Muller, G; Spassovski, M; Henschler, D
Trichloroethylene (Tri) metabolites, i.e. chloral hydrate (Chl), trichloroethanol (TCE) and trichloroacetic acid (TCA), were administered to volunteers to determine the pharmacokinetic activity in the blood and urine. Immediate oxidation of Chl to TCA amounting to approx. 50% was followed by slow subsequent formation of TCA persisting for 30 h. TCA was also formed from TCE over a prolonged interval. After incorporation of Tri, Chl, or TCE, identical half-lives were found for TCE (approx. 12 h), while the TCA half-lives differed greatly, being most prolonged after Tri (approx. 100 h), somewhat lowered after Chl and TCE (approx. 65 h), and shortest after TCA (50 h). The reported findings indicate storage of both Tri and TCE in the tissues from which they are slowly released. As metabolite recovery invariably accounts for less than 50% of the doses ingested, it is suggested that additional pathways of elimination must be operative, chloroform constituting only a minor portion.
During industrial operations the degree of Tri inhalation varies considerably from one hour to the next and from day to day. Due to the completely different pharmacokinetic behavior of TCE and TCA, it is not permissible to evaluate previous exposure to Tri on the basis of the urinary TCE and/or TCA excretion.
