ACUTE CHEMICAL TOXICITY OF URANIUM

Although human experience with uranium spans more than 200 years, the LD₅₀ for acute intake in humans has not been well established. Large acute doses of uranium can produce death from chemical toxicity in rats, guinea pigs, and other small experimental animals, with variation in sensitivity among species. However, there has never been a death attributable to uranium poisoning in humans, and humans seem to be less sensitive to both acute and chronic toxic effects of uranium than other mammalian species studied. Highly relevant data on uranium toxicity in humans are available from the experience of persons administered large doses of uranium for therapy of diabetes and from acute accidental inhalation intakes. Although the data on which to establish oral and inhalation acute LD₅₀ for uranium in humans are sparse, they are adequate to conclude that the LD₅₀ for oral intake of soluble uranium compounds exceeds several grams of uranium and is at least 1.0 g for inhalation intakes. For intakes of uranium compounds of lesser solubility, acute LD₅₀ values are likely to be significantly greater. It is suggested that 5 g be provisionally considered the acute oral LD₅₀ for uranium in humans. For inhalation intakes of soluble compounds of uranium, 1.0 g of uranium is proposed as the provisional acute inhalation LD₅₀.