Epidemiologic study for occupational bladder cancer in Japan.

本研究的目的是估计联苯胺和β-萘胺的潜在致癌期。此外，本研究重新考虑的重要性，持续密切监测的染料工人谁从事这些化学品的生产过程中，在本研究的第一年，我们调查了膀胱癌的发病率在一组236染料厂工人谁曾接触这些染料从1962年至1996年。19名工人（8.1%）被发现患有膀胱癌。这19个肿瘤发展的暴露期为82.0（S.D：50.2）个月。从受试者的初始和最终暴露到肿瘤发生的潜伏期分别为29.5（S.D：8.2）年和20.1（S. D：8.2）年。：10.6）年。显著地，在暴露期与从暴露结束到癌症发作的潜伏期之间观察到负相关（Pearson）（R=-0.544，p<0.05）。这些化学品的潜伏期比预期的要长，因此，必须继续对接触这些化学品的工人进行密切检查。第二年，我们利用3109名接触染料的男性的资料，估计了膀胱肿瘤的潜伏期。首先，我们使用Kaplan-Meier方法计算膀胱癌的累积发病率，并将其与潜伏期作图。其次，我们将逻辑曲线拟合到散点图（即，累积发病率和潜伏期之间的关系）。我们确定相关系数最高的逻辑斯谛曲线上界表示潜伏期最长。BZ暴露诱发膀胱癌的最长潜伏期为51.3年，根据比例风险模型分析，暴露时间和初次接触时的年龄是诱发膀胱癌的危险因素。

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.