OBJECTIVESIt is crucial to consider covariates relevant for outcome variables in developing dose-effect relations of environmental hazardous toxins. The aim of this study was to clarify the covariates affecting hand tremor and postural sway in children.

METHODSHand tremor and postural sway, as well as hair mercury concentrations, were measured in 155 boys and 148 girls at age 7 years.

RESULTSCurrent mercury concentrations in child hair ranged from 0.35 to 6.32 μg/g (geometric mean, 1.71 μg/g for boys and 1.58 μg/g for girls), and were not significantly correlated with the neuromotor parameters. All hand tremor and postural sway parameters, except for tremor intensity at 1-6 Hz with non-dominant hand, were significantly larger in the boys than in the girls. Using multiple regression analysis, some postural sway parameters were related negatively to age in the boys and girls (p<0.05), and positively to height (p<0.05). Similarly, hand tremor parameters were positively related to age, height and heart rate either in the boys or in the girls (p<0.05). Also, there were positive relationships between tremor intensity at 1-6 Hz and transversal and sagittal sways at 1-2 Hz and 2-4 Hz (p<0.05).

CONCLUSIONSHeart rate and postural sway, together with age, sex, and height, should be considered in interpreting hand tremor in children. Hand tremor or postural sway may not be so sensitive or specific to methylmercury exposures at levels of less than 7 μg/g in hair.

OBJECTIVEThe aim of this study was to determine the level of exposure of mercury (Hg) miners and smelter workers to elemental mercury (Hg(0)) vapor in China, who work in Hg mines without using protective equipment against Hg(0) vapor. In addition, the level of methylmercury (MeHg) intake by the workers was estimated from the MeHg concentration in their hair.

METHODSUrinary total mercury (THg) and hair THg and MeHg concentrations were measured in 26 Hg miners and smelter workers (i.e., exposed group), and 48 unexposed people (unexposed group).

RESULTSThe exposed group showed high geometric mean THg concentrations in urine (258 ng/ml, 226 μg/g creatinine) and hair (20.0 μg/g). The urinary THg concentration of the smelter workers in particular was extremely high (338 μg/g creatinine in urine). The highest urine THg concentration reached 4577 μg/g creatinine. THg concentrations in urine and hair showed a significant correlation in the exposed group (r=0.62), indicating the adhesion of Hg(0) vapor to hair. However, no such significant correlation was found in the unexposed group. Hair MeHg concentration in the exposed group (1.97 μg/g) was about threefold higher than that in the unexposed group (0.60 μg/g).

CONCLUSIONSThis study shows that smelter workers in a Chinese Hg mine are exposed to extremely high levels of Hg(0) vapor, and that Hg miners are exposed to higher levels of MeHg than the unexposed subjects. Further study is needed to determine the cause of the higher hair MeHg concentration in the exposed group.

OBJECTIVESExposure misclassification is a major obstacle to obtain accurate dose-response relationships. In order to solve this problem, the impact of hair treatment on total mercury in hair was assessed in Japanese women.

METHODSA cross-sectional study was carried out among 327 women at age 24-49 years to determine hair mercury levels and estimate daily mercury intakes from seafood by using a food frequency questionnaire.

RESULTSHair mercury levels in the women and daily mercury intake ranged from 0.11 to 6.86 (median 1.63) μg/g and from 0.77 to 144.9 (median 15.0) μg/day, respectively. The hair mercury was positively correlated with the daily mercury intake (p<0.001). When the women were divided into two subgroups based on artificial hair-waving, hair coloring/dyeing, residence (non-fishing and fishing areas), and working status, a significant difference in the hair mercury level was observed between the women with and without artificial hair-waving only (p<0.001). The multiple regression analysis showed that the log-transformed hair mercury level was significantly related to the log-transformed daily mercury intake (standardized regression coefficient βs=0.307) and artificial hair-waving (βs=-0.276); but not to hair coloring/dyeing, residence, working status or age. Permanent hair treatment was estimated to reduce total mercury in hair by approximately 30%, after adjusting for daily mercury intake and other possible factors.

CONCLUSIONSThese findings suggest that hair mercury is not the best biomarker of methylmercury exposure when a study population includes women with artificial hair-waving.

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.

BACKGROUND: In health examinations for local inhabitants in cadmium-polluted areas, only healthy people are investigated, suggesting that patients with severe cadmium nephropathy or itai-itai disease may be overlooked. Therefore, we performed hospital-based screening to detect patients with cadmium nephropathy in two core medical institutes in cadmium-polluted areas in Akita prefecture, Japan. METHODS: Subjects for this screening were selected from patients aged 60 years or older with elevated serum creatinine levels and no definite renal diseases. We enrolled 35 subjects from a hospital in Odate city and 22 from a clinic in Kosaka town. Urinary ß-microglobulin and blood and urinary cadmium levels were measured. RESULTS: The criteria for renal tubular dysfunction and the over-accumulation of cadmium were set as a urinary ß-microglobulin level higher than 10,000 μg/g cr. and a blood cadmium level higher than 6 μg/L or urinary cadmium level higher than 10 μg/g cr., respectively. Subjects who fulfilled both criteria were diagnosed with cadmium nephropathy. Six out of 57 patients (10.5% of all subjects) had cadmium nephropathy. CONCLUSIONS: This hospital-based screening is a very effective strategy for detecting patients with cadmium nephropathy in cadmium-polluted areas, playing a complementary role in health examinations for local inhabitants. REGISTRATION NUMBER No. 6, date of registration: 6 June, 2010 (Akita Rosai Hospital), and No. 1117, date of registration: 26 December, 2013 (Akita University).
Aged ; Aged, 80 and over ; Cadmium ; adverse effects ; urine ; Cadmium Poisoning ; blood ; complications ; urine ; Creatinine ; urine ; Environmental Exposure ; adverse effects ; Environmental Monitoring ; Environmental Pollutants ; adverse effects ; urine ; Female ; Hospitals ; Humans ; Japan ; Kidney Diseases ; chemically induced ; urine ; Male ; Middle Aged ; Sex Distribution