Accumulation kinetics of trichloroethylene and its metabolites during multiple exposures. A theoretical study (author's transl)

In attempting to establish an excretory TLV for trichloroethylene, the rates at which trichloroethylene and its metabolites accumulate in the body with increasing number of exposures and their plateau values attained after repetition of an infinite number of exposures were estimated theoretically with a mathematical model. After a single inhalation exposure to trichloroethylene is over, its concentration in the blood, x, and the amount of its urinary metabolites, [D]to, as a function of time t are expressed as a sum of three exponentials: (formula: see text). where A1-A3 and D1-D3 are constants depending on the inhaled air concentration of trichloroethylene, and alpha 1-alpha 2 and kA-K3 rate constants. When the same degree of exposure is repeated for n consecutive days, the blood concentration, t hours after the nth day's exposure, becomes (formula: see text). From the experimental results of a single human exposure reported previously, the concentration of trichloroethylene in the blood was predicted to change only to a negligible degree after repetition of an infinitive number of exposures, whereas the amount of total urinary metabolites was predicted to increase by twice as much as that excreted after the single exposure.