Effects of methylmercury on neurodevelopment in Japanese children in relation to the Madeiran study

Murata, Katsuyuki; Sakamoto, Mineshi; Nakai, Kunihiko; Weihe, Pál; Dakeishi, Miwako; Iwata, Tetsu; Liu, Xiao Jie; Ohno, Tomoko; Kurosawa, Tomoko; Kamiya, Kazuko; Satoh, Hiroshi

doi:10.1007/s00420-004-0542-1

Cited by 60 publications

(46 citation statements)

References 32 publications

(55 reference statements)

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“…These functions did not seem to be affected by a diurnal variation because no special conditions such as sleep deprivation or night work existed [14][15][16] . Also, postural sway in children tends to be larger in boys than in girls, but tremor does not differ according to sex 17) . The comparison between the exposed and unexposed subjects was performed by the analysis of covariance with covariates such as age, gender, smoking status, and alcohol consumption (and height, when the postural parameters were analyzed).…”

Section: Methodsmentioning

confidence: 85%

Effects of Mixed Organic Solvents on Neuromotor Functions among Workers in Buddhist Altar Manufacturing Factories

Iwata

Mori²,

Dakeishi

et al. 2005

Journal of Occupational Health

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Effects of Mixed Organic Solvents on Neuromotor Functions among Workers in BuddhistAltar Manufacturing Factories: Toyoto IWATA, et al. Department of Environmental Health Sciences, Akita University School of Medicine-To clarify the neuromotor effects of long-term exposure to mixed organic solvents, postural sway and tremor were measured in 62 solvent workers of four Buddhist altar manufacturing factories who had worked for 1-46 (mean 12) yr. By using the passive gas sampler, 8-h time-weighted average concentrations in the workers were estimated to be 0.02-8.7 ppm for toluene, 0.02-7.7 ppm for xylene, 0.02-5.5 ppm for styrene and 0.02-40.5 ppm for n-hexane. Sagittal sway and sway area of the posturography with eyes closed were significantly larger in the solvent workers than in 35 age-matched controls (p<0.05), and there was a significant difference in Romberg quotient of sagittal sway between the two groups (p<0.05). Also, tremor intensities at 1.0-5.9 Hz, 6.0-9.9 Hz and 10.0-13.9 Hz with the right hand, and at 6.0-9.9 Hz with the left hand were significantly stronger in the solvent workers than in the controls. Among the solvent workers, transversal and sagittal sways with eyes open and tremor intensity at 10.0-13.9 Hz were significantly related to toluene exposure (p<0.05), which may have been due to the acute effects of such solvents. These findings suggest that longterm exposure to mixed organic solvents may impair neuromotor functions as measured by postural sway and tremor. (J Occup Health 2005; 47: 143-148)

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Section: Methodsmentioning

confidence: 85%

Effects of Mixed Organic Solvents on Neuromotor Functions among Workers in Buddhist Altar Manufacturing Factories

Iwata

Mori²,

Dakeishi

et al. 2005

Journal of Occupational Health

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“…In interpreting epidemiological studies based on hair mercury only, attention should be directed toward the consequences of exposure misclassification. Rather, mercury in blood or methylmercury in cord tissue, together with hair mercury, may be recommended in such studies on risk assessment (9,12,24), because the usefulness of the mercury concentration in cord blood has been emphasized as a main risk indicator (25).…”

Section: Discussionmentioning

confidence: 99%

“…In Japan, there were many mines and smelters 30 years ago, and it is probable that soil or water was contaminated by lead, cadmium, mercury vapor, etc; therefore, the study population did not include people who came from such areas. Finally, 327 mothers participated (12). This study was carried out with the approval of the ethical review committee at the Akita University School of Medicine.…”

Section: Subjectsmentioning

confidence: 99%

Effects of hair treatment on hair mercury—The best biomarker of methylmercury exposure?

Dakeishi

Nakai

Sakamoto

et al. 2005

Environ Health Prev Med

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Objectives: Exposure 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.Methods: A 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.Results: Hair 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.Conclusions: These findings suggest that hair mercury is not the best biomarker of methylmercury exposure when a study population includes women with artificial hair-waving.

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“…Irrespective of the sources of Hg contamination, exposure and the mechanism involved in its accumulation in the brain, increased brain Hg concentration is likely to result in oxidative stress and damage to cells as indicated by the results of our glial cultures. Japanese studies have shown that Hg exposure, indicated by hair Hg levels above 6.9 ng g 1 (34.5 pmol g 1 ), significantly affected brain stem auditory evoked potential (BAEP) [76] . It is interesting that BAEP abnormalities have been observed in autism [77] , although reported changes have not been consistent [78] .…”

Section: Increased Cerebellar Hg In Autism?mentioning

confidence: 99%

Oxidative Stress in Autism: Elevated Cerebellar 3-nitrotyrosine Levels

Sajdel-Sulkowska¹,

Lipiński²,

Windom³

et al. 2008

American J. of Biochemistry and Biotechnology

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It has been suggested that oxidative stress and/or mercury compounds play an important role in the pathophysiology of autism. This study compared for the first time the cerebellar levels of the oxidative stress marker 3-nitrotyrosine (3-NT), mercury (Hg) and the antioxidant selenium (Se) levels between control and autistic subjects. Tissue homogenates were prepared in the presence of protease inhibitors from the frozen cerebellar tissue of control (n=10; mean age, 15.5 years; mean PMI, 15.5 hours) and autistic (n=9; mean age 12.1 years; mean PMI, 19.3 hours) subjects. The concentration of cerebellar 3-NT, determined by ELISA, in controls ranged from 13.69 to 49.04 pmol g 1 of tissue; the concentration of 3-NT in autistic cases ranged from 3.91 to 333.03 pmol g 1 of tissue. Mean cerebellar 3-NT was elevated in autism by 68.9% and the increase was statistically significant (p=0.045). Cerebellar Hg, measured by atomic absorption spectrometry ranged from 0.9 to 35 pmol g 1 tissue in controls (n=10) and from 3.2 to 80.7 pmol g 1 tissue in autistic cases (n=9); the 68.2% increase in cerebellar Hg was not statistically significant. However, there was a positive correlation between cerebellar 3-NT and Hg levels (r=0.7961, p=0.0001). A small decrease in cerebellar Se levels in autism, measured by atomic absorption spectroscopy, was not statistically significant but was accompanied by a 42.9% reduction in the molar ratio of Se to Hg in the autistic cerebellum. While preliminary, the results of the present study add elevated oxidative stress markers in brain to the growing body of data reflecting greater oxidative stress in autism.

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Effects of methylmercury on neurodevelopment in Japanese children in relation to the Madeiran study

Cited by 60 publications

References 32 publications

Effects of Mixed Organic Solvents on Neuromotor Functions among Workers in Buddhist Altar Manufacturing Factories

Effects of Mixed Organic Solvents on Neuromotor Functions among Workers in Buddhist Altar Manufacturing Factories

Effects of hair treatment on hair mercury—The best biomarker of methylmercury exposure?

Oxidative Stress in Autism: Elevated Cerebellar 3-nitrotyrosine Levels

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