Carcinogenicity and chronic toxicity of vinyl acetate monomer (VA) were examined in male and female Crj:BDF1 mice and F344/DuCrj Rats. Groups of 50 mice and 50 rats of each sex were orally administered VA in drinking water containing 0, 400, 2,000 or 10,000 ppm (g/g) VA for 104 wk. Squamous cell tumors were clearly evident in the upper digestive tract of treated mice and rats, and in the larynx of treated mice of both sexes. In mice, squamous cell carcinomas and papillomas were observed in the oral cavity, esophagus, forestomach and larynx of the 10,000 ppm group, together with basal cell hyperplasia, squamous cell hyperplasia and epithelial dysplasia. In rats, incidences of squamous cell carcinomas and papillomas were increased in the oral cavity of the 10,000 ppm group of both sexes, and an esophagus squamous cell carcinoma was observed in a 10,000 ppm female. Pre-neoplastic hyperplasias were also noted. Mapping of the neoplastic and pre-neoplastic lesions in the oral cavity of the 10,000 ppm group revealed that both the lesions occurred predominantly at Level V in mice and at Level VI in rats. A lower confidence limit of a benchmark dose (BMDL10) of 477 mg/kg/d was obtained from a dose-response relationship between combined incidence of squamous cell carcinomas and papillomas in the oral cavity of mice and rats and the estimated daily VA intakes per body weight, and compared with literature values.
Although back disorders are a major occupational problem for nursing staff, few studies distinguish different types. By means of a structured questionnaire, we performed a cross-sectional study on the prevalence of diagnosed lumbar disc hernia, chronic low-back pain (LBP) (at least 90 d in the preceding 12 months) and acute LBP (intense pain for at least 1 d) with respect to physical, individual and psychosocial factors among female nurses (n=587), nursing aides (n=228) and head-nurses (n=43) working in a university hospital (95% of the female workforce). Almost all respondents reported known high-risk occupational activities. Overall prevalence of reported back disorders was 44% (acute LBP 19%, chronic LBP 17%, lumbar hernia 8%). On multinomial logistic regression analysis, scoliosis and commonly stress-related psychosomatic symptoms were associated with all three types of back disorder; trauma/fractures of the spine, pelvis and/or legs and a global work-environment/job-satisfaction score with acute LBP; increasing age with lumbar disc hernia. While confirming the relevance of considering different definitions of back disorder, our data indicate items for investigation in cohort studies. These include: identification of specific risk factors for lumbar hernia; avoidance of possible work-environment risk factors such as hurried execution of different tasks at the same time; and influence on job suitability of underlying spinal pathologies such as scoliosis.
This study aims at clarifying the semen indices of insecticide sprayers who are exposed mainly to organophosphorus and pyrethroid insecticides. Eighteen male sprayers out of 54 working for 9 companies in central Japan and 18 age-matched students or medical doctors as unexposed controls participated in detailed reproductive check-ups conducted in summer and the following winter. The sprayers were exposed to insecticides more in summer, the busiest season, than winter, the off-season (p<0.05). Erythrocyte true cholinesterase activities in the sprayers were lower than in the controls in summer (p<0.05), and decreased in significant association with the increase in exposure frequency. Testicular volumes in the sprayers tended to be smaller than in the controls (p=0.06). The serum testosterone concentration in winter in the sprayers was higher than in the controls (p<0.05), though luteinizing hormone and follicle stimulating hormone concentrations were not significantly different. The sperm counts and vitality were comparable between the groups, but detailed sperm motility analysis in summer revealed that the percentages of slow progressive and nonprogressive motile sperm were twice as high in the sprayers (p<0.05), and that of rapid progressive sperm tended to be lower (p=0.06). Such differences were not observed in winter. Differential sperm morphology counts showed that interaction of group and abstinence effects were significant in sperm with normal morphology and with head deformity only in the summer check-up. Despite possible inherent differences between the groups, the above season-dependent differences suggested that the observed lower semen quality in the sprayers was associated with pesticide spraying work.
In a previous epidemiological study we reported that the prevalence (45.8%) of low-back pain (LBP) and the two-year incidence (25.9%) of LBP in 284 male taxi drivers in Japan was comparable with rates reported for other occupational drivers in which LBP frequently occurs. LBP was significantly related with the level of uncomfortable road vibrations, and, importantly, increased with total mileage. The aim of this study was to measure whole-body vibration (WBV) on the driver's seat pan of 12 taxis operating under actual working conditions. The results were evaluated according to the health guidelines in International Standard ISO 2631-1:1997. Finally, the relation between total mileage and WBV was investigated. The majority of the frequency-weighted r.m.s. accelerations of the taxis fell into the “potential health risks” zone, under ISO 2631-1:1997. It was clear that the taxi drivers were exposed to serious WBV magnitudes. Therefore, occupational health and safety management should be carried out to help prevent adverse health effects in taxi drivers. In particular, reduction of WBV in taxis and shortening of driving time to reduce duration of WBV exposure should be considered. Moreover, because many taxi drivers work 18 h every other day, the shortening of working hours and taking of rest breaks while working should be considered. Frequency-weighted r.m.s. accelerations of taxis had a tendency to decrease as total mileage increased. The relation between total mileage and WBV should be investigated by taking measurements on the floor and the back rest in addition to the seat pan.
The aim of this study was to evaluate heart rate variation and urinary catecholamines in response to acute psychological stress in hand-arm vibration syndrome (HAVS) patients and healthy controls. LF% (indicator of both the sympathetic and parasympathetic nervous activity), HF% (indicator of the parasympathetic nervous activity) and their ratio LF/HF (indicator of sympathovagal balance) were calculated from short-term electrocardiographic data from 16 HAVS patients and 14 healthy controls before and immediately after exposure to acute psychological stress. Urinary catecholamines (norepinephrine, epinephrine and dopamine) were analyzed from urine samples collected from every subject during rest and after exposure. The LF% and LF/HF of the patients significantly increased after exposure. The after exposure LF/HF of the patients was significantly greater than that of the controls. The amount of norepinephrine in the patients significantly increased after exposure. The after exposure amount of norepinephrine and epinephrine in the patients were significantly greater than the respective amount of the controls. The results of the present study indicated the predominance of sympathetic tone in the cardiac sympathovagal balance and greater sensitivity of the sympathoadrenal medullary system in response to acute psychological stress in the patients than in the healthy controls.
The purpose of the present study was to determine the efficiency of respiratory protective equipment in a fibreglass reinforced plastic factory by comparing results of environmental and biological monitoring of exposure to styrene. Five factories including 39 workers were investigated. Three types of respiratory protective equipment were tested: one was a half-mask air-purifying respirator equipped with a cartridge for organic solvents, another was a disposable gauze respirator impregnated with charcoal filter, and the third was a dust-proof respirator. The frequency of cartridge exchange of a half-mask respirator was twice a day only at one factory, and that was less than once a month at other factories. The site concentrations exceeded 20 ppm at 10 of the 82 sampling points (12.2%), and 22 of the 39 workers’ (56.4%) personal exposure exceeded 20 ppm which is the current occupational exposure limit recommended by the Japan Society for Occupational Health. The efficiency of disposable gauze respirators and dust-proof respirators was low or rather zero. The average efficiency of half-mask respirators in which cartridges were exchanged twice a day and once a month was 83.6% and 46.6%, respectively. There was a significant disparity in the efficiency of the respirator depending on the frequency of cartridge exchange (p<0.05). Overall this study showed that even though a half-mask respirator is used and its cartridge is exchanged every half a day, workers exposed to a styrene concentration at or over 122 ppm are expected to inhale more than 20 ppm of styrene.
Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are important perfluorochemicals (PFCs) in various applications. Recently, it has been shown that these chemicals are widespread in the environment, wildlife and humans. But the kinds of factors that affect their levels in serum are unclear, and it is also not clear whether exposure to them is increasing or not. To investigate the impacts of time, geographical location and sex on the levels of these chemicals, we measured PFOS and PFOA concentrations in human sera samples collected both historically and recently in Miyagi, Akita and Kyoto Prefectures in Japan. The PFOS and PFOA levels in sera [Geometric Mean (Geometric Standard Deviation)] (μg/L) in 2003 ranged from 3.5 (2.9) in Miyagi to 28.1 (1.5) in Kyoto for PFOS and from 2.8 (1.5) to 12.4 (1.4) for PFOA. Historical samples collected from females demonstrated that PFOS and PFOA concentrations have increased by factors of 3 and 14, respectively, over the past 25 yr. There are large sex differences in PFOS and PFOA concentrations in serum at all locations. Furthermore, there are predominant regional differences for both PFOS and PFOA concentrations. In Kyoto the concentrations of PFOA in dwellers who had lived in the Kinki area for more than 2 yr were significantly higher than in people who had recently moved into the area, in both sexes. This finding suggests that there are sources of PFOA in the Kinki area that have raised the PFOA serum levels of its inhabitants. Further studies are needed to elucidate these sources in the Kinki area of Japan.
A study was conducted to evaluate the health impact of airborne pollutants on incinerator workers at IZAYDAS Incinerator, Turkey. Ambient air samples were taken from two sampling points in the incinerator area and analyzed for particulate matter, heavy metals, volatile and semi-volatile organic compounds (VOCs and SVOCs) and dioxins. The places where the maximum exposure was expected to occur were selected in determining the sampling points. The first point was placed in the front area of the rotary kiln, between the areas of barrel feeding, aqueous and liquid waste storage and solid waste feeding, and the second one was near the fly ash transfer line from the ash silo. Results were evaluated based on the regulations related to occupational health. Benzene, dibromochloropropane (DBCP) and hexachlorobutadiene (HCBD) concentrations in the ambient air of the plant were measured at levels higher than the occupational exposure limits. Dioxin concentrations were measured as 0.050 and 0.075 pg TEQ.m-3, corresponding to a daily intake between 0.007 and 0.01 pg TEQ. kg body weight-1.day -1. An assessment of dioxin congener and homologue profiles suggested that gaseous fractions of dioxin congeners are higher in front of the rotary kiln, while most of them are in particle-bound phases near the ash conveyor. Finally, the necessity of further studies including occupational health and medical surveillance assessments on the health effects of the pollutants for the workers and the general population in such an industrialized area was emphasized.
Allergic diseases have increased in many developed countries including Japan. Doctors are also at risk for allergic diseases from exposure to allergens in working conditions and hospital environments. We investigated the factors relating to occupational allergy in doctors. Self-administered questionnaires were mailed to all doctors (n=895) who had previously graduated from School of Medicine, Fukui Medical University. Data from 307 responders (response rate: 34.3%, male 241, female 66, mean age ± S.D., 30.8 ± 4.2) were analyzed. Eighty-nine doctors stated that they had occupational allergy including contact dermatitis, allergic rhinitis and/or asthma. Fifty-four had contact dermatitis caused by surgical gloves; 77 had contact dermatitis from disinfectants, e.g. 23 from chlorhexidine gluconate; 21 from povidone iodine; and 15 from ethanol. Fifteen doctors experienced allergic rhinitis and/or asthma caused by handling laboratory animals. Univariate analysis showed that profession (surgical doctors) and past histories of allergic diseases (rhinitis, sinusitis, or atopic dermatitis) were significantly related to occupational allergy in doctors, but that gender, smoking or physical exercise were not significantly related to it. A logistic regression analysis showed that past histories of allergic diseases and the profession of surgical doctors were significantly related to occupational allergy, but that gender, age or smoking were not significantly related to it. The results of the present study suggest that past history of allergic diseases is a factor predisposing to occupational allergy in doctors. It is necessary and possible to extend more prophylactic measures for doctors, especially for surgeons, because exposure to responsible agents and materials for them can be more frequent.
We examined the chronological change in Type A behavior pattern (TABP) among Japanese male workers for 5 yr. A brief questionnaire to measure TABP was administered to 21,711 male workers who underwent health check-ups at least once during the period from 1995 to 1999 and were born in 1936-1965. The mean TABP scores decreased year by year linearly. Then the repeated measurement analysis of variance was performed with the data of 5,689 subjects who completed the questionnaire successively through the study period. Both year and the age effects were highly significant (p<0.001, respectively), whereas the time trends were comparable by baseline age. In conclusion, TABP among Japanese male workers decreased in all generations during the period from 1995 to 1999.