Application of urinary mutagen testing to detect workplace hazardous exposure and bladder cancer

The objectives of this biochemical epidemiologic case-control study were to evaluate urinary mutagen testing for occupational exposure assessment, and for possible screening for bladder cancer in the workplace. Thirty-seven patients (19 bladder cancer cases and 18 controls) completed a questionnaire. Two urine samples, i.e. a work sample taken while at work, and a home sample, were requested from each patient. Twenty-six patients (17 cases and 9 controls) gave a total of 47 24-h urine samples for mutagenicity testing by the Ames test. A positive Ames test was found to be associated significantly with current occupation with hazardous exposure (odds ratio = 3.7, 95%CI 1.1-12.9), and non-significantly with bladder cancer (odds ratio = 1.8, 95%CI 0.5-7.1). Our results show that the urinary Ames test has the potential of being used as a surveillance for current workplace hazardous exposure (sensitivity = 52%, specificity = 77%, positive predictive value = 72%, negative predictive value = 59%, positive likelihood ratio = 2.3), but not as a screening test for bladder cancer cases (sensitivity = 42%, specificity = 71%, positive predictive value = 3%, negative predictive value = 98%, positive likelihood ratio = 1.5).