosed in the United States each year. While occupational asbestos exposure is the primary risk factor, genetic predisposition also influences development of this cancer. Seventy to eighty percent of mesothelioma patients have a history of working with asbestos. The disease does not generally develop until thirty to fifty years after exposure. In addition, people living with those who are exposed industrially are also at risk.
The typical patient with mesothelioma will be a male in his 50s to 70s with a history of working in a profession where there is a high risk of exposure to asbestos. Women also do develop mesothelioma, but it is more common in men at a ratio of 3:1. Women who develop mesothelioma also have a history of working in high risk professions for asbestos exposure or may have been exposed to secondary asbestos by inhaling fibers off of the clothing of a person who has been exposed to asbestos. The period between exposure to asbestos and developing symptoms of malignant mesothelioma can range from 20-40 years. Survival rate after the onset of symptoms can be as little as five months in extensive disease and sixteen months in localized disease. The majority of patients die within a year after diagnosis.