Reevaluation of lung cancer risk in the acrylonitrile cohort study of the National Cancer Institute and the National Institute for Occupational Safety and Health.
OBJECTIVE
The present study provides additional analyses of data obtained earlier on lung cancer risk among workers with acrylonitrile exposure.


METHODS
The original authors provided the data. For total mortality and the cancer sites of a priori interest (lung, stomach, brain, breast, prostate, and the lymphatic and hematopoietic systems), standardized mortality ratios (SMR) and 95% confidence intervals (95% CI) were computed, the total United States and surrounding counties being used as standard populations. Regional rate-based SMR values were also computed between lung cancer and cumulative acrylonitrile exposure.


RESULTS
Except for lung cancer, the external comparisons corroborated the earlier internal comparisons (no increased cancer mortality risk). For lung cancer, the external comparisons revealed death deficits for the unexposed workers (SMR 0.68, 95% CI 0.5-0.9) and all categories of acrylonitrile-exposed workers. The SMR obtained using external rates and the most exposed group (SMR 0.92. 95% CI 0.6-1.4) differed from the corresponding relative risk (RR) of the internal rates (RR 1.5, 95% CI 0.9-2.4).


CONCLUSIONS
The analysis of the present study provides little evidence that acrylonitrile exposure increases the mortality risk of cancers of a priori interest, including lung cancer. The lung cancer findings of the external comparison differed from the earlier findings of the internal comparisons. Selection bias (as the healthy worker effect) was probably not responsible. Additional follow-up and analyses, especially of the unexposed workers with low lung cancer rates, may help elucidate the internal and external comparison differences. Results from both comparisons should be presented when the relative risks differ markedly, as both have advantages and disadvantages.
Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pennsylvania 15261, USA. gmarsh@pitt.edu
G M
GM
Marsh
A O
AO
Youk
J J
JJ
Collins
D000181:Acrylonitrile / Q000009:adverse effects* / Q000737:chemistry; D000328:Adult; D001943:Breast Neoplasms / Q000139:chemically induced / Q000401:mortality; D002273:Carcinogens / Q000009:adverse effects* / Q000737:chemistry; D002423:Cause of Death; D016543:Central Nervous System Neoplasms / Q000139:chemically induced / Q000401:mortality; D002617:Chemical Industry; D015331:Cohort Studies; D016001:Confidence Intervals; D016208:Databases, Factual / Q000592:standards; D005260:Female; D019337:Hematologic Neoplasms / Q000139:chemically induced; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D009314:National Institute for Occupational Safety and Health, U.S.; D016273:Occupational Exposure / Q000009:adverse effects*; D011471:Prostatic Neoplasms / Q000139:chemically induced / Q000401:mortality; D012042:Registries; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000139:chemically induced / Q000401:mortality; D016019:Survival Analysis; D014481:United States / Q000453:epidemiology
D002273:Carcinogens; D000181:Acrylonitrile