Epidemiologic study for occupational bladder cancer in Japan.

本研究的目的是估算联苯胺和β-萘胺的潜在致癌期。此外，这项研究重新考虑了对从事这些化学品生产过程的染料工人进行持续密切监测的重要性。在这项研究的第一年，我们调查了1962年至1996年期间接触这些染料的236名染料厂工人的膀胱癌发病率。检出膀胱癌19例(8.1%)。这19个肿瘤发展的曝光期为82.0(S.D：50.2)个月。从初次暴露到最后一次暴露到肿瘤发生的潜伏期分别为29.5年(S.D.：8.2)和20.1(S.D.：10.6)年。显著的是，暴露时间与暴露结束至癌症发病的潜伏期之间存在负相关(P<0.05)(R=-0.544，p&lt；0.05)。这些化学品的潜伏期比预期的要长，因此，必须继续密切检查接触者。此外，尿细胞学被认为对检测和监测膀胱肿瘤有价值。在第二年，我们使用3109名接触染料的男性的数据估计了潜伏期。首先，我们用Kaplan-Meier方法计算膀胱癌的累积发病率，并将其与潜伏期相比较。其次，通过改变上界，反复将Logistic曲线与散点图(即累积发病率与潜伏期之间的关系)进行拟合。相关系数最大的Logistic曲线上界表示潜伏期最长。BZ暴露引起膀胱癌的最长潜伏期估计为51.3年，根据比例风险模型分析，暴露年限和初次暴露年龄是增加膀胱癌风险的因素。

The purpose of this study is to estimate the latent carcinogenic period of benzidine and beta-naphthylamine. Furthermore, this study reconsiders the importance of continuous close surveillance for the dyestuff workers who engaged in the manufacturing process of these chemicals.In the first year of this study, we surveyed the incidence of bladder cancers in a group of 236 dyestuff plant workers who had been exposed to these dyestuffs from 1962 to 1996. Nineteen workers (8.1%) were found to have bladder cancers. The exposure period for these 19 tumor developments was 82.0(S.D : 50.2) months. The latent period from the subjects' initial and final exposure until tumor development was 29.5(S.D : 8.2) years and 20.1(S.D. : 1O.6) years respectively. Significantly, a negative correlation (Pearson) was observed between the exposure period and the latent period from the end of exposure to cancers' onset (R=-0.544, p<O.O5). Latent periods of these chemicals were longer than expected, and therefore, exposed workers must continue to be closely examined. Also, urine cytology is thought to be valuable for detecting and monitoring bladder tumors.In the second year, we estimated the latent period using the data of 3109 men exposed to the dyestuffs. Firstly, we computed the cumulative incidence of the bladder cancer using Kaplan-Meier method, and plotted it against latency period. Secondly, we fitted the logistic curves to the scatter plot (i.e., to the relationship between cumulative incidence and latency period) repeatedly by varying the upper bounds. We decided that the upper bound of logistic curve where the correlation coefficient showed the highest value indicated the longest latency period. The longest latent period of bladder cancer caused by exposure to BZ was estimated at 51.3 years.According to proportional hazards model analysis, exposure period and age at the initial exposure were confirmed to raise the risk of bladder cancer.