There is evidence of some degree of toxicity of rubidium for humans. In experiences with animals, the inclusion of the element in the diet can cause neuromuscular hyperirritability symptoms and reproductive deficiencies. In extreme cases it causes violent muscular spasms or even death. By skin contact, metallic rubidium causes serious cutaneous burns, in spite of the fact that most of its compounds only slightly irritate the skin. The most toxic rubidium compounds are the fluoride, the hydroxide and the cyanide.