In order to obtain bioassay data for carcinogenicity and chronic toxicity of an organic solvent being absorbed into the body through multiple media by inhalation and ingestion, an exposure system for combined inhalation and oral exposures of rats to the organic solvent was constructed. Operational performance of the system was examined by monitoring air and water concentrations of chloroform or 1,4-dioxane in both an inhalation exposure chamber and an automatic watering system, while groups of 50 male rats each were exposed to chloroform or 1,4-dioxane by inhalation for 6 h/d, 5 d/wk and 104 wk and by water drinking for 24 h/d and 7 d/wk throughout the 104 wk. Day-to-day and time-to-time variations in concentrations in the exposure chamber were maintained at less than 0.8% C.V. and 4.8% C.V., respectively, in the case of chloroform, and less than 1.2% and 8.1%, respectively, in the case of 1,4-dioxane. The mean 6-h averaged concentrations deviated by less than 0.4% from the respective target concentrations for all sets of the combined exposures. The watering system which was composed of a drinking valve, in-between piping, a container and a solenoid drainage valve was used for giving ad libitum drinking water containing 1000 ppm chloroform or 1,4-dioxane to rats. Mean water concentrations of chloroform and 1,4-dioxane were attenuated by 3-8% and by 1% in the container after 1-week’s supply, respectively. It was concluded that this exposure system can give accurate and reproducible air and water concentrations of chloroform and 1,4-dioxane for long-term combined inhalation and oral exposure.
From the point of view of industrial medicine, the maintenance of industrial health and safety standards to minimize health hazards for staff is the most important item in dealing with biological materials at work. With regard to the rubbish industry, it is therefore mandatory to recognize every possible health hazard in order to supplement preventive measures and to increase industrial medical prevention. In a cross-sectional study of industrial medicine, 83 trash collectors were medically examined, their case history having been taken by means of a standardized questionnaire. The immunobiological examination consisted of the measurement of specific IgE and IgG antibodies to Aspergillus fumigatus. An immunoblot was used to supplement the investigation and to illustrate individual epitopes of allergens of Aspergillus fumigatus. In 16 trash collectors (19%) there was a specific sensitization against Aspergillus fumigatus Type I and Type III simultaneously, as proven by the standards of Coombs and Gell. Specific antibodies to Aspergillus fumigatus were discovered in 27 employees. Neither the information given by the dust collectors nor medical examination results allowed the deduction of the presence of an allergy in the sense of typical health disturbances. Based on the results of this study, however, the immunological parameters may indicate a possible sensitization of the employees in the rubbish industry.
This case-control study assessed the relationships between certain individual characteristics (age, body mass index, training, length of time in present job, sleep disorders, certain disabilities, smoking habits, sporting activities) and occupational accidents in construction male labourers: 880 cases with at least one occupational accident in 1995-1996, 880 controls with no occupational accident during the previous five years, matched to cases on the job. A standardised questionnaire, filled in by the occupational physician, was used. The statistical analyses were made by the conditional logistic regression method for paired data. The main causes of accidents were handling or carrying objects, falls to a lower level, construction machinery and devices, falls on the same level, moving objects, hand tools. For all accidents combined, the factors with significant adjusted odds-ratios (OR) were: age<30 yr (OR 1.30, 95%CI 1.01-1.68), sleep disorders (1.97, 1.42-2.73), and current smoker (1.27, 1.04-1.54). Sleep disorders were a significant factor in falls to a lower level (OR 2.25, 95%CI 1.14-4.44), age<30 yr and sleep disorders for accidents caused by moving objects (4.64, 1.48-14.5 and 13.11, 2.64-65.2 respectively), and no sporting activity for injuries by handling or carrying objects (1.70, 1.11-2.60). Sleep disorders were significant for accidents with sick leave lengths of ≥15 d, whereas age<30 yr and current smoker were significant for the others (≤14 d). A relationship was observed between the severity of sleep disorders and accidents. Occupational accidents are mainly due to work conditions, but certain individual characteristics may also play a role; this should be confirmed by further studies.
The presence of allergies, respiratory symptoms and skin-prick reactions was evaluated in trained home-helpers (THH), and indoor allergen levels were measured at their work sites. A questionnaire was answered by 118 THHs and forty THHs consented to skin-prick tests. The indoor allergen levels in the settled house dust from the clients’ homes of 17 prick tested THHs were determined by two-site monoclonal antibody ELISA methods. Forty-eight percent of the THHs had one or more symptoms at least weekly. The presence of respiratory symptoms and atopy was not particularly high in THHs. Prick tests revealed that 11 THHs (28%) had positive reactions to one or more of the allergens tested. A significant correlation was observed between the frequency of reported symptoms and positive prick reactions. Fel d 1 was found in 98% and Can f 1 in 96% of the dust samples, but Der p 1 in only 21% of the samples, though the levels remained rather low. The sensitization threshold suggested for cat allergen (1μg/g) was exceeded in 26%, and that for dog allergen (2μg/g) in 32% of the sites studied. These results showed that THHs are occupationally exposed to allergen levels sufficient to result in sensitization.
Excessive daytime sleepiness (EDS) has been noted as a tremendous burden on our modern society and life, but evidence on EDS is limited for white-collar workers in occupational settings. To estimate the prevalence rate of EDS and examine its associated factors, we investigated 3,909 male non-shift white-collar employees aged 20-59 working in a telecommunications company in the Tokyo metropolitan area between December 1999 and January 2000 (a response rate of 91.0%). Our main findings in the present study were that the prevalence rate of EDS was 7.2% and five factors associated with EDS were identified in a multivariate logistic regression model (p<0.05): nocturnal sleep duration, sleep-wake schedules, depression, marital status and smoking. These results suggest that the individual behavioral modification of sleep habits and lifestyle is one of the promising strategies for reducing EDS. More importantly, it is possible that occupational and health promotion policies such as a ban on overtime work and the provision of mental health hygiene and social support at worksites are effective for the prevention of EDS in the workplace.
Aim: Recent studies have made it clear that brassica vegetables contain 2-thiothiazolidine-4-carboxylic acid (TTCA), which is the most widely used biological monitoring index of exposure to carbon disulfide (CS2). This study aimed to assess the time-course of TTCA excretion in urine (TTCA-U) after eating brassica vegetables. Methods: After a 1-d break from eating brassica vegetables, ten volunteers (6 males and 4 females) ingested 100 grams of chopped raw cabbage containing 4.3 mg/kg of TTCA, and the TTCA concentration in urine samples was determined over 24 h. TTCA concentrations in brassica vegetables purchased from a local supermarket were also measured. Results: TTCA-U reached peak concentrations 3-9 h after cabbage intake, gradually decreased, and was below the detection limit (<0.1 mg/l) in 8 of 10 volunteers in the last urine samples. The total amount of TTCA excreted in 24 h ranged from 0.19 to 0.42 mg, and half of the total TTCA was excreted within 6.5 h on average (range: 4.5-10.1). The excretion profiles of young and middle-aged volunteers seemed to differ, but not those of young males and young females. TTCA was detected in both raw and boiled cabbage, Japanese radish, turnip, and broccoli, but was not detected in Chinese cabbage or chingentsuai. Conclusion: TTCA-U may be overestimated as an index of CS2 exposure when brassica vegetables are ingested within approximately 24 h before collection of the urine sample.
To investigate the effects on the central nervous system of subchronic exposure to 1-bromopropane (1-BP), which is a substitute for chlorofluorocarbons, we measured the hippocampal excitability of 1-BP-treated rats electrophysiologically. Male Wistar rats were exposed to 1-BP for 6-h in a day in an exposure chamber (1,500 ppm) for 4 wk. After the 1-, 3- and 4-wk inhalation, field excitatory postsynaptic potentials (fEPSPs), population spikes (PSs), fEPSP/spike (E/S) curve, paired-pulse profiles of fEPSP slopes and PS amplitudes recorded from CA1 pyramidal neurons, and dentate granule cells of the hippocampal slice obtained from the rats were analyzed. In 1-BP treated rats, E/S potentiation and a lower subthreshold of PSs were observed in the dentate gyrus (DG) after the 3 and 4-wk inhalation. Paired-pulse inhibition was reduced at 5-50 ms in the CA1 and at 5-20 ms in the DG after all of the inhalation. These changes were not associated with paired-pulse inhibition of fEPSPs. In the DG, the paired-pulse inhibition at the short interpulse intervals in rats exposed to 1-BP was pronounced by an application of A type gamma aminobutyric acid (GABA) receptor agonist pentobarbital. Impaired paired-pulse inhibition of granule cells at the short interpulse intervals was recovered after the application of N-methyl-D-aspartate (NMDA) type glutamate receptor antagonist DL-2-amino-5-phosphonopentanoic acid. Convulsing rats observed after the 4-wk inhalation exhibited multiple PSs in the DG, and their second component was abolished by an application of this antagonist. Inhalation of 1-BP increased the neuronal excitability in the hippocampal CA1 and the DG. The hyperexcitability of the granule cells in the DG was at least due to an over-activation of NMDA receptors.
We performed a prospective study to assess the acceptability and long-term compliance with drug treatment for hypercholesterolemia in Japanese male workers aged 40 to 57 yr with hypercholesterolemia detected in legally required periodical physical examinations. This paper describes the acceptability of statin-based drug treatment. All eligible workers who had not improved after 3-month diet therapy were recommended for drug treatment with simvastatin, a 3 hydroxy-3-methylcoenzyme A reductase inhibitor. Subsequently, according to each individual preference, the subjects were divided to two groups: a group which accepted drug treatment (DT) and a group which rejected it. The subjects who did not accept drug treatment were further assigned to two groups according to their preference: a group which accepted only dietary intervention (DI) and a non-treatment group (NT). Among 1,278 workers recruited, 656 (51.3%) were placed in the DT group, 414 (32.4%) in the DI group and 208 (16.3%) in the NT group. In the DT group, mean serum total cholesterol (TC) was the highest [272±30 (SD) mg/dl]. The acceptability of drug treatment was significantly associated with the serum TC level, pre-existing medical history of hypertension and a family history of ischemic heart disease (IHD). The occupational issues such as type of job, overtime worked, sleeping time and psychological status were different among the three groups, and habits of taking breakfast and daily exercise were associated with acceptability of drug treatment. These data suggest that acceptability of the drug treatment is low and associated with the work- and lifestyle- related issues as well as IHD risk factors.
Carcinogenicity and chronic toxicity of biphenyl were examined in 50 male and 50 female F344 rats exposed to 0, 500, 1,500 or 4,500 ppm biphenyl in the diet for 105 weeks. Bladder tumors were found in the 4,500 ppm males, as evidenced by significantly increased incidence of carcinoma (24/50) and papilloma (10/50) of the transitional cells as well as one rarely observed case both of carcinoma and papilloma of the squamous cells. The survival rate of the 4500 ppm males significantly decreased, due to the bladder tumors and the hematuria accompanied by bladder calculi. The bladder calculi were found in 43 males in the 4,500 ppm group, but in only 8 females. Urinary pH significantly increased in the males, and occult blood was observed both in males and females in the 4,500 ppm group. The pre-neoplastic lesions were hyperplasia of transitional epithelium (simple, nodular and papillary hyperplasia) in the bladder of the 4,500 ppm males. Incidences of calculus formation and transitional cell hyperplasia in the renal pelvis also significantly increased in the 4,500 ppm males and females. On the other hand, the incidences of the transitional cell hyperplasia and the calculus formation in the bladder and the renal pelvis were far lower in females than in males, and no bladder tumors were observed in the females. Causative factors of the bladder tumors and their male predominance were discussed with reference to the findings reported in the literature and the previous study of biphenyl metabolism.