OBJECTIVESTo study the contact allergenic activities of trichloroethylene (TCE) and its three metabolites trichloroacetic acid, trichloroethanol and chloral hydrate.

METHODSA modified guinea pig maximization test (GPMT) was adopted. The skin sensitization (edema and erythema) was observed in trichloroethylene, trichloroacetic acid, trichloroethanol, chloral hydrate and 2,4-dinitrochlorobenzene.

RESULTSThe allergenic rate of TCE, trichloroacetic acid and 2,4-dinitrochlorobenzene was 71.4%, 58.3% and 100.0% respectively, and that of trichloroethanol and chloral hydrate was 0%. The mean response score of TCE, trichloroacetic acid and 2,4-dinitrochlorobenzene was 2.3, 1.1, 6.0 respectively. The histopathological analysis also showed an induction of allergenic transformation in guinea pig skin by both TCE and trichloroacetic acid.

CONCLUSIONTCE appears to be a strong allergen while trichloroacetic acid a moderate one. On the other hand, both trichloroethanol and chloral hydrate are weak sensitization potentials. Immunologic reaction induced by TCE might be postulated as the pathological process of this illness. Consequently, it is suggested that in the mechanism of Occupational Dermatitis Medicamentose-Like (ODML) induced by TCE, the chemical itself might be the main cause of allergy. As one of its metabolic products, trichloroacetic acid might be a subordinate factor.

Allergens ; toxicity ; Animals ; Chloral Hydrate ; toxicity ; Dermatitis, Allergic Contact ; etiology ; immunology ; Dermatitis, Irritant ; etiology ; immunology ; Ethylene Chlorohydrin ; analogs & derivatives ; toxicity ; Guinea Pigs ; Skin ; drug effects ; immunology ; Toxicity Tests ; Trichloroacetic Acid ; toxicity ; Trichloroethylene ; metabolism ; toxicity