FRACTIONAL MERCURY LEVELS IN BRAZILIAN GOLD REFINERS AND MINERS

A field study survey of individuals residing in the region of Para, Br azil, war conducted to determine fractional mercury levels in individu als at risk for exposure in the Brazilian Amazon region. Subjects with a history of exposure to mercury either in the gold mining or refinin g industry, or exposure to these processes through proximity were incl uded. Three groups were identified as either having recent (less than 2 d since last exposure), intermediate (less than 60 d), or remote (gr eater than 60 d) exposure to mercury vapors. Fractional blood and urin ary mercury levels were assessed for these groups. Group I (recent) ha d the highest geometric mean blood 24.8 (SD 44.1, range 7.6-158.8) mu g/L and urine 75.6 (SD 213.4, range 6.5-735.9) mu g/g-cr (microgram me rcury per gram of creatinine) mercury; intermediate (group II) geometr ic mean blood 7.6 (SD 5.5, range 2.2-19.4) mu g/L and urine levels 23. 8 (SD 84.0, range 7.8-297.0) mu g/g-cr; the lowest levels in remote ex posure (group III): geometric mean blood 5.6 (SD 3.3, range 3.1-14.3) mu g/L and urine 7.0 (SD 9.8, range 3.1 to 32.9) mu g/g-cr. The fracti on of organic was lowest in group I (32.4%), higher in group II (65.7% ), and highest in group III (72.2%). While the frequency of symptoms w as comparable in the recent and intermediate groups (2.6 mean, SD 2.3, range 0-8, and 3.1 mean, SD 1.9, range 0-7, symptoms per patient), th ose with remote exposure demonstrated the highest rate of reporting (6 .4 mean, SD 4.1, range 0-11, symptoms per patient). There is significa nt exposure to mercury for those working in or living near the mining and refining industry. Blood and urine levels are a better marker of r ecent than remote exposure. The fraction of organic mercury increases with time since exposure. Symptoms may be persistent and low levels of blood and urine mercury do not exclude remote or cumulative toxicity.