radioactivity of in ground uranium, page-2

Before the discovery of radioactivity, uranium was primarily used in small amounts for yellow glass and pottery glazes, such as uranium glass and in Fiestaware.

The discovery and isolation of radium in uranium ore (pitchblende) by Marie Curie sparked the development of uranium mining to extract the radium, which was used to make glow-in-the-dark paints for clock and aircraft dials.[14] This left a prodigious quantity of uranium as a waste product, since it takes three metric tons of uranium to extract one gram of radium. This waste product was diverted to the glazing industry, making uranium glazes very inexpensive and abundant. Besides the pottery glazes, uranium tile glazes accounted for the bulk of the use, including common bathroom and kitchen tiles which can be produced in green, yellow, mauve, black, blue, red and other colors.

Biotic and abiotic
Main article: Uranium in the environment Uranium is a naturally occurring element that can be found in low levels within all rock, soil, and water. Uranium is also the highest-numbered element to be found naturally in significant quantities on earth and is always found combined with other elements.

the above is from wikipedia......i have to say that there would be a plethora of medical papers citing that all humans beware of certain rock formations and water flows that are likely to be contaminated bu uranium in its natural state.......much like cyanide occurs in abundance yet is not the killer until compounded, concentrated and of course aimed in a specific manner......