AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 44:282–290 (2003) The Drake Health Registry Study: Cause-Speciﬁc Mortality Experience of Workers Potentially Exposed to Beta-Naphthylamine Laura D. Cassidy, PhD,  Ada O. Youk, PhD, and Gary M. Marsh, PhD Objective To examine the cause-speciﬁc mortality experience of an occupational cohort with probable past exposure to beta-naphythylamine (BNA). Methods Subjects were 374 male and 26 female workers employed at a Pennsylvania chemical plant that produced or used beta-naphthylamine (BNA) between 1940 and 1981. Vital status through 1998 was determined for 97.5% of the cohort and cause of death for 100% of 79 deaths. Limited industrial hygiene data and reports from former employees were used to categorize workers as high, medium, or low risk for BNA exposure. Statistical analyses included US and local county-based standardized mortality ratios (SMRs). Results We observed statistically signiﬁcantly elevated county rate-based SMRs for all causes combined (SMR ¼ 1.98, 95% conﬁdence interval (CI) ¼ 1.56 – 2.49), all malignant neoplasms combined (28 deaths, SMR ¼ 3.08, 95% CI ¼ 2.05–4.46), respiratory system cancer (12 deaths, SMR ¼ 3.91, 95% CI ¼ 2.02–6.83), and bladder cancer (four deaths, SMR ¼ 16.83, 95% CI ¼ 4.59–43.1). Three bladder cancer cases were classiﬁed as high risk (SMR ¼ 26.79, 95% CI ¼ 5.53–78.29). Mortality risks were also elevated for most other malignant and non-malignant cause of death categories examined. Conclusions Bladder cancer risk remains highly elevated among Drake/Kilsdonk workers and appears to be causally related to past BNA exposure. While lifestyle and behavioral risk factors may explain some of the mortality excesses for non-urological cancers, the possibility remains that BNA exposure may have also played a role in these and other observed cancer excesses. Am. J. Ind. Med. 44:282 – 290, 2003. ß 2003 Wiley-Liss, Inc. KEY WORDS: bladder cancer; beta-naphthylamine; cancer screening; occupational epidemiology; mortality INTRODUCTION Increased risk of bladder cancer in dye production workers following occupational exposures to beta-naphthy- lamine (BNA) and/or benzidine has been well documented in epidemiologic studies conducted in the United States, China, Britain, Japan, and Russia [Case et al., 1954; Mancuso and El-Attar, 1967; Tsachiya et al., 1975; Rubino et al., 1982; Schulte et al., 1986; Xue-Yun et al., 1990; Bi et al., 1992; Bulbulyan et al., 1995]. These studies have reported risk ratios for bladder cancer of 3.9, 30, 87, and 150 [Case et al., 1954; Mancuso and El-Attar, 1967; Rubino et al., 1982; Schulte et al., 1986]. In one study, all 15 plant workers involved in distilling BNA in a small plant in England developed bladder cancer [Case et al., 1954]. This important observation demonstrates that in situations with high levels of exposure to potent carcinogens, individual susceptibility is irrelevant [Vineis and Pirastu, 1997]. The US and UK both observed a decrease in the incidence of bladder cancer in chemical workers since the ban of carcinogenic arylamines in ß 2003 Wiley-Liss, Inc. Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania Contract grant sponsor: Pennsylvania State Department of Health, Cancer Control Board. *Correspondence to: Laura D. Cassidy, Department of Biostatistics, A-414 Crabtree Hall, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA15261. E-mail: lcs3@pitt.edu Accepted 21May 2003 DOI10.1002/ajim.10268. Published online in Wiley InterScience (www.interscience.wiley.com)