OBJECTIVEExposure to polychlorinated biphenyls (PCBs) is considered to have culminated between 1950 and 1970 in Japan, and exposure through diet, the major exposure route, has decreased significantly over the last 10 years. The primary goal of the present study was to investigate the long-term trends and congener profiles of serum and dietary levels of PCBs using historical samples.

METHODSUsing banked samples collected in 1980, 1995, and 2003 surveys, we determined the daily intakes and serum concentrations of 13 PCB congeners (#74, #99, #118, #138, #146, #153, #156, #163, #164, #170, #180, #182, and #187) in women.

RESULTSThe total daily PCB intake [ng/day, geometric mean (geometric standard deviation)] decreased significantly from 523 (2.5) in 1980 to 63 (3.2) in 2003. The serum total PCB level (ng/g lipid) in women <40 years of age decreased significantly from 185 (1.8) in 1980 to 68 (1.8) in 2003. In contrast, the level in women >50 years of age increased significantly from 125 (1.7) in 1980 to 242 (1.7) in 2003. Specifically, the serum concentrations of hexa (#138, #146, #153, #156, #163, and #164) and hepta (#170, #180, #182, and #187) congeners increased significantly. A comparison of the serum PCB levels of women born from 1940 to 1953 revealed that their serum total PCB level was significantly higher in the 2003 survey [242 (1.7), n = 9] than in the 1995 [128 (2.0), n = 17] surveys. This increase in the total PCB level was attributable to increases in the hepta congener groups.

CONCLUSIONPresent results suggest a decreased rate of elimination of hepta congeners with aging in females, rather than a birth-generation phenomenon.

The present study was initiated to make an urban-rural comparison of the prevalence of cases positive to hepatitis B and C virus (HBV and HCV, respectively) infection markers in densely populated eastern half of China. For this purpose, 10 survey sites were selected, i.e., six sites in urban areas (the city group; Beijing, Shanghai and four provincial capitals) and four sites in rural areas (the village group ; one village each in Jilin and Shandong Provinces, and two villages in Shaanxi Province). About 50 adult women per site volunteered to participate, from whom 494 valid blood samples were collected. Positivities to HBsAg (HBsAg+), anti-HBs (anti-HBs+) and anti-HBc (anti-HBc+) were examined by RIA methods, and that to anti-HCV (anti-HCV+) by either EIA or RIA. Those positive to any one of the three HBV infection markers were taken as HBV infection-positive (HBV+). The prevalence of HBsAg+, HBV+ and anti-HBc+ was 8%, 70% and 2.7% in the city group, and 8%, 65% and 2.0% in the village group, and no significant difference was found between the two groups. The overall prevalence was 8% for HBsAg+, 68% for HBV+, and 2.4% for anti-HCV+. The results were discussed in reference to some 20 papers each on HBV+ and anti-HCV+ prevalence in China published since 1991. The reviewing of these papers confirmed that the prevalence of HBV was high (i.e., in excess of 50%), whereas the prevalence of anti-HCV was low (well below 5%), and that no substantial difference was found between the rural and urban populations.

Triplet surveys were conducted in the city of Xi' an and two villages (one in the vicinity and the other at a distance) in Shaanxi Province in China in October-November (when agricultural activitis were low), 1997, to elucidate nutrient intakes with a focus on possible urban-rural differences. Total food duplicate samples were collected from non-smoking and non-habitually drinking adult healthy women (about 50 subjects per site and 149 in total). The nutrient intakes were estimated from the weight of food items in reference to national food composition tables. On average, the women took 1873 kcal energy, 54 g protein and 37 g lipid per day, with a lipid energy ratio of18.4%. Both excess and insufficient energy intake was observed as a result of food intake analysis and body mass index determination. With regard to minor nutrient intakes, insufficiency was serious in the case of calcium, vitamin A and vitamin B2, but not with iron. Whereas dependency on plant foods for sources of energy and protein was common to the three regions, Xi' an people consumed more animal foods than those in the villages. Intake of fish and shellfish was quite low throughout the three regions. Among the four types of cereals, wheat was consumed most substantially in the three regions and in three meals (except for the village where people essentially did not take lunch in reflection of low agricultural activities), whereas rice was consumed more in Xi' an than in the two villages. Maize consumption was higher in the two villages (especially for breakfast) than in the city.In contrast, foxtail millet (although in small amounts) was taken primarily in Xi'an and only at the time of breakfast.