Coal Workers’ Pneumoconiosis (CWP)
CWP is a chronic, disabling, and sometimes fatal dust disease of the lungs caused by inhaling coal mine dust. The prevalence of CWP reported here is based on data for underground coal miners who participated in the U.S. National Coal Workers’ X-Ray Surveillance Program (CWXSP). In the CWXSP, CWP is defined as agreement between two Readers (one of whom must be a B Reader*) that small pneumoconiotic opacities are present at a category of 1/0 or higher, using the International Labour Office (ILO) International Classification of Radiographs of Pneumoconioses.
Among miners in this program with 25 or more years of underground coal mining, the prevalence of CWP category 1/0 or greater was 34% during 1973–1978; but it declined to 4% during 1996–1999 (Figure 2–181). Among miners with the same number of years of underground coal mining, the prevalence of a more severe CWP category (2/1 or greater) declined from 10.5% during 1970–1973 to less than 1% during 1996–1999 (Figure 2–182). During 1970–1999, decreases in CWP prevalence occurred in all categories of tenure in underground coal mining (Figures 2–181 and 2–182).
Deaths from CWP declined significantly, from a high of 2,870 in 1972 to 1,003 in 1999 (Figure 2–183). West Virginia had the highest age-adjusted mortality rate—nearly 20 times the rate of 7.56 per million for the entire United States (Figure 2–184). Coal mining and metal mining had the highest PMRs for CWP among industries, and mining machine operators had the highest PMR among the occupations (Figure 2–185).
*See Reader in Glossary.
Magnitude and Trend
What was the prevalence of CWP category 1/0 or greater among underground coal miners participating in the CWXSP during 1970–1999?
 | Figure 2-181 Prevalence of CWXSP-examined miners with CWP category 1/0 or greater by tenure in underground coal mining, 1970-1999. During 1970-1999, the prevalence of CWP category 1/0 or greater decreased among all tenure groups toward the prevalence of the baseline tenure group (0-9 years in underground coal mining). (Source: NIOSH [2002g].) |
What was the prevalence of CWP category 2/1 or greater among underground coal miners participating in the CWXSP during 1970–1999?
 | Figure 2-182 Prevalence of CWXSP-examined miners with CWP category 2/1 or greater by tenure in underground coal mining, 1970-1999. During 1970-1999, the prevalence of CWP category 2/1 or greater decreased among all tenure groups toward the prevalence of the baseline tenure group (0-9 years in underground coal mining). (Source: NIOSH [2002g].) |
How did the pattern of CWP mortality change during 1968–1999?
 | Figure 2-183 Number of deaths of U.S. residents aged 15 or older with CWP recorded as an underlying or contributing cause on the death certificate, 1968-1999. The number of CWP deaths experienced a long-term decline during 1968-1999, from more than 2,500 deaths per year in the early 1970s and 1980s to fewer than 1,500 in the late 1990s. Although the annual number of deaths declined steadily after 1982, the proportion of deaths with CWP listed as the underlying cause on the death certificate remained fairly constant, hovering around 37% from 1980 to 1999. (Source: NIOSH [2002f].) |
Rates among States
How did CWP mortality rates differ by State during 1990–1999?
 | Figure 2-184 Age-adjusted mortality rates for CWP in U.S. residents aged 15 or older by State, 1990-1999. West Virginia had the highest CWP mortality rate-nearly 20 times the rate of 7.56 per million for the entire United States. The second highest rate category included the Appalachian and western coal mining regions. (Source: NIOSH [2002f].) |
Occupation and Industry
Which industries and occupations were associated with CWP mortality during 1990–1999?
 | Figure 2-185 PMRs and 95% confidence intervals for CWP in U.S. residents aged 15 or older by industry and occupation, adjusted for age, race, and sex, 1990-1999. Among industries, coal mining and metal mining were associated with elevated CWP mortality during 1990-1999. Among occupations, the three highest significant PMRs were associated with mining. (Note: This figure presents the highest significant PMRs based on 10 or more deaths.) (Source: NIOSH [2002f].) |
