Lifestyle-Determined Gender and Hierarchical Differences in the Lead Contamination of Bones from a Feudal Town of the Edo Period: Tamiji NAKASHIMA, et al. Department of Anatomy, University of Occupational and Environmental Health, Japan-We analyzed lead concentrations in bones from both genders of Japanese merchants (including rohnin; masterless samurai) and farmer classes, and compared the findings with those of the samurai class in the Edo period (1603-1867) to clarify gender and hierarchical (or occupational) differences in lead exposure during the Japanese feudal age. Merchant class females had significantly higher lead exposure (90.8 µg Pb/g dry bone; n=20) than males of the same class (39.9 µg Pb/g dry bone; n=31) (p<0.01), indicating a remarkable gender difference in the urban population. In contrast to these high concentrations, males and females of the farmer class living in agricultural (or semi-rural) areas had significantly lower exposure (total mean value; 9.2 µg Pb/g dry bone; n=4) than both genders of the merchant class (p<0.001), and the gender difference was not significant in this class. (J Occup Health 2007; 49: 134-139)

An outbreak of enterohaemorrhagic Escherichia coli O157 occurred in multiple prefectures of Japan in November 2009. We conducted two case-control studies with trace-back and trace-forward investigations to determine the source. The case definition was met by 21 individuals; 14 (66.7%) were hospitalised, but no haemolytic uraemic syndrome, acute encephalopathy or deaths occurred. Median age was 23 (range 12-48) years and 14 cases were male (66.7%). No significant associations with food were found in a case-control study by local public health centres, but our matched case-control study using Internet surveys found that beef hanging tender (or hanger steak), derived from the diaphragm of the cattle, was significantly associated with illness (odds ratio = 15.77; 95% confidence interval, 2.00-124.11). Pulsed-field gel electrophoresis analysis of isolates from patients and the suspected food showed five different patterns: two in faecal and food samples, and another three in patient faecal samples only, although there were epidemiological links to the meat consumed at the restaurants. Trace-back investigation implicated a common food processing company from outside Japan. Examination of the logistics of the meat processing company suggested that contamination did not occur in Japan. We concluded that the source of the outbreak was imported hanging tender. This investigation revealed that Internet surveys could be useful for outbreak investigations.