Airway disease in highway and tunnel construction workers exposed to silica.
BACKGROUND
Construction workers employed in a unique type of tunnel construction known as tunnel jacking were exposed over an 18-month period to respirable crystalline silica at concentrations that exceeded the OSHA permissible exposure limit. The present study examines workplace exposures and occurrence of airway disease in these workers.


METHODS
Medical and occupational histories and chest radiographs were obtained on 343 active construction workers who had worked on the site during the period in question. Chest radiographs were interpreted according to the ILO-1980 system of classification. Standardized questions were used to develop an algorithm to define symptoms consistent with asthma (SCA) and to determine these respiratory outcomes: chronic bronchitis, shortness of breath (SOB), and physician-diagnosed asthma (current vs. not current). Relationships with each of three work activities were examined: slurry wall breakthrough (SWB), chipping caisson overpour, and tunneling/mining.


RESULTS
Participants included laborers, carpenters, tunnel workers, ironworkers, operating engineers, and electricians. No cases of silicosis were found on chest X-ray. Overall prevalence of chronic bronchitis, SCA, SOB, and physician-diagnosed asthma was 10.7%, 25%, 29%, and 6.6%, respectively. Odds ratios (OR) for carpenters compared to laborers were significantly elevated for chronic bronchitis, SCA, and SOB. SWB was associated with chronic bronchitis and SCA (OR 4.93, 95% CI = 1.01, 24.17; OR 3.32, 95% CI = 1.25, 8.84, respectively). The interaction between SWB, SCA, and trade was significant for carpenters (OR 6.87, 95% CI = 1.66, 28.39). Inverse trends were observed for months on the site and chronic bronchitis, SCA, and SOB (P = 0.0374, 0.0006, and 0.0307, respectively).


CONCLUSIONS
Tunnel construction workers exposed to respirable crystalline silica and cement dust are at increased risk for airway disease. Extent of risk varies by trade and work activity. Our data indicate the importance of bystander exposures and suggest that tunnel jacking may be associated with greater risk compared to more traditional methods of tunnel construction. A healthy worker effect is suggested.
Oliver
L Christine
LC
Occupational Health Initiatives, Brookline, Massachusetts 02446, USA. coliver@ohiinc.com
Miracle-McMahill
Heidi
H
D000328:Adult; D000395:Air Pollutants, Occupational / Q000009:adverse effects* / Q000032:analysis; D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D001900:Boston; D001991:Bronchitis / Q000453:epidemiology / Q000209:etiology*; D003252:Construction Materials / Q000009:adverse effects* / Q000032:analysis; D004391:Dust / Q000032:analysis; D004417:Dyspnea / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008452:Maximum Allowable Concentration; D008875:Middle Aged; D009784:Occupational Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D016272:Occupational Health; D009790:Occupations; D016017:Odds Ratio; D011859:Radiography; D012134:Respiratory Protective Devices / Q000706:statistics & numerical data; D012822:Silicon Dioxide / Q000009:adverse effects* / Q000032:analysis; D014186:Transportation; D014481:United States; D014489:United States Occupational Safety and Health Administration
D000395:Air Pollutants, Occupational; D004391:Dust; D012822:Silicon Dioxide