Occupational hand dermatitis among cement workers in Taiwan.

BACKGROUND/PURPOSE: Occupational dermatitis among cement workers is a major occupational health concern. The two most important occupational hazards for cement workers are irritant and allergic cement contact dermatitis. The objective of this study was to investigate the severity of occupational cement contact dermatitis and the common allergens among cement workers in Taiwan. METHODS: A total of 97 cement workers from the Cement Workers' Association of Tainan City and County participated in this study. A structured questionnaire was used to evaluate the demographic data and work-related activities of these cement workers. A complete skin examination was conducted, and skin manifestations were assessed by a dermatologist. Allergens from European Standard Tray (Chemotechnique Diagnostic AB, Sweden) with a total of 25 substances were used for patch testing. RESULTS: Our results showed that 65 out of 97 cement workers were suffering from occupational cement hand contact dermatitis. The most affected skin area was the hand. Thickening of the dorsal surface of the hand, especially around the metacarpophalangeal joint area, and hyperkeratosis of the palm were the major skin manifestations. The results of the patch test showed that 24 out of 97 were allergic to potassium dichromate, nine were allergic to thiuram mix, nine were allergic to fragrance mix and seven were allergic to cobalt chloride. The final diagnosis, based on the results of the skin examination and the patch test, showed that 43 of 97 cement workers had irritant cement contact dermatitis and 22 had allergic cement contact dermatitis. CONCLUSION: We conclude that occupational cement hand dermatitis among cement workers is an important and severe issue in Taiwan, and the most common allergens among cement workers are potassium dichromate, thiuram mix, fragrance mix and cobalt chloride. The high positive rate of chromium hypersensitivity among cement workers reflects the urgency to regulate the addition of ferrous sulfate to cement in Taiwan.

N-acetylcysteine inhibits chromium hypersensitivity in coadjuvant chromium-sensitized albino guinea pigs by suppressing the effects of reactive oxygen species.

BACKGROUND: Chromium hypersensitivity is an important issue in occupational skin disease. When hexavalent chromium enters the cell, it can be reduced to trivalent chromium, resulting in the formation of reactive oxygen species (ROS). ROS are considered to play an important role in the progression of allergic contact dermatitis. N-acetylcysteine (NAC) could increase glutathione levels in the skin and act as an antioxidant. AIMS: We attempted to demonstrate that NAC could inhibit chromium hypersensitivity in a coadjuvant chromium-sensitized albino guinea pig model by counteracting the formation of ROS. METHODS: We utilized a coadjuvant chromium-sensitized albino guinea pig model to evaluate both the severity of the skin reaction by intradermal and epicutaneous elicitation tests and the sensitization rate of chromium hypersensitivity in NAC-treated and NAC-untreated albino guinea pigs (GP). Furthermore, three ROS parameters, including H(2)O(2,) malondialdehyde (MDA) levels in the skin and the oxygen radical absorbance capacity (ORAC) in plasma, were analyzed in NAC-treated and NAC-untreated coadjuvant chromium-sensitized albino GP. RESULTS: The severity of the skin reaction in the intradermal and epicutaneous elicitation test significantly diminished when the albino GP were treated with a dose of 1200 mg/kg/day of NAC. This dose also significantly decreased the sensitization rate of chromium hypersensitivity. In addition, treatment with 1200 mg/kg/day of NAC significantly reduced the H(2)O(2) and MDA levels in the skin and significantly increased the ORAC in the plasma of albino GP. Therefore, NAC could be a potential chemopreventative agent to prevent the progression of chromium hypersensitivity.

Assessment of airborne and dermal exposure to 2-ethoxyethyl acetate in an occupational environment.

BACKGROUND: Because of its chemical-physical properties, 2-ethoxyethyl acetate (EEAc) can penetrate through the skin. However, no actual occupational environmental studies or empirical dermal exposure measurements have been performed. METHODS: Twenty workers from a commercial label silk screening shop were recruited and they completed a questionnaire of demographic information. Environmental monitoring of EEAc exposure via respiratory and dermal routes was performed for five consecutive working days. RESULTS: Airborne EEAc concentration was over the permissible exposure limit of 5 ppm in 90% of the participants. The dermal EEAc concentration was highest on the palms. The EEAc concentration correlated with skin exposure level (P < 0.001). The dermal EEAc concentrations in individuals who did not wear gloves were higher than in those who wore gloves. CONCLUSIONS: EEAc on the skin is strongly associated with airborne EEAc. Wearing impermeable gloves during high-risk tasks (cleaning process) can reduce EEAc dermal exposure on the palms.

Asthma-like syndrome in school children after accidental exposure to xylene and methylene diphenyl diisocyanate.

BACKGROUND AND PURPOSE: We assessed the signs and symptoms, pulmonary function changes and residual chemical body burden of school children in the vicinity of an accidental exposure to volatile xylene and methylene diphenyl diisocyanate (MDI). METHODS: After the exposure episode, children with significant symptoms after MDI exposure (e.g., dizziness, nausea, sore throat, and breathing difficulties) were sent to nearby emergency medical units for evaluation and admission if necessary. Clinical work-up included pulmonary function tests and measurement of residual MDI in the body by high-performance liquid chromatography analysis of urine. RESULTS: 203 students appeared to develop symptoms associated with contaminant exposure, and 173 affected students were sent to nearby emergency units. In the subsequent surveillance, 22 of 203 affected students (10.8%) revealed a positive history of asthma, which was strongly correlated with the incidence of dyspnea arising from the incident. For children with no previous history of asthma, 60.8% (110 of 181) complained of dyspnea during the episode, and 16.2% required inhaled bronchodilator therapy at the emergency medical units for relief of wheezing symptoms. In a simulation, we found the raw material used for tract surfacing, primarily MDI dissolved in xylene, to be present at a concentration (870 ppm w/w) more than 8000-fold the level defined as safe for a working environment. CONCLUSIONS: We have detected a direct cause-effect relationship between the accidental spillage of MDI and the appearance of an acute asthma-like syndrome among previously unexposed school children.

The total body burden of chromium associated with skin disease and smoking among cement workers.

BACKGROUND: Hand eczema and other skin diseases have been associated with the exposure of chromium among cement workers. Studies on skin disease and other factors associated with the body burden of chromium are limited. OBJECTIVE: The present study investigated the role of skin disease and smoking in the association with body burden of chromium among cement workers. METHODS: Forty-five workers (38 men and 7 women) were recruited for this study and interviewed to obtain information on demographic status, lifestyle, employment history, and affecting factors. Urine samples were collected to measure the urinary chromium concentration to represent the body burden of chromium. RESULTS: The average urinary chromium concentration was approximately 6 times higher in non-smoking workers with hand eczema than in non-smoking workers with no skin disease (45.5 vs. 7.6 microg/L). The average chromium level increase to 87.0 microg/L for smokers with the disease. Compared with workers with no hand eczema, the odds ratio of having urinary chromium concentration exceeding the biological exposure index level significantly increased to 11.6 (95% CI=1.3-102.2) for non-smoking workers with skin disease, and to 48.0 (95% CI=4.5-510.8) for smoking workers with skin disease. The multiple regression analysis showed that the use of gloves may reduce significantly the chromium exposure. CONCLUSIONS: Inadequate protection and personal behavior increase the internal dose of chromium in cement workers. Total body burden of chromium are higher among cement workers with skin disease and smoking habit. These workers deserve intervention education on personal hygiene to reduce the exposure of chromium.

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

BACKGROUND: Ferrous sulfate (FeSO(4)) 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 FeSO(4) has not been previously explored. OBJECTIVE: The objective of this study was to compare the urinary chromium levels before and after FeSO(4) addition among cement workers with or without hand dermatitis. METHODS: Thirty-five male workers were recruited in this study for two consecutive years: 2003 without using FeSO(4) and 2004 after adding FeSO(4). Urinary chromium was used as a biomarker to estimate the total body burden of chromium. RESULTS: Urinary chromium concentration showed significant decreases after FeSO(4) was used, and a larger decrease of urinary chromium was observed in workers with hand dermatitis than for those without hand dermatitis. Moreover, a significant decrease of urinary chromium was observed in workers with hand dermatitis in both 2003 and 2004. CONCLUSION: FeSO(4) decreases the total body burden of chromium, especially in workers with severe and continuous hand dermatitis.

Mitochondrial DNA alterations in blood of the humans exposed to N,N-dimethylformamide.

N,N-Dimethylformamide (DMF) has been widely used in industries because of its extensive miscibility with water and solvents. Its health effects include hepatotoxicity and male reproductoxicity, possibly linked with mitochondrial DNA (mtDNA) alterations including mtDNA common deletion (DeltamtDNA(4977)) and mtDNA copy number. The relationship between DMF exposure and mtDNA alterations, however, has not been postulated yet. The purposes of this study were to investigate whether the DMF exposure is associated with DeltamtDNA(4977) and mtDNA copy number and to evaluate the DMF-derived mtDNA alterations are more associated with exposure to the airborne DMF concentrations or to the levels of two urinary DMF biomarkers of N-methylformamide (NMF) and N-acetyl-S-(N-methylcarbamoryl) cysteine(AMCC). Thirteen DMF-exposed workers and 13 age and seniority-matched control workers in a synthetic leather factory were monitored on their airborne DMF, NMF and AMCC in the urine as well as DeltamtDNA(4977) and mtDNA copy number in blood cells. We found that the frequencies of relative DeltamtDNA(4977) in DMF-exposed group were significantly higher than those in the control group. Moreover, elevation in the proportion of DeltamtDNA(4977) of individuals with high urine AMCC (U-AMCC) and airborne DMF levels were significantly higher than those without. We conclude that long-term exposure to DMF is highly associated with the alterations of mtDNA in urine and blood cells. The DeltamtDNA(4977) was more significantly related to repeated exposure to DMF and mtDNA copy number was more closely related to short-term DMF exposure. We also confirmed that U-AMCC is more appropriate to serve as a toxicity biomarker for DMF exposure than U-NMF. Further study with a larger number of subjects is warranted.

Combining novel strategy with kinetic approach in the determination of respective respiration and skin exposure to N,N-dimethylformamide vapor.

N,N-dimethylformamide (DMF) could be readily absorbed via skin and inhalation routes. It is difficult, however, to separate the internal dose contribution from skin vapor and inhalation exposure. This study attempts to quantitatively determine the separate skin vapor and inhalation exposure contributions using a semi-actual exposure approach. Six volunteers were tailgated by DMF-exposed employees completely for two exposure scenarios: with and without wearing a respirator. Individual airborne DMF (A-DMF) exposure was evaluated by integrating real-time DMF monitoring and time-activity log. Urinary N-methylformamide (U-NMF) concentrations in 4-h and 8-h one urine sample plus 24-h consecutive urine sample were determined to evaluate the internal DMF exposure dose. The average A-DMF concentrations for all participants were 8.10 (2.75) and 9.52 (3.47) ppm, respectively, for with respirator and without respirator scenarios. Area under the curve of U-NMF throughout 24-h showed 71% and 29% contribution from skin and inhalation exposure, respectively, indicates that the absorbed dose of DMF via skin vapor exposure was much greater than inhalation. In conclusion, the semi-actual approach provides a novel measure to accurately determine the relative skin vapor and inhalation exposure contributions to the internal dose. The skin vapor exposure deserves more attention in the prevention of chemical hazards in the exposed environment.

Hematological follow-up of an intervention program adding rubber glove-wearing to local ventilation for 2-ethoxyethanol acetate-exposed workers.

The objective of this study was to evaluate an intervention program, implemented in year 1999, of wearing rubber gloves in addition to engineering control, and to follow-up the hematological effects of 2-ethoxyethanol acetate (2-EEA) exposure among workers in a silk-screening factory. All workers from the printing department with direct exposure to 2-EEA were recruited as the exposed group. Workers from the other departments were recruited as the comparison group. Hematological parameters were measured during health surveys conducted 3 times every two years. Information on personal characteristics and working habits was obtained through a structured questionnaire. More female workers were involved in manual printing resulting in higher exposure to 2-EEA. Hemoglobin and haematocrit levels in female exposed workers were significantly lower than those of female comparison workers in the 1st (1998) health survey, but not in the 2nd (2000) and 3rd (2002) health surveys. No difference was found between male exposed and comparison workers for all three surveys. Longitudinal analysis after adjusting for confounders using the general estimating equation model showed the hemoglobin, haematocrit, and RBC count were significantly higher for 2-EEA exposed workers than comparison workers across the 3 surveys (n=42). The results show that wearing rubber gloves in addition to local ventilation was effective at preventing direct dermal exposure to 2-EEA and ameliorated the hematological effects of 2-EEA exposure.

Electrocardiographic abnormality for workers exposed to carbon disulfide at a viscose rayon plant.

OBJECTIVE: This study investigated electrocardiography (ECG) manifestations for male workers with carbon disulfide exposure at rayon manufacturing plants. METHODS: A total of 251 men in the exposure group and 226 administrative clerks in the reference group received physical examinations and completed questionnaires. RESULTS: The prevalence of ECG abnormalities was much higher in the carbon disulfide exposure group (25.9%, n = 65) than in the reference group (2.7%, n = 6), with an odds ratio (OR) of 12.8 (95% confidence interval [CI] = 5.4-30.2). The foremen were at the highest risk of abnormal ECG (OR = 20.6, 95% CI = 6.5-65.2), followed by filament-spinning workers (OR = 14.2, 95% CI = 5.7-35.3), viscose-manufacturing workers (OR = 11.3, 95% CI = 4.3-30.1), and carbon disulfide-manufacturing workers (OR = 8.1, 95% CI = 2.7-25.6). The multivariate logistic regression analysis based on cumulative exposure index also showed a dose-response relationship with the exposure, and the risk of ECG abnormality could be initiated at the exposure history of 31 to 57 year-ppm with an OR of 7.2 (95% CI = 1.5-36.7). CONCLUSIONS: In general, the ECG abnormalities observed in workers at the permissible exposure level of carbon disulfide implicate the importance of environmental control of the chemical and of workers' education in exposure prevention at work.

Human PCDD/PCDF levels near a pentachlorophenol contamination site in Tainan, Taiwan.

A pentachlorophenol (PCP) manufacturing plant in southern Taiwan discontinued production in 1989. The site of the abandoned plant was heavily contaminated by PCDD/PCDFs, impurities formed in the PCP production process. Serum samples collected from 27 residents living near the deserted plant were evaluated to determine whether this contamination had associated serum levels of PCDD/PCDFs in local residents. The average level of 17 tested congeners ranged from 556 to 5240 pg/g lipid (mean, 1670 pg/g lipid). The corresponding 2,3,7,8-TCDD toxicity equivalent quotient values calculated by international toxicity equivalent factors (I-TEFs) and those recommended by WHO (WHO-TEFs) were 47.2 pg I-TEQ/g lipid and 53.4 pg WHO-TEQ/g lipid, respectively. Levels in other parts of Taiwan typically range from 15 to 20 pg WHO-TEQ/g lipid; therefore, it is likely that the heavily contaminated plant site caused these unusually high serum levels. The average PCDD/PCDF levels of 29 fish-tissue and nine soil samples collected from the sea reservoir surrounding the abandoned PCP plant were also abnormally high: 8630 pg/g lipid (985 pg WHO-TEQ/g lipid) and 606000 pg/g-sample (922 pg WHO-TEQ/g-sample), respectively. Factor analysis indicated that the congener pattern of human serum samples collected from residents living near the abandoned PCP plant different from samples collected from other areas in Taiwan without known PCDD/PCDF pollution. Similar results were observed for the fish tissue and soil samples. The current study may have discovered a "hot spot" for elevated dioxin human exposure in Taiwan. The preliminary finding has raised a public health concern in the inspected area and requires further investigations to clarify the nature of the contamination and potential impact on the local environment and human health.

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

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.

Transepidermal water loss and skin capacitance alterations among workers in an ultra-low humidity environment.

No studies have been performed evaluating skin barrier alterations in humans exposed to ultra-low humidity (ULH) in spite of several lines of evidence from animal experiments suggesting that the skin barrier is altered on exposure to ULH. The objectives of this study were to assess barrier function changes in workers occupationally exposed to ULH (relative humidity 1.5%), and to evaluate whether the exposure duration shows a dose-response relationship with transepidermal water loss (TEWL) and skin capacitance. A total of 49 male workers exposed to ULH for 12 h per working day were classified into five subgroups based on their ULH exposure duration (<0.5 months, 0.5-1.0 month, 1.1-10.0 months, 10.1-20.0 months, and >20.0 months). A group of 12 age-matched male laboratory workers from a normal humidity environment were recruited as a control group. TEWL and skin capacitance were measured to evaluate their skin barrier function. TEWL measurements showed a significant decline (8.3+/-0.4 vs 10.0+/-0.4 g m(-2) h(-1), P < 0.05) but no differences were found in skin capacitance (39.7+/-1.3 a.u. vs 45.0+/-2.4 a.u., P = 0.68) between the whole ULH exposure group and the control group. Maximum decreases in TEWL and skin capacitance were seen in the subgroups exposed for <0.5 months and 0.5-1.0 month, respectively. Almost completely natural recovery occurred in skin capacitance after 20 months ULH exposure, in contrast to less than 90% recovery in TEWL. Three stages were defined according to the pattern of alterations in TEWL and skin capacitance in relation to ULH exposure duration. A positive association between TEWL and skin capacitance occurred in the control group and stage I but a negative correlation in stage II. No correlation was found in stage III. Our study demonstrated that workers exposed to a ULH environment could exhibit skin barrier alterations. Both TEWL and skin capacitance decreased within 2 weeks of ULH exposure. The maximum alterations in TEWL and skin capacitance occurred during 0.5-1.0 months and 2 weeks, respectively. TEWL recovered partially and more slowly than skin capacitance which recovered earlier and almost completely.

Topical exposure to carbon disulfide induces epidermal permeability alterations in physiological and pathological changes.

Carbon disulfide (CS2) has been suggested its possible skin toxicity. Neither a dose-response relationship nor any mechanism of CS2-exposure regarding epidermal permeability alterations has been postulated. The objectives of this study were to evaluate the dose-dependent association and the pathological changes with CS2 topically applied to mouse epidermis. Four concentrations of CS2 (0% (controls), 10%, 15%, and 20% in ethanol) were topically applied to a 1.8 cm2 area of the lateral abdomen of female nude mice for 10 min. Time-series transepidermal water loss (TEWL) profile, morphological examinations by both light microscopy (hematoxylin/eosin stain and Nile Red stain) and electronic microscopy, and lipid analysis by high performance thin-layer chromatography (HPTLC) were used to evaluate the epidermal impairment. We found no recovery occurred within 72 h exposure to 20% CS2 in contrast to substantial recovery found in 10% and 15% CS2-exposure. Clear dose-dependent fashions were shown in TEWL elevations, recovery retardation, and lipid extraction across the ethanol (control), 10%, 15%, and 20% CS2 exposures. Two mechanistic pathways were raised to account for CS2-induced epidermal alterations: intercellular lipid depletion and keratinocyte damage. A study with different test animal species is warranted owing to the discrepancies in epidermis between nude mice and other species.

The effects of simultaneous exposure to methyl ethyl ketone and toluene on urinary biomarkers of occupational N,N-dimethylformamide exposure.

General regulations and risk assessment regarding toxicants are single-compound oriented even though humans are exposed to multi-chemicals in the general environment. This study investigated the effects of different levels of N,N-dimethylformamide (DMF) and co-exposure levels of methyl ethyl ketone (MEK) and toluene (TOL) on two biomarkers of DMF exposure: non-metabolized urinary (U-)DMF and the DMF metabolite urinary N-methylformamide (NMF). Thirty-five workers were selected from a two-stage field investigation strategy and were classified into four groups based on DMF exposure and co-exposure levels. Breathing-zone air concentrations of DMF, MEK, and TOL as well as dermal DMF exposure were determined. Post-shift U-DMF and U-NMF levels were determined for each individual. U-DMF concentrations were significantly higher in high-DMF groups than in low-DMF groups, but U-NMF concentrations were significantly (P<0.05) lower in the high-DMF-high-co-exposure group than in the high-DMF-low-co-exposure group; there were no significant differences between two low-DMF groups. The ratio of U-NMF to U-DMF showed the biotransformation from DMF to NMF was significantly suppressed at high co-exposure (P<0.001) for high-DMF exposure groups, possibly because of competitive inhibition of CYP2E1, the responsible enzyme involved. Due to the ubiquity of MEK/TOL in DMF-exposed occupational settings, the biological exposure index for occupational DMF exposure should be re-evaluated at high co-exposure levels.

Serum concentrations and profiles of polychlorinated biphenyls in Taiwan Yu-cheng victims twenty years after the incident.

In 1979, about 2000 people in central Taiwan were intoxicated via rice oil consumption that was contaminated with polychlorinated biphenyls (PCBs). This "Yu-cheng" incident was one of the two known major human PCB intoxication episodes. Twenty years after the intoxication, serum samples of 435 Yu-cheng victims, 414 adults and 21 children, were collected. Sixteen PCB congeners were analyzed with a gas chromatograph-electron capture detector. We found the median concentration of total PCBs in the adult serum was 1500 ng/g lipid, still substantially higher than that of the general population in Taiwan (3.7-fold) and most seafood consumers in the world. Most of analyzed PCB congeners in children were below or around the detection limits. Congener #138, however, had the highest concentrations, approximately accounting for 55% and 29% in the child and adult groups, respectively. Given that PCBs are persistent organic pollutants and endocrine disruptors, the concentrations and congener-specific profiles regarding the Yu-cheng victims provide valuable information for the investigation of such chemicals in humans.

Narrow-band UVB treatment of vitiligo in Chinese.

Narrow-band ultraviolet B (NBUVB) phototherapy has recently been reported to be an effective and safe treatment modality for vitiligo. In the present report, we evaluated the efficacy and safety of NBUVB therapy for vitiligo in Chinese patients. Seventy-two vitiligo patients treated from 2000 to 2003, were included retrospectively (male: female=33:39, mean age: 38.5). Among them, 61 were non-segmental type and 11 the segmental type. Treatments were given two to three times a week for a maximum period of one year with an initial dose of 0.2 J/cm2 and a 0-20% increment each session (mean accumulation dose: 155.3 J/cm2). Computer image analysis by Supervise classification was used to estimate the area of vitiligo involvement before and after treatment. An excellent response (75-100% area of repigmentation) was obtained in 9 patients (12.5%) and a good response (50-75%) in 24 (33.3%), a moderate response (25-50%) in 20 (27.8%), and a poor response (0-25%) in 19 (26.4%). In summary, 45.8% of our patients had more than 50% repigmentation. Burns were a side effect in 5 patients (7%) and transient erythema with itching or xerosis was noted in 5 patients (7%). These results indicate that NBUVB phototherapy is an effective and safe treatment choice for generalized vitiligo.

Hearing loss in workers exposed to carbon disulfide and noise.

Simultaneous exposure to carbon disulfide and noise may have a combined effect on hearing impairment. In this study we investigated hearing loss in 131 men with exposure to noise [80-91 A-weighted decibels; dB(A)] and CS(2) (1.6-20.1 ppm) in a viscose rayon plant. These men were compared with 105 men in the adhesive tape and electronic industries who were exposed to noise only and with 110 men employed in the administrative office of the rayon plant who were exposed to low noise and no CS(2). We conducted interviews to obtain sociodemographic information and exposure assessments, and we performed physical examinations, including hearing tests. Results showed that the prevalence of hearing loss of > 25 dB hearing loss (dBHL) in rayon workers (67.9%) was much higher than that in administrative workers (23.6%) and in the adhesive tape and electronic industrial workers (32.4%). Hearing loss occurred mainly for speech frequencies of 0.5, 1, and 2 kHz. When the CS(2) exposure was measured by the product of CS(2 )exposure level and employment years, the adjusted odds ratios of hearing loss of > 25 dBHL in rayon workers, compared with administrative workers, were 3.8 [95% confidence interval (CI), 1.5-9.4] for those with the exposure of 37-214 year-ppm, 14.2 (95% CI, 4.4-45.9) with 215-453 year-ppm exposure, and 70.3 (95% CI, 8.7-569.7) with exposure of > 453 year-ppm. The study suggests that CS(2) exposure enhances human hearing loss in a noisy environment and mainly affects hearing in lower frequencies.

Sperm function in workers exposed to N,N-dimethylformamide in the synthetic leather industry.

OBJECTIVE: To determine whether occupational exposure to N,N-dimethylformamide (DMF) for men has adverse effects on sperm function. DESIGN: Cross-sectional study. SETTING: A synthetic leather factory in Taiwan. PATIENT(S): Twelve DMF-exposed workers in a synthetic leather factory and 8 socioeconomically matched control workers from another non-DMF-exposed manufacturing plant in the vicinity were recruited. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Breathing-zone monitoring of DMF exposure covering the full work shift was implemented on each participant. Urine specimens were collected from each worker immediately after their work shift in parallel with environmental sampling. Environmental DMF and urinary N-methylformamide (NMF) levels were measured by gas chromatograph. Analysis of semen samples was performed to measure semen volume, sperm concentration, morphology, and motility in accordance with World Health Organization criteria. RESULT(S): Both conventional microscopy and computer-assisted semen analysis showed that sperm motility in DMF-exposed group was significantly reduced from that in controls. Motility parameters were related to urinary NMF in a dose-response manner but were not related to airborne DMF. CONCLUSION(S): Workers occupationally exposed to DMF could be at risk of sperm motility perturbation. The responsible toxicant for the alterations of sperm function could be the active NMF metabolite instead of DMF, but this conclusion warrants a further complete investigation.

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.