The Acute Inhalation Toxicity of Monomethylhydrazine Vapor

摘要

The lack of adequate data and the increased used of monomethylhydrazine (MMH), a rocket propellant, prompted additional studies of the acute inhalation toxicity of this compound. The reactive nature of MMH necessitated the use of modified test systems designed to minimize the degradation of MMH during animal exposures. Rats, mice, beagle dogs, squirrel monkeys, and rhesus monkeys were exposed to various measured concentrations of MMH vapor for specified time periods. Rodents were exposed for 30-, 60-, 120-, and 240-minute periods; dogs and squirrel monkeys, for 15, 30, and 60 minutes; and rhesus monkeys for 60 minutes only. The toxicity of MMH for the five animal species was defined by determinations of LC50 values, pathology examination of organs, observations of symptoms, measurements of body weight in rats and mice, and blood chemistry and hematology tests on dogs and rhesus monkeys. Squirrel monkeys proved to be the most sensitive and rats the least sensitive to the lethal effects of MMH. MMH exposure produced definite hemolytic changes in dogs and, to a lesser extent, in rhesus monkeys. These experiments show MMH to be a highly toxic compound. Studies are currently in progress to determine the level at which MMH produces no irreversible injury. (Author)