Preliminary study on health risk from mercury exposure to residents of Wujiazhan town on the Di'er Songhua river, Northeast China.
ABSTRACT Mercury concentrations in hair are typically used as a biomarker to assess exposure to mercury. A total of 108 hair samples were collected from residents (age range 5-73 years) of Wujiazhan town, northeast China, to determine total mercury concentrations. Hair mercury concentrations ranged from 0.16 to 199 mg kg(-1) with an average value of 3.41 mg kg(-1). The relationships between mercury concentration and gender and between hair mercury concentration and age were not significant. Overall, 16.7% of all samples were above the RfD value published by the United States Environmental Protection agency. The results indicate that there may be some been health risk from mercury exposure to the residents in the study area.
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ABSTRACT: Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic (methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children's health.Current problems in pediatric and adolescent health care 09/2010; 40(8):186-215. · 1.56 Impact Factor
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ABSTRACT: This study aims to investigate the methylmercury contamination of fish from the Songhua River, China. A total of 328 fish representing various trophic levels were captured from ten reaches of the river and determined for methylmercury by gas chromatography method. Total mercury in fish, water and sediments from three typical reaches were analyzed simultaneously. Methylmercury concentrations in fish from the Second Songhua River and the mainstream of the Songhua River were 0.024 ± 0.016 and 0.015 ± 0.007 mg/kg fresh weight, respectively. The proportion of methylmercury to total mercury ranged from 21.8% to 69.7%, with the mean value of 42.6%. The observed methylmercury concentrations were much lower than the historical values and were generally within the reported literature range, and health hazard assessment showed no health risk from exposure to methylmercury by consuming fish from this river, demonstrating that mercury contamination of the Songhua River has been effectively controlled by nearly 30 years of environmental governance and natural purification.Environmental Monitoring and Assessment 03/2011; 184(1):77-88. · 1.68 Impact Factor
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ABSTRACT: It is shown that for directed graphs, reachability can not be expressed by an existential monadic second-order sentence. The proof makes use of Ehrenfeucht-Fraisse games, along with probabilistic. However, it is shown that for directed graphs with degree at most k, reachability is expressible by an existential monadic second-order sentence. One reason for the interest in the main result is that while there is considerable empirical evidence (in terms of the efficiency of algorithms that have been discovered) that reachability in directed graphs is 'harder' than reachability in undirected graphs, this is the first proof in a precise technical sense that this is so.Foundations of Computer Science, IEEE Annual Symposium on. 10/1988;