Cadmium (Cd) is a heavy metal known to be toxic and carcinogenic, but its mechanism of action remains to be elucidated. Development of the DNA microarray technology has recently made the comprehensive analysis of gene expression possible, and it could be a powerful tool also in toxicological studies. With microarray slides containing 7,000-9,000 genes, we have been studying the gene expression profiles of a human cell line exposed to Cd. By exposure to a non-lethal concentration of Cd, 46 upregulated and 10 downregulated genes whose expression levels changed twofold or greater were observed. The expression of genes related to cellular protection and damage control mechanisms such as those encoding metallothioneins, anti-oxidant proteins and heat shock proteins was simultaneously induced. In addition, altered expression of many genes involved in signaling, metabolism and so on was newly observed. As a whole, a number of genes appear to be coordinately regulated toward survival from Cd toxicity. When cells were exposed to a higher concentration of Cd, more remarkable effects were observed both in the number of affected genes and in the extent of altered expression. These findings will contribute to the understanding of the complicated biological effects of Cd.
Obesity occurs less frequently in Japanese than in various other ethnic populations. A person with abnormal glucose tolerance is often found to have one or more of the other cardiovascular disease risk factors, such as obesity, hypertension and hyperlipidemia. This clustering has been labeled as metabolic syndrome (WHO, 1998). It was suggested that Japanese, categorized as having normal weight (BMI of less than 25.0), as defined by the WHO (2000), have an increasing tendency toward metabolic syndrome. Our objective was to analyze metabolic syndrome in “Overweight” with BMI of 23.0-24.9 in Japanese workers, and to assess the suitability for Asians of the Regional Office for the Western Pacific Region of WHO criteria pertaining to obesity (WPRO criteria, 2000). We conducted a cross-sectional study in the workplace setting and investigated the relationship between BMI classification based on WPRO criteria and metabolic syndrome by gender and age group (18-44 yr vs. 45-60 yr). Three hundred seventy-nine men and 432 women Japanese workers participated in this study. BMI were categorized as 20% “Overweight” (23.0-24.9 BMI), 20% “Obese I” (25.0-29.9 BMI) and 2% “Obese II” (over 30.0 BMI), based on WPRO criteria. Graded increases in BMI were positively associated with body fat percentage, waist circumference, hip circumference and waist/hip ratio in both genders and age groups. A progressively increasing BMI category in the elder group aged 45-60 yr in both genders was positively related with parameters constituting metabolic syndrome. Graded increases in BMI classes in elder workers based on WPRO criteria were positively associated with prevalence of metabolic syndrome, and “Overweight” elder women had significantly higher prevalence of metabolic syndrome. The present investigation, based on the increasing risks of “Overweight” with a BMI of 23.0-24.9, suggests that WPRO criteria are suitable for Japanese workers aged over 45 yr.
Insomnia is one of the most common complaints at worksites, as well as in the general population. This study aims to assess the effect of insomnia on the development of hypertension in Japanese male workers. Using the annual health examination database of a Japanese telecommunication company, eligible middle-aged male participants in the 1994 health examination were followed up until 1998 or the development of hypertension (either initiation of antihypertensive therapy or a systolic blood pressure ≥140 mmHg and/or a diastolic blood pressure ≥90 mmHg). The effect of difficulty initiating sleep (DIS) was assessed with a DIS dataset (n=4,794), which included non-DIS (n=4,602) and persistent-DIS (n=192) subjects. That of difficulty maintaining sleep (DMS) was assessed with a DMS dataset (n=4,443), which included non-DMS (n=4,157) and persistent-DMS (n=286) subjects. The incidence of hypertension among persistent-DIS (40.1%; 130.7 per 1,000 person-yr) was significantly higher than that among non-DIS (30.6%; 89.9 per 1,000 person-yr). The incidence of hypertension among persistent-DMS (42.3%; 136.7 per 1,000 person-yr) was significantly higher than that among non-DMS (30.7%; 90.8 per 1,000 person-yr). After adjusting for potential confounding factors (i.e. age, body mass index, smoking, alcohol drinking, and job stress), persistent complaints of DIS and DMS were significantly associated with an increased risk of hypertension (OR=1.96; 95%CI: 1.42-2.70 and OR=1.88; 95%CI: 1.45-2.45, respectively). Persistent insomnia may be a useful predictor of hypertension in Japanese male workers.
Cumulative trauma disorder (CTD) is a term used to describe a class of soft tissue injuries that result due to a number of occupational activities. These disorders commonly occur among workers who are engaged in highly repetitive jobs involving continuous hand exertion, vibration and localized mechanical pressure.In the present investigation, an attempt was made to evaluate the prevalence of CTD among workers associated with strenuous hand intensive jobs in unorganized sectors in India and to highlight the unsafe working conditions to which these workers have been exposed for several years. For this purpose, an experiment was performed on 25 male workers from each group. The groups were classified into meat cutters, typists, tailors, visual display terminal (VDT) operators & weavers. For the symptom survey, a questionnaire and checklist method was implemented. Along with these, a detailed time study was performed among the workers during different activities in the total work cycle. For this study a two-tail chi-square test of independence was applied to determine whether or not the feeling of discomfort had any significant association with the repetitiveness of the work. From the observations and analysis of the results, it was revealed that all the activities are repetitive, i.e. over 50% of the work cycle of each activity involved the respective main activity where similar kinds of motion patterns were performed. Therefore it can be concluded that high repetitiveness, prolonged work activity and remaining in static posture for a prolong period of time may be regarded as the causative factors in the occurrence of CTD.
The role of the police in Western society is undergoing a transformation that reflects the economic social and technological changes in the community and the assertion of individual rights within a democracy. The aim of this study is to evaluate level of stress among a group of French policemen and to examine the association between policing, potential stressors and stress levels. The sample is drawn from a large metropolitan police force (n=617). The population extends from the first line policeman to top senior management. Each policeman is matched for age (more or less five years) and sex, to a control. Policemen and controls complete a self administered questionnaire including demographic, occupational and health characteristics, and a stress level assessment with the help of a visual analogue scale. The average age of the two groups is 40 yr. Eighty-four percent are men. The total score for average sources is not statistically significantly different for policemen and controls. Comparison of a police group with a high stress level to a police population with a low and moderate stress level is made. The comparison is done first only with men, and second with the whole population. Policemen with a high stress level (same results only for men and the whole population) belong to the following groups: more than 15 yr service, sergeant, officer and administrative employee rank, divorced experience, age over 30, no leisure-time activities and no hobbies. Multivariate analysis shows that the two last parameters are bound to the stress level. For the whole population, age over 30 has to be added, and for the group of men, length of service over five years should be noted. Stress at work is an ill-health provoking factor. Police from minority groups such as ageing subjects or police officers have been reported to experience greater stress. This population is adversely affected by lack of available manpower and long working hours. In fact sources of stress in the police population are found both in the weariness of the job and private life planning.
In order to better characterize the toxicity of N,N-dimethylformamide (DMF) and to provide its basic toxicity data for risk assessment of workers exposed to DMF, F344 rats and BDF1 mice of both sexes were exposed by inhalation (6 h/d × 5 d/wk) to 100, 200, 400, 800 or 1,600 ppm DMF for 2 wk, and 50, 100, 200, 400 or 800 ppm DMF for 13 wk. Three male and 7 female rats died during the 2-wk exposure to 1,600 ppm DMF, but no death of the exposed rats or mice occurred under any other exposure conditions. Massive, focal and single cell necroses were observed in the liver of DMF-exposed rats and mice. The massive necrosis associated with the centrilobular fibrosis occurred at the highest exposure concentration. The single cell necrosis was associated with fragmentation of the nucleoli as well as an increased mitotic figure. The 13-wk exposures of rats and mice to DMF were characterized by increases in the relative liver weight and the incidence of the centrilobular hepatocellular hypertrophy as well as increased serum levels of AST, ALT, LDH, total cholesterol and phospholipid. Lower confidence limits of the benchmark dose yielding the response with a 10% extra risk (BMDL10) were determined for the relative liver weight and the incidence of hepatocellular hypertrophy of the 13-wk exposed animals. The BMDL10 resulted in 1 ppm for the increased relative liver weight of male rats and mice and 17 ppm for the hepatocellular hypertrophy of male mice.
Comet assays were carried out to evaluate DNA damage in human lymphocytes from 20 volunteers before and after hair dyeing. DNA damage in lymphocytes was found to be slightly higher in volunteers after hair dyeing. Tail moments before and after hair dyeing were 1.47 ± 0.41 and 1.75 ± 0.29 respectively (p<0.0008). DNA damage in lymphocytes showed significant difference with treatment and heating time. The tail moments after 15 min of treatment time before and after hair dyeing were 1.44 ± 0.22 and 1.85 ± 0.36, respectively (p=0.0004) and the corresponding tail moments in 20 min of heating time before and after were 1.37 ± 0.15 and 1.78 ± 0.34 (p=0.0002). In conclusion, we found that an acute exposure of hair dyes with heating caused DNA damages in peripheral lymphocytes and that this damage had significant association with treatment and heating time.
This study assessed the associations of job and some individual factors with occupational injuries among employed people from a general population in north-eastern France; 2,562 workers were randomly selected from the working population. A mailed auto-questionnaire was filled in by each subject. Statistical analysis was performed with loglinear models. The annual incidence rate of at least one occupational injury was 4.45%. Significant contributing factors for occupational injuries were job category (60.8%), sex (16.2%), regular psychotropic drug use (8.5%), age groups (7.5%), and presence of a disease (7.0%). The men had higher risk than the women (adjusted odds-ratio 1.99, 95% CI 1.43-2.78). Compared to executives, intellectual professionals and teachers, labourers had the highest risk (6.40, 3.55-11.52). They were followed by farmers, craftsmen and tradesmen (6.18, 2.86-13.08), technicians (3.14, 1.41-6.70), employees (2.94, 1.59-5.48) and other subjects (3.87, 1.90-7.88). The young (≤29 yr) showed an increased risk. Similar odds-ratios were observed for regular psychotropic drug use (1.54, 1.16-2.05) and the presence of a disease (1.50, 1.11-2.02). Univariate analysis showed that smoking habit, overweight and excess alcohol use were also associated with injuries. The loglinear model results showed that there were associations between some of these independent factors. It was concluded that job, sex, young age, smoking habit, excess alcohol use, overweight, psychotropic drug use, and disease influenced the occupational injuries. Preventive measures concerning work conditions, risk assessment and job knowledge should be conducted in overall active population, especially in men, young workers, smokers, alcohol users, overweight workers and in individuals with a disease or psychosomatic disorders.
The purpose of the study is to elucidate the relationship between social support, health care consciousness and mental health in developing the industrial health education aimed at improving the health habits of male employees. A questionnaire survey concerning health practices, mental health based on the General Health Questionnaire, social support from social support networks, and health care consciousness based on the Health Locus of Control was conducted on male employees in three companies in Osaka Prefecture. A total of 1634 questionnaires were collected. Analyses by age group showed that in all age groups, the higher the social support score, the more favorable the mental health became and the stronger the family care in health care consciousness became. The better the mental health, the greater the number of good health practices was and the lower the fortune dependence in health care consciousness tended to be. The results of the study reconfirm the previous findings that it is necessary to put the mental health of male employees in good condition before everything else in effectively developing health education aimed at improving their health habits. This study also indicates that the level of perception of social support and their internal control of self and family in health care consciousness are definitely related to the stability of subjects' mental health. It is therefore presumed that measures to raise the revel of perception of social support are important since they may improve the mental health of subjects.
Thioglycolic acid (TGA) is the active ingredient of permanent-waving solution (PWS). TGA has been shown to be a chemical of high toxicity, which can be absorbed through intact skin and cause damage to organs or systems in animals. This study evaluated the effect of TGA-containing PWS on the health of a human population in 3 substudies. Firstly, 57 female hairdressers exposed to TGA-containing PWS (cases) and 64 female schoolteachers (controls) were studied. Their menstruation state was evaluated with information obtained from interviews. The results revealed that the menoxenia rate in the cases was significantly higher than that in the controls (22.81% vs 9.38%, p<0.05). Secondly, 8 female hairdressers selected from those that participated in the above survey underwent a fluctuation test for the mutagenic activity of urine. Eight female medical students were chosen as controls. Difference in the mutagenic activity of urine on TA100 between the two groups was highly significant (110.30 ± 45.95 vs 28.43 ± 19.33, p<0.01). Finally, a micronucleus assay was carried out on scalp hair follicle cells in healthy volunteers. Scalp hair with the follicle cell mass was sampled from 8 male and 8 female volunteers before permanent waving and at 24, 48 and 72 h after waving. One thousand hair follicle cells were examined by light microscopy. The number of cells containing a micronucleus and the number of micronuclei in each cell was determined. The permillages of micronuclei in hair follicle cells before and after permanent waving were compared. Micronuclei presence reached its peak value (12.44) 24 h after permanent waving, which was significantly higher than that before waving (3.13, p<0.001). The rate decreased progressively after 24 h. Our results suggest that the reproductive function of hairdressers may be affected by long-term exposure to PWS, probably due to the presence of TGA, and more attention should be paid to its potential carcinogenic effects.