To investigate the possible work-relatedness of obstructive lung disorders, 402 male Japanese employees who had continued to work in two natural mineral fiber processing factories (97% of the total number of employees) were first surveyed in 1985 and 1986. Follow-up surveys were repeated essentially annually until 1995. The surveys included forced spirometry and questionnaires concerning respiratory status. Pulmonary function in 328 workers could be examined acceptably for three years or more with at least three acceptable survey results. Correlation analyses clearly indicated that second-order height proportional values should be used to standardize conventional spirometric indices for subjects' body size difference. No consistent association was observed between pulmonary function values and room temperature at the time of measurement. Within-subject coefficient of variations of forced expiratory volume in one second and forced vital capacity were as low as 2% to 3% for data one year apart. Those coefficients of variations were almost constant throughout the entire study period. It seems critically important to minimize the measurement error of forced expiration maneuvers and keep it constant throughout all of the surveys, by striving to control the quality of pulmonary function data.
The research was carried out among 3787 workers in the harbour of Rijeka (Croatia), divided into six professional groups: harbour-transportation workers, administration staff, warehouse and assistant workers, artisans, motor vehicles drivers and seamen aboard the tugboats. The prevalence of arterial hypertension (AH) in relation to age and body mass index (BMI) was analysed. Significant correlation between prevalence of AH and age (r=0.97) and between prevalence of AH and BMI (r=0.98) was proven. Prevalence of AH for all the subjects was 10.6%. The lowest prevalence (7.3%) was established for harbour-transportation workers, who were the youngest on average and who were of lowest mean value of BMI. The highest prevalence of AH (16.6%) was for the warehouse and assistant workers, who were the oldest on average and were of highest mean value of BMI. Those differences were statistically significant in relation to other groups but in relation to the average age and the average values for those professional groups they fitted into the expected values. Results did not confirm positive relationship between potentially harmful working conditions of the surveyed professions and the development of AH. Age and BMI as reliable predictors of AH were pointed out.
A rare outbreak of acute hepatic damage in workers exposed to dichloropropanols (DCPs) was reported recently. The purpose of the present study is to examine the effects of DCPs on various organs, the dose dependency and the pathogenetic potential of DCP hepatotoxicity. A single intraperitoneal injection was given to six groups of rats with 0.2ml of 20% ethanol (control), or 1/8×, 1/4×, 1/2×, 1×, and 2×LD50 (0.11ml/kg) of 1, 3-dichloro, 2-propanol (DC2P) diluted in 20% ethanol. After blood samplings, all organs were subjected to histologic examinations with light and electron microscopes. Fresh liver tissues from further 4 control and 4 experimental rats sacrificed 6 hours after the injection of 20% ethanol and 1×LD50 of DC2P were homogenized and subjected to evaluate lipid peroxidation, glutathione S-transferase activity and reduced glutathione contents in the liver. The rats administered with only ethanol or 1/8 and 1/4 LD50 of DC2P showed no serological or histopathological abnormalities. Marked elevation of serum glutamate pyruvate transaminase (SGPT) with a diffuse massive necrosis of the liver cells were noted in all rats of both the 1× and 2×LD50 groups, and irregular zonal necroses were found in 3 of 4 rats injected with 1/2 LD50. There were no serious toxic changes in other organs. Hepatic malondialdehyde level was significantly increased, associated with decreases of liver glutathione S-transferase activity and reduced glutathione content. It was concluded that the serious DC2P-toxicity was mainly found in the livers, dose dependently, and one of the causative mechanisms of this hepatotoxicity might be the lipid peroxidation.
To examine the mechanisms involved in the progression of mercury chloride (HgCl2)-induced acute tubular necrosis (ATN), we investigated the histopathological changes and the expression of inducible nitric oxide synthase (iNOS) mRNA and protein in renal cortices of rats at 20 hours after exposure to HgCl2. The expression of iNOS mRNA was significantly augmented in renal cortices of rats with HgCl2-induced acute renal failure (ARF). Likewise, the induction of iNOS protein was observed in damaged proximal tubule epithelial cells of rats with HgCl2-induced ARF. Pretreatment of rats with iNOS inhibitor aminoguanidine, however, suppressed the development of proximal tubule epithelial cell injury and prevented an increase in blood urea nitrogen and serum creatinine as well as resulting in a marked fall in iNOS mRNA and protein in rats with HgCl2-induced ARF. These observations indicate that the induction of iNOS may play a role in the progression of HgCl2-induced ATN through the exacerbation of proximal tubule epithelial cell damage.
Triethyl neopentoxy lead (TEneoPOL: (C2H5)3Pb[OCH2C(CH3)3] liquid) was administered to rabbits in a single dose of 10mg/kg body weight (5.4mg Pb/kg body weight), and the urinary and fecal excretions of lead were measured to determine the fate of this triethyllead derivative. About 4% of the administered amount of was excreted into the urine during the 7 days after the injection; and about 68%, into the feces. In other words, the fecal excretion of total lead was about 17 times as great as the urinary excretion. About 85% of the urinary excretion of total lead was composed of diethyllead (Et2Pb2+), and about 92% of the fecal excretion consisted of inorganic lead (Pb2+). The major chemical species of lead excreted in the urine was Et2Pb2+, while the major species excreted in the feces was Pb2+. These results were similar to those of administration of tetraethyllead (Et4Pb) to rabbits. One of the 7 rabbits died on the day following the injection, and TEneoPOL, a triethyllead derivative, proved to be no less toxic than Et4Pb. However, this compound is immediately hydrolyzed by the ambient moisture to form a white solid compound, so that it is not accompanied by as great a risk of airway exposure as Et4Pb.
Although cigarette smoking is one major determinant of lung carcinogenesis, not all smokers develop cancer. This phenomenon is due to individual variation in genetic susceptibility to carcinogens, nutrition, and lifestyle. Previous studies have shown that genetic polymorphism of metabolic enzymes and plasma micronutrients are associated with lung cancer risk. DNA adducts may serve as a molecular dosimeter for exposure to carcinogens. In this cross-sectional study, we analyzed the blood samples of 158 subjects to evaluate the effects of polymorphisms of cytochrome P450 1A1 (CYP1A1), glutathione S-transferase M1 (GSTM1, T (GSTT)), N-acetytransferase 2 (NAT2), and aldehyde dehydrogenase 2 (ALDH2) as well as the effects of plasma β-carotene and α-tocopherol on lymphocyte DNA adducts measured by 32P-postlabeling analysis. The DNA adduct level of smokers (mean±SD, 1.26±0.79/108 nucleotides) was significantly higher than that of nonsmokers (0.87±0.33, P=0.007). Smokers with CYP1A1 minor homozygotes and GSTM1 null genotypes had a significantly higher level of DNA adducts than those without (P=0.027 for homozygotes, P=0.049 for heterozygotes). Smokers with NAT2 minor homozygotes also tended to have a higher DNA adduct level than those with heterozygotes and wild alleles, but the difference was not statistically significant. The DNA adduct level of smokers with ALDH2 heterozygotes was significantly higher than that of smokers with minor homozygotes (P=0.045). When smokers were divided into “high” and “low” groups according to mean level of plasma β-carotene or α-tocopherol, in the low β-carotene group, the subjects with CYP1A1 minor homozygotes had higher DNA adduct levels than those with other CYP1A1 genotypes. Smokers with GSTT null genotype and high β-carotene tended to have a higher DNA adduct level than those with GSTT present and high β-carotene (P=0.07), and those with GSTT null genotype and low β-carotene (P=0.07). There was weak correlation between DNA adduct level and number of cigarettes smoked per day in the low plasma β-carotene group (r=0.28, n=36, p<0.1). These results suggested that polymorphisms of CYP1A1, GSTM1, T, NAT2, and ALDH2, and plasma β-carotene may modulate the level of DNA adducts.
The objective of this study was to examine the relationship between post-nap measures of alertness and performance and non-rapid eye movement (NREM) sleep and parasympathetic activity during brief naps. Thirty healthy subjects were randomly assigned to no-nap, 15-min, and 45-min nap conditions after normal home sleep at prior night. Each nap was taken after lunch and monitored by electroencephalogram (EEG), electromyogram, electrooculogram, and electrocardiogram (ECG). Deep NREM sleep was quantified by EEG delta power density and the parasympathetic activity was quantified by the ECG high-frequency (HF) component of R-R interval variability during the 15- and 45-min naps. The P300 event-related potential, subjective sleepiness, and performance on a 90-min English transcription task were measured 30min and 3hr after the naps and tested for their association with the EEG and ECG measures. A positive correlation was obtained between EEG delta power density during the naps and P300 latency 30min after the naps (r=0.476, p<0.05). The HF component during the naps was negatively correlated with the P300 latency 3hr after the naps (r=-0.519, p<0.05). These results suggest that the sleep inertia prolongs the P300 latency immediately after the naps, and that the parasympathetic predominance during the naps may improve subsequent alertness as assessed by the shortened P300 latency 3hr after the naps.
Among the multiple factors affecting the human eye in work environment, ultraviolet B irradiation (UVB) has received much attention recently. To provide a clear information for the association between cataract and UVB irradiation, the prevalence data from the Patient Survey and UVB estimates in all the 47 prefectures in Japan were used to examine the relationship between cataract and UVB. In analyzing the relationship, we controlled possible effect modifiers; which were aged, that is 65 years old (yo.) or older, population per ophthalmologist, proportions of all the patients among the aged population and proportion of very elderly population (75 yo. or older) among the aged population. A sex-specific logistic regression analysis revealed that the adjusted odds ratio in women was 1.118 with a 95% confidence interval of 1.058-1.183. However, the adjusted odds ratio in men was not statistically significant (1.048 with 95% confidence interval 0.968-1.135). The unstable results of this study may be largely due to the non-definitive estimation of UVB exposure that this kind of study should be repeated when more valid UVB estimates is available.
A field survey of 71 salesmen (22-60 years) in a machinery manufacturing company was conducted to investigate the effect of working hours on biological functions related to the cardiovascular system. The subjects were divided into four groups by age, and those in each age group were further divided into shorter (SWH) and longer (LWH) working hour subgroups by weekly working hours. Rates of complaints of subjective fatigue for LWH were significantly higher than those for SWH on the whole. Although the mean amplitude of respiratory sinus arrhythmia at rest decreased with age, no significant difference between SWH and LWH was found in this function. Systolic blood pressure for LWH was significantly higher than that for SWH in the 50-60 year group. The serum total cholesterol level for LWH was significantly lower than that for SWH in the 40-49 year group. Comparison of biological functions related to cardiovascular system was also made between fatigue complaint and no-complaint subgroups. Significant differences were found between the two subgroups: systolic blood pressure was higher and the total cholesterol level was lower in the fatigue complaint subgroups. Summarizing our results, it appeared that long working hours might increase systolic blood pressure and lower the total cholesterol level due to fatigue.
This paper evaluates the effectiveness of a smoking cessation program, known as “Smoke Busters.” A quasi-experimental design was used. The experimental group consisted of 35 workers (33 males and 2 females) who smoked and volunteered to take part in the program held at a chemical company. Thirty five age-, sex-, and job category-matched smokers who did not participate in the program were used as controls. The program consisted of 6 sessions held over a period of 6 months. The sessions were organized in a workshop style, with 6 groups, each consisting of 5-6 participants, meeting for 2hr during working hours. The effectiveness of the program was evaluated by the abstinence rate among the participants at one year after the start of the program. The abstinence rates of the experimental group and control group were 22.9% and 5.7%, respectively. Thus net abstinence rate was 17.2%. Given that 13% is considered as a reasonable benchmark for assessing the effectiveness of smoking cessation programs based on the results of the studies conducted in North America, one-year abstinence rate of 17% in this study, though not statistically significant (0.05<p<0.1) encourages larger experiments.
Epidemiological research during the past 40 years has demonstrated with increasing clarity that amphibole asbestos fibres-crocidolite, amosite and tremolite-are more carcinogenic than chrysotile. A smaller number of well-controlled studies using lung burden analyses, while adding to the specificity of this conclusion, have shown that amphibole fibres also differ from chrysotile in being far more durable and biopersistent in lung tissue. Analyses of mesothelioma and lung cancer in a large cohort of Canadian chrysotile miners and millers have recently shown that the low-level presence of fibrous tremolite in these mines, rather than the chrysotile, may well be responsible. The high risk of lung cancer, but not of mesothelioma, in the chrysotile textile industry remains anomalous and cannot be explained in this way. These various findings are directly relevant to the choice of the experimental methods which should be used for screening man-made fibres for industrial use. Although it is clear that biopersistence is a major determinant of cancer risk in animals, and perhaps also in man, other factors affecting the biological activity of mineral fibres may also be important.
It is known that some organophosphates produce not only well-known acute toxicity but also characteristic delayed neurotoxicity. Tri-ortho-tolyl phophate (TOTP), which was formerly named Tri-ortho-cresyl phosphaete (TOCP), was first noticed in an incident of poisoning as the compound which produced organophosphate induced delayed neurotoxicity (OPIDN). It is said that triphenyl phosphite (TPP) is also one of the organophosphates which possesses OPIDN. However, it is thought that TPP-induced delayed neurotoxicity (TPP-DN) is not identical with classical OPIDN. An intermediate syndrome was later proposed as the third neurotoxicity caused by organophosphates. We think that TPP is a Model chemical of the third neurotoxicity. We compared TOTP with TPP using Japanese quails. We Measured cholinesterase (ChE) activity and clearly demonstrated the difference between the two chemicals, that is to say, the activity recovered after 72hrs from the administration of TPP, whereas the inhibition continued for More than 11days after the administration of TOTP.
120 chest radiographs of dust exposed persons were classified twice by each of 39 physicians, and three times by 37 of them. All film readers used both the 22 standard films accompanying the current International Labour Office's (1980) Classification of Radiographs of Pneumoconioses, and a modified set that reproduced selected parts from some of them as quadrants of full-size films. Variability within and between readers in small opacity profusion classifications was high, but similar when using the two sets of standards. Some readers recognised irregularly shaped small opacities more frequently, in low profusion categories, when using the quadrant standards. Small rounded opacities were classified more frequently higher on the scale when using the current standards. The effects found were small although the test films included a high proportion with some small opacities. It is concluded that use of the new quadrant standards is unlikely to introduce any important bias into results from occupational health surveys.
A standard reference 10 sample-set of fibrous minerals were prepared by the Japan Fibrous Material Research Association (JFMRA) under the name of JMF standard reference samples. In this paper, the fiber number per unit weight of JFM standard reference samples was determined with a scanning electron microscope. Fiber numbers per unit weight (f/μg) and standard deviations observed in this experiment were as follows: glass wool (GW1) 7.0±0.1×102, rock wool (RW1) 1.7 ±0.2×103, micro glass fiber (MG1) 6.5±0.4×104, refractory ceramic fibers; (RF1) 8.8±0.7×103, (RF2) 8.7±0.8×103, mullite fibers (RF3) 3.5±0.7×103, pottasium titanate whisker (PT1) 5.9±0.3 ×105, silicon carbide whisker (SC1) 4.1±0.4×105, titanium oxide whisker (rutile) (TO1) 6.4±0.6× 105, and wollastonite (WO1) 2.4±0.1×104. Fiber numbers per unit weight would change in proportion to the cube or cube root of the fiber size if the fibers have the same density and the same aspect ratio. JFM standard reference samples should be used taking into consideration the difference in fiber number per unit weight when users conduct in vitro and/or in vivo (injection) biological experiments using these samples.
The following study was conducted to closely examine the evolution and formation of the occupational health service system in Korea during different historical periods. Korea's industrial structure has changed rapidly in the last 30 years from 1960's to 1990's, moving from a primary industry to a secondary or tertiary focused structure. Industrial accidents and occupational diseases are related closely to industrialization. Also, the new occupational health service system of each historical period has its political background. Until the mid 1980's, Korea's Occupational Health Service System was more a by-product of contemporary political, social, and economical situations rather than an effort to aggressively solve domestic industrial safety and health problems presented by laborers on the basis of academic development of industrial medicine. Therefore, the methods were to bestow a favor or one-sided. However, as Korea achieved democracy toward the end of the 1980's, it can be seen that industrial safety administration leaned toward actively dealing with the social demands of the working class.