Three workers engaged in the production of mercuric acetate (Chap. 95) were admitted to the hospital within 22 calendar days of each other, 30, 48, and 5 days, respectively, after their last working day. The workers served the same reactor in which elemental mercury was oxidized by peroxide to mercuric oxide and mercuric acetate was formed by the reaction of mercuric oxide with acetic acid. They all presented with neurologic findings, including ataxia, dysarthria, tremor, deteriorating vision, and cerebellar signs. The first 2 workers had rapidly progressive downhill courses to coma that ended in death. The diagnosis of mercury vapor intoxication of the first 2 patients was established 21 and 16 days after their admission, when the third worker was admitted and hospitals were informed about their exposure. Blood mercury concentrations in all 3 patients were approximately 2,000 mcg/L with low urine mercury concentrations. All patients were chelated with penicillamine without any noticeable effect. Organic mercury probably was formed as an unintended byproduct of this reaction. In this reaction, methyl mercury acetate, which is 5.4 times more volatile than mercury vapor, could have been formed. The incorrect diagnosis of mercury vapor exposure in these cases was established even though (1) the observed signs of a rapid irreversible clinical course, ataxia, dysarthria, and constriction of visual fields are rarely present in mercury vapor poisoning and are characteristic of organic mercury poisoning; (2) the degree of deterioration after removal from exposure further implicated organic mercury, not mercury vapor; (3) blood mercury concentrations were in the range associated with severe poisoning in the Iraq methyl mercury epidemic; (4) patients had little response to treatment with penicillamine, the opposite of what is expected with mercury vapor; and (5) the blood-to-urinary mercury concentration ratios were high, but this ratio usually is less than 0.5 in mercury vapor toxicity or in workers exposed to mercury vapor. The other important facet of these cases is the public health implications of this sentinel health event. Three employees in this workplace were affected by this exposure. Further investigation of the workplace revealed that no other workers were affected but also that there were no changing facilities so employees wore their work clothes home. Investigation of their homes revealed elevated environmental mercury concentrations and elevated blood mercury concentrations in family members. Here, an occupational exposure became an environmental exposure for the community.
Many important problems are associated with the diagnosis and treatment of occupational and environmentally caused diseases, including (1) the ability to correctly establish the diagnosis as originating from an exposure, (2) the ability to correctly treat the condition, and (3) the ability to correctly act on any public health issues related to the exposure. The following discussion instructs clinicians on how to assemble adequate information to achieve the appropriate diagnosis and treatment.
TAKING AN OCCUPATIONAL HISTORY
Because time spent at work is a large percentage of ...