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Latency Period
A latency period, or latent period, is the time between exposure to a disease-causing agent and the onset of the disease. Sometimes the term is used synonymously with "incubation period", and though they not the same, in some cases the latency period and incubation period are the same length of time. The distinction is that the latency period involves the time between exposure and evidence that the disease has manifested (i.e., it is clinically detectable); the incubation period, on the other hand, refers to the period where an individual has been infected with a disease (and it is therefore clinically detectable), but the disease is dormant and asymptomatic. The incubation period ends when the disease becomes symptomatic (1).
Diseases associated with asbestos typically have a long latency period. The onset of asbestosis, for example, averages from about 10 to 20 years after exposure to asbestos fibers. Similarly, the latency period for mesothelioma typically ranges from 20 to 40 years (1, 2). There are many factors that influence the length of the latency period in asbestos-related illnesses, such as size of asbestos fibers and whether or not the individual who was exposed is a smoker (3).
Asbestos exposure peaked in the mid-1970s in the U.S., when many consumer and industrial products contained asbestos, and asbestos-containing materials were commonly used in public buildings and workplaces for purposes of soundproofing. Safeguards to protect against exposure were not in place until about 1980, and even today the risk of exposure remains high in certain industries, such as construction (4). With the extremely long latency periods associated with these diseases, it is likely that medical conditions arising from asbestos exposure will be prominent in the years ahead.
- John Last. "Latent Period." From the Encyclopedia of Public Health at eNotes.com. Available: http://health.enotes.com/public-health-encyclopedia/latent-period （Accessed July 21, 2007）.
- "Asbestos Awareness Program." From the University of Missouri-Rolla Environmental Health and Safety website. Available: http://campus.umr.edu/ehs/Asbestos_Awareness/Asbestos_Awareness_Program.html (Accessed July 21, 2007).
- Roberta C. Barbalace. (2004) "Asbestos: A Manufacturing Health Hazard Dating to Prehistoric Times." From EnvironmentalChemistry.com. Available: http://EnvironmentalChemistry.com/yogi/environmental/asbestoshealthhazards2004.html (Accessed July 21, 2007).
- "The Asbestos Epidemic in America." From the Environmental Working Group and EWG Action Fund's website. Available: http://reports.ewg.org/reports/asbestos/facts/fact1.php (Accessed July 21, 2007).