Hazard Of Proteinuria In Workers Who Handle Ethylbenzene : The Retrospective Cohort Study
Creators: name: Mitsuhashi, Toshiharu
Publisher: name: Zenodo
Year: 2018
Subjects: occupational health
ethylbenzene
proteinuria
public health

description: <strong>Introduction</strong><br>
Ethylbenzene (EB) is contained in solvent-based paints, and is widely used industrially. In Japan, Regulation for EB was added by modified Ordinance on prevention of hazards due to specified chemical substances (effective January 1, 2013). EB exposure has adverse health effects such as carcinogenicity and reproductive toxicity. In health check, urine protein test is one of the objective indicators of adverse health effects. In this study, I examined the effect of EB exposure on urine protein test results after EB regulation was added. After strengthening EB regulations, I will clarify whether the proportion of urine protein of EB handling workers is equivalent to that of EB non-handling workers.

<strong>Subjects and Methods</strong><br>
General health check data of the workplace where a certain occupational health association conducted EB special health check from 1st January 2013 to 30th June 2015. The data includes those who do not have EB special health check. General health examination with EB special health examination within 180 days before and after was defined as the observation that the exposure exists (EB+). I defined urinalysis findings of (±), (+), (2+), or (3+) as positive. During the study period, the subject will undergo multiple health checks. I dealt with data as observations (health check) being nested in subjects. Outcome may occur multiple times in the same subject. Therefore, using Andersen-Gill model , the hazard ratio (HR) and its 95% confidence interval (CI) were calculated. Outcome was treated as a binary variable. The CHAID model was adopted and a decision tree analysis was carried out. Since the data structure can not be reflected, it is assumed that each observation is independent. In order to ensure reproducibility, random number generation seed was fixed.

<strong>Results</strong><br>
There were 503 workplaces where EB usage work was held, and the total number of workers was 18,560 people (total number of health check 50,887). The total risk person-year and outcome number were about 1,090,000 person-year and 3,557 cases respectively. In the crude model, the HR of the exposed group was 1.66 (95% CI 1.51-1.82), and in the adjusted model, HR was 1.68 (95% CI 1.52-1.85). In the decision tree analysis using the same variables, it was classified into 4 clusters by smoking, age, EB.

<strong>Discussion</strong><br>
The hazard of urine protein was significantly higher in the EB+ group than in the EB- group. In decision tree analysis EB was chosen as branching condition. For EB handling workers, urinalysis is highly likely to be protein positive. EB was designated as "Specified Chemical Substances" by Japanese law. As a result, measures to prevent exposure to EB were strengthened, such as stricter danger display and obligation to use full mask in the tank and so on. However, as there are many urinary protein findings, it is suggested that EB exposure to workers still remains.