Effects of As₂O₃ and DHA on lipid peroxidation, as determined by intracellular TBARS content. Cells were treated with 1 μM As₂O₃, 25 μM DHA, or the combination of both substances for 18 hours. For comparison, cells were treated with 25 μM OA ± 1 μM As₂O₃ or left untreated (control). To demonstrate the blocking effect of the antioxidant vitamin E, one set of cultures received 20 μM vitamin E simultaneously with As₂O₃ and DHA. After treatment, the cells were harvested and analyzed by means of the thiobarbituric acid assay. Values represent the mean ± SD of 6 independent experiments and are expressed as picomoles of TBARS per 1 × 10⁶ cells. Statistical comparison of DHA- and As₂O₃/DHA-treated cultures was performed by means of one-way analysis of variance (ANOVA) and Tukey post-hoc analysis. P < .05 was considered statistically significant.