[Analysis of monitoring results of occupational hazard factors in workplaces in Zhejiang Province, China in 2006 - 2010].

OBJECTIVE: To analyze the monitoring results of the occupational hazard factors in workplaces in Zhejiang Province, China in 2006 - 2010. METHODS: Descriptive analysis was performed on the monitoring results of the occupational hazard factors in workplaces in Zhejiang Province from 2006 to 2010. RESULTS: From 2006 to 2012, the number of monitored objects for each occupational hazard factor increased gradually, and the qualified rate for each factor remained unchanged or rose slightly. The qualified rates for silica dust and asbestos dust were less than 60%. The qualified rates for benzene, toluene, and xylene, which were always the factors highlighted in the monitoring of toxic chemicals, were all above 85%. The numbers of monitored objects for hexane, hydrogen sulfide, and cyanide grew significantly in recent years. However, the qualified rates for physical factors, which mainly included high temperature and noise, were less than 70%, lower than those for chemical factors. CONCLUSION: The qualified rate is as important as the number of monitored objects in the monitoring of the occupational hazard factors in workplaces in Zhejiang Province, China. The acute and chronic factors, physical and chemical factors, and traditional and new factors should be balanced in monitoring.

[Survey on individual occupational health protection behaviors of welding workers using theory of reasoned action].

OBJECTIVE: To apply theory of reasoned action at survey on welding workers occupational health protection behaviors and explore related influencing factors. METHODS: nine companies were randomly selected from areas with many welding works in Zhejiang Province. All welding workers were surveyed using a questionnaire based on theory of reasoned action. RESULTS: 10.06%, 26.80% and 37.50% of the respondents never or seldom used eyeshade, mask and earplug, respectively. After controlling the socio-demographic factors, welding workers' behavioral belief was correlated with the behaviors of eyeshade-mask and earplug use (χ(2) = 31.88, 18.77 and 37.77, P < 0.01). the subjective norm of company was correlated with all protection behaviors (χ(2) = 20.60, 10.98 and 19.86, P < 0.01), the subjective norm of colleague was correlated with mask and earplug use, (χ(2) = 27.43, 36.39, P < 0.01), and the subjective norm of family was correlated with mask use (χ(2) = 5.73, P < 0.05). CONCLUSION: Theory of reasoned action is suitable for welding worker occupational health related behaviors. It is useful to improve occupational health education, to effectively select health education objective and to tailor health education contents.

[Genotoxicity of organic bentonite particles in vitro].

OBJECTIVE: To study the genotoxicity induced by organic bentonite particles in vitro. METHODS: Human B lymphoblast cells (HMy2.CIR) were exposed to organic bentonite particles at the doses of 0, 1.88, 3.75, 7.50 and 15.00 µg/ml for 24, 48 and 72 h, calcium sulfate (30 µg/ml) and SiO2 (30 and 240 µg/ml) served as negative and positive controls, respectively. The genotoxicity of organic bentonite particles and soluble fraction was detected using comet assay and Cytokinesis-block micronucleus (CBMN) assay. RESULTS: The results of comet assay indicated that % tail DNA increased with the exposure doses and time in organic bentonite group, % tail DNA at the dose of 15.00 µg/ml for 24 h, 48 h and 72 h in organic bentonite group were 3.20 ± 0.19, 4.63 ± 0.88 and 9.49 ± 1.31 respectively which were significantly higher than those in calcium sulfate group (1.40 ± 0.11, 1.37 ± 0.22 and 0.90 ± 0.16) and those in 30 µg/ml SiO2 group (1.83 ± 0.21, 1.41 ± 0.27 and 2.48 ± 0.25) (P < 0.01). The results of CBMN assay showed that micronucleus frequencies (MNF) in organic bentonite group (except for 1.88 µg/ml for 24 h) were significantly higher than those in 30 µg/ml calcium sulfate group (MNF for 24, 48 and 72 h were 1.33‰ ± 0.58‰, 1.33‰ ± 1.15‰ and 1.33‰ ± 0.58‰) and those in 30 µg/ml SiO2 group (2.00‰ ± 0.00‰, 1.68‰ ± 0.58‰ and 2.33‰ ± 0.58‰) (P < 0.01). The results of two assays demonstrated that the soluble fraction of organic bentonite did not induce the genotoxicity. CONCLUSION: The organic bentonite dusts can induce the genotoxicity in vitro, which may be from the particle fraction.

Apoptotic-related protein changes induced by hexavalent chromium in mice liver.

Although it has been reported that hexavalent chromium (Cr(VI)) could induce apoptosis in a variety of cell types, the molecular mechanisms underlying this process is still largely unknown. This study was undertaken to determine effects of single oral 0, 25, 50, and 100 mg/kg body weight doses of potassium dichromate on the expression level of p53, Bcl-2, Bax, cytochrome c, and caspase-3, which are vital regulators of apoptosis, in mice liver. The results showed that Cr(VI) could upregulate the protein expression of p53, Bax, cytochrome c, and caspase-3 and downregulate the expression of Bcl-2 in mice liver. All these results suggested that p53, Bcl-2, Bax, cytochrome c, and caspase-3 may be involved in the regulation of Cr(VI) induced apoptosis in vivo.

[Comparative study of cytotoxicity induced by two kinds of bentonite particles in vitro].

OBJECTIVE: To study comparatively the cytotoxicity induced by acid bentonite and organic bentonite. METHODS: The cytotoxicity of two kinds of bentonite was detected using CCK8 assay, neutral red uptake (NRU) assay, lactate dehydrogenase (LDH) leakage assay, apoptosis assay and hemolysis assay. In hemolysis assay human erythrocytes served as target cells and were exposed to the two kinds of bentonite at the doses of 0, 0.3125, 0.6250, 1.2500 and 2.5000 mg/ml for ten min. In other four assays, human B lymphoblast cells (HMy2.CIR) served as target cells and were exposed to the two kinds of bentonite at the doses of 0, 10, 20, 30, 60, 120 and 180 microg/ml for four h. RESULTS: In hemolysis assay, the hemolysis rates induced by two kinds of bentonite at all doses were significantly higher than that of control (P<0.05); in CCK-8 assay, the cellular activities in acid bentonite group at the doses > or =30 microg/ml and in organic bentonite group at the doses > or =20 microg/ml were significantly lower than that of control (P<0.01); the similar results appeared in NRU assay and LDH assay, and the dose-effect relationship was observed in above 4 assays. In apoptosis assay, the early apoptosis cell rates in acid bentonite group at the dose of 180 microg/ml and in organic bentonite group at the doses of 120,180 microg/ml were significantly higher than that of control (P<0.05). Moreover, the results of five in vitro assays indicated the cytotoxicity induced by organic bentonite was higher than that induced by acid bentonite. CONCLUSION: Two kinds of bentonite could induce cytotoxicity, such as apoptosis and damage of cell membrane. The cytotoxicity of organic bentonite is higher than that of acid bentonite due to the different industrial treatment and characteristics of two kinds of bentonite particles.

Morphological and biochemical changes associated with apoptosis induced by okadaic acid in human amniotic FL cells.

The marine toxin okadaic acid (OA) is an apoptosis inducer and a tumor promoter. During recent years, extensive studies have demonstrated that OA can induce apoptosis in a wide variety of cell types. In contrast to the relatively longer incubation time or higher treatment concentrations of OA in apoptosis shown previously, relatively lower concentrations (

Alteration of proteins expression in apoptotic FL cells induced by MCLR.

Microcystins (MCs) are a family of monocyclic heptapeptide hepatotoxins produced by freshwater species of cyanobacteria. Microcystin-LR (MCLR) is the most frequently studied and most toxic in over 80 MC congeners. Great deals of studies have demonstrated that MCLR can induce apoptosis in a wide variety of cell types. Although much evidence indicates that mitochondria play a pivotal role in MCLR-induced apoptosis, the complicated apoptosis mechanisms induced by MCLR have not been completely characterized. It is possible that there are other apoptotic pathways existing in MCLR-induced apoptosis. The present study was undertaken to determine the expression of PP2A, CHOP, Bax, Bcl-2, and p53 proteins in MCLR-induced apoptosis in FL cells. The results showed that MCLR could induce apoptosis in FL cells and the process was accompanied with the upregulation of PP2A, Bax, and p53 proteins and the downregulation of Bcl-2 proteins. In addition, the CHOP protein was upregulated at most treatment groups and decreased at the highest concentration group. These results, especially the alteration of PP2A and CHOP proteins might provide new insights into MCLR-induced apoptosis.

Oral administration of Cr(VI) induced oxidative stress, DNA damage and apoptotic cell death in mice.

Potassium dichromate (Cr(VI)) was given orally to Swiss mice for 1 and 5 days with the dose of 25, 50 and 100 mg/kg body weight per day, respectively. Oxidative stress including the level of reactive oxygen species (ROS), the extent of lipid peroxidation and the activity of antioxidant enzymes in liver and kidney was determined. DNA damage in peripheral blood lymphocytes was determined by single-cell gel electrophoresis (comet assay). Apoptotic cell death in liver was detected using transmission electron microscopy and TUNEL assay. The results indicated that administration of Cr(VI) had caused a significant increase of ROS level in liver both after 1 and 5 days of exposure, accompanied with a dose-dependent decrease in superoxide dismutase (SOD) and catalase (CAT) activities. The malondialdehyde (MDA) content in liver was not changed as compared to the control animals. In contrast to the liver, no significant changes were observed in kidney on ROS, SOD, CAT and MDA as compared to the control animals. Dose- and time-dependent effects were observed on DNA damage after 1 and 5 days treatment. Significant difference was observed on the number of TUNEL positive liver cells between the control and Cr(VI) treatment groups. The apoptotic cells were also identified by characteristic ultrastructural features. The results obtained from the present study showed that Cr(VI) given orally to mice could induce dose- and time-dependent effects on DNA damage, hepatic oxidative stress and hepatocytes apoptosis. No significant oxidative stress observed in kidney in the study may suggest that the way of Cr(VI) exposure is an important factor affecting its toxicity.