| Project/Area Number |
09670364
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Hygiene
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| Research Institution | KEIO UNIVERSITY |
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Principal Investigator |
KONDO Takefumi Keio University, School of Medicine, Professor, 医学部, 教授 (20234940)
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| Co-Investigator(Kenkyū-buntansha) |
TACHIBANA Masaaki Keio University, Shool of Medicine, Assistant Professor, 医学部, 専任講師 (70129526)
SHIMADA Naoki Keio University, School of Medicine, Assistant Professor, 医学部, 専任講師 (90255430)
宮川 路子 慶應義塾大学, 医学部・衛生学公衆衛生学教室, 専任講師 (30276216)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1998: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1997: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | occupational bladder cancer / benzidine / beta-naphthylamine / exposure period / latent period / Kaplan-Meier method / Cox's proportional hazard model / epidemiologic study / 疫学研究 / 曝露評価 / カプランマイヤー法 / 比例ハザードモデル / β-ナフテルアミン / 発がん性物質 / 量反応関係 |
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| Research Abstract |
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.
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