Airway responsiveness and job selection: a study in coal miners and non-mining controls.
BACKGROUND
It has been suggested that health related job selection is a major cause of the healthy worker effect, and may result in inaccurate estimates of health risks of exposures in the working environment. Improved understanding of self selection, including the role of airway hyperresponsiveness, should improve accuracy in estimating occupational risks.


METHODS
We evaluated symptoms of the respiratory tract, lung function, occupational and smoking histories, and airway responsiveness from a cross sectional survey of 478 underground bituminous coal miners and non-mining controls. Workers with abnormal spirometry were excluded from methacholine testing.


RESULTS
Methacholine responsiveness (> or = 15% decline in forced expiratory volume in one second) was associated in both miners and controls with reduced ventilatory lung function and an increased risk of respiratory symptoms. Miners with the longest duration of work at the coal face had a low prevalence of methacholine responsiveness, compared with miners who had never worked at the coal face (12% v 39%, P < 0.01). Throughout their mining careers, miners who responded to methacholine were consistently less likely to have worked in dusty jobs than miners who did not respond to methacholine.


CONCLUSIONS
These results provide evidence that workers who are employed in dusty jobs are less likely than their unexposed coworkers to show increased non-specific airway responsiveness, presumably as a result of health related job selection. Surveys of workers in which responsiveness data are unavailable may underestimate the effects of dust exposure on respiratory health.
National Institute for Occupational Safety and Health, Division of Respiratory Disease Studies, Morgantown, West Virginia 26505-2888, USA.
E L
EL
Petsonk
E M
EM
Daniloff
D M
DM
Mannino
M L
ML
Wang
S R
SR
Short
G R
GR
Wagner
D000328:Adult; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D016022:Case-Control Studies; D003032:Coal Mining; D005541:Forced Expiratory Volume; D015989:Healthy Worker Effect; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D016210:Methacholine Chloride; D016273:Occupational Exposure / Q000009:adverse effects*; D011237:Predictive Value of Tests; D014797:Vital Capacity
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride