In a cross-sectional study, prevalence of dysfunctions of the central nervous system was assessed in 134 male workers exposed to different levels of carbon disulfide (CS₂) in a rayon viscose plant and compared to 38 non-exposed workers. In three groups of workers from the same plant with different levels of CS₂ (heavy, intermediate, none) estimated by personal samplers, disorders in the central nervous system were examined by means of psychiatric examination and questionnaire 16 (Q16). Unconditional logistic regression was calculated adjusted for age, alcohol consumption and education. Psychoorganic syndrome was diagnosed significantly more often in workers with heavy CS₂ exposure, with adjusted OR of 17.9 (95% CI 2.18-146.73), and insignificantly in workers with intermediate exposure. Prevalence of workers with more than 6 positive answers on the Q16 was higher in the heavily exposed workers (OR=4.76; 95% CI 1.80-12.60). A similar result was found for almost all the questions in the Q16, and the most pronounced psychological symptom was of less interest in sex (adjusted OR=8.14; 95% CI 2.19-30.22). High correlation was found between symptoms recorded on neuropsychiatric examination and on Q16. Both neuropsychiatric exams and Q16 indicated disturbances in the central nervous system due to the long-term heavy exposure to CS₂. Disorders of the central nervous system were found more often in workers with heavy exposure to CS₂. Questionnaire Q16 is a valuable means for selecting workers for further neuropsychiatric testing.

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The present cross sectional study was carried out among 134 ex-workers from quartz stone crushing units. Using the interview technique as a tool for data collection, demographic and occupational details of the subjects were recorded on the predesigned proforma. Standard diagnostic criteria were used for diagnosing silicosis and silico-tuberculosis. The pulmonary functions of the subjects were measured with Spirovit SP-10. The mean age of the males was found to be 33.18 ± 10.39 yr and that of the females was 30.10 ± 9.3 yr and for the whole group was 31.77 ± 9.99 yr. Mean duration of exposure was 2.74 ± 1.65 yr. The study variables included age, sex, duration of exposure, smoking and respiratory morbidity. Forced Vital Capacity (FVC) which suggests lung parenchymal disorders was found to be significantly reduced with female sex, presence of smoking, increasing duration of exposure and presence of pneumoconiosis, whereas the lung function parameters indicating the status of airways were found to be significantly reduced with all the factors. Therefore, it was concluded that quartz stone workers exposed to approximately 100% free silica had deteriorated lung function which can be attributed mainly to respiratory disorders along with other epidemiological factors such as age, sex, duration of exposure and smoking.

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Infrared Spectrophotometry (IR) is now widely used to determine crystalline silica in industrial dust samples. Though the IR method has many advantages when dealing with respirable dust samples, some serious analytical errors are often caused by interference minerals contamination. These minerals have a characteristic absorption band corresponding in position to the analytical peak for crystalline silica. In this paper, six typical interference minerals (Kaolinite, Mullite, Muscovite, Pyrophyllite, Montmorillonite and Amorphous silica) were pre-size controlled to respirable range and their infrared spectra were measured by means of an FT-IR with the well-known potassium bromide tablet technique. The effects of these interference minerals on the Japanese OEL or the administrative control level for respirable dust which depend on the silica content were calculated and expressed in figures. The measured absorption coefficients of the interference minerals and quartz were 1.36-6.98 Abs/mg and 24.46 Abs/mg, respectively. The absorption band height ratios of each interference minerals were also measured. Then the efficiency and applicability of two spectrum correction methods for the interference minerals, absorbance ratio method and difference spectrum method were examined by using artificially mixed samples (standard interference mineral + standard quartz). By comparing the quantifying results for the mixture samples, it was revealed that the interfered spectra were almost corrected successfully when using the difference spectrum method, whereas correction by the absorbance ratio method resulted in apparent negative errors. Furthermore, the difference spectrum method was proven to be superior to the absorbance ratio method in applicability.

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-Objective-It is important to have data about occupational magnetic field intensity to consider the contribution of occupational magnetic field exposure on the human body. We conducted research on exposure to occupational magnetic fields and tried to qualify data on the distribution of magnetic field' intensity in certain general working environments with individual measurements. Subjects and Methods-We performed sample research on the exposure to low-frequency magnetic fields of workers in certain occupations and in the working environment. We also assessed the relationship between working environmental magnetic field distribution and individual exposure. Results-Some occupations were found to be exposed to high magnetic fields. We observed that some workspaces, such as the transformer substation, generally had a uniform and high magnetic field measurement but employees were exposed to a lower intensity. We also found that welders were exposed to high magnetic fields at about 600 μT in a very short time but with a geometrical value of 0.08 μT. Conclusion-The determination of administrative levels and control levels, not only of the time weighted average of threshold limits or short term exposure limits, but also ceiling limits should be considered. More systematic research is necessary to determine variables such as operating conditions, measuring position, and frequency bands. Also, further studies will be needed to make a job-exposure matrix for the magnetic fields for each occupation type and to combine it with exposure in non-occupational settings such as commuting and ordinary life situations to explore the causal relationship between exposure to magnetic fields and disease.

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-Objectives-A six-year prospective cohort study was conducted to clarify whether the current carbon disulfide (CS₂) exposure level is low enough to prevent subclinical health impairment and/or to ameliorate health effects due to previous high exposure. This paper describes the follow-up results, exposure assessment, and effects on the endocrine system. Methods-The study subjects were 432 male workers exposed to CS₂ at one of the 11 rayon factories in Japan and 402 referent workers from the same factories, all of whom were examined in 1992-93. 251 CS₂-exposed, 140 former-exposed and 359 referent workers participated in the follow-up survey (follow-up rate 89.9%) in 1998-99. Urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) at the end of a shift as internal exposure index and the time-weighted average CS₂ concentration as external exposure index were measured twice a year from 1992-1993. By using various blood indices, we evaluated effects on thyroid, hypophysis, and gonad function, as well as effects on glucose metabolism. Information on potential confounding factors, such as age, smoking and alcohol drinking, were collected and adjusted for. Results-When the individual exposure level was represented by arithmetic mean for TTCA and CS₂ concentration, geometric means (SD) of CS₂ workers were 1.61 (1.91) mg/g.crea and 5.02 (1.84) ppm, respectively. There were no exposure-related differences in glucose metabolism or any of the endocrinological indices. Conclusions-No biologically significant effects of CS₂ were found on endocrine function in Japanese rayon manufacturing workers when the average internal and external exposure levels were maintained below the current occupational exposure limit.

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We used a case-crossover approach to assess the association between air pollution and daily mortality in Shanghai from June 2000 to December 2001. By design, this method can avoid some common concerns about the time-series approach, which was most frequently used to assess the short-term effects of air pollution. Different control periods (unidirectional and bi-directional control samplings) were used for the analysis. With a bi-directional six control sampling approach, the results from a conditional logistic regression model controlling for weather conditions showed that each 10 μg/m³ increase over a 48-h moving average of PM₁₀, SO₂ and NO₂ corresponds to 1.003 (95%CI 1.001-1.005), 1.016 (95%CI 1.011-1.021), and 1.020 (95%CI 1.012-1.027) relative risk of non-accident mortality, respectively. The association between air pollution and mortality for chronic obstructive pulmonary diseases (COPD) and cardiovascular causes was found to be closer than that for all causes. The results confirmed the deleterious role of the current air pollution level on human health in Shanghai, and provided information on the applicability of case-crossover design in studying the acute health effects of air pollution.

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In Japan, relative humidity (RH) shows the lowest achievement rate among the various general air quality standards for work environment. It has been mainly contributed by airtight design of modern buildings and occurrence of dry outdoor air in winter. Furthermore, an ultra-dry air environment of nearly 0% RH is often required in sophisticated industries. In order to assess the adverse health effects of the ultra-dry air environment, using a self-reported questionnaire, we have undertaken a study of over 200 employees of a high-tech device developing laboratory having a room at 2.5% RH (ultra-dry room). Those who worked in the ultra-dry room were identified and the prevalence of symptoms was compared with the other workers. Analysis was performed by Wilcoxon's test and Fisher's exact test. In the ultra-dry room, all the twelve workers covered their skin with long-sleeve clothes, paper caps, paper masks and latex gloves. They reported skin symptoms more often (p<0.05) than the other workers (N=143). The prevalence of atopic dermatitis was also higher in the exposed workers (p<0.05). The complaints of workers in the ultra-dry environment were similar to preceding reports concerning moderately dry environmental exposures. The current precautions to protect the workers from the adverse effects of ultra-low RH appear to be insufficient, indicating that additional measures such as selection of appropriate clothing to mere skin coverage should be considered.

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