Introduction. Glyphosate is a broad-spectrum, non-selective herbicide and commonly used to eliminate weeds in agricultural and forest settings. Studies evaluating glyphosate toxicity in animals and environment show that commercial formulations of glyphosate are more toxic than the active component itself.Objectives. Technical grade glyphosate was compared with the commercial formulation Roundup® in their respective toxicities on human peripheral blood mononuclear cells. Materials and methods. Human peripheral blood mononuclear cells were exposed to different concentrations of glyphosate, either technical grade or in the form of Roundup for 24 h, 48 h, 72 h, and 96 h. Cytotoxicity was assayed by trypan blue dye exclusion method and reduction of (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2Htetrazolium-5-carboxyanilide inner salt) XTT reagent.Results. Both technical grade glyphosate and Roundup® formulation were toxic to human peripheral blood mononuclear cells. Cytotoxicity of Roundup® was higher than cytotoxicity of glyphosate, since the LC50 (50% lethal concentration) determined by the trypan blue exclusio nmethod at 24 h was the equivalent of 56.4 μg/ml of glyphosate in the form of Roundup® and 1,640 μg/ml (1.64 mg/ml) for technical grade glyphosate.Conclusions. This in vitro study confirmed the toxic effects on human cells by glyphosate and its commercial preparations. Commercial formulations were more cytotoxic than the active component alone, supporting the concept that additives in commercial formulations play a role in the toxicity attributed to glyphosate-based herbicides.Introducción. El glifosato es un herbicida de amplio espectro, no selectivo, utilizado comúnmente en agricultura para eliminar malezas. Los estudios que han evaluado la toxicidad del glifosato en animales y en ambiente muestran que las formulaciones comerciales son más tóxicas que el componente activo
