Ho-Yuan Chang

Effect of smoking on blood lead levels in workers and role of reactive oxygen species in lead-induced sperm chromatin DNA damage.

OBJECTIVE To investigate whether cigarette smoking affects the blood lead levels (BLL) and whether exposure to lead introduces sperm chromatin DNA damage in factory workers. DESIGN Cross-sectional study. SETTING A battery plant in Taiwan. PATIENT(S) Eighty male workers employed within a battery plant. INTERVENTION(S) Standard semen analysis was performed according to the World Health Organization guidelines. MAIN OUTCOME MEASURE(S) Assessment of BLL, sperm chromatin DNA structure, reactive oxygen species generation and other conventional parameters of semen quality. RESULT(S) As compared with nonsmoking workers, the BLL were found to be considerably higher among smokers. Statistically significant differences were found in the sperm DNA denaturation (alphaT) induction and the percentage of sperm with increased DNA denaturation (COMP alphaT) in workers with moderate BLL (>or=25 microg/dL). After adjustment for smoking propensity, a positive correlation was discernible between BLL and alphaT, COMP alphaT, and morphologic abnormality. Furthermore, alphaT and COMP alphaT were also found to have positive correlations with sperm superoxide anion production. CONCLUSION(S) Workers with higher BLL were found to be at a higher risk of sperm morphologic abnormality and chromatin DNA integrity. These data are significant because they can facilitate the estimation of lead exposure in reproductive toxicology.

Total body burden arising from a week's repeated dermal exposure to N,N-dimethylformamide

Background: Hazardous chemicals and their metabolites may accumulate in the body following repeated airborne exposures and skin contact. Aims: To estimate the contribution of skin absorption to total body burden of N,N-dimethylformamide (DMF) across a working week in two groups with similar levels of respiratory exposure but dissimilar skin contact. Methods: Twenty five workers in a synthetic leather (SL) factory, 20 in a copper laminate circuit board (CLCB) factory, and 20 age and sex matched non-DMF exposed subjects, were recruited. Environmental monitoring of DMF exposure via respiratory and dermal routes, as well as biological monitoring of pre-shift urinary N-methylformamide (U-NMF), were performed for five consecutive working days. Results: Environmental and biological monitoring showed no detectable exposure in controls. The average airborne DMF concentration (geometric mean (GM) 3.98 ppm, geometric standard deviation (GSD) 1.91 ppm), was insignificantly lower for SL workers than for CLCB workers (GM 4.49, GSD 1.84 ppm). Dermal DMF exposure and U-NMF values, however, were significantly higher for SL workers. A significant pattern of linear accumulation was found across a five day work cycle for SL workers but not for CLCB workers. Conclusions: Dermal exposure to DMF over five consecutive days of occupational exposure can result in the accumulation of a significant DMF body burden. The long term exposure response under both repeated and intermittent conditions of substantial skin exposure is worthy of note.

Evaluation of the protective effectiveness of gloves from occupational exposure to 2-methoxyethanol using the biomarkers of 2-methoxyacetic acid levels in the urine and plasma

Aims: To evaluate the protective effectiveness of gloves from occupational exposure to 2-methoxyethanol (2-ME); and to examine the association of 2-methoxyacetic acid (MAA) in urine and plasma collected simultaneously from low 2-ME exposure and high 2-ME exposure workers in a semiconductor copper laminate circuit board manufacturing plant. Methods: Eight hour time weighted breathing zone monitoring was performed to verify the 2-ME exposure classification between workers in regular and special operations. Urine and plasma samples were simultaneously collected from 74 exposed and 80 non-exposed workers. MAA concentrations in the urine (UMAA) and plasma (PMAA) were measured using previously published methods. Three types of gloves worn by workers (cotton, rubber, and no gloves) were recorded by direct observations in the workplace and validated by person-to-person interview. Protective effectiveness indices (PEI) were used to evaluate the glove effectiveness. Results: There was no detectable 2-ME/MAA in the air, or in urine and plasma samples in non-exposed workers. The average UMAA and PMAA in special operations were 72.63 mg/g Cr. and 29.72 mg/l, significantly higher than values in regular operations (5.44 mg/g Cr. and 2.58 mg/l, respectively). PMAA showed satisfactory correlation to UMAA in all participants from both regular and special operations. The rubber gloves provided significant reduction in 2-ME uptake, whereas cotton gloves provided little protection with fluctuating effectiveness, based on PEI estimates. Conclusions: PMAA, similar to UMAA, could serve as a specific biomarker for 2-ME exposure. Wearing impermeable rubber gloves during high risk tasks can reduce major 2-ME exposure. Other improvements, including engineering control, should be provided to diminish worker exposure to 2-ME in occupational environments.

Dopamine transporter binding study in differentiating carbon disulfide induced Parkinsonism from idiopathic Parkinsonism

Long-term exposure to carbon disulfide (CS(2)) may induce parkinsonian features. There may be confusion in distinguishing between CS(2) parkinsonism and idiopathic parkinsonism, especially for workers who developed parkinsonian features in viscose rayon plants. We performed clinical examinations, and laboratory studies including magnetic resonance imaging (MRI) and dopamine transporter (DAT) studies with (99m)Tc-TRODAT-1 brain single photon emission computed tomography (SPECT) in three workers who had long-term exposure to CS(2). Patient 1 had polyneuropathy, and encephalopathy with tremor; patient 2 had polyneuropathy, and encephalopathy with parkinsonian features; and patient 3 had pure parkinsonian features without polyneuropathy or cerebellar signs. The treatment with l-dopa was effective in patient 3, but non-effective in patient 2. Brain MRI revealed multiple high signal intensities over the subcortical white matter, basal ganglia, and/or even the brainstem in patients 1 and 2, but normal in patient 3. In DAT studies, the bindings were normal in patients 1 and 2 and was decreased in patient 3. We conclude that CS(2) exposure may induce polyneuropathy, and cerebellar dysfunction in addition to parkinsonian features and that brain MRI may show multiple lesions in the cerebral white matter and basal ganglia. In addition, DAT with (99m)Tc-TRODAT-1 brain SPECT may provide a useful information in differential diagnosis between CS(2) parkinsonism and idiopathic parkinsonism.

Elevated triglyceride and decreased high density lipoprotein level in carbon disulfide workers in Taiwan

Carbon disulfide (CS2) is a man-made product utilized primarily in the manufacture of viscose rayon. Overexposure to CS2 has been associated with an increase in coronary heart disease. The aims of this study were to examine the dose-response relationship of CS2 exposure and elevated lipid profile tests among CS2-exposed workers in Taiwan. A total of 132 workers were recruited from two viscose rayon plants. Air sampling was performed to determine the CS2 exposure of workers. Demographic data and work history were gathered by a standard self-administered questionnaire. Lipid profile tests were also performed by routine methods. The average CS2 exposure concentration was 50.6 ± 25.6 ppm (range: 24–127 ppm) in the high-exposure group, 12.9 ± 5 ppm (range: 5.2–22.3 ppm) in the mid-exposure group, and 3.5 ± 1.2 ppm (range 0.97–5.2 ppm) in the low-exposure group. There were 21 out of 33 (63.7%) elevated triglyceride levels among high-CS2-exposure workers, 27 out of 64 (42.2%) among the middle-CS2-exposure, and 14 out of 35 (40%) among low-CS2-exposure workers, respectively. Compared to the low-CS2-exposure workers, the age- and weight-adjusted odds ratios (and 95% confidence intervals) of the prevalence of elevated triglyceride value were 1.12 (0.5, 2.7) for middle-CS2-exposure workers, and 2.81 (1.02, 7.8) for high-CS2-exposure workers. There was a significant linear trend between CS2 exposure and the prevalence of elevated triglyceride value (P = 0.046) after adjusting for other factors. There was also a lower prevalence of elevated HDL level in high-CS2-exposure workers than low-CS2-exposure workers (15.2% versus 31.4%). Compared to the low-CS2-exposure workers, the age- and weight-adjusted odds ratio (and 95% confidence intervals) of elevated HDL level were 0.34 (0.1, 1.18) for high-CS2-exposure workers, which was borderline significant. In conclusion, this study suggests that elevated triglyceride level and decreased HDL level are associated with CS2 exposure. The study also suggests that exposure to CS2 (concentration >23.2 ppm, which was above the current TLV-TWA of 10 ppm) are significantly associated with increased risk and decreased protective effect for coronary heart disease.

Effect of hand dermatitis on the total body burden of chromium after ferrous sulfate application in cement among cement workers

Background:  Ferrous sulfate (FeSO4) added to cement has been used to reduce the prevalence of dermatitis in workers. However, the effect of dermatitis on the total uptake of chromium in cement with or without FeSO4 has not been previously explored.

Biological monitoring of carbon disulphide: kinetics of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) in exposed workers

The objectives of this study was to establish the kinetics of urinary 2-thiothiazolidine-4-carboxylic acid (UTTCA) for workers exposed to carbon disulphide (CS2) and to investigate the effects of volume and creatinine adjustment methods for urine measurement. Ten workers in the spinning department of a rayon factory were individually monitored for airborne CS2 concentrations, with consecutive urine samples collected for 24-38 hours after termination of exposure. The U-TTCA, urine volume and creatinine level were measured for each sample. First-order and biphasic kinetics were determined using the curve-fit method, for the measurement series. For the first-order kinetics linearity fit, statistically significant correlation coefficients of 0.74-0.98 and 0.86-0.99 were derived for the volume- and creatinine-adjusted methods, respectively. For the biphasic kinetics approach, the overall correlation coefficients were 0.544-0.999 and 0.171-0.999 for the first and second phases of the creatinine-adjusted method, respectively. A post-shift U-TTCA of 3.0 mg/g Cr. equivalent, 40% below the current BEI setting at nearly PEL exposed level, was found. In conclusion, first-order kinetic response was confirmed for U-TTCA. Both volume- and creatinine-based urine adjustment are satisfactory for TTCA assessment as a biomarker of individual CS2 exposure although the correlation for creatinine-based measurement was modestly superior to the volume-based analogue. Based on the results of this study, we recommend a re-evaluation of the current biological exposure index of 5 mg/g creatinine at a CS2 exposure level of 10 ppm.

Evaluation of current biological exposure index for occupational N,N-dimethylformamide exposure from synthetic leather workers

The aim of this study was (1) to investigate the correlation between external exposure to N, N-dimethylformamide (DMF) and urinary excretion of DMF and N-methylformamide; (2) to assess whether the correspondence between the current occupational exposure limit setting and recommended urinary biological exposure index is substantial; and (3) to evaluate whether coexposure to toluene, methyl ethyl ketone, and ethyl acetate has an effect on urinary excretion of DMF and N-methylformamide (NMF). Urinary DMF and NMF were significantly correlated (P < 0.01) with one another and also significantly correlated with airborne DMF (P < 0.01) over the range of 1.55 to 152.8 mg/m3. Urinary DMF can be considered a complementary marker for short-term exposure. Urinary concentration of NMF and DMF, corresponding to the 8-hour exposure to airborne DMF at 30 mg/m3, was estimated to 38.4 mg/L or 39.4 mg/g creatinine for NMF and to 0.92 mg/L or 0.96 mg/g creatinine for DMF.

Using urine specific gravity to evaluate the hydration status of workers working in an ultra-low humidity environment

Using Urine Specific Gravity to Evaluate the Hydration Status of Workers Working in an Ultra‐Low Humidity Environment: Shih‐Bin SU, et al. Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Taiwan—In environments with ultra‐low humidity, workers may have excessive body water loss due to evaporation through the skin, which can lead to dehydration. Before the development of clinical symptoms and signs, concentrated urine may be applied as an early indicator of dehydration. We used urine specific gravity (USG) as a biomarker to evaluate the hydration status of workers working in such an environment. We collected the urine samples from workers at a lithium battery plant during their annual health examination, and the relative humidity of some working areas called “dry rooms” in the plant was 1.5 ± 1%. We recruited workers in those dry rooms as the exposure group (N=50) and defined the remaining workers, including administration office workers, as the comparison group (N=122). The prevalence of abnormally concentrated urine (USG>1.030) and related factors were compared between these two groups. While the exposure group were younger and had shorter employment durations compared to the comparison group (p<0.05), they had a higher prevalence of abnormally concentrated urine (p<0.01). After adjusting for age, gender, employment duration, and body surface area, we found that working in the dry rooms was associated with an odds ratio of 11.9 (95% confidence interval: 2.5 to 56.9) of having abnormally concentrated urine. Therefore, USG is a good biomarker for evaluating the hydration status of workers working in ultra‐low humidity environments, who need proper protection and adequate fluid supply to prevent excess water loss and its adverse health effects.

Microwave-assisted acid hydrolysis of toluene diamine conjugates in urine samples for biomarkers in toluene diisocyanate analysis

Toluene diamines (TDAs) in urine have been used widely to determine the amount of toluene diisocyanate (TDI) absorbed by humans. Conventional hydrolysis to prepare a sample of urine takes approximately 16h. An attempt is made to apply microwave-assisted heating (MAH) to reduce the duration of analysis. Urine collected from rats exposed to a mixture of 2,4- and 2,6-TDI was diluted with non-exposed human urine 1/1250-, 1/500- and 1/250-fold. The urine samples were hydrolyzed by both conventional heating and MAH. The hydrolysis efficiency obtained using MAH significantly exceeded that obtained using conventional heating. Hydrolysis by MAH required only 20min, 48 times faster than with conventional heating. The use of the MAH method in hydrolysis was demonstrated to be reproducible, timesaving and efficient technique in measuring the concentration of urinary TDAs.