Acute mercury intoxication and use of chelating agents

There is a great hazard of mercury intoxication in the third world for artisanal miners using mercury as amalgam for extracting and refining gold. In developing countries, there is the possibility of risk regarding exposure to Hg from amalgam tooth fillings, ethyl-Hg (thimerosal) added as antiseptic to vaccines and methyl-Hg in fish. In one case, a 41-year-old man attempted suicide by ingesting 100 mg of HgCl2. After 8 hours, he developed hematemesis and entered the intensive care unit; his urinary Hg was 10.1 mg/l. Treatment with 2,3-dimercaptopropanol (BAL) was started by intramuscular route after 16 hours at the dosage of 5 mg/kg body weight every 4 hours on days 2-3 and 3 mg/kg every 6 hours on days 4-5 and then every 12 hours on days 6-14 without adverse side effects. Acute Hg intoxication can be managed with BAL as first choice chelator, whereas the less toxic 2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercaptopropane-1-sulfonic acid (DMPS) should be reserved for cases of less severe inorganic Hg or methyl-Hg acute intoxication. Such agents, recommended only for the treatment of acute Hg poisoning, should not be used for patients suffering from neurological diseases in which environmental Hg exposure is hypothesised.