The relatively high and almost constant absorption/min of trichloroethylene (TRI) is explained by the relatively high partition coefficient between blood and air (.lambda.b/g = 15) combined with the rapid metabolism (75%). Tetrachloroethylene (PERC) has about the same .lambda.b/g as TRI but the metabolism is insignificant (2%); therefore, the amount taken up per min decreases in the course of exposure. The .lambda.b/g (5) for 1,1,1-trichloroethane (MC) is smaller and the metabolism is insignificant (3.5%); therefore, the capacity of the body to absorb MC is relatively small and the uptake per min decreases fast during exposure. Due to the lower .lambda.b/g the excretion of MC after exposure is much faster than that of PERC. As a result of the metabolism of TRI only a relatively small amount of TRI absorbed is excreted by the lungs after exposure. [This study is relevant to occupational toxicology.].