A nonoccupational outbreak of inorganic mercury vapor poisoning

An outbreak of inorganic mercury vapor poisoning involving 12 people occurred in a trailer park in Mississippi in 1973-74. For information concerning levels of mercury in hair and blood of humans with short-term exposures, these individuals were observed for as long as 10 months after the end of their exposures, and the amount of mercury in their blood and scalp hair was serially measured. Specimens were also obtained from nonexposed individuals in the trailer park. Inorganic mercury was measured in 1-cm segments of hair samples obtained both 6 and 9 months after termination of exposure. Over a 3-month period, the peak amount of inorganic mercury per gram of hair shifted in position from 7 cm to 13 cm from the scalp. The average mercury concentration in newly formed hair (the 4 cm of hair closest to the scalp) decreased fourfold over the same time period. Surface contamination of exposed hair by exogenous mercury also occurred. Levels of inorganic mercury in blood from exposed individuals ranged from 183 to 620 ng/ml and fell to levels similar to those of controls 4 to 6 months after ending exposure. The source of the outbreak was metallic mercury spilled on rugs. Attempts to remove the mercury failed and actually dispersed the metal over a larger surface area. Air mercury levels as high as 1.0 mg/m3 of air were found in one of the contaminated house trailers. Rugs or carpets contaminated with metallic mercury are a significant health risk.