Japanese Journal of Hygiene最新文献

The brain and mind are not only determined genetically but are also nurtured by environmental stimuli in early life. However, the relationship between early life environment and phenotypes in adulthood remains elusive. Using the IntelliCage-based competition task for group-housed mice, we previously found that maternal exposure to a low dose of an environmental pollutant, dioxin, resulted in abnormal social behavior, that is, low competitive dominance, which is defined by decreased occupancy of limited resource sites under highly competitive circumstances. Although we were unable to identify which behavioral phenotype applies to abnormalities such as "human social nature", we found signs of hypoactivation of the medial prefrontal cortex, as seen in patients with autism spectrum disorder. In addition, another model of environmental factors, repeated isolation during development, and that of genetic factors including mice with neuronal heterotopia, which refers to brain malformations resulting from deficits of neuronal migration, showed low competitive dominance. These results indicate that a constitutive approach to capture the neural network of the whole brain is necessary especially in cases where the temporal gap of causal relationships is large such as DOHaD.

In recent years, the birthrate has been continuously declining in Japan. The main causes of the decline are social factors. On the other hand, there is increasing evidence that many environmental chemicals show endocrine disrupting properties. Thus, we hypothesized that exposure to these chemicals would also be a causal for the fertility crisis. In this review, we examined current evidence that focused on environmental chemical exposure in utero and its association with reproductive hormones in children. We have included the findings from a prospective birth cohorts, the Hokkaido Study on Environment and Children's Health Sapporo cohort. According to the literature, environmental chemical levels in utero, such as polychlorinated biphenyl, dioxins, perfluorinated chemical substances, phthalates, and bisphenol A were somewhat associated with the levels of reproductive hormones, such as testosterone, estradiol, progesterone, inhibin B, and insulin-like factor-3 in cord blood, in early childhood and adolescence. The literature also suggests the association between exposure to these chemicals and brain-sexual differentiation or the anogenital distance, which suggests the disruption of androgen shower during the developmental stage in the fetal period. There are still knowledge gaps on whether these hormones at an early stage affect the pubertal development and reproductive functions in later life. In addition, alternative chemicals are produced after banning one type. The health effects of alternative chemicals should be evaluated. Effects of exposure to a mixture of the chemicals should also be examined in future studies. In conclusion, the prevention of environmental chemical hazards in relation to human reproductive function is important. It would be one of the countermeasures to the falling birthrate caused by fertility issues.

Introduction: From 2007, competitive bidding for procurement became widely employed by the Japanese Government, and health check providers for government workers are selected every year by this method. Deterioration of health check quality due to excessive price competition is a serious concern. The National Federation of Industrial Health Organization (Zeneiren) conducted an investigative research on the contracting of health check providers and occupational physicians in workplaces in 2015-2016 in an effort to prevent low-cost but low-quality health checks. The report of the research is available on the homepage of Zeneiren. In this paper, we provide a brief overview of the report, and deterioration of health check quality due to dumping by and switching of health check providers is discussed from economic and legal viewpoints.

Method: Information was obtained from articles in print and on the Internet.

Results: A questionnaire survey of health check providers revealed that excessive discounts due to both competitive bidding and demand from companies commissioning health checks occurred on a routine basis, and some providers were concerned about worsening business conditions in the future. In a separate questionnaire survey of occupational physicians, it was discovered that they were able to evaluate the quality of health checks, whereas administrative officials responsible for selecting the providers were seldom able to adequately evaluate the health check quality, resulting in contracting providers of questionable quality, which in turn caused considerable dissatisfaction on the part of occupational physicians. Moreover, when health check providers were switched, the reporting format of health check results changed. The physicians did not favor such a change because of the considerably increased workload involved in coordinating past and current data and the risk of decreased occupational health service quality.

Discussion: Dumping makes the management of health check providers very difficult and is a cause of loss of social capital. If health check providers of good quality withdraw from the market, the supply of high-quality health checks decreases. This corresponds to external diseconomy caused by dumping on the part of the health check providers and loss of social surplus (economic surplus).

Conclusions: To avoid deterioration of occupational health service due to low-quality health checks and changes in the reporting format, occupational physicians must actively engage in the selection of health check providers of good quality.

Objectives: In this study, we examined whether a combined regimen of a short-term nap and a light physical exercise is effective in improving sleep among elderly individuals with mild-to-moderate dementia in communal living group homes.

Methods: Twenty-three female residents (aged 87.4±5.6 years) living in two group homes for the elderly with dementia were included in the present study. After undergoing an assessment for eligibility, they were randomly allocated to either the study group (N=11), who participated in the regimen of a short-term nap (<30 min) and light physical exercise for four weeks, or the control group (N=12), who received the usual nursing care without participating in the nap and exercise regimen. The lengths of sleep time and wake time were measured using a sleep monitor with a radiofrequency motion sensor. The frequencies of nocturnal behavioral and psychological symptoms associated with dementia including excitement, violence, night delirium, wandering, and unhygienic behavior were investigated throughout the study period.

Results: The subjects participating in the nap and physical exercise regimen showed a significant increase in sleep efficacy as well as a reduction in the total nocturnal wake time, whereas no clear change was observed in the control subjects. The frequencies of nocturnal episodes of urination in the study group also decreased during the course of the study. However, there was no significant decrease in the frequencies of nocturnal behavioral or psychological symptoms associated with dementia.

Conclusions: The findings of this study suggest that a short-term nap and a light physical exercise may be effective in adjusting the sleep-wake biorhythm in elderly patients with mild-to-moderate dementia and may improve sleep among these individuals.

Objectives: The purposes of this study were to clarify the microbial growth when drinking a beverage directly from its plastic bottle using models under consumption conditions characteristic for nursing students in a university and their awareness about microbial contamination in unfinished beverages in bottles.

Methods: Three types of bottled beverages were tested: mineral water, Japanese green tea with catechin, and a lactic acid beverage. The ways of drinking were putting the entire lip of a bottle into the mouth (type A) and holding half of the lip out of the mouth (type B). The bottles were kept at room temperature for 8 hours. Samples from unfinished beverages were cultured to detect viable bacteria. An anonymous questionnaire was sent to 324 nursing students of a university, among which 279 responded.

Results: The number of viable bacterial cells was larger in type A of drinking than in type B. It increased in mineral water until 2 hours, after which it remained the same. It decreased in Japanese green tea with catechin and the lactic acid beverage. However, even the smallest number exceeded the standard number for drinking beverages. Among the nursing students, 62.7% were aware of microbial contamination in unfinished beverages, but despite this awareness, they did not consume their beverages as soon as possible.

Conclusion: It is necessary to provide the nursing students with health education on the safety of partially consumed bottled beverages with respect to food hygiene, even if microorganisms do not grow in some types of beverages.

Objectives: To clarify the association between job stress and the number of physical symptoms among newly certified female nurses.

Methods: In this cross-sectional self-administered survey, we investigated 313 female nurses working at three medical-university-affiliated hospitals in February 2016. We investigated working conditions including numbers of working and on-call hours, work-life balance, Job Content Questionnaire (JCQ) scores, and 16 physical symptoms perceived more often than once a week.

Results: Among the 313 participants (mean age, 31.9), 57% were aged 21-29 years and 70% were single. Of the 16 physical symptoms investigated, fatigability was the most frequent complaint (66.1%), followed by lower back pain (44.7%). Univariate analysis showed that significant factors related to physical symptoms are job demands (p<0.001) and social support (p<0.001) in JCQ, binary index of supports (p<0.001), and total working hours per day (p =0.025). Multivariable-adjusted logistic regression analyses demonstrated that the likelihood of reporting a greater number (n≥3) of physical symptoms increased by 7% [95% confidence interval (CI), 2-13%] with a one-unit increase in job demand degree, and decreased by 16% (95% CI, 10-22%) in social support degree. When binary JCQ indexes were assessed, the high-support group [odds ratio (OR) 0.36; 95% CI, 0.23-0.59] was protectively associated with a greater number of physical symptoms while long working hours was significantly associated with a higher risk (OR 18%, 95% CI, 1-38%).

Conclusions: Reporting a greater number of physical symptoms may be a good indicator of job stress perceived by a nurse in a university hospital setting.

Multiple chemical sensitivity (MCS), also known as idiopathic environmental intolerance, has been described as a chronic acquired disorder characterized by nonspecific symptoms in multiple organ systems and is associated with exposure to low-level chemicals. The name was established by Cullen, in 1987, although the name and diagnostic criteria are still under debate even now. A number of hypotheses concering the etiology and pathogenesis of MCS have been proposed, including impairmens of neurological, immunological and psychological systems. However, research on the possible mechanisms underlying MCS is far from complete. The name and diagnostic criteria of its history as well as theoretical and experimental mechanisms underlying MCS are reviewed here.

Polysomnography (PSG), which records physiological phenomena including brain waves, breathing status, and muscle tonus, is useful for the diagnosis of sleep disorders as a gold standard. However, measurement and analysis are complex for several specific sleep disorders, such as rapid eye movement (REM) sleep behavior disorder (RBD). Usually, brain waves during REM sleep indicate an awakening pattern under relaxed conditions of skeletal and antigravity muscles. However, these muscles are activated during REM sleep when patients suffer from RBD. These activated muscle movements during REM, so-called REM without atonia (RWA) recorded by PSG, may be related to a neurodegenerative disease such as Parkinson's disease. Thus, careful analysis of RWA is significant not only physically, but also clinically. Commonly, manual viewing measurement analysis of RWA is time-consuming. Therefore, quantitative studies on RWA are rarely reported. A software program, developed from Microsoft Office Excel^®, was used to semiautomatically analyze the RWA ratio extracted from PSG to compare with manual viewing measurement analysis. In addition, a quantitative muscle tonus study was carried out to evaluate the effect of medication on RBD patients. Using this new software program, we were able to analyze RWA on the same cases in approximately 15 min as compared with 60 min in the manual viewing measurement analysis. This software program can not only quantify RWA easily but also identify RWA waves for either phasic or tonic bursts. We consider that this software program will support physicians and scientists in their future research on RBD. We are planning to offer this software program for free to physicians and scientists.

In this review, we examine house dust and its effect on inhabitants' health. Residential house dust includes components from plants, pollens, microorganisms, insects, skin flakes, hairs and fibers. It also includes materials contaminated with chemicals from combustion, furniture, interior materials, electronics, cleaning agents, personal care products. Nowadays, most people spend their time indoors. Thus, dust is an important medium of exposure to pollutions. According to United States Environmental Protection Agency Exposure Factors Handbook, the estimated amount of dust ingestion is 30 mg/day for adults, and 60 mg/day for children over 1 year of age. Since 2003, we have been conducting epidemiological studies to find the association between the indoor environment and the inhabitants' health. The levels of mite allergens, endotoxins, and β-1,3-d-glucan in house dust were measured as biological factors. Semi volatile organic compounds (SVOC) such as phthalates and phosphate flame retardants (PFRs) in dust were also analyzed. As a result, we found that the ORs (95%CI) of nasal and optical symptoms of sick building syndrome (SBS) were 1.45 (1.01-2.10) and 1.47 (1.14-1.88), respectively, when there was a 10-fold increase in the levels of mite allergens. There was no association of mite allergens with allergies. Endotoxins and β-1,3-d-glucan did not show any association with SBS. Regarding SVOC, increased levels of phthalates and PFR increased the risk of allergies. The association between phthalates and increased risk of allergies was clearer among children than adults. There were no gold standards of dust sampling and pretreatment methods. Thus, caution is needed when comparing findings of various studies. Methods should accurately reflect exposure levels.

Since "Our Stolen Future" by Theo Colborn was published in 1996, global interest on the impact of chemical substances, such as the endocrine-disrupting action of chemicals, has increased. In Japan, "The Hokkaido Study on Environment and Children's Health: Malformation, Development and Allergy" was launched in 2001. It was a model of Japan Environment and Children's Study of the Ministry of the Environment. In a large-scale, Hokkaido cohort, we obtained the consent of 20,926 mothers at the organogenesis stage with the cooperation of 37 obstetrics clinics in Hokkaido. We tracked the effects of endocrine disruptors on developmental disorders. In a small-scale Sapporo cohort, we observed in detail the neuropsychiatric development of children with the consent of 514 mothers in their late pregnancy. We examined how prenatal exposure to low concentrations of environmental chemicals affect the development of organs and the postnatal development of children. Maternal exposure to POPs, such as PCB/dioxins and perfluorinated alkyl substances, has affected not only children's birth size, thyroid functions, and sex hormone levels, but also postnatal neurodevelopment, infection, and allergy among others. The associations of short-half-life substances, such as DEHP and BPA, with obesity, ASD, and ADHD have been investigated. Gene-environment interactions have been found for smoking, caffeine, folic acid, and PCB/dioxin. In 2015, our center was officially designated as the WHO Collaborating Centre for Environmental Health and Prevention of Chemical Hazards, and we continue to the contribute to the global perspectives of child health.