Methylmercury stimulates the exhalation of volatile selenium and potentiates the toxicity of selenite.

The aim of the present experiments was to investigate whether a single dose of 24 mumol/kg methylmercuric chloride (MeHgCl) in rats can influence the effect of an equimolar dose of sodium selenite (Na2SeO3) on body weight or the exhalation of dimethylselenide, a volatile metabolic product of selenium. Due to the difference in their single-dose toxicities, only selenite depressed body weight gain, when given alone. The experiments indicated that methylmercury, irrespective of whether it was given 1-2 h before, or at the same time as sodium selenite, potentiated the effect of the latter on body weight. Methylmercury also increased the exhalation of volatile selenium, but this effect decreased when the administration of selenite was delayed.