Comments
In the first quarter of the 20th century, watch dial painters ingested small amounts of radium in the luminous paint. Mortality studies showed increased rates of bone-related cancers in these workers. [Sullivan, p. 757-8] There is sufficient evidence that ingestion of radium-228 causes bone sarcomas and that ingestion of radium-226 causes bone sarcomas and carcinomas of the paranasal sinuses and mastoid processes. [IARC]
Most Important Radionuclide: Ra-226
Source: Decay product of U-238 decay series;
Half-Life: 1600 years
Effective Half-Life: 44 years
Specific Activity: 1 Ci/gm
Decay Mode: Alpha
GI Absorption: 20%
Lung Clearance Half-Time: Weeks
Critical Organ: Bone
Internal Toxicity: Very High
Annual Limit on Intake: 0.0006 mCi
Radiation Energy (MeV): Alpha 4.78 (95%); Gamma 0.186 (4%) + daughters;
Radiation Accidents: Ingestion of 2 mCi of radium bromide resulted in death 4 years later; Two incidents of "Meltings of Radioactive Materials";
[See Glossary for references.] See "Radiation, ionizing."