A latency period is the amount of time that passes before a disease shows symptoms after exposure to a chemical or toxin. In the case of mesothelioma, the latency period refers to the time between initial exposure to asbestos and the presentation of symptoms. It is not known in any case when actual tissue damage or cell mutation takes place after exposure to asbestos. Compared to other types of cancer and asbestos diseases, mesothelioma has a very long latency period making it more difficult to research. Studies typically put the average latency period of mesothelioma at about 15 to 50 years.1 However, there have been cases where mesothelioma has occurred much sooner after asbestos exposure (as little as 5 years) and much later (over 60 years after exposure).2
The latency period for mesothelioma is much longer than it is for other lung cancers. Typical lung cancer has a latency period of approximately 15 to 20 years. The mesothelioma latency period is twice as long on the far end. This adds an emotional aspect to this disease because people who have knowledge of asbestos exposure live for decades wondering if they will develop mesothelioma.
Some studies have reported that the latency period for peritoneal mesothelioma is shorter than for pleural mesothelioma. However, it must also be taken into consideration that most patients with peritoneal mesothelioma usually have had longer exposure to asbestos than the patients with pleural mesothelioma. Experts have concluded that people with the greatest exposure to asbestos will have shorter latency times before the disease presents any symptoms. That makes sense since high exposure rates means a greater likelihood of a person inhaling or ingesting large amounts of asbestos fibers.
Since the peak period for asbestos production in the United States was in the 1970s, it is expected that the highest rates of mesothelioma would have occurred 30-40 years afterwards in 2000-2010. During this time period, the US had approximately 2,000-3,000 diagnosed cases of mesothelioma yearly. In many European counties, asbestos production didn’t reach its peak until a decade later so these countries may see their peaks of mesothelioma diagnoses in 2010-2020.
However, there are two points to keep in mind when considering the statistics. First is the fact that there are still tens of thousands of buildings containing asbestos in use in the United States. The theory is that as long as the asbestos is not disturbed and fibers cannot get into the air then people are safe. Second is the fact that people did not live as long decades ago and so died before the mesothelioma would present itself. People live longer now giving the disease more time to progress. It is quite possible that the number of mesothelioma cases will begin to grow again.
In the past two decades, the use of asbestos has been banned or has tapered off in many nations worldwide. Experts thus expect that the number of mesothelioma cases will taper off in other nations. However, various factors could change this fact around the world. As mentioned, people are living longer today everywhere than in the past so workers exposed to asbestos may live long enough for the mesothelioma latency period to catch up with them. While asbestos is not being widely produced or used anymore, it is still found widely throughout many public and private buildings. Even this minimal exposure to asbestos when combined with longer lifespan could result in more cases of mesothelioma being diagnosed.
A Recent Asbestos Exposure
After the World Trade Center attack of 9/11, over 100 thousand people – including first responders, workers and residents – were exposed to asbestos which was released into the air from the rubble of the building. On first responder was diagnosed early with mesothelioma in 2006. The case has been linked to the World Trade Center. Additionally, approximately 85% of the first responders have shown respiratory symptoms.3
During the end of the latency period, there may be very minor symptoms that are written off as common ailments. You may develop a periodic cough or have mild breathing problems and believe it is a cold developing or allergies. You may feel mild chest discomfort and will tell yourself that it is due to your diet. As more people who have been exposed to asbestos learn about mesothelioma, the more likely they are to question even the mild symptoms. So much more medical data and information is needed to make progress in the early diagnosis and treatment of this terrible disease.
Unlike the countless people exposed to asbestos in the past, most people today are aware of the risks of asbestos. Anyone who was exposed to the rubble of the World Trade Center after the tragedy should be screened regularly for asbestos-related diseases. Early detection of mesothelioma can significantly improve the prognosis. By detecting mesothelioma in its earliest stages and also being able to pinpoint exposure, experts may be able to learn valuable information about mesothelioma latency from the first responders at the World Trade Center.
References
1 Mesothelioma Disease Development and Progression (2010) Retrieved from Mesothelioma Applied Research Foundation at: http://www.curemeso.org/site/c.kkLUJ7MPKtH/b.4023387/k.643A/Mesothelioma_Information.htm#Disease_Development_And_Progression
2 Tischoff I., Neid, M., Neumann V. and Tannapfel A. (2011) Pastohistological diagnosis and differential diagnosis. Recent Results Cancer Research, v189; 57-78.
3 Asbestos – World Trade Center: Full Report in HTNL (September 2002) Retrieved from Agency for Toxic Substances & Disease Registry at: http://www.atsdr.cdc.gov/asbestos/asbestos/types_of_exposure/WTC_FullReport.html
