Subject(s)
Environmental Exposure , Food Contamination , Mercury Poisoning/epidemiology , Mercury/blood , Adolescent , Adult , Aged , Animals , Brazil , Child , Child, Preschool , Diet , Female , Fishes , Health Surveys , Humans , Infant , Infant, Newborn , Male , Mercury/adverse effects , Mercury/analysis , Mercury Poisoning/etiology , Middle Aged , Soil Pollutants/analysis , Urban PopulationSubject(s)
Mercury/urine , Mining , Occupational Exposure , Adolescent , Adult , Cross-Sectional Studies , Female , Health Status , Humans , Male , Mercury/analysis , Middle Aged , Urban PopulationABSTRACT
In widespread informal gold mining in the Amazon Basin, mercury is used to capture the gold particles as amalgam. Releases of mercury to the environment have resulted in the contamination of freshwater fish with methylmercury. In four comparable Amazonian communities, we examined 351 of 420 eligible children between 7 and 12 years of age. In three Tapajós villages with the highest exposures, more than 80% of 246 children had hair-mercury concentrations above 10 microg/g, a limit above which adverse effects on brain development are likely to occur. Neuropsychological tests of motor function, attention, and visuospatial performance showed decrements associated with the hair-mercury concentrations. Especially on the Santa Ana form board and the Stanford-Binet copying tests, similar associations were also apparent in the 105 children from the village with the lowest exposures, where all but two children had hair-mercury concentrations below 10 microg/g. Although average exposure levels may not have changed during recent years, prenatal exposure levels are unknown, and exact dose relationships cannot be generated from this cross-sectional study. However, the current mercury pollution seems sufficiently severe to cause adverse effects on brain development.
Subject(s)
Brain/drug effects , Child Behavior/drug effects , Fetus/drug effects , Gold , Methylmercury Compounds/toxicity , Mining , Prenatal Exposure Delayed Effects , Adult , Child , Cross-Sectional Studies , Feeding Behavior , Female , Hair/chemistry , Humans , Male , Mercury/analysis , Pregnancy , Regression AnalysisABSTRACT
A new portable tremometer allows determination of tremor intensities at different tremor frequencies. Based on past studies, two tremor frequency windows of similar size were chosen at 3.0-6.5 Hz and 6.6-10.0 Hz to reflect major tremor intensities in Parkinson's disease and mercury vapor poisoning, respectively. In 81 healthy controls, total tremor intensity was higher for the preferred hand and depended on age. Ten patients treated for Parkinson's disease showed substantially increased tremor intensity, especially within the low-frequency window. This pattern was also apparent in 14 patients with de novo Parkinson's disease whose overall tremor intensity was only mildly elevated. In contrast, ten patients with essential tremor had peak frequencies in both windows, and some patients had increased tremor on one side only. Sixty-three Brazilian gold traders exposed to mercury vapor showed increased tremor predominantly in the high-frequency window. Three of the gold traders had a narrower tremor peak at frequencies of 7-8 Hz. While the urine-mercury concentration was significantly associated with the current number of burning sessions per week, it did not correlate with tremor intensities. However, eight traders had a urinary mercury excretion level above 50 microg and at the same time a greatly increased average tremor intensity within the high-frequency window. These patterns were statistically significant for relative tremor intensities, but were less clear when total intensities were used. These observations suggest that the relative distribution of tremor intensities in specific frequency bands may be a valuable supplement to current diagnostic methods for subjects with mercury vapor exposure.