Effects of occupational exposure to carbon black on peripheral white blood cell counts and lymphocyte subsets.

The International Agency for Research on Cancer has classified carbon black (CB) as a possible (Group 2B) human carcinogen. Given that most CB manufacturing processes result in the emission of various types of chemicals, it is uncertain if the adverse health effects that have been observed in CB-exposed workers are related to CB specifically or are due to other exposures. To address this issue, we conducted a cross-sectional molecular epidemiology study in China of 106 male factory workers who were occupationally exposed to pure CB and 112 unexposed male workers frequency-matched by age and smoking status from the same geographic region. Repeated personal exposure measurements were taken in workers before biological sample collection. Peripheral blood from all workers was used for the complete blood cell count and lymphocyte subsets analysis. Compared to unexposed workers, eosinophil counts in workers exposed to CB were increased by 30.8% (P = 0.07) after adjusting for potential confounders. When stratified by smoking status, statistically significant differences in eosinophils between CB exposed and unexposed workers were only present among never smokers (P = 0.040). Smoking is associated with alterations in various cell counts; however, no significant interaction between CB exposure and smoking status for any cell counts was observed. Given that inflammation, characterized in part by elevated eosinophils in peripheral blood, may be associated with increased cancer risk, our findings provide new biologic insights into the potential relationship between CB exposure and lung carcinogenesis. Environ. Mol. Mutagen. 57:589-604, 2016. © 2016 Wiley Periodicals, Inc.

Reduced pulmonary function and increased pro-inflammatory cytokines in nanoscale carbon black-exposed workers.

BACKGROUND: Although major concerns exist regarding the potential consequences of human exposures to nanoscale carbon black (CB) particles, limited human toxicological data is currently available. The purpose of this study was to evaluate if nanoscale CB particles could be responsible, at least partially, for the altered lung function and inflammation observed in CB workers exposed to nanoscale CB particles. METHODS: Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Brunauer-Emmett-Teller were used to characterize CB. Eighty-one CB-exposed male workers and 104 non-exposed male workers were recruited. The pulmonary function test was performed and pro-inflammatory cytokines were evaluated. To further assess the deposition and pulmonary damage induced by CB nanoparticles, male BALB/c mice were exposed to CB for 6 hours per day for 7 or 14 days. The deposition of CB and the pathological changes of the lung tissue in mice were evaluated by paraffin sections and TEM. The cytokines levels in serum and lung tissue of mice were evaluated by ELISA and immunohistochemical staining (IHC). RESULTS: SEM and TEM images showed that the CB particles were 30 to 50 nm in size. In the CB workplace, the concentration of CB was 14.90 mg/m³. Among these CB particles, 50.77% were less than 0.523 micrometer, and 99.55% were less than 2.5 micrometer in aerodynamic diameter. The reduction of lung function parameters including FEV1%, FEV/FVC, MMF%, and PEF% in CB workers was observed, and the IL-1ß, IL-6, IL-8, MIP-1beta, and TNF- alpha had 2.86-, 6.85-, 1.49-, 3.35-, and 4.87-folds increase in serum of CB workers, respectively. In mice exposed to the aerosol CB, particles were deposited in the lung. The alveolar wall thickened and a large amount of inflammatory cells were observed in lung tissues after CB exposure. IL-6 and IL-8 levels were increased in both serum and lung homogenate. CONCLUSIONS: The data strongly suggests that nanoscale CB particles could be responsible for the lung function reduction and pro-inflammatory cytokines secretion in CB workers. These results, therefore, provide the first evidence of a link between human exposure to CB and long-term pulmonary effects.

[Analysis of musculoskeletal disorders, work load and working postures among manufacturing workers].

OBJECTIVE: To analyze the distribution of the musculoskeletal disorders, work load and working postures in different factories, gender, education levels, age and working years among manufacturing workers. METHODS: In a cross-sectional study of 5134 manufacturing workers in 12 factories, the morbidities for musculoskeletal disorders in one year period were measured with questionnaires. RESULTS: The morbidities for musculoskeletal disorders in body sites: waist, neck, shoulder, wrist, ankle/feet, knee, hip/buttocks and elbows were 59.7%, 47.9%, 38.1%, 33.7%, 26.9%, 25.4%, 15.2%, and 14.9%, respectively in one year period. There were significant differences of morbidities for musculoskeletal symptoms in body sites of workers among different factories (P < 0.05 or P < 0.01). The morbidities of musculoskeletal symptoms in elbows, waist, wrists and ankle/feet of the workers in refractory material and chemical fiber factories were higher than those in other factories, the morbidities for musculoskeletal symptoms of workers in garments and diamond factories were lower than those in other factories. The morbidities for musculoskeletal symptoms in neck, shoulders and wrists of female workers were significantly higher than those of male workers (P < 0.01). There were significant differences of the morbidities for musculoskeletal symptoms in body sites among workers with different educational levels (P < 0.05 or P < 0.01). There were significant differences of the morbidities for musculoskeletal symptoms in neck, shoulders, wrists, hip/buttocks and knee among groups with different age or different working years (P < 0.01), and the morbidities for musculoskeletal symptoms increased with age and working years. The proportions of unhealthy working postures and high working load among workers in refractory material and chemical fiber factories were higher; but those in garments and diamond factories were lower. CONCLUSION: The morbidities for musculoskeletal symptoms in waist, neck, shoulder and wrists of workers in manufacturing workers were higher; the gender, education level, age and working years could influenced the morbidities for musculoskeletal disorders.

[Association between occupational stress and musculoskeletal disorders in lower extremity].

OBJECTIVE: To explore the relationship between occupational stress and musculoskeletal disorders in lower extremity. METHODS: The cross-sectional study was used to investigate 5338 workers in 13 factories and companies for prevalence of musculoskeletal disorders in lower extremity, working postures and occupational stress were investigated with questionnaires for past year. Perceived occupational stress was evaluated by the Chinese version of the Job Content Questionnaire (JCQ) and Effort-Reward Imbalance (ERI) Model Questionnaire. Logistic regression analyses were conducted to estimate the associations between occupational stress and prevalence of musculoskeletal disorders in lower extremity. RESULTS: In the main dimensions of job strain and ERI model, physical demands and effort were risk factors of hip disorders, but job control was a protective factor of hip disorders. When job strain and ERI model scales were analyzed simultaneously, only physical demands were risk factor of hip disorders. When job strain and the effort-reward imbalance were computed by creating four independent categories, job strain was a risk factor of hip disorders, ERI was a risk factor of hip and knee disorders. The risk of imbalance between job strain and effort-reward the protective effect of job control increased with the disorder regions. According to continuous variable analysis, job strain by calculated with physical demands was risk factor of hip disorders, continuous ERI variable was risk factor of hip and knee disorders. CONCLUSION: Occupational stress is associated significantly with musculoskeletal disorders in lower extremity. The control of occupational stress and increase of job control should be considered for preventing the musculoskeletal disorders in lower extremity.

[Gender difference of relationship between occupational stress and depressive symptoms].

OBJECTIVE: To explore gender difference of relationship between occupational stress and depressive symptoms. METHODS: The cross-sectional study was used to investigate 5338 workers in 13 factories and companies, the depressive symptoms were assessed with Epidemiologic Studies Depression Scale (CES-D) and the perceived occupational stress was evaluated by the Chinese version of the Job Content Questionnaire (JCQ) and Effort-Reward Imbalance (ERI) Model Questionnaire. Logistic regression analyses were conducted to estimate the associations between occupational stress and prevalence of depressive symptoms. RESULTS: Prevalence of depressive symptoms was 31.8% for all subjects, 33.8% for males and 27.7% for females, gender difference of prevalence was significant (P < 0.01). Psychological demands, physical demands, job control, effort, overcommitment and negative affectivity scores for males were significantly higher than those for females(P < 0.01 or 0.05), social support, reward and job satisfaction scores for males were significantly lower than those for females (P < 0.01). Psychological demands, physical demands, job control, effort, overcommitment and negative affectivity scores for workers with depressive symptoms were significantly higher than those for workers without depressive symptoms (P < 0.01) but job control, social support, reward, job satisfaction and positive affectivity scores for workers with depressive symptoms were significantly lower than those for without depressive symptoms (P < 0.01). Psychological demands, physical demands, job control, effort, overcommitment and negative affectivity scores for male workers with depressive symptoms were significantly higher than those for female counterparts (P < 0.01), but social support, reward, job satisfaction scores for male workers with depressive symptoms were significantly lower than hose for female workers with depressive symptoms (P < 0.01). Ratio of male workers and male workers with depressive symptoms with job strain and ERI > 1, high demands and low control, and high effort and low reward were higher than female counterparts (P < 0.01). The risk of depressive symptoms for female with high demands and low control was about two times as high as that for female workers with low demands and high control for psychological demands and physical demands (OR = 2.0), risk for females was slightly higher than that for males (OR = 2.04 and 2.17, respectively). The risk of depressive symptoms for workers with high efforts and low rewards was about two times as high as that for workers with low efforts and high rewards (OR = 1.70). No interactive effect between gender and job strain and ERI on depressive symptoms were found. CONCLUSION: The gender difference of relationship between depressive symptom prevalence and job strain may due to the difference of psychosocial factors between females and males. There may be no interactive effect between psychosocial factors and gender on depressive symptoms.