Sangyo igaku. Japanese journal of industrial health最新文献

The present study was undertaken to investigate central axonal neuropathy caused by 2,5-hexanedione (2,5-HD) administration. The effects of 2,5-HD on rat pyramidal tract were studied electrophysiologically and histopathologically. Male rats were given 0.5% 2,5-HD in their drinking water for 4, 6 or 8 wk. Spinal motor conduction velocity was measured by direct electrical stimulation and was examined histopathologically by electron microscopy. Rats treated with 2,5-HD had reduced spinal motor conduction velocity at 6 wk and their pyramidal tract axons had decreased cross-sectional areas at 4 wk. The mean number of neurofilaments in myelinated axons of rats treated with 2,5-HD for 8 wk was 42.1% of that found in control rats, but the number of microtubules was not significantly different. The ratio of neurofilaments to microtubules in rats treated with 2,5-HD for 4 wk was less than 1.0 in 30.9% of myelinated fibers, while in control rats it was greater than 1.0 in all axons. These changes in spinal pyramidal tract were detected relatively early after 2,5-HD administration. These results in rats indicate the need for further studies of 2,5-HD neurotoxicity in the human central nervous system.

A questionnaire survey was conducted in 1991 in order to elucidate depressive state among 352 nursing teachers and guidance workers working in 71 homes for mentally retarded children. The data were analyzed by means of Zung's SDS to study the causative factors in relation to personal attributes, conditions and variables pertaining to work, professional characteristics, and nearby people's expectations and mental support. The results obtained were as follows: 1) The level of depression in the subject population was not particularly higher than that in the general public or other professional groups. 2) The results of multiple regression analysis indicated that labor-related problems, including dissatisfaction with one's work and sense of being overburdened, constituted a factor that led to depression. The condition worsened in proportion to the excess in workload, work hours, and responsibility, irregularity of work shift, along with lack of a sense of fulfillment and teamwork. 3) The factor which counteracted depression was support and mutual reliance from colleagues and supervisors as well as from the children and their families. The more strongly a subject felt mentally supported by these people, and had someone to turn to for advice concerning personal problems, the lower his or her depression score tended to be. 4) Of the professional characteristics specific to the guidance of mentally retarded children, the factors leading to depression were not workload but dissatisfaction or doubt concerning one's own instruction and negative mental attitude toward the children and their families, that is, consciousness and emotion that partly resembled burnout syndrome.

We investigated the background levels of total mercury in blood and urine samples from Japanese subjects without occupational exposure to mercury vapor. Blood and urine specimens were decomposed in sealed Teflon containers, and total mercury concentration was measured by reductive vaporization-gold amalgam capture-atomic absorption spectrophotometry. The mean total mercury concentration in the blood of 56 women aged 34-65 was 18.2 +/- 9.9 ng/ml (range 3.9-56.8 ng/ml). The mean total mercury concentration in the urine of 130 men aged 22-39 was 2.33 +/- 1.50 micrograms/l (range 0.27-10.26 micrograms/l). The mean total mercury concentration in urine adjusted by specific gravity was 2.19 +/- 1.15 micrograms/l (range 0.68-7.68 micrograms/l), and that adjusted by creatinine was 1.51 +/- 0.68 micrograms/g creatinine (range 0.39-4.21 micrograms/g creatinine). These concentrations did not differ greatly from those reported from Europe and Japan. In expressing the total mercury concentration in urine, the creatinine-adjusted range between the minimum and maximum values was smaller than the range adjusted by specific gravity.

In Japan "the Regulation on the Prevention of Lead Poisoning" and "the Regulation on the Prevention of Organic Solvent Poisoning" were partially amended in 1989 to introduce biological monitoring in the special medical examinations of workers exposed to lead and 8 organic solvents (toluene, xylene, styrene, N,N-dimethylformamide, n-hexane, tetrachloroethylene, 1,1,1-trichloroethane, trichloroethylene). Since many companies entrust these medical examinations to the Occupational Health Organizations (OHOs), a survey of OHOs which collect blood and urine samples for biological monitoring was made in August 1992, to ascertain the actual status of their activities from April of 1991 to March of 1992. The following findings were obtained through this survey. 1) One hundred and eighty-six OHOs collected 129,996 blood samples to measure the concentration of lead, and the median number of samples collected per organization was 356. 2) Thirty-nine OHOs (21.0%; Group A) measured all samples in their own laboratories. The number of samples measured was 55,462 (42.7%). However, 133 OHOs (71.5%; Group B) entrusted the measurement of all samples to registered laboratories. 3) The median number of samples collected by OHOs in Group A was 1,121, and the median number of Group B was 211. 4) One hundred and eighty-three OHOs collected 126,915 urine samples to measure the concentration of delta-aminolevulinic acid and the median number of samples collected per organization was 358. 5) The blood samples as well as the urine samples were divided into three groups according to the levels of lead or delta-aminolevulinic acid concentration. The concentration is relatively low in Group 1 and relatively high in Group 3. The cut-off values for this classification are legally set in the Regulation on the Prevention of Lead Poisoning. The frequency of each group was as follows: lead (Group 1; 93.8%, Group 2; 4.9%, Group 3; 1.3%), delta-aminolevulinic acid (Group 1; 96.8%, Group 2; 3.1%, Group 3; 0.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Utility of multivariate analysis in evaluating the values of laboratory tests on the basis of intra-individual variations (IV) was studied. Periodic health examination on workers has many clinical laboratory tests and these values are generally evaluated in comparison with "normal ranges." Recently it has been ascertained that the individual normal ranges were narrower than the populational normal ranges. Although the values of an individual should be estimated with normal ranges of the individual, it is almost impossible to determine the normal ranges from only one or two health examinations conducted per annum at the place of work. The author in his study could easily determine IV with a method using Mahalanobis' distance on a basis of populational normal range. In this method, if many values of a person in the tests vary in several years, the distance becomes larger, and if a value in a test falls outside the normal limit, it also becomes larger. This method makes it possible to detect not only an "abnormal" value out of the normal range but also a large value out of IV. To examine the practical validity of the method, the data of 24 employees (males, 45 to 65 years old) from 3 periodic health examinations and those of 20 persons (males, 48 to 71 years old) from 3 to 6 medical checkups were analyzed with regard to 11 items. It was found that 33 out of 44 persons were abnormal in one or more items and that 10 abnormal persons had large IV. They would be missed in the judgement with the use of only "normal ranges." As the distances were computed by a portable computer with a basic program, the method can be easily used in a small place of work. It is considered that this new method is effective and valuable not only as the screening procedure but also in the evaluation of IV.

Based on a longitudinal questionnaire survey of 11,121 subjects (males aged 30-59, engaged in various occupations and firms), this study examined the relationships of the baseline psychosocial work environment and personal health practices to mental disorders which occurred during an 18-month follow-up period. The onset of mental disorders during the follow-up period was assumed to be the time when the subject reported to have received medical treatment for the first time due to mental disorder. The psychosocial factors of the work environment were conceptually constructed from two aspects of working conditions and occupational stress. Working conditions were assessed by actual working hours, frequencies of late night work (10 p.m.-5 a.m.), and role in the organization. Occupational stress was measured by psychological work overload and job characteristics (job demands, decision latitude). Various factors associated with positive health behavior were examined through an index based on six variables, that is, supper time, exercise, smoking, alcohol consumption, sleep and weight. Multiple logistic analysis showed that both psychological work overload and late night work have a significant independent effect on the onset of mental disorders after controlling for other variables.