POLY(VINYL CHLORIDE) FORMULATIONS - ACUTE TOXICITY TO CULTURED HUMAN CELL-LINES

Two quantitative cytotoxicity assay methods (cytoplasmic retention of carboxyfluorescein and mitochondrial cleavage of 3-(4,5-dimethylthiazo l-2-yl)-2,5-diphenyl tetrazolium bromide (MTT)) have been used to eval uate the response of two cultured human cell lines; HepG2 (hepatoma) a nd WI38va13 (transformed lung fibroblasts) to extracts of a range of p oly(vinyl chloride) (PVC) formulations. Two plasticizers; di(2-ethylhe xyl)phthalate (DEHP) and di-isooctyl phthalate and a range of tin and non-tin stabilizers were incorporated in the study. Only those formula tions containing both a plasticizer and a tin-based stabilizer produce d extracts which were toxic. Extracts of those formulations which cont ained both plasticizer and dibutyl tin dimaleate stabilizer were toxic to both cell lines in both assay methods. Extracts of a formulation c ontaining plasticizer and a dioctyl tin mercaptide were toxic to both cell lines in the carboxyfluorescein assay but were only toxic to the WI38va13 cells in the MTT assay. The WI38va13 cells were generally mor e sensitive to the extracts than the HepG2 cells. When serial dilution s of the extracts were evaluated, the carboxyfluorescein assay proved to be the more sensitive of the two. The acute toxicity of extracts of these PVC formulations cannot be directly attributed to the plasticiz ers or to the tin stabilizers. It is likely that a synergistic mechani sm, such as plasticizer facilitated extraction of the tin stabilizer, exists.