A maximum allowable atmospheric level of a substance in workplace air averaged over an 8-hour shift.

A radioactive metallic element similar chemically to uranium that is formed as several isotopes (239-242) by decay of neptunium.

A radioactive metallic element that emits an alpha particle to form an isotope of lead.

The destruction of the cells in the initial part of the urine collecting tubes in the kidney, called the proximal tubular region. Heavy metals, such as uranium, are just one of several potential causes of proximal tubular necrosis.

The Nuclear Regulatory Commission defines public dose as the radiation dose received by a member of the public from a licensed source of radiation. The public dose does not include the occupational dose or doses from background radiation, from any medical procedures, or from voluntary participation in medical research programs.