Trends of allergic symptoms in school children: large-scale long-term consecutive cross-sectional studies in Osaka Prefecture, Japan.

BACKGROUND: Trends in the prevalence rates of allergic symptoms in children have been discussed extensively, but it remains uncertain which symptoms increase or decrease over time owing to the lack of large-scale long-term consecutive cross-sectional studies performed on a representative population of children. OBJECTIVE: To clarify the trends in the prevalence rates of allergic symptoms in Japanese children. METHODS: Total population questionnaire surveys were conducted 15 times from 1975 to 2006 for all children attending public elementary schools in Osaka Prefecture, Japan, with the number of subjects ranging from 460,000 to 900,000. Parents of the children completed the questionnaire about allergic symptoms and other symptoms, including wheeze, physician-diagnosed atopic dermatitis, rhinitis, and itching eyes. RESULTS: Response rates were consistently over 90%. The prevalence of wheezing was constant until 1983, then increased from 1983 until 1993, then stabilized at about 4.4%. The lifetime prevalence of atopic dermatitis increased to 24% by 1993, and then decreased. The prevalence of rhinitis increased to 25% by 2003, whereas the prevalence of non-seasonal symptoms plateaued from 1993 on at 11% and vernal symptoms increased. The prevalence of itching eyes continued to increase to 21% in 2006, and vernal symptoms increased sharply. CONCLUSIONS: In Osaka Prefecture, Japan, the turning point when the prevalence of wheezing in schoolchildren had begun to increase was 1983. And the turning point when the increase in the prevalence of wheezing, atopic dermatitis, and non-seasonal allergic rhinitis turned to decrease or constant was 1993. The prevalence of rhinitis and itching eyes in spring was still increasing in 2006.

[Indoor air pollution in newly built or renovated elementary schools and its effects on health in children].

PURPOSE: To elucidate the actual status of indoor air pollution at newly built or renovated elementary schools, and to evaluate its effects on health symptoms in the affected children. METHODS: In the classrooms of four newly built or renovated elementary schools in Osaka Prefecture, indoor air levels of formaldehyde and volatile organic compounds (VOC) were measured immediately, 1 month, 3 months, 10 months and 22 months after the completion of the construction work. Also, questionnaire surveys regarding subjective symptoms of sick building syndrome were conducted before and after the renovation on the children who attended classes in the renovated rooms. RESULTS: In the newly built computer classroom, more formaldehyde was detected one month after the completion of the construction work, when computers and furniture were carried in, than immediately after the completion of the work. Then, during the summer season, even 10 months and 22 months after completion of the new building, formaldehyde above the guideline values was detected. In the renovated common classrooms, the formaldehyde level was the same as that in the classrooms which did not undergo renovation, but VOC levels were higher immediately after the completion of the construction work, and the toluene level was above the guideline value. In 4-story reinforced concrete school buildings, indoor air pollution tended to be higher on the third and the fourth floors than on the first and the second floors. In 3-story school buildings, indoor air pollution tended to be higher on the third floor than on the second floor. The survey of subjective symptoms of the children revealed a tendency toward an increase in the prevalence of sick building syndrome after a renovation. However, the actual number of the children complaining of the symptoms hardly changed. Instead, the number of symptoms for each subject increased, and this increase was significant in 5th and 6th grade boys. CONCLUSION: In the some classrooms of newly built or renovated elementary schools, chemical substances above the guideline values may be detected. In such classrooms, more ventilation is required.

Ecological association of water hardness with prevalence of childhood atopic dermatitis in a Japanese urban area.

The prevalence of symptoms of atopic eczema among Japanese children aged 6-7 years is the second highest in 56 countries. Reasons for such a high prevalence are unknown. This ecological study examined whether the positive association of water hardness with atopic dermatitis among British primary-school children also exists in Japan. Study subjects were 458,284 of 489,725 children, aged 6-12 years, in 1,016 public elementary schools in Osaka Prefecture with 44 municipalities. The study used data on water hardness and chlorine content of the water supply; prevalence of atopic dermatitis diagnosed by physicians and episodes of wheezing reported by the parents; and potential confounding factors by socioeconomic and health care status per municipality. The prevalence of atopic eczema was significantly higher in the highest water hardness category than that in the lowest (24.4% [n=2,288/9,362] and 22.9% [n=77,408/33,8267], respectively; adjusted odds ratio 1.12, 95% confidence interval 1.06-1.18; P<0.0001 for trend). A significant and slightly J-shaped relationship between chlorine content of the water supply and prevalence of atopic dermatitis was observed after adjustment for confounding factors. There were no apparent associations of water hardness and chlorine content of the water supply with prevalence of wheeze. Water hardness may increase the risk of atopic dermatitis among elementary-school children in Japan, as well as in the United Kingdom.

[Intrapair comparisons of diet and food preference in adult twins].

OBJECTIVES: An investigation was conducted on the influence of genetic and lifestyle factors related to the determination of eating behavior of human beings. The objective was to obtain information about lifestyle factors that may help health professionals intervene in terms of the prevention of diet-related diseases. METHODS: The subjects were 180 pairs of adult twins aged over thirty, comprising of 134 monozygotic (MZ) and 46 dizygotic (DZ) pairs. Every subject was given an interview concerning dietary habits, food preference, food intake, as a part of medical examination. The intake of food containing salt and fat, the intake of food meals, the frequency of daily meals, and the frequency of eating 18 sorts of food were assessed on an individual basis, with a questionnaire on nutrition. The expected and observed values of intrapair concordance rates were calculated, and compared within each zygosity, using the chi-square test. RESULTS: Significant differences between the expected and observed for intrapair concordance rates were shown with monozygotic twins, regarding every category of question. Comparing MZ pairs who had lived apart before their twenties with the other MZ pairs, the latter had a tendency to show significant differences between the expected and observed values of intrapair concordance rate, regarding every category of question. In each case, the observed values were higher than the expected values. CONCLUSIONS: The study implied that both genetic and lifestyle factors influence the determinants of eating behavior of human beings. This finding shows the importance of understanding individual characteristics of food preference and eating behavior for intervention regarding lifestyle factors for prevention of diet-related diseases.

A gerontological cohort study of aged twins: the Osaka University Aged Twin Registry.

We describe subject recruitment and research results from the Osaka University Aged Twin Registry (OUATR). The research focus of OUATR is the genetic and environmental contributions to physical-cognitive-mental aging which we examined in Japanese twins in later adulthood. Within this large-scale registry (12,000 pairs) of oriental twins born between 1900 and 1935, approximately 10% of participants are MZ twins reared apart from early childhood. Two hundred and fifty pairs have had comprehensive medical examinations, including various blood chemical panels, lymphocyte subtests, WAIS (Wechsler Adult Intelligence Scale), and urine analysis. The future foci of this study are primarily on longevity, decline of cognitive functions with aging, bio-physiological functions, lifestyle and behavior genetics, and psycho-spiritual functions.