Prognosis of mercury poisoning in mercury refinery workers

The prognosis of chronic metallic mercury poisoning in two groups of patients from the mercury refinery of a mercury mine was evaluated by reexamination which included an interview, physical and neurological examination and determination of urinary mercury. Group I consisted of 70 male patients, who had been exposed to metallic mercury for 1.6-17.8 years, 15 of whom had been diagnosed 10 years earlier as having severe chronic metallic mercury poisoning, and the rest moderate chronic metallic mercury poisoning. At the time of reexamination, they had been removed from mercury exposure for 2 months-17 years. None of them had been treated with any chelating agent. Group 2 comprised 84 male patients from the same mercury mine, who had been exposed to metallic mercury for 2-10 years after 1962 and had been previously diagnosed as having mild chronic metallic mercury poisoning. They were reexamined after 2 months of hospital admission and chelation treatment with unithiol or sodium dimercaptosuccinate (Na-DMS). Based on clinical evaluation, the condition of the patients in both groups had all improved, even in the severe cases. The overall prognosis of chronic metallic mercury poisoning in mercury refinery workers was encouraging after termination of mercury exposure. Chelation therapy with unithiol or Na-DMS was evidently beneficial for reducing urine mercury and some symptoms, but not for neurological and stomal signs.