Uranium: active even at low doses

The human body, in normal conditions, contains 40 to 90 10-6 grams of uranium, this quantity is mainly stored in the bones (66%), in the kidneys (8%) and in soft tissues. Man daily absorbs between 1 to 3 10-6 grams of uranium. A recent experiment on rats has showed that water contaminated with low quantities of uranium (10-6 grams a day and per rat) can lead to short-term memory impairment, to higher level of anxiety and to a 38% increase of the paradoxal sleep. No toxic effects on liver and kidneys have been found but it has been showed that low quantities of uranium can entail changes, in some organs, concerning the expression of the genes coding the P450 cytochromes. (A.C.)