[Daily information-gathering behavior of natural disaster victims: Focusing on residents who experienced the Great East Japan Earthquake and the Kanto-Tohoku Heavy Rainfall Disaster].

Objectives　To obtain suggestions for improving disaster-prevention literacy, this study elucidated the daily information-gathering behavior of residents living in areas affected by two Japanese natural disasters (the Great East Japan Earthquake of 2011 and the Kanto-Tohoku Heavy Rainfall Disaster in September 2015) and examined factors affecting life backgrounds and disaster experiences.Methods　In June 2017, we administered a cross-sectional survey using a self-administered questionnaire to 1,065 households in areas affected by the Great East Japan Earthquake and the Kanto-Tohoku Heavy Rainfall. One person in each household responded to the questionnaire. Of 362 respondents (response rate 34.0%), 336 with definite attributes were analyzed. After ascertaining their daily information-gathering behavior, we applied binary logistic regression analysis, incorporating-as dependent variables-three variables previously used in times of disaster.Results　Of the respondents, 179 were men (53.3%); the average age (standard deviation) was 65.5 (10.6) years. Information-gathering modes used by more than half the subjects were "television," "newspaper," "conversation/word of mouth," "radio," and "community magazine" in descending order of use.　Examination of the factors of the three variables revealed the following. (1) Four variables were significantly and positively correlated with "conversation/word of mouth": "woman" (1.82 odds ratio [OR]; 1.05-3.15 95% confidence interval [CI]); "I have" a co-resident family member (OR, 2.46; 95% CI, 1.06-5.72); "I can expect" mutual aid from community residents (OR, 2.31; 95% CI, 1.27-4.21); and "I feel more" fear of typhoons and heavy rains now than before (OR, 1.82; 95% CI, 1.04-3.18). (2) "Radio" has two variables with significant and positive correlations: "I have" a co-resident family member (OR, 3.22; 95% CI, 1.35-7.67) and "I was affected" by the Great East Japan Earthquake and the Kanto-Tohoku Heavy Rainfall Disaster (OR, 1.73; 95% CI, 1.01.2.97). (3) Two variables are significantly correlated with "Internet service": "Age" has a negative correlation (OR, 0.91; 95% CI, 0.88-0.94); "I can expect" mutual aid from community residents has a positive correlation (OR, 2.66; 95% CI, 1.19-5.93).Conclusion　Damage and fear instilled by natural disasters influence subsequent information-gathering behavior. Disaster prevention literacy in ordinary times can be improved because of the correlation between awareness of mutual aid in local communities and information-gathering behavior.

Power-frequency magnetic fields and childhood brain tumors: a case-control study in Japan.

BACKGROUND: The strength of the association between brain tumors in children and residential power-frequency magnetic fields (MF) has varied in previous studies, which may be due in part to possible misclassification of MF exposure. This study aimed to examine this association in Japan by improving measurement techniques, and by extending measurement to a whole week. METHODS: This population-based case-control study encompassed 54% of Japanese children under 15 years of age. After excluding ineligible targeted children, 55 newly diagnosed brain tumor cases and 99 sex-, age-, and residential area-matched controls were included in the analyses. The MF exposures of each set of matching cases and controls were measured in close temporal proximity to control for seasonal variation; the average difference was 12.4 days. The mean interval between diagnosis and MF measurements was 1.1 years. The weekly mean MF level was defined as the exposure. The association was evaluated using conditional logistic regression analysis that controlled for possible confounding factors. RESULTS: The odds ratios (95% CI) for exposure categories of 0.1 to 0.2, 0.2 to 0.4, and above 0.4 microT, against a reference category of <0.1 microT, were 0.74 (0.17-3.18), 1.58 (0.25-9.83), and 10.9 (1.05-113), respectively, after adjusting for maternal education. This dose-response pattern was stable when other variables were included in the model as possible confounding factors. CONCLUSIONS: A positive association was found between high-level exposure-above 0.4 microT-and the risk of brain tumors. This association could not be explained solely by confounding factors or selection bias.

Childhood leukemia and magnetic fields in Japan: a case-control study of childhood leukemia and residential power-frequency magnetic fields in Japan.

Residential power-frequency magnetic fields (MFs) were labeled as a possible human carcinogen by the International Agency for Research on Cancer panel. In response to great public concern, the World Health Organization urged that further epidemiologic studies be conducted in high-exposure areas such as Japan. We conducted a population-based case-control study, which covered areas inhabited by 54% of Japanese children. We analyzed 312 case children (0-15 years old) newly diagnosed with acute lymphoblastic leukemia (ALL) or acute myelocytic leukemia (AML) in 1999-2001 (2.3 years) and 603 controls matched for gender, age and residential area. Weekly mean MF level was determined for the child's bedroom. MF measurements in each set of a case and controls were carried out as closely in time as possible to control for seasonal variation. We evaluated the association using conditional logistic regression models. The odds ratios for children whose bedrooms had MF levels of 0.4 microT or higher compared with the reference category (MF levels below 0.1 microT) was 2.6 (95% CI=0.76-8.6) for AML+ALL and 4.7 (1.15-19.0) for ALL only. Controlling for some possible confounding factors did not alter the results appreciably. Even an analysis in which selection bias was maximized did not fully explain the association. Most of the leukemia cases in the highest exposure category had MF levels far above 0.4 microT. Our results provided additional evidence that high MF exposure was associated with a higher risk of childhood leukemia, particularly of ALL.