ANALYSIS OF CURRENT TRENDS IN UNITED-STATES MESOTHELIOMA INCIDENCE

Mesothelioma incidence often is interpreted as an index of past exposu re to airborne asbestos, The mesothelioma rate for US males exhibits a n increasing trend throughout the 1970s and early 1980s. The trend has been attributed to occupational exposure in the shipbuilding industry during World War II, in manufacturing, and in building construction. Incidence data (1973-1992) from the Surveillance, Epidemiology, and En d Results Program were used to investigate current trends in age-adjus ted and age-specific mesothelioma rates. An age and birth-cohort model was used to project both lifetime probabilities of mesothelioma by co hort and the annual number of cases expected over the next 70 years. T he current trend in female rates is flat (age-adjusted rate = 0.30 per 100,000). The estimated lifetime risk for females is 2.5 x 10(-4), in dependent of birth cohort. The projected average annual number of fema le cases is 500. For males, the age-adjusted mesothelioma rate is incr easing solely due to the age group 75 years and over, albeit at a decl ining growth rate. Lifetime risk for males peaks at 2 x 10(-3) for the 1925-1929 birth cohort, then decreases to 5 x 10(-4) for the 1955-195 9 birth cohort. The pattern of rates reflected in the age and birth-co hort model suggests a peak in the annual number of mesothelioma cases for males at 2,300 before the year 2000. The number of male cases then will drop during the next 50-60 years toward 500. These trends mirror the US trend in raw asbestos consumption and a reduction in workplace airborne asbestos levels.