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We evaluated total body burden of N,N-dimethylformamide (DMF) taken through the lung and skin by personal exposure of workers to DMF and urinalysis of N-methylformamide (NMF) and N-acetyl-S(N-methylcarbamoyl)-cysteine (AMCC). A total of 270 workers were engaged in four different jobs in a workplace distant from main production lines emanating high levels of DMF. They were not required to wear any personal protective equipment including respirators or gloves. We found that log-transformed urinary levels of NMF and AMCC increased with an increase in log-transformed concentrations of exposure to DMF. Urinary levels of NMF and AMCC were significantly higher in the summer than the winter, although there was no significant seasonal difference in the concentrations of exposure to DMF. Our findings suggested that the increased urinary levels of NMF and AMCC in the summer resulted in increased skin absorption of DMF due to an increased amount of DMF absorbed by the moisturized skin under humid and hot conditions. Seasonal changes in the relative internal exposure index confirmed the present finding of enhanced summertime skin absorption of DMF. AMCC is thought to be a useful biomarker for assessments of cumulative exposure to DMF over a workweek and for evaluations of workers' health effects.

This study was aimed at clarifying the effect of exposure to N-methyl-2-pyrrolidone (NMP) on workers' health. Fifteen male NMP-exposed workers and 15 referent male workers were recruited for this study. Exposure concentrations were assessed by determining NMP in the breathing zones and urinary NMP. Clinical examinations, motor and sensory nerve conduction velocities in the dominant arm, and neurobehavioral tests were carried out. The subjects were asked to complete self-administered questionnaires for subjective symptoms and psychological assessment. The mean NMP exposure concentrations ranged from 0.14 to 0.26 ppm, and urinary NMP levels at the end of each workday ranged from 0.17 to 0.22 mg/l, throughout the work week. In terms of clinical data, motor and sensory nerve conduction velocities, neurobehavioral tests, and subjective symptom assessments, there were no differences and no dose-dependent changes in either the means or the prevalence of abnormal findings between NMP-exposed and referent workers.

A 19-year-old man suffered hepatic dysfunction after 5 months of exposure to N,N-dimethylformamide (DMF) at his job in the synthetic resins industry. Laboratory data revealed elevated levels of AST (578 IU/l), ALT (1193 IU/l), and gamma-GTP (107 IU/l), no viral infection with HAV, HBV, or HCV, and no history or evidence of hepatic injury, although he did have a slight abdominal abnormality and swelling which was detected by palpation. His urinary N-methylformamide level, as a biological exposure index of DMF, was 42.8 mg/l, indicating 10-30 ppm of DMF exposure. After 2 months he was reinstated in two workplaces, the former where he worked in the morning and the other in the afternoon where environmental DMF concentrations were less than those in the former workplace. On the 18th day after his reinstatement, his liver function became exasperated again. After the second period of medication and one month of rest from work, he had fully recovered and was reinstated, but to a workshop without DMF exposure.

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.

A simple sampling and analytical method for monitoring carbon disulfide (CS2) vapor was investigated to assess exposure to low levels of CS2 in a viscose rayon factory. CS2 vapor was adsorbed on polymer beads (poly (2,6-diphenyl-p-phenylene oxide)) packed in a diffusive sampling tube. The sampling tube was heated at 180 degrees C for 7 min using a Daily Exposure Limit Test Apparatus, and thermally desorbed CS2 was measured by a stain tube for CS2. In laboratory experiments, the indicated CS2 levels measured by this method were highly correlated with calibrated CS2 concentrations (1-40 ppm), exposure duration (1-8 hr) and cumulative exposure levels. The CS2 values were stable up to 7 days after sampling when the diffusive tubes were stored at 4 degrees C and 20 degrees C. The effects of relative humidity, wind velocity and hydrogen sulfide on the measured values were negligible. In a field survey, 65 workers in a viscose rayon factory wore both the diffusive sampling tube and a commercially available 3M 3500 organic vapor monitor on their collar during their 8-hr work period. CS2 concentrations obtained by the two methods were comparable and the correlation coefficient was 0.931. This method proved to be useful in determining the concentrations of CS2 to which workers were exposed.

Breakthrough times of a commercially-available respirator cartridge packed with a small amount of activated carbon were determined by three different flow patterns: workers' respiratory patterns, conventional steady-state flows, and three standard patterns consisting of rectangle, sine, and triangle waves. A mechanical breathing simulator was used to reproduce the three standard wave patterns as well as the workers' respiratory patterns, which had been recorded from three workers of a paint manufacturing plant wearing a gas mask equipped with a respirator cartridge. The breakthrough test was carried out with 300 ppm carbon tetrachloride vapor at average flow rates of the respiratory and standard patterns equivalent to the steady-state flow rates. The breakthrough times determined by the workers' respiratory patterns were found to be shorter than those by a steady-state flow of the equivalent flow rate, and to be as short as those by sine and triangle wave patterns. It was considered that shorter breakthrough times in the workers' respiratory patterns could be attributed to a faster maximum inspiratory flow rate than that in the case of steady-state flow. The present results suggest that the passing time of CCl4 molecules through the thin activated carbon layer of respirator cartridge may be too short to attain an adsorption equilibrium.

The study was undertaken to assess the potential risk of exposure to methyl bromide (MB) gas of plant quarantine fumigators who wore full facepiece gas masks with respirator canisters. The mean ambient concentrations of MB determined by a personal sampling device exceeded the TLV-ACGIH level of 5 ppm in the degassing processes at three fumigation sites except at the silos. The mean urinary bromine concentration of 379 non-MB workers was 6.3 +/- 2.5 mg/l with 95% confidence limits of 10 mg/l. There were 44.6% of 251 MB workers whose urinary bromine levels exceeded the 10 mg/l. There was a significantly positive correlation between the urinary bromine concentrations of the MB workers and the ambient MB concentrations in the degassing process. The MB levels in the workers' exhalation were positive in the degassing process, while those were below the detection limit in the dispersion process. Three possible routes through which the workers are exposed to MB gas are considered to exist: leakage through the interstice between the facepiece of a gas mask and the wearer's face, breakthrough of MB gas in the respirator canister, and percutaneous absorption of MB gas. Biological monitoring of urinary bromine and exhalatory MB as well as environmental monitoring of the ambient MB provided useful information for evaluating exposure of workers to MB.

Methylmercury chloride (MMC)-induced alterations in circradian sleep rhythmicity of the rat were statistically evaluated by application of cosinor method to hourly values of slow-wave sleep (SWS) and paradoxical sleep (PS) obtained4 days before and Days 23-26 after oral administration of MMC (15 mg/kg/day for 2 cosecutive days). The cosinor analysis revealed that the most prominent changefollowing MMC administration was a delay by 5 h of the circadian PS acrophase.Weattempted to elucidate the altered circadian PS rhythm in the term of brain noradrenaline (NA) metabolism. Rats administered orally with MMC at the same dose orwith a vehicle solution as a control were sacrificed by decapitation at 6 different times on Day 23 after the first administration. Noradrenaline (NA) and 3-methoxy-4-hydroxy-phenylethyleneglycol (MHPG) of the frontal cortex and the hippocampus were determined by high-performance liquid chromatography with electrochemical detection. Cortical NA levels of the MMC-administered rats were significantly lowered at 0200 h and 0600 h, as compared to those of the control rats. Cortical MHPG level of the MMC-administered rats increased significantly at 1000 h and then decreased significantly at 2200 h, whereas hippocampal MHPG levels of the MMC-administered rats decreased significantly at 1800 h and 2200 h. A plausible mechanism underlying the MMC-induced delay in the circadian PS acrophase was discussed in the light of cortical and hippocampal changes in NA metabolism.

Two kinds of respirator canisters, an organic vapor (OV) canister containing activated carbon and a methyl bromide (MB) canister containing activated carbon impregnated with triethylenediamine were investigated for their filtration efficiency of MB gas under various conditions of MB concentration, humidity and temperature. At lower MB concentrations, the breakthrough time of the OV canister was shorter than that of the MB canister. It also decreased with an increase in temperature, whereas the breakthrough time of the MB canister did not change with temperature. Humidity affected the breakthrough times of the OV canister as much as those of the MB canister. The desorption and the remaining filtration efficiency of MB gas were examined in both canisters which had been used for fumigation in plant quarantine. More than 5 ppm of MB gas leaked from 11 out of 18 used OV canisters, whereas less than 0.1 ppm MB leaked out from each of the used MB canisters. The mean remaining breakthrough time of the used OV canisters was 9.3 min, whereas that of the used MB canisters was 74.4 min. From the present study, it was shown that the gas masks with the OV canisters were not suitable for fumigating with MB gas.