Occupational and Environmental Toxicology of Mercury and Its Compounds.

Abstract

Mercury exists in various chemical forms. The important forms from a toxicological viewpoint are the metallic form, also called the elemental form, the divalent inorganic forms and methylmercury compounds. Elemental (Hg 0 ) mercury has a high vapor pressure and the vapor causes a number of cases of poisoning via inhalation. Classical mercury poisoning is characterized by a triad of signs, namely tremors, erethism and gingivitis. Mercurial erethism, which is characterized by behavioral and personality changes such as extreme shyness, excitability, loss of memory, and insomnia are also observed. Recently, the effects of mercury exposure at levels around 0.05 mg/m 3 or lower have been of concern and may include minor renal tubular damage, increased complaints of tiredness, memory disturbance and other symptoms, subclinical finger tremor, abnormal EEG by computerized analysis and impaired performance in neurobehavioral or neuropsychological tests. Abnormal gait, dysarthria, ataxia, deafness and constriction of the visual field are typical of the symptoms of methylmercury poisoning observed in Minamata and Iraqi outbreaks, as well as in occupational methylmercury poisoning cases. Furthermore, an infant born to a mother with excessive methylmercury consumption showed various neurological disturbances and delayed development. Since several populations are believed to be still exposed to methylmercury through the consumption of fish and sea mammals, neurobehavioral deviations in children of these populations have recently been investigated.

Mercuralismo metálico crônico ocupacional

“…36,66,81 Contudo, vários autores têm encontrado a síndrome mesmo em trabalhadores expostos a valores considerados seguros (World Health Organization), 81 como 0,1 por m 3 no ar e abaixo de HgU de 50 µg/g creatinina.…”

“…20,49,66,76 Contraditoriamente, no meio acadêmico e na prática médica têm-se extrapolado desses estudos conceitos equivocados em relação à intoxicação pelo mercúrio metáli-co. 77 Deste modo, os estudos dessas epidemias terminaram contribuindo pouco para o avanço do conhecimento da intoxicação ocupacional, que tem peculiaridades clínicas e toxicológicas diferentes. Na última década, os estudos das alterações imunológicas e renais na evolução da intoxicação pelo Hg têm colaborado significativamente para a retomada da investigação sobre o hidrargirismo.…”

A Review of the Occupational and Environmental Health Hazards of Bauxite Mining in Malaysia

“…al, 2012;Bernhoft, 2012;Bernhoft, 2013). In children, heavy metals are linked to high death risk, delayed nerve development, intellectual and behavioural problems, as well as peripheral nerve damage and hearing loss (Satoh, 2000;Crossgrove, 2004;Flora et. al, 2012).…”

“…These comprise lead, arsenic, mercury, cadmium, chromium, manganese and nickel and cause central and peripheral nerve harm. They affect nervous and cognitive functions, increases renal toxicity, with hypertension, cardiovascular problems, skin sensitivity and high mortality (Barceloux, 1999;Satoh, 2000;Lustberg and Silbergeld, 2002;Ratnaike, 2003;Crossgrove, 2004;Nawrot et. al, 2006;Das et.…”

“…Long term mercury poisoning causes Minamata disease due to intake of methyl mercury containing seafood, or from workplace exposure. Mercury passes through bloodbrain barrier, affects the brain and causes neurological problems; such as weakness, tiredness, tremors and loss of motor control, with ataxia and sensory loss affecting sight, hearing and speech (Satoh, 2000;Bernhoft, 2012). Long term cadmium exposure causes renal and bone toxicity and manifest as Itai-Itai disease with fractures, osteoporosis, osteomalacia and renal tubular malfunction (Bernhoft, 2013).…”