Myocardial infarction in Swedish subway drivers.
OBJECTIVE
Particulate matter in urban air is associated with the risk of myocardial infarction in the general population. Very high levels of airborne particles have been detected in the subway system of Stockholm, as well as in several other large cities. This situation has caused concern for negative health effects among subway staff. The aim of this study was to investigate whether there is an increased incidence of myocardial infarction among subway drivers.


METHODS
Data from a population-based case-control study of men aged 40-69 in Stockholm County in 1976-1996 were used. The study included all first events of myocardial infarction in registers of hospital discharges and deaths. The controls were selected randomly from the general population. National censuses were used for information on occupation. Altogether, 22 311 cases and 131 496 controls were included. Among these, 54 cases and 250 controls had worked as subway drivers.


RESULTS
The relative risk of myocardial infarction among subway drivers was not increased. It was 0.92 [95% confidence interval (95% CI) 0.68-1.25] when the subway drivers were compared with other manual workers and 1.06 (95% CI 0.78-1.43) when the subway drivers were compared with all other gainfully employed men. Subgroup analyses indicated no influence on the risk of myocardial infarction from the duration of employment, latency time, or time since employment stopped.


CONCLUSIONS
Subway drivers in Stockholm do not have a higher incidence of myocardial infarction than other employed persons.
Bigert
Carolina
C
Department of Occupational and Environmental Health, Norrbacka 4th Floor, SE-171 76 Stockholm, Sweden. carolina.bigert@sll.se
Klerdal
Kristina
K
Hammar
Niklas
N
Gustavsson
Per
P
D000328:Adult; D000368:Aged; D000395:Air Pollutants, Occupational / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000209:etiology; D016273:Occupational Exposure; D011890:Railroads; D013548:Sweden / Q000453:epidemiology
D000395:Air Pollutants, Occupational