Effects of toner-handling work on respiratory function, chest X-ray findings, and biomarkers of inflammation, allergy, and oxidative stress: a 10-year prospective Japanese cohort study

Abstract

Background Exposure to toner, a substance used in photocopiers and printers, has been associated with siderosilicosis and other adverse effects. However, these findings are limited, and there is insufficient evidence on the long-term effects of toner exposure. Using longitudinal analysis, this study aimed to examine the effects of work involving toner exposure on the respiratory system over time. Methods We conducted a prospective cohort study in a Japanese toner and copier manufacturing enterprise between 2003 and 2013. The cohort included a total of 1468 workers, which comprised 887 toner-handling workers and 581 non-toner-handling workers. We subdivided the toner-handling workers into two groups according to the toner exposure concentration, based on the baseline survey in 2003. We compared the chest X-ray results, respiratory function indicators, and serum and urinary biomarkers of inflammation, allergy, and oxidative stress among the three groups: high-concentration toner exposure group, low-concentration toner exposure group, and non-toner-handling group. To consider the effects of individual differences on the longitudinal data, we used a linear mixed model. Results Similar chest X-ray results, the biomarkers, and most of the respiratory function indicators were found in the non-toner-handling and toner-handling groups. There were no significant yearly changes in the percentage of vital capacity (%VC) in the high-concentration toner exposure group, while there was a significant yearly increase in %VC in the low-concentration toner exposure group and non-toner-handling group. The yearly change in each group was as follows: high-concentration toner exposure group, − 0.11% (95% confidence interval [CI], − 0.29 to 0.08; P = 0.250); low-concentration toner exposure group, 0.13% (95% CI, 0.09–0.17; P < 0.001); and non-toner-handling group, 0.15% (95% CI, 0.01–0.20; P < 0.001). Conclusions In our 10-year prospective study, toner-handling work was not associated with the deterioration of respiratory function and an increase in biomarker values for inflammation, allergy, and oxidative stress. This finding suggests that toner-handling work is irrelevant to the onset of respiratory disease and has minimal adverse effects on the respiratory system under a well-managed work environment.

Results of a Series of Epidemiological Investigations on Health Effects in Toner-Manufacturing Workers

“…Dust concentration measurements in toner handling workplaces were evaluated through individual exposure measurements and workplace dust concentration measurements. As mentioned in the Terunuma paper [12,22], there were differences in individual exposure concentrations among work categories by toner operation, with significantly higher concentrations in the machine recycling and toner manufacturing work categories than in the other work categories. This trend is similar to that observed in the Kitamura paper [13], where results of individual exposure measurements showed that the average dust concentration over the 10-year observation period ranged from 0.109 to 0.215 mg/m 3 for toner manufacturing, 0.038 to 0.575 mg/m 3 for toner research and development, and 0.044 to 0.323 mg/m 3 for engineering.…”

“…Changes in respiratory function over time due to toner exposure were estimated by stepwise multiple regression analysis. In the Terunuma paper [12,22], chi-square and Fisher's exact tests, simple t-test and Welch's t-test for quantitative variables, logistic regression analysis with generalized estimating equations (GEE), two-way repeated measures analysis of variance (ANOVA), and linear mixed models (LMM) were used. In all analyses, the significance level was less than 0.05.…”

“…Each establishment's survey method used the same items and procedures as much as possible. The findings of five of the six companies surveyed were published in an English academic paper [11][12][13][14][15]. Table 1 shows the survey period profile and items at each tonermanufacturing company.…”

“…N/A N/A Terunuma et al [12,22] Chronic cough, chronic phlegm, chronic cough and phlegm, wheezing without an asthmatic response, and shortness of breath. asthma, allergic rhinitis, allegic dermatitis, pneumonia, sinusitis They adjusted for the effects of potential con-founders in four models with additional variables (Model 1 to Model 4).Models 1 through 3 show the estimated effect of toner exposure on the annual change in each respiratory subjective symptom as a quotient of the odds ratio of annual change in the toner-handling group divided by the odds ratio in the non-toner-handling group.…”

“…Our department has conducted studies on the health effects of toner handling workers and published several papers [11][12][13][14][15][16][17][18][19][20][21]. This paper presents the 10-year cohort of papers we have submitted and published to date and outlines the health effects of toner p article exposure among toner handling workers.…”