Mortality among Japanese construction workers in Mie Prefecture

AIMS

A historical cohort mortality study was conducted among 17 668 members of the Construction Workers' Health Insurance Society of Mie Prefecture in Japan, in order to verify the relation between occupations and mortality status.

METHODS

The cohort was followed from 2 April 1973 to 1 April 1998. Standardised mortality ratios (SMR) were calculated for all members and each job classification.

RESULTS

98.7% of the members were traced successfully until the date when the follow up terminated. When all members were considered together, significant excess mortality was observed for "accidents and adverse effects". Significant excess mortalities were also observed for lung cancers among scaffold men and ironworkers, for cancer of the oesophagus among plumbers, and for "chronic liver disease and cirrhosis" among scaffold men and painters.

CONCLUSION

Results suggest that more detailed investigations, which would include some minor job classifications should be undertaken. This is an updated cohort study which was partially completed in 1997.

Involvement of Bcl-2 family genes and Fas signaling system in primary and secondary male germ cell apoptosis induced by 2-bromopropane in rat

Epidemiological surveys and animal experimental studies suggest that exposure to 2-bromopropane (2-BP) could result in reproductive and hematopoietic disorders. The objectives of this study were to investigate the role of apoptosis in 2-BP-induced testicular toxicity and whether this process involves Bcl-2 family genes and the Fas signaling system. Rats were injected percutaneously with 1350 mg/kg 2-BP for 1 to 5 days and then were euthanized at 6 or 12 h after one dose, 6 h after two, three, or five doses, and 2 or 9 days after the final treatment. Light and electron microscopic analyses, TUNEL staining of DNA fragments, agarose gel electrophoresis of low-molecular-weight DNA, and Western blotting analysis of Bcl-2 family proteins and Fas receptor and ligand were conducted. Two-day treatment resulted in selective degeneration of spermatogonia with marked nuclear chromatin condensation. DNA ladder formation on the agarose gel further validated the findings of TUNEL-stained apoptotic cells. The percentage of apoptotic-positive tubules and apoptotic cell index increased time dependently. 2-BP treatment resulted in two distinct morphological changes: an immediate effect on spermatogonia and secondary apoptosis of spermatocytes 9 days after treatment. Downregulation of Bcl-2 after the first or second injection of 2-BP and upregulation of Bax after the first treatment contributed to the initiation of primary apoptosis of spermatogonia. Expression of FasL was inhibited while expression of Fas increased after the 2-BP treatment and remained at levels about two times of the control. However, it increased about sixfold of the control by day 9 after final injection, which contributed to the induction of secondary apoptosis of spermatocytes. Our results indicate that 2-BP resulted in apoptotic death of testicular germ cells and that this process involves the Bcl-2 family genes and the Fas signaling system.

Long working hours and subjective fatigue symptoms

Presuming that overtime work may associate with chronic fatigue and then decrease cardiovascular function, this report was prepared to find out the definite positive relationship between long working hours and subjective fatigue complaints. We analysed the data of a field survey of 238 men who were working at the department of research & development of three electronics manufacturing companies in S. Korea. The field survey consisted of self-report questionnaires on the working hours, health conditions, and fatigue. For data analysis, the subjects were divided into 3 groups on the criteria of 60 and 70 working hours per week: less longer (LLWH), longer (LWH), and more longer (MLWH) working hour groups. We compared the age-adjusted mean % scores of fatigue complaints among LLWH, LWH, and MLWH. The rate of complaints of subjective fatigue before going to work for LWH and MLWH tended to be significantly higher than those for LLWH. Hence, we conclude that the questionnaire on the subjective fatigue complaints is a good screening tool for early detection of cumulative fatigue due to chronic job stress such as long working hours.

Regular overtime and cardiovascular functions

It was concluded that there was sufficient evidence about a possible link between long working hours particularly exceeding 50 a week and the risk of significant health outcomes, including cardiovascular disease from literature review by Spurgeon et al.. This study was conducted to find out the single effect of regular overtime work on the cardiovascular functions through objective biological indices such as blood pressure or heart rate variability. We conducted a field survey of 238 male engineers who were working at the department of research & development of three electronics manufacturing companies in S. Korea. The field survey consisted of (1) self-report questionnaire (working hours and health conditions, and fatigue) and (2) measurements of blood pressure and heart rate variability. By multivariate analyses we could show the relationship between overtime work and some cardiovascular functions after controlling the effects of major confounders such as age and sleeping hours, which were pointed out by Iwasaki et al. (1998) and Sasaki et al. (1999). Especially, low frequency component (power in the low frequency range, 0.04-0.15 Hz) of the heart rate variability during work might be used as early objective biological indices for chronic effect of regular overtime work on cardiovascular functions. However, we should confirm those effect through the well-designed prospective study.

Airborne fiber concentration and size distribution of mineral fibers in area with serpentinite outcrops in Aichi prefecture, Japan

Airborne fiber concentrations and size distributions of both asbestos and nonasbestos fibers were determined at property boundaries of 4 serpentinite quarries producing crushed stone (quarry property boundary), 10 sites within 10 km of the area with serpentinite outcrops (serpentinite area), and 2 sites in a reference area. The asbestos was identified in 7 rock and 3 soil samples collected in the serpentinite area. The geometric means of airborne concentrations of asbestos and nonasbestos fibers longer than 0.2 microm in length were: 384 and 447 fibers/liter (f/L) in the quarry property boundary (in operation), 12 and 124 f/L in the quarry property boundary (in closed), 5 and 103 fibers/liter in the serpentinite area, and less than 2 and 59 fibers/liter in the reference area, respectively. There was a significant difference in airborne concentrations of both asbestos and nonasbestos fibers among the areas. Ttremolite/actinolite were found with chrysotile in the stones. Airborne concentrations of tremolite/actinolite were higher than those of chrysotile at the quarry property boundary and in the serpentinite area. Tremolite/actinolite were also found in the soils. There was no significant difference among the areas in the arithmetic means of fiber size distribution of both asbestos and nonasbestos fibers.

Lower percentage of CD56+ cells associated with long working hours

In a study of 142 Japanese men from a cross-section of the workforce of a technology development company, we found that the percentage of CD56+ cells was inversely correlated with the number of hours worked per week. A low CD56+ cell percentage was associated with longer weekly working hours and shorter daily sleeping hours.

Urinary 8-oxo-7, 8-dihydro-2'-deoxyguanosine and biopyrrins levels among construction workers with asbestos exposure history

It has been suggested that oxidative stress is associated with the cancers caused by asbestos. Since construction workers are sometimes exposed to low levels of asbestos, we investigated whether oxidative stress was elevated in construction workers who had been exposed to low levels of asbestos. The subjects were 48 Japanese construction workers. The defined asbestos-exposed group consisted of subjects who had the history of suspected exposure to asbestos and were diagnosed to have irregular opacities or pleural plaques. We measured the amount of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) and biopyyrins in the urine of the subjects. The results showed that 8-oxodG and biopyyrins levels in the defined asbestos-exposed group were higher, although they were not statistically significant, than those in the control group. In addition, the urinary 8-oxodG levels tended to correlate positively with the duration of suspected exposure to asbestos. These results suggest that even low-level asbestos exposure may induce oxidative stress and that the resulting's the oxidative stress might be related to lung cancer in construction workers.

Construction of an exposure chamber for animals and its use for inhalation exposure to welding fumes and gases

An inhalation exposure system, consisting of an inhalation chamber and an generating and feeding device for welding fumes and gases with a welding robot, was constructed and examined for its application to experimental toxicology for ventilatory responses of conscious rats to welding fumes and gases. The exposure system allowed an inhalation of fresh welding fumes and gases, and could supply airflow containing stable concentrations of fumes and ozone even the levels exceeding those corresponding occupational exposure limit values were supplied into the exposure chamber. The air temperature in the chamber was kept constant under rat's physiological conditions. Rats were exposed to fresh welding fumes and gases and examined for their ventilatory responses with a body plethysmograph in the chamber. A transient increase in breathing frequency with a concomitant decrease in the tidal volume was observed within several minutes immediately after the start of welding operation. The rapid, shallow breathing response disappears after repeated exposures, indicating rapid adaptation of this ventilatory response to inhalation of welding fumes and gases.

Laboratory measurement of hazardous fumes and gases at a point corresponding to breathing zone of welder during a CO2 arc welding

Concentrations of fumes, ozone (O3), carbon monoxide (CO), nitric oxide (NO), manganese (Mn) and total and hexavalent chromium (Cr) as well as size distribution of fumes were measured at a point corresponding to the welder's breathing zone during CO2-arc welding, using a welding robot and three kinds of wires. Concentrations of fumes, O3, CO, Mn and total-Cr were found to exceed their corresponding occupational exposure limit (OEL) values, while the concentrations of NO and Cr(VI) were below those OEL levels. Airborne concentration of Mn exceeded its OEL value, and the Mn content was 8 times higher in welding fumes than in the wire. Using an additive equation of OEL and exposure concentration of each hazardous component, health risk in welders with combined exposure to welding fumes and gases was assessed as 18.6 to 46.0 times of OEL, which exceeded the unity. This finding suggests that effective protection of welders from the exposure can be attained by use of the supplied-air respirator or combined use of a dust respirator and a local exhaust system.

Association between musculoskeletal pain in Japanese construction workers and job, age, alcohol consumption, and smoking

A cross-sectional epidemiologic study was conducted to determine the prevalence of self-reported musculoskeletal pain (MSP) in construction workers and identify associations between MSP and individual factors (i.e., job, age, alcohol consumption, and smoking). The prevalence of total hand/arm pain (T-HAP), total shoulder pain (T-SP), and total low-back pain (T-LBP) was 28.4%, 28.7%, and 53.2%, respectively. Risk factors for total pain and for relatively severe pain in the hand/arm (RS-HAP), shoulder (RS-SP), and low-back (RS-LBP) were estimated by multiple logistic regression analysis. The results showed that musculoskeletal pain was significantly associated with age, and that the odds ratios (ORs) for relatively severe musculoskeletal pain increased almost linearly with age. Regarding job, compared with architects whose work is presumed to be sedentary, almost all ORs for T-HAP, T-SP, and T-LBP for non-sedentary construction jobs were significantly high. Current smokers of 20 cigarettes a day or more had significantly higher ORs for RS-HAP and RS-LBP than "never smokers". We suppose that 1) total and relatively severe pain were associated with age, 2) non-sedentary work was at higher risk of total MSP than sedentary work, and 3) heavy smoking contributed to RS-LBP.

Association of working hours with biological indices related to the cardiovascular system among engineers in a machinery manufacturing company

A field survey of 278 engineers (20-59 years) in a machinery manufacturing company was conducted to investigate the association of working hours with biological indices related to the cardiovascular system (heart rate variability, blood pressure and serum levels of magnesium, dehydroepiandrosterone sulfate <DHEA-S> and cholesterol). Average working hours (defined as <"hours at workplace" + "half a commuting time">) and sleeping hours in this study were 60.2 +/- 6.3 hr/week and 6.6 +/- 0.8 hr/day respectively. There were no significant relationships between working hours and biological indices related to the cardiovascular system, but sleeping hours was closely related to working hours negatively. Furthermore, the serum DHEA-S level was significantly related to sleeping hours positively. Combining these two results, it appeared that long working hours might lower the serum DHEA-S level due to the reduction of sleeping hours.

2-Bromopropane causes ovarian dysfunction by damaging primordial follicles and their oocytes in female rats

Ovarian dysfunction induced by 2-bromopropane (2-BP) has been described in female factory workers and experimental animals. However, the underlying mechanism is still unclear. To establish the reproductive target site and define mechanisms of 2-BP toxicity in adult female rats, we examined the effects of different doses and duration of exposure to 2-BP in female rats. In the dose-dependent experiments, female rats were exposed to 2-BP at 100, 300, or 1000 ppm or fresh air (n = 9 each) in exposure chambers for 8 h/day for 9 weeks. In the time-course experiments, female rats were exposed to 2-BP at 3000 ppm for 8 h (n = 7 each). The rats were then euthanized 1, 3, 5, and 17 days after exposure. Differential follicle counts and in situ terminal deoxynucleotidyl transferase assay were used to evaluate 2-BP effect on primordial, growing, and antral follicles. Exposure to 2-BP at 300 and 1000 ppm produced a significant reduction in the percentage of primordial, growing, and antral follicles in a dose-dependent manner. Significant reduction in the percentage of primordial follicles at 17 days after exposure was observed in time-course experiments. Exposure to 2-BP at 3000 ppm for 8 h resulted in histological changes in primordial follicles complex at 5 and 17 days after exposure. These changes consisted of distortion of the symmetry of oocytes and their nuclei at Day 5 after exposure and appearance of eccentric pyknotic cells and shrinkage of oocyte nuclei at Day 17 after exposure. In situ end labeling showed increased numbers of apoptotic oocytes and granulosa cells in primordial follicles at Days 5 and 17 after exposure. Our results suggested that ovarian dysfunction induced by 2-BP was caused by the destruction of primordial follicle and its oocyte due to the induction of apoptosis. Our studies also show that the follicle differential count is a more sensitive method than the vaginal smear in monitoring the female reproductive disorders induced by 2-BP.

Effect of inhalation exposure to 2-bromopropane on the nervous system in rats

Exposure to 2-bromopropane (2-BP) is suspected to have adverse effects on the nervous system. The aim of this study was to investigate whether the exposure of rats to 2-BP had neurotoxic effects using histological and electrophysiological studies. Wistar strain male rats were exposed daily to either 100 or 1000 ppm 2-BP or to fresh air for 8 h a day for 12 weeks. Body weight was measured before exposure and every 2 weeks. Motor nerve conduction velocity (MCV) and distal latency (DL) were measured before exposure and every 4 weeks during exposure. Histological examination of the nervous system was also performed. Exposure of rats (n = 9) to 1000 ppm resulted in suppression of body weight gain and a significant decrease in brain weight compared to the control (n = 9). Electrophysiological measurements showed a significant decrease in MCV in 1000 ppm exposed rats at 8 weeks and significant prolongation of DL at 8 and 12 weeks. Abnormalities of the myelin sheath were detected in the common peroneal nerves. In 100-ppm exposed rats (n = 9), no significant changes were noted in body weight and the peripheral nerve. In conclusions, long-term exposure to 1000 ppm of 2-BP may result in peripheral neuropathy in rats.

Shift work-related problems in 16-h night shift nurses (2): Effects on subjective symptoms, physical activity, heart rate, and sleep

We compared the shift work-related problems between 16-h night shift and 8-h evening/night shifts among nurses in a university hospital with respect to subjective symptoms, physical activity, heart rate (HR), and sleep. The nurses of one group (n = 20) worked a 16-h night shift under a rotating two-shift system, while those of the other group (n = 20) worked an 8-h evening or night shift under a rotating three-shift system. The 16-h night shift was staffed by three or four nurses who alternately took a 2-h nap during the shift, and had at least one day off after each shift. Subjective symptoms and daily behavior were measured every 30 min by the nurses before, during, after each shift as well as during days off using a time-budget method. Also, physical activity, heart rate (HR), and posture were recorded during shifts. The results showed similar or lower levels of sleepiness, difficulty in concentration, fatigue, physical activity, and HR during the 16-h shift compared to the 8-h shifts. No differences in subjective symptoms between the two shift schedules were observed before or after the shifts or during days off. The main sleep was longer after the shifts and during days off in the 16-h shift group than in the 8-h shift group. Our results suggest that the work-related problems in 16-h night shift nurses may not be excessively greater than those in 8-h evening/night shift nurses, as long as appropriate countermeasures are taken during and after the extended shift.

Shift work-related problems in 16-h night shift nurses (1): Development of an automated data processing system for questionnaires, heart rate, physical activity and posture

To assess the shift work-related problems associated with a 16-h night shift in a two-shift system, we took the following important factors into consideration; the interaction between circadian rhythms and the longer night shift, the type of morningness and eveningness experienced, the subjective sleep feeling, the subjects' daily behavior, the effectiveness of taking a nap during the long night shift, and finally the effectiveness of using several different kinds of measuring devices. Included among the measuring devices used were a standard questionnaire, repetitive self-assessment of subjective symptoms and daily behavior at short intervals, and a continuous recording of such objective indices as physical activity and heart rate. A potential problem lies in the fact that field studies that use such measures tend to produce a mass of data, and are thus faced with the accompanying technical problem of analyzing such a large amount of data (time, effort and cost). To solve the data analysis problem, we developed an automated data processing system. Through the use of an image scanner with a paper feeder, standard paper, an optical character recognition function and common application software, we were able to analyze a mass of data continuously and automatically within a short time. Our system should prove useful for field studies that produce a large amount of data collected with several different kinds of measuring devices.

Rapid and simple analysis of urinary vanilmandelic acid by high-performance liquid chromatography with electrochemical detection

We examined an analytical method for urinary vanilmandelic acid (VMA) by high-performance liquid chromatography with electrochemical detection from the viewpoint of practical analysis and application. The sample pretreatment in our method is only the dilution of urine samples with citrate buffer. The calibration curve for VMA was linear within the range 0.2 to 20 ng. The detection limit was 50 pg at a signal-to-noise ratio of 3 and the coefficients of variation were 2.30-4.30%. Variations in the urinary levels of VMA, noradrenaline (NA) and adrenaline (Ad) during and after exercise were investigated for 5 males (mean +/- SD, 42.4 +/- 4.3 years of age). The high levels of urinary NA and Ad during 1 hr exercise rapidly decreased after exercise, whereas urinary VMA increased after exercise rather than during exercise and decreased later. The correlation of the urinary levels of VMA and NA for 71 salesman (mean +/- SD, 40.6 +/- 11.7 years of age) in a field study was significantly positive (r = 0.426, p < 0.001). These results suggest that urinary VMA mostly reflects NA, but the excretion rate of VMA is slower than that of NA.

Effect of working hours on cardiovascular-autonomic nervous functions in engineers in an electronics manufacturing company

A field survey of 147 engineers (23-49 years) in an electronics manufacturing company was conducted to investigate the effect of working hours on cardiovascular-autonomic nervous functions (urinary catecholamines, heart rate variability and blood pressure). The subjects were divided into 3 groups by age: 23-29 (n = 49), 30-39 (n = 74) and 40-49 (n = 24) year groups. Subjects in each age group were further divided into shorter (SWH) and longer (LWH) working hour subgroups according to the median of weekly working hours. In the 30-39 year group, urinary noradrenaline in the afternoon for LWH was significantly lower than that for SWH and a similar tendency was found in the LF/HF ratio of heart rate variability at rest. Because these two autonomic nervous indices are related to sympathetic nervous activity, the findings suggested that sympathetic nervous activity for LWH was lower than that for SWH in the 30-39 year group. Furthermore, there were significant relationships both between long working hours and short sleeping hours, and between short sleeping hours and high complaint rates of "drowsiness and dullness" in the morning in this age group. Summarizing these results, it appeared that long working hours might lower sympathetic nervous activity due to chronic sleep deprivation.

Effect of working hours on biological functions related to cardiovascular system among salesmen in a machinery manufacturing company

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.

[Types and dimensions of mineral fibers in the atmosphere and from lungs of residents in the urban area]

OBJECTIVE

The objective of this study was to estimate the types and origin of the mineral fibers in the lungs of residents in the urban area.

METHODS

Mineral fibers in the atmosphere from 21 urban areas were analyzed by direct transfer-analytical transmission electron microscopy (ATEM). Lung tissues of 36 urban residents without occupational asbestos exposure were also analyzed by ATEM after low temperature ashing. Measurement of dimensions of all types of mineral fibers, identification of asbestos, and classification of nonasbestos fibers according to the combination of main elements were carried out.

RESULTS

1. Chrysotile, amosite, actinolite, tremolite and 11 types of nonasbestos fibers were found in both the lung tissues and the atmospheric samples. The fibers, mainly composed of Al and Si, contributed 16.3% and 62.3% of the atmospheric samples and lung tissues respectively. On the other hand, the proportion of the fibers mainly composed of S and Ca were 43.7% and 0.0% in the atmosphere and lung tissues respectively. Those fibers mainly composed of P and Fe were 0.4% and 18.4% in the atmosphere and lung tissues respectively. 2. Fifteen types of nonasbestos fibers were found exclusively in the atmosphere. The average proportions for ten of these were less than 0.5% each. 3. Crocidolite was found exclusively in the lung tissues. 4. No significant difference in the geometric mean of length and diameter of asbestos was found between the atmospheric samples and lung tissues. Some types of nonasbestos fibers had significantly larger length and diameter in the atmospheres than in the lung tissues (p < 0.01).

CONCLUSION

The results suggest that mineral fibers found in lung tissues could be classified into three groups on the basis of their behavior. 1) Some fibers, such as amphibole asbestos and fibers composed of Al and Si, are inhaled from the atmosphere and remain in the lung tissues for a long time. 2) Some fibers, such as those composed of S and Ca, are inhaled from the atmosphere and eliminated from the lung tissues within a relatively short time. 3) Some fibers found more in the lung tissues than in the atmospheres, such as those composed of P and Fe, are suspected to be generated in the lungs.

A probable case of chronic occupational thallium poisoning in a glass factory

A male worker who handled thallium-containing raw material for glass manufacturing over a period of four years complained of alopecia, abdominal pain, diarrhea and tingling in the four extremities. Neurological examination of this patient revealed signs of mild glove-stocking-type polyneuropathy. Lower sensory nerve conduction velocity of the median nerve in the right hand than in the left hand suggested that conduction function in the dominant hand was reduced. The thallium content of the hair, as determined by an ICP-MS method, was 20 ng/g for the patient and 576 ng/g for his successor in the time of 32 months and 13 months, respectively, after they had ceased their glass production work. Those levels of thallium exposure were considered high, compared with the control levels so far reported. The clinical course of signs and symptoms, neurophysiological findings and thallium content of hair suggested that the patient suffered from chronic poisoning due to occupational exposure to thallium-containing dust.

Sitting posture and neck and shoulder muscle activities at different screen height settings of the visual display terminal

The effects of the VDT screen height on working posture and electromyographic (EMG) activities of the neck and shoulder muscles were determined in 10 healthy subjects. The subjects performed a mouse-driven interactive task at the screen height settings of 80, 100 and 120 cm. Changes in body positions were measured by video image and frame analysis. Surface EMG recordings were done on the neck extensor muscle and the descending part of the trapezius muscle, both on the right side. The results of the postural analysis showed that at higher screen height settings, the neck became significantly more erect. The subjects also assumed a more backward-leaning trunk position at higher screen heights. The EMG activities of the neck and shoulder muscles were related to the neck angle and trunk inclination, respectively. A more flexed neck produced significantly higher neck extensor muscle activities. A backward-leaning trunk was also noted to decrease trapezius muscle activity in some subjects.

A cohort mortality study of construction workers

This report presents a mortality study among the 17,344 members of the Construction Workers' Health Insurance Society of Mie Prefecture in Japan. The study period was between 1973 and 1993. During this period, 480 members died. Age-specific mortality rates of Mie Prefecture were used as comparison standards. Significantly elevated standardized mortality ratio (SMR) and proportionate mortality ratio (PMR) were observed for "accidents and adverse effects." In addition, the PMRs of all cancers and "cancers of trachea, bronchus and lung" were also significantly elevated. The job classifications were reorganized into three groups, according to the frequency of asbestos exposure the workers experienced on the construction sites. The asbestos exposure was based on job classifications among 7,411 workers who had completed a self-administered survey questionnaire. In the frequent-exposure group, the PMR was significantly elevated for all cancers. In the medium-exposure group, the SMRs were significantly elevated for all cancers and "cancer of trachea, bronchus and lung." The PMR was significantly elevated for "cancer of trachea, bronchus and lung." In the less-exposure, group, the PMR was significantly elevated for "accidents and adverse effects." This study provided support for the hypothesis that working in the construction industry might be associated with high risks for asbestos-associated cancers and accidental deaths.

The effect of a back belt on torso motion--survey in an express package delivery company

According to the Labor Standard Bureau of Japan, accidental back injuries accounted for about 60% of all occupational injuries and diseases in the last decade. The Ministry of Labor issued guidelines to prevent low back injuries in 1994 to address the problem. The use of back belts is recommended for some special working conditions but details on its proper use were not given. This study was planned to evaluate a newly developed back belt and was done at an express package delivery company where the incidence of low back injury was high. The BackTracker was used to evaluate the effect of the back belt on the range and velocity of torso motion. The results indicated that there were no significant differences in the range of motion (ROM) during flexion/extension, lateral bending, and rotation between with and without the belt. The maximum angular velocity (MAV) of flexion decreased significantly (average decrease: 30 +/- 28.3 degrees/sec) when the back belt was worn. The MAV of extension with belt showed a decreasing tendency though not significant. No notable trends were observed in the MAV, during lateral bending and rotation of the subjects while wearing and not wearing the belt. The results also indicated that the back belt affected differently the torso motion of each subject. This study suggested that this back belt could be useful for tasks with high velocity of flexion/extension and that proper instruction on the use of the back belt is needed for each worker.

Pulmonary metal distribution in urban dwellers

To clarify the factors influencing the concentrations and distribution of metal elements in the lung, we analyzed the following 8 metals in the 5 lung lobes of 17 autopsied urban dwellers by flame or flameless atomic absorption spectrometry: aluminum (Al), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), manganese (Mn), copper (Cu), and Zinc (Zn). The arithmetic mean value (in micrograms of metal per gram of dry weight) calculated for five lobar metal concentrations in each subject ranged from 80 to 681 for Al, from 0.34 to 3.41 for Cd, from 0.41 to 12.7 for Cr, from 0.22 to 1.93 for Ni, from 0.15 to 1.47 for Pb, from 0.64 to 2.36 for Mn, from 2.84 to 7.24 for Cu, and from 40.7 to 77.6 for Zn. The eight metals were classifiable into two groups on the basis of the interindividual and interlobar concentration variations. The first group, consisting of Cu and Zn, was characterized by smaller interindividual variations (co-efficient of variation, CV < 30%) and smaller inter lobar variations (mean CV < 15%). Their levels were not affected significantly by sex, smoking habits, or possible occupational exposure to metal-containing dust. In contrast, the second group, consisting of Al, Cd, Cr, Ni, Pb, and Mn, exhibited larger interindividual variations (CV > 45%) and larger interlobar variations (mean CV > 25%). Concentrations of these metals, except for Cd, tended to be higher in the upper lobes than in the lower lobes. The concentrations of Al and Cr were significantly higher in men than in women. Smoking significantly elevated the levels of Cr, Cd, Ni, and Pb, and the concentrations of Al, Cr, Ni, and Mn were higher in subjects with possible occupational exposure to metal-containing dust than in those without such exposure. However, the interlobar distribution patterns of the metals did not seem to be influenced by sex, smoking habits, or occupational exposure to metal-containing dust.

[Concentration and fiber size of asbestos in lungs of residents living close to the serpentinite area]

Concentrations and fiber size distribution of asbestos in the lung tissue of 16 ( 8 males and 8 females) rural residents living close to the serpentinite area (neighboring group) were analyzed by low temperature ashing-analytical transmission electron microscopy, and were compared with those of 5 (5 males) rural and 53 (34 males and 19 females) urban residents living away from the serpentinite area (reference group). The results are as follows; 1. Pulmonary asbestos fibers were found in all rural residents. The types of asbestos fibers were chrysotile, amosite, crocidolite, actinolite, and tremolite. These findings were very similar to results for urban residents. 2. In males, the geometric mean concentration of actinolite-tremolite in the neighboring group (1.78 x 10(6) fibers/g dry lung) was significantly higher than those in the reference groups (rural: 0.32 x 10(6), urban: 0.31 x 10(6), p < 0.01). In females also, the geometric mean concentration of actinolite-tremolite in the neighboring group (0.59 x 10(6)) was significantly higher than that in the reference group (urban: 0.16 x 10(6), p < 0.05). There were no significant differences in the actinolite-tremolite concentrations between males and females in the neighboring group. 3. The serpentinite in this area have contained not only chrysotile but also both actinolite and tremolite. There was no significant relationship between actinolite-tremolite concentration and occupational history in the neighboring group. It is possible that actinolite and tremolite are liberated from the serpentinite to the atmosphere and inhaled by the residents near the serpentinite area which increases pulmonary actinolite-tremolite concentration. 4. The difference in the geometric mean concentration of chrysotile between the neighboring and the reference group was not statistically significant for both sexes, possibly due to the poor durability of chrysotile in the lung tissue. 5. There were no significant differences in the geometric mean of fiber length and diameter of actinolite-tremolite between the neighboring and the reference group.

Toluene induces behavioral activation without affecting striatal dopamine metabolism in the rat: behavioral and microdialysis studies

We examined the effects of toluene on the release of dopamine (DA) and its metabolites in rat striatum using microdialysis. Intraperitoneal injection of 800 mg/kg toluene significantly increased motor activity in rats, as did methamphetamine (MAP) (1 mg/kg). However, 800 mg/kg toluene did not affect the extracellular levels of DA, 3,4-dihydroxyphenylacetic acid, homovanillic acid, or 5-hydroxyindoleacetic acid. This is in contrast to MAP, which significantly increased extracellular DA and decreased the extracellular levels of its metabolites. These results suggest that toluene-induced behavioral augmentation may not be associated with alterations in DA or serotonin neurochemistry such as are associated with MAP-induced behavioral augmentation.

Metabolic acidosis and renal tubular injury due to pure toluene inhalation

A 22-y-old woman was hospitalized for muscle weakness of her lower extremities after she sniffed approximately 6 l of pure toluene during the month prior to admission. The examinations on serum and urine revealed mixed hyperchloremic and high anion gap metabolic acidosis accompanied by impaired urinary acidification. Histopathological changes of the kidney were patchy areas of tubular injury. Acidosis normalized on the fourth day of admission, but both proximal and distal tubular dysfunction persisted. These findings indicate that toluene is a tubular toxin and may contribute to the development of distal renal tubular acidosis.

Asbestos and nonasbestos fiber content in lung tissue of Japanese patients with malignant mesothelioma

BACKGROUND

Pulmonary fiber content of both asbestos and nonasbestos types were evaluated in Japanese patients with malignant pleural mesotheliomas.

METHODS

Pulmonary fiber content was analyzed in 16 patients and 16 case-matched control subjects by transmission electron microscopy with energy-dispersive X-ray analysis using a low-temperature ashing procedure.

RESULTS

The geometric mean content of total asbestos was significantly higher in the patients (22.0 x 10(6) fibers/g dry lung) than in the control subjects (2.24 x 10(6) fibers/g dry lung) (P < 0.01). When the asbestos content was analyzed by fiber type, the geometric means were also consistently and significantly higher among the patients compared with the control subjects (P < 0.01). Results were as follows: (1) amosite: patients 3.94 times 10(6) versus control subjects 0.23 x 10(6); (2) crocidolite: patients 3.56 times 10(6) versus control subjects 0.35 times 10(6); (3) total amphiboles: patients 16.0 times 10(6) versus control subjects 0.77 times 10(6); and (4) chrysotile: patients 3.76 times 10(6) versus control subjects 1.01 times 10(6). However, when individual total asbestos content was considered, 7 of the 16 patients (44%) had levels lower than the highest value noted among the control subjects. Pulmonary fiber content of patients and control subjects also revealed the presence of nonasbestos fibers. The geometric mean of nonasbestos fibers was significantly higher in the patients (87.3 x 10(6)) than in control subjects (33.8 x 10(6)) (P < 0.01). The major type of nonasbestos fibers in both groups was aluminum silicates. The mean of ratios of nonasbestos fiber contents to total asbestos contents in the patients and control subjects was 7.0 and 17.3, respectively.

CONCLUSIONS

The results were mainly in agreement with the findings of earlier investigations, but fiber content of both chrysotile and nonasbestos fiber as well as those of amphibole asbestos were significantly higher in the patients than in the control subjects.

[Medical examination of workers exposed to lead in the Philippines]

The medical examination of workers exposed to lead was conducted as part of the activity of the Occupational Safety and Health Center (OSHC) Project in the Philippines (JICA Project). The subjects of the medical examination were 21 male and 193 female workers of a semi-conductor plant (abbreviated A company), 59 male and 6 female workers of a refrigerator manufacture (B company); 199 male workers of a storage battery manufacturer (C company); and 107 male and 6 female workers of a lead smelter (D company). Among the examination items were questions regarding occupational history, subjective complaints and objective signs, determination of blood lead levels, urine delta aminolevulinic acid levels, and examination for anemia. The survey was conducted from June to September in 1990. The following results were obtained: 1) The mean age of the workers ranged from 21.8 to 33.8 years. Those of companies A and B were younger than those of companies C and D. The mean employment duration of males at C company was 10.7 yr, and the longest among the four companies. That in both sexes for A company was 1.8 yr and the shortest among the above mentioned companies. 2) The blood lead geometric mean levels of companies C and D showed the highest concentration. The level in males of C company was 64.5 micrograms/dl and that of D company was 80.8 micrograms/dl. The level in females of A company was 9.9 micrograms/dl and the lowest in concentration. The urine delta aminolevulinic acid geometric mean levels were less than 6.0 mg/l in the four companies. There was no company having hemoglobin mean values less than 14.0 g/dl in males or less than 12.0 g/dl in females. 3) The proportion of blood lead levels of 60 micrograms/dl or more was 67.3% in males of C company, and 89.7% in males and 16.7% in females of D company. The proportion of urine delta aminolevulinic acid levels of 6 mg/l or more was 1.0% in females of A company, 20.1% in males of C company, and 43.0% in males of D company. The proportion of hemoglobin values less than 14.0 g/dl in males or less than 12.0 g/dl in females was 4.7% in females of A company, 1.7% in males of B company, 3.5% in males of C company, and 12.1% in males of D company.(ABSTRACT TRUNCATED AT 400 WORDS)

[Inhaled nonasbestos fibers; pulmonary concentrations and fiber size in autopsied urban residents]

Nonasbestos fiber concentrations and fiber size distribution in autopsied lung tissues of 53 urban residents (34 males and 19 females) were analyzed by low temperature ashing-analytical transmission electron microscopy. The following findings were obtained. 1. Pulmonary nonasbestos fibers were found in all samples. Fiber consisting mainly of aluminum and silicon represented 80.0% of the total nonasbestos fibers observed. 2. The geometric mean concentration of nonasbestos fiber was significantly higher in males (47.6 x 10(6) fibers/g dry lung) than in females (18.2 x 10(6) fibers/g dry lung) (p < 0.05). This may be caused by differences in occupational exposure to nonasbestos fibers between males and females. 3. In females, the geometric mean concentration of nonasbestos fibers of smokers (34.6 x 10(6) fibers/g dry lung) was higher than that of nonsmokers (11.4 x 10(6) fibers/g dry lung), while, in males, the geometric mean concentration of nonasbestos fibers was lower in smokers (53.9 x 10(6) fibers/g dry lung) than in nonsmokers (89.1 x 10(6) fibers/g dry lung). These differences were not statistically significant. 4. The mean value for the ratio of nonasbestos fiber to asbestos concentration which ranged from 2.3 to 268 in males, and from 1.3 to 52.0 in females, was 30.1 and 20.2 respectively. 5. The mean length, diameter and aspect ratio for nonasbestos fibers were 1.01 microns, 0.103 microns and 11.3, respectively. Although nonasbestos fibers were almost equal in length to asbestos, the mean diameter of nonasbestos fibers was almost one-half of that of asbestos. Most of nonasbestos fibers (99.0%) were too small to be visible by light microscopy.

Urinary metabolite levels and symptoms in Filipino workers using organic solvents

To compare symptoms with urinary metabolite levels, 900 workers from 7 organic solvent-using industries were studied. Urinary metabolites were determined using a high performance liquid chromatograph. Urinary hippuric acid concentrations exceeding the reference value (2.5 g/g creatinine) were found in 78 (8.7%) workers. However, only 3 (0.3%) and 1 (0.1%) of the participants exceeded the reference value for mandelic (0.8 g/g creatinine) and total methylhippuric acid (1.5 g/g creatinine), respectively. The sum of the values of the ratio of measured urinary metabolite concentration to the corresponding ACGIH's biological exposure indices (BEI) [(HA/BEI of HA + MHA/BEI of MHA + MA/BEI of MA)] exceeded 1.0 in 166 (18.4%) workers. Majority of them were from the footwear manufacturing industry (63/129 or 49.2%). Questionnaire interviews were also administered to determine the prevalence of symptoms while at work (acute symptoms) or within the past 6 months (chronic symptoms). Urinary metabolite levels of individual and mixed solvents were compared with the symptoms of all workers. Analysis using Spearman's rank correlation showed in workers whose urinary hippuric acid exceeded 3.75 g/g creatine (1.5 x BEI), significant correlation between their hippuric acid levels and subjective complaints. Workers whose sum of the values of the ratio of measured urinary metabolite concentration to corresponding BEI exceeded 1.5 were selected and comparing this level with their symptoms, significant correlation was also noted in some complaints.

Modification of metabolism and neurotoxicity of hexane by co-exposure of toluene

The effects of co-exposure of hexane and toluene were investigated in field surveys and animal experiments. One field survey suggested that increase of hexane content in adhesives might have caused an outbreak of polyneuropathy in a vinyl sandal manufacture in Japan. The animal experiments proved that co-exposure of hexane and toluene decrease hexane neurotoxicity and urinary excretion of hexane metabolites in rats. The results also suggested that toluene might inhibit metabolism of hexane. Another recent field survey indicated that the ratio of urinary 2,5-hexanedione to hexane exposure in the workers co-exposed to hexane and toluene decreased in parallel with in more crease of toluene concentration. The results indicated that urinary excretion of 2,5-hexanedione could be depressed by co-exposure of toluene even in the workers exposed to relatively low concentrations. These above-mentioned results suggest that co-exposure of hexane and toluene could inhibit hexane metabolism and decrease hexane neurotoxicity in both experimental animals and workers. Although metabolism of hexane could be easily modified by toluene or other solvents and might not be a good indicator for hexane exposure in mixed exposure, urinary 2,5-hexanedione might be a good indicator for neurotoxicity of hexane even in mixed exposure.

Absence of blue-yellow color vision loss among workers exposed to toluene or tetrachloroethylene, mostly at levels below occupational exposure limits

Possible color vision loss was examined with Lanthony's new color test and Ishihara's color vision test in 261 solvent workers and 120 controls (48 men and 72 women). The solvent workers were exposed to either predominantly toluene [46 ppm as geometric mean (GM); 63 men and 111 women], tetrachloroethylene alone (13 ppm; 30 men and 34 women), or a mixture (14 men and 9 women) of tetrachloroethylene (12 ppm) and trichloroethylene (7 ppm). The only instances of color vision loss that were detected in either the exposed workers or the controls were six cases of red-green loss (all in men). These six cases of red-green loss showed an unbiased distribution between the exposed workers and the nonexposed controls.

[Asbestos concentration and fiber size in lungs of the urban residents]

Asbestos fiber concentrations and fiber size distribution in lung tissues of 53 urban residents (males: 34, female: 19) were analyzed by low temperature ashing-analytical transmission electronmicroscopy. The following findings were obtained. 1. Pulmonary asbestos fibers were found in 51 out of 53 patients. The types of asbestos fibers were chrysotile, amosite, crocidolite, actinolite and tremolite. 2. Thirty-six of 53 patients had no history of occupational asbestos exposure, and their geometric mean concentration of asbestos fibers was 1.67 x 10(6) fibers/g dry lung. Most of these asbestos fibers are probably attributable to general environmental contamination. Thirteen patients who had a history of occupational asbestos exposure showed a geometric mean of their pulmonary asbestos concentrations (5.82 x 10(6) fibers/g dry lung) which was significantly higher than that of patients without occupational asbestos exposure (p less than 0.01). 3. The geometric mean concentration of asbestos fiber in males (2.70 x 10(6)) was higher than in females (1.59 x 10(6)), probably due to a difference in the occupational asbestos exposure between males and females. 4. Regardless of the patient's sex, the geometric mean concentration of asbestos fibers in patients without a history of smoking (male: 4.91 x 10(6), female: 1.78 x 10(6)) was higher than that in patients with a smoking history (male: 2.76 x 10(6), female: 1.37 x 10(6)). The difference, however, was not statistically significant, and no correlation was seen between the concentration of asbestos fibers and smoking history. 5. Although most asbestos fiber utilized in Japan is chrysotile, the geometric mean concentration of chrysotile (0.87 x 10(6)) was almost identical to that of amphibole asbestos fiber (0.90 x 10(6)). 6. Of the asbestos fibers observed, 95% of chrysotile and 85% of amphibole asbestos were less than 5 microns in length and 93% of the total asbestos fibers were too small to be visible by light microscopy.

Determination of urinary 2,5-hexanedione concentration by an improved analytical method as an index of exposure to n-hexane

2,5-Hexanedione is a main metabolite of n-hexane and is considered as the cause of n-hexane polyneuropathy. Therefore, it is useful to measure 2,5-hexanedione for biological monitoring of exposure to n-hexane. The analytical methods existing for n-hexane metabolites, however, were controversial and not established enough. Hence, a simple and precise method for determination of urinary 2,5-hexanedione has been developed. Five ml of urine was acidified to pH 0.5 with concentrated hydrochloric acid and heated for 30 minutes at 90-100 degrees C. After cooling in water, sodium chloride and dichloromethane containing internal standard were added. The sample was shaken and centrifuged. 2,5-Hexanedione concentration in an aliquot of dichloromethane extract was quantified by gas chromatography using a widebore column (DB-1701). Urinary concentration of 2,5-hexanedione showed a good correlation with exposure to n-hexane (n = 50, r = 0.973, p less than 0.001). This method is simple and precise for analysis of urinary 2,5-hexanedione as an index of exposure to n-hexane.

Effects of subacute toluene exposure on neuronal and glial marker proteins in rat brain

The behavior of marker proteins of neurons (gamma-enolase) and glial cells (alpha-enolase, beta-S100 protein and creatine kinase-B) was investigated quantitatively by using enzyme immunoassay systems in toluene-exposed rat brains. Three groups of animals were exposed to toluene vapor at 300 ppm, 1000 ppm, and 3000 ppm, respectively, 8 h/day, 6 days/week, for 2 weeks. After subacute repeated solvent exposure, both neuron-specific gamma-enolase and glial marker proteins displayed an overall concentration-dependent increase tendency in separate brain regions. In cerebrum, only the 3000 ppm group showed a significant increase in alpha-enolase by 27% and creatine kinase-B (CK-B) by 26%. alpha-Enolase and gamma-enolase exhibited a pronounced elevation in cerebellum relative to other brain regions, while beta-S100 protein appeared to be the most markedly altered marker in brainstem. The development of gliosis, which is a frequent phenomenon following CNS damage, is presumed to be responsible for the elevation of glial marker content. Energy metabolism disruption in brain tissues may also bring about the compensatory oversynthesis of glycolytic enzymes such as gamma-enolase, alpha-enolase and CK-B. The dose-dependent alteration patterns following toluene exposure suggest the feasibility of using these brain specific markers to evaluate solvent-induced CNS effects.

Effects of MEK on kinetics of n-hexane metabolites in serum

The neurotoxicity of n-hexane is thought to be caused ultimately by 2,5-hexanedione (2,5-HD), one of the n-hexane metabolites. The potentiation of n-hexane neurotoxicity by co-exposure with MEK, therefore, is suspected to be related to kinetics of 2,5-HD in blood. To clarify the kinetics of n-hexane metabolites in the mixed exposure of n-hexane and MEK, rats were exposed to 2000 ppm n-hexane or a mixture of 2000 ppm n-hexane and 2000 ppm MEK, and the time courses of serum n-hexane metabolites were determined. 2,5-HD in serum increased until 2 h after the end of exposure, when serum 2,5-HD concentration reached a peak of 16.35 micrograms/ml in the n-hexane-alone group. In contrast, 2,5-HD in the mixed exposure group increased much more slowly during and after exposure than in the n-hexane-alone group. It reached a peak of 2.12 micrograms/ml at 8 h after the end of exposure. Serum MBK, a precursor of 2,5-HD in the co-exposure group, was about half in the n-hexane-alone group during exposure. However, MBK decreased more slowly in the co-exposure group than in the n-hexane-alone group after the end of the exposure. The results suggest that co-exposed MEK might inhibit oxidation of n-hexane and decrease clearance of n-hexane metabolites. Co-exposed MEK did not increase serum 2,5-HD, which was considered a main neurotoxic metabolite. Therefore the enhancement of neurotoxicity could not be attributed to increased serum 2,5-HD in the co-exposed group.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in urinary n-hexane metabolites by co-exposure to various concentrations of methyl ethyl ketone and fixed n-hexane levels

To make clear how the n-hexane metabolism is modified by co-exposure with MEK, rats were exposed to various concentrations of MEK mixed with a fixed concentration of n-hexane. Twenty-four male Wistar rats were divided into four equal groups. Each group was exposed for 8 h to 2000 ppm n-hexane, 2000 ppm n-hexane plus 200 ppm MEK, 2000 ppm n-hexane plus 630 ppm MEK and 2000 ppm n-hexane plus 2000 ppm MEK, respectively. Free metabolites and the sum of free and conjugated metabolites of n-hexane were analyzed by gas chromatography. The main metabolite was 2-hexanol during the exposure and 2,5-hexanedione (2,5-HD) after the exposure in any group. The main metabolites, 2-hexanol and 2,5 HD, decreased in inverse proportion to the co-exposed MEK concentrations. The results suggest that augmentation of n-hexane neurotoxicity by MEK co-exposure could not be explained only by 2,5-HD. In addition, 2,5-HD is recommended as an index for biological monitoring of n-hexane exposure. However, one should be careful to evaluate the exposed n-hexane concentration by urinary 2,5-HD, because n-hexane metabolism could be largely modified by co-exposure with MEK.

Effects of chronic n-hexane exposure on nervous system-specific and muscle-specific proteins

Two kinds of nervous system-specific and muscle-specific proteins, enolase and S-100 protein, were quantitatively determined in peripheral nerves and skeletal muscles of rats chronically exposed to a neurotoxic solvent - n-hexane. Three groups of animals were exposed to n-hexane vapor at three different solvent concentrations (500 ppm, 1200 ppm, 3000 ppm) for 12 h/day, 7 days/week for 16 weeks. The body weight gain and motor nerve conduction velocity (MCV) in exposure groups show progressively concentration-dependent decreases compared to control values. Histopathological examination also demonstrates the degeneration of peripheral nerves in 3000 ppm- and 1200 ppm-exposed rats. The significant decrease in the amount of S-100 protein in peripheral nerves was observed not only in the high level exposure groups (3000 ppm and 1200 ppm), but also in the lowest level group (500 ppm), although the MCV and morphological examination remained unchanged at this level. In addition, the muscle-specific S-100 protein in 3000 ppm exposed rats' soleus also displayed a significant reduction. In contrast to this, however, enolase isozymes were not significantly changed by either dosage level in both nervous tissue and skeletal muscle. The experiment suggests that beta- and alpha-S-100 proteins which are specifically localized in nervous system and muscles, respectively, are more vulnerable than enolase isozymes under treatment with n-hexane, and may possibly serve as a specific indicator to evaluate the neurotoxic effects. Further research would be worthwhile to elucidate the role of the specific S-100 protein in evaluating the neurologic damage induced by various industrial chemicals.

Asbestos fibers in human pulmonary and extrapulmonary tissues

The association between asbestos fibers in human lung tissues and those in other extrapulmonary organs was studied by analysing three autopsied cases, one of whom had a high pulmonary asbestos burden, one an intermediate burden, and one a low burden. The amount, types and sizes of asbestos fibers in the tissues of lung, liver, spleen, pancreas, kidney, and gastrointestinal tract were identified and measured by transmission electron microscopy equipped with an energy dispersive X-ray analyser. The following results were obtained: 1) The concentrations of asbestos fibers in extrapulmonary organs tended to increase with that in lung tissues. 2) The types of fibers identified in lungs were approximately consistent with those in other organs. 3) A relatively large range of fiber length was observed in both lungs and other organs. The findings extend and support previous light microscopic studies comparing asbestos bodies in various organs, and may imply that persons with high levels of asbestos in their lungs are also likely to have the same types and high levels of asbestos in their other tissues.

Relationship between chlordane and its metabolites in blood of pest control operators and spraying conditions

Chlordane has been widely used to protect soil and house foundations against termite infestation. Pest control operators (PCOs) are occupationally exposed to chlordane. The relationship between chlordane and its metabolites in blood of PCOs and spraying conditions were investigated. Chlordane and its metabolites were detected in the blood of some chlordane-exposed PCOs, but not in that of the controls. Trans-nonachlor and the metabolites oxychlordane and heptachlor epoxide were detected in the blood of PCOs. Total concentration of chlordane and its metabolites in blood (trans-nonachlor + oxychlordane + heptachlor epoxide) was less than 5.6 ppb (mean: 0.89 ppb). The concentration of chlordane and its metabolites in blood of chlordane-exposed PCOs was significantly correlated with the number of spraying days and the amount of chlordane sprayed, particularly with a large correlation coefficient (r = 0.81, P less than 0.001) with the spraying days in the three months prior to the medical examination. The concentration of chlordane and its metabolites in blood is considered to be a useful indicator of biological monitoring for chlordane exposed workers (PCOs).

[A nationwide survey on the use of organic solvents in Japan]

A total of 1,179 organic solvent products used as thinners, paint, degreasers, inks, adhesive and others, were collected nationwide from factories of various sizes and kinds in Japan, and analyzed by gas chromatography. Solvent components per sample, frequency of each solvent component, and contents of each component were analyzed and classified by use. Paints, inks, and adhesives which contained nonvolatile substances were analyzed by head space techniques. Seventy-seven percent of all samples, 93% of paints, 85% of thinners, 73% of adhesives, and 52% of degreasers contained mixed organic solvents. The average numbers of solvent components per sample were 4.14 (max. 13) in thinner, 3.29 (max. 7) in paint, 2.23 (max. 5) ink, 2.19 (max. 6) in adhesive, 1.71 (max. 6) in degreaser, when gasoline was excluded. Toluene, xylene, methylalcohol, isopropylalcohol, ethylacetate, methylethylketone, industrial gasoline were widely used in the above-mentioned products. Toluene was the most popular component in the solvent products, excluding degreasers. Many kinds of solvent components were used in thinner and paint. However, toluene, xylene and industrial gasoline were their main components and contents per sample were very high. Acetates, alcohols, ketones and glycols were frequently detected in solvent products, but their contents per sample were relatively low, because these solvent components were usually used as subordinate solvents. The chlorinated hydrocarbons such as trichloroethylene, tetrachloroethylene and 1,1,1-trichloroethane, and industrial gasoline were the most popular components in degreasers. 1,4-dioxane was detected in a relatively large number of the samples, but its content per sample was very low, because it is usually used as an additive to 1,1,1-trichloroethane. Toluene was the most popular component in ink solvents, too. In addition, isopropylacohol, methylalcohol, methylethylketone were frequently detected in inks. Toluene was also the most popular component in adhesives, and n-hexane was also frequently detected in them. In order to prevent poisoning by industrial solvents, special attention should be paid to toluene and xylene, which are frequently and largely used for wide purposes, trichloroethylene which is largely used as a degreaser and has a severe toxicity, n-hexane which is frequently used in adhesives and has a high volatility and severe neurotoxicity, and other popular and toxic solvents. The severely toxic solvents such as benzene, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane and carbon disulfide were detected in few samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of n-hexane neurotoxicity and its urinary metabolites by long-term co-exposure with MEK or toluene

It is well known that the neurotoxicity of n-hexane may be modified upon co-exposure with other organic solvents. In order to elucidate this mechanism further, rats were exposed to 500ppm n-hexane, 500ppm n-hexane plus 500ppm methyl ethyl ketone (MEK), 500ppm n-hexane plus 500ppm toluene, or air only for 8h per day for 33 weeks. The body weight, motor nerve conduction velocity (MCV) and distal latency (DL) were determined before exposure and after 4, 8, 12, 16, 20, 24, 29, and 33 weeks of exposure. From each group one rat was histologically examined after 33 weeks of exposure. To establish a relationship between the n-hexane neurotoxicity and changes in biotransformation, urinary metabolites (2-hexanol, methyl n-butyl ketone (MBK), 2,5-hexanedione, 2,5-dimethylfuran, and gamma-valerolactone) were measured by gas chromatography on the first exposure day, and after 1, 2, 4, 8, 12, 16, 20, 24, 29, and 33 weeks of exposure. The total amounts of metabolites of n-hexane in the urine significantly decreased upon co-exposure of n-hexane, with MEK as well as with toluene, in comparison with those of animals exposed to n-hexane alone. 2,5-Hexanedione, which is considered the ultimate neurotoxic metabolite of n-hexane, also decreased. Electrophysiological and histological studies did not reveal statistically significant differences between any two groups among the four groups. It is considered that the present results might explain the combined effects of n-hexane and toluene which decrease n-hexane neurotoxicity, but do not explain those of n-hexane and MEK. Therefore, other mechanisms of the combined effects of n-hexane and MEK should be studied.

[Vibration hazards in quarry workers]

Vibration hazards were surveyed in a population of quarry workers using chipping hammers and to a lesser extent, rock drills. Sixty-nine male quarry workers, aged 49.1 +/- 8.7 and exposed to vibration for 16.4 +/- 5.1 years, were surveyed in 1981-82. They were exposed to vibration for about 2-4 hours per days, mainly under a piece-work pay system. They had a high prevalence of Raynaud's phenomenon (36.2%) and numbness in upper extremities (53.6%). It is considered that the high prevalence was mainly due to large vibration levels in chipping hammers and rock drills and long daily exposure time. The attacks of Raynaud's phenomenon were found predominantly in the left hand, which held chisels, whereas the restriction of motion in the elbow was predominantly in the right arm which pushed chipping hammers. The same 49 male quarry workers in this population were also surveyed in 1976-77 and the prevalence of their complaints between 1976-77 and 1981-82 was compared. The prevalence of Raynaud's phenomenon was the same, but the frequency of the attacks increased between the two periods. The prevalence of other complaints such as numbness, pain and chills in the upper extremities also increased. Between 1976-77 and 1981-82, the prevalence of Raynaud's phenomenon, numbness, and pain in the upper extremities increased in the population of quarriers exposed to vibration for above 2.6 hours per day and 200 days per year, or 600 hours per year. On the other hand, the prevalence of these complaints mostly decreased in the population of quarriers with less exposure.