Glyphosate-based herbicides with different adjuvants are more potent inhibitors of 3T3-L1 fibroblast proliferation and differentiation to adipocytes than glyphosate alone

Glyphosate-based herbicides are extensively used for weed control all over the world. Thus, it is important to investigate the putative toxic effects of these commercial formulations which contain not only glyphosate but also different adjuvants. 3T3-L1 fibroblasts are a useful tool in the study of adipocyte differentiation. We have previously reported that a commercial glyphosate formulation inhibits proliferation and differentiation in these cells. In the present investigation, we further evaluated the effect of different commercial glyphosate-based herbicides on 3T3-L1 fibroblast proliferation and differentiation and compared their effect with glyphosate itself. After treatment of 3T3-L1 fibroblasts with different concentrations of three glyphosate formulations or glyphosate itself, the increase in cell number or cytosolic lipid accumulation was determined. To evaluate the presence of polyethoxylated adjuvants, matrix-assisted laser desorption/ionization (MALDI) analysis of the three commercial glyphosate-based herbicides was also performed. We found that the three commercial formulations tested were more potent inhibitors of both physiological processes: proliferation and differentiation to adipocytes of 3T3-L1 fibroblasts than glyphosate. We also found by MALDI analysis that the adjuvants were polyethoxylated in two of the formulations but not in the third one. It is well known the toxic effect of polyethoxylated adjuvants, but according to our results, non-polyethoxylated adjuvants may also contribute to the toxic effects. Our results further support the ability of glyphosate-based herbicides to disturb cellular physiology and highlight the importance of toxicological assessment of commercial formulations rather than glyphosate alone.