One EU equals approximately 0.1 to 0.2 ng endotoxin/mL of solution. Due to the serious risks associated with endotoxin contamination, the US Food and Drug Administration (FDA) has set limits on concentration of endotoxin for medical devices and parenteral drugs that researchers should be aware of. - See more at: http://www.sigmaaldrich.com/life-science/stem-cell-biology/3d-stem-cell-culture/learning-center/what-is-endotoxin.html#sthash.Ah4ZOkRv.dpuf