Cellular Toxicity of Surfactants Used as Herbicide Additives

The cellular toxicities of surfactants, a solvent, and an antifreeze that are included in herbicide formulations were assessed by measuring their effects on membrane integrity, metabolic activity, mitochondrial activity, and total protein synthesis rate in a cell culture. Polyethylene glycol, propylene glycol, and monoethylene glycol exhibited no cellular toxicity even at a high concentration of 100 mM. Sodium lauryl ether sulfate and polyoxyethylene lauryl ether significantly damaged the membrane, disturbed cellular metabolic activity, and decreased mitochondrial activity and the protein synthesis rate; however, their toxicity was far below those of the severely toxic chemicals at comparable concentrations. The severely toxic category included polyoxypropylene glycol block copolymer, polyoxyethylene tallow amine, and polyoxyethylene lauryl amine ether. These surfactants were cytotoxic between 3.125 microM and 100 microM in a dose-dependent manner. However, the toxicity graph of concentration vs toxicity had a point of inflection at 25 microM. The slope of the toxicity graph was gentle when the concentration was below 25 microM and steep when the concentration was greater than 25 microM. In conclusion, our results suggest that the toxicity of surfactants be taken care of pertinent treatment of acute herbicide intoxication.

Cytotoxicity of endodontic irrigants containing calcium hydroxide and sodium lauryl sulphate on fibroblasts derived from mouse L929 cell line

The aim of this study was to evaluate the cytotoxicity of root canal irrigating solutions containing calcium hydroxide and sodium lauryl sulphate on fibroblasts derived from L929 cell line. Saturated calcium hydroxide aqueous solution (CH), sodium lauryl sulphate (SLS) and SLS associated with calcium hydroxide (HCT20) were diluted with sterile distilled water at 50 percent, 20 percent, 10 percent and 5 percent concentrations. Minimum essential medium (MEM) served as the control group. The cytotoxicity of the solutions was evaluated on L929 mouse fibroblast cell line, at 4 and 24 h of contact time by the 51Cr radiotracer method. Data were compared and statistical inferences were made with the chi-square test. In all analysis, significance level was set at 5 percent. CH and HCT20 showed toxicity at 50 percent concentration, while at concentrations lower than 50 percent these solutions showed cell tolerance. SLS was cytotoxic at all concentrations. In conclusion, the association of calcium hydroxide and SLS (HCT20) combines the beneficial properties of these solutions and was not harmful to the fibroblast cell line, seeming to be a suitable endodontic irrigating solution.

O objetivo desta pesquisa foi avaliar a citotoxicidade de soluções irrigadoras de canais radiculares contendo hidróxido de cálcio e lauril sulfato de sódio em linhagem de fibroblastos L929. Solução aquosa saturada de hidróxido de cálcio, lauril sulfato de sódio e HCT20 (lauril sulfato de sódio e hidróxido de cálcio) foram diluídos em água destilada em concentrações de 50 por cento, 20 por cento, 10 por cento e 5 por cento. O grupo controle foi representado por meio de cultura de células (MEM - minimum essential medium). A citotoxicidade das soluções sobre os fibroblastos foi avaliada em 4 e 24 h de contato, pelo método do cromo radioativo. Os resultados foram analisados estatisticamente pelo teste do qui-quadrado. Em todas as análises, o intervalo de confiança referente às médias entre os grupos foi estabelecido em 95 por cento. As soluções saturadas de hidróxido de cálcio e o HCT20 apresentaram toxicidade nas concentrações de 50 por cento. O lauril sulfato de sódio foi tóxico em todas as concentrações. As soluções de hidróxido de cálcio em concentrações menores que 50 por cento apresentaram tolerância celular, assim como combinadas ao lauril sulfato de sódio. Tal comportamento não foi observado na solução pura de lauril sulfato de sódio em todas as concentrações.

Lysosomal stability in Oreochromis mossambicus (Peters) on exposure to surfactants.

The three commonly used surfactants viz. anionic sodium dodecyl sulfate (SDS), cationic cetyl tri methyl ammonium bromide (CTAB) and non-ionic triton X-100 were toxic even at sub lethal levels (1 ppm for 30 days) to 0. mossambicus. Lysosomal stability index (LSI) was lowest in triton-exposed animals in vitro. In vivo, CTAB was the most toxic. SDS, the anionic surfactant was the least toxic. The possible role of surfactant structure, critical micellar concentration (CMC) and metabolism in influencing the toxicity is discussed and mechanism of action via membrane lipid peroxidation is suggested.

Surfactant-induced lipid peroxidation in a tropical euryhaline teleost Oreochromis mossambicus (Tilapia) adapted to fresh water.

Exposure to anionic (sodium dodecyl sulfate, SDS), cationic (cetyl trimethyl ammonium bromide CTAB) and non ionic (Triton X-100) surfactants at a sub lethal concentration of 1 ppm resulted in severe oxidative stress in the hepatic, renal and cardiac tissues of fresh water adapted Oreochromis mossambicus. Hepatic catalase showed significant increase (P<0.001) in all the surfactant exposed fish, but the renal enzyme was significantly increased only in CTAB dosed fish (P<0.001) and the cardiac enzyme showed significant increase in Triton (P<0.05) and CTAB dosed fish (P<0.001). SOD levels were significantly increased (P<0.001) in hepatic, renal and cardiac tissues of all the surfactant-treated fish. Glutathione reductase also was significantly increased (P<0.001) in the hepatic and renal tissues of surfactant dosed fish except cardiac tissues of CTAB exposed animals. Glutathione levels in the tissues studied were significantly higher in the surfactant treated animals (P<0.001) whereas malondialdehyde levels were significantly elevated only in the hepatic tissues of animals exposed to Triton (P<0.001). The surfactants based on their charge, antioxidant profile and in vivo metabolism may be arranged in the order of decreasing toxicity as CTAB > Triton > SDS. Thus it may be inferred from the present study that the antioxidant defenses and the in vivo metabolism of the surfactants are key factors in deciding the surfactant toxicity.