Am. J. Respir. Crit. Care Med., Vol 153, No. 5, 05 1996, 1560-1566.
Coal mine dust exposure and spirometry in experienced miners
PK Henneberger and MD Attfield
Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Morgantown, West Virginia 26505, USA.
In a previous study of new miners from the National Study of Coal Workers'
Pneumoconiosis (NSCWP), researchers examined changes in spirometry values
associated with coal mine dust exposure (Br J Ind Med 1993; 50:929-937). An
unusual pattern of dust-related effects was observed: initial sharp
decrements in FVC and FEV1 were followed by partial recovery. In the
current study, similar methods were used to analyze data from experienced
miners. Each of 1,915 male subjects contributed data from two of the NSCWP
field surveys: either Round 1 (1969-71) and Round 2 (1972-75) and Round 4
(1985-88). From the cross- sectional analysis at Round 1 or Round 2
(R1/R2), changes of +0.6 ml FVC and -0.5 ml FEV1 were associated with each
mg/m3-yr of cumulative coal mine dust exposure, but were not statistically
significant (p > 0.05). From the analysis of longitudinal change in
spirometry from R1/R2 to Round 4 (R4), annual declines in FVC (-0.10 ml/yr
per mg/m3- yr, p = 0.003) and FEV1 (-0.07 ml/yr per mg/m3-yr, p = 0.006)
were associated with pre-R1/R2 exposure. Both the pattern and the magnitude
of the exposure-response relationship were different for experienced versus
new miners. Possible reasons for these contrasts include differences in
cumulative exposure between the two groups and the healthy worker effect
among experienced miners.
