This article focuses on the risks of nanomaterials and nanotechnologies, and the challenges they pose to European consumer law. These risks are exemplary for the sociological phenomenon of modern risk society, living under the condition of uncertainty with regard to the likelihood and the extent of possible negative effects. Generally, in law important functions in risk societies are fulfilled by the precautionary principle. It serves both, as a justification for state measures vis-a-vis other legal interests, especially economic human rights, and as a request for state action in response to possible risks. This paper will argue that the precautionary principle applies at least to health protection as a core part of consumer protection and basically EU law is well equipped to deal with uncertainties. This is established in case law and practice. However, although there is pressure to apply the precautionary principle to nanomaterials and nanotechnologies, the European Commission has adopted a rather modest approach. That has been criticized especially by the European Parliament. For dealing with the gap in basic research and methodology, this article suggests a burden sharing in financing taking into account both, the precautionary principle and the principle of proportionality.