Radium [Ra, 88]
255
Dust samples collected from the air of New York City contained 226 Ra at 8 × 10 −5
and 228 Ra at 1.5 × 10 −4  pCi/m 3 (ATSDR 2002b).
People who work at factories that process U ores or work with P fertilizers are
exposed to higher levels of Ra radionuclides in ambient air.
35.5 PLANTS
The content of Ra in plants is roughly estimated to be 0.03–1.6 ng/kg. It is relatively
easily available to plants and is also easily moved from roots to shoots. Soil properties,
especially cation-exchange capacity and SOM, control its bioavailability. The order
of plants’ capability to take up Ra from soils is as follows: leafy vegetables > root
vegetables > grasses > corn stems > grains. The mean value of the transfer factor of
Ra (ratio of plant content to soil content) is estimated to be 6.4 × 10 −3 , being lowest
for potato and highest for green leek (Uchida and Tagami vide Kabata-Pendias 2011).
The same authors reported that 226 Ra contents in food plants vary from <0.02 Bq/kg
in barley grains to 1.43 Bq/kg in carrot roots. Vegetables collected in Poland (during
1991–1996) contain this radionuclide from 0.087 in cucumber to 0.594 Bq/kg in carrot, respectively (Rosiak and Pietrzak-Flis vide Kabata-Pendias 2011).
35.6 HUMANS
Radium can be taken into the human body by eating food, drinking water, or breathing air. It is not known if it can be taken in through the skin. Most of Ra is taken in
by ingestion (about 80%) and will promptly leave the body in feces. Its remaining
20% enters the bloodstream and is carried to all parts of the body. Inhaled Ra can
remain in the lungs for several months and will gradually enter the bloodstream and
be carried to all parts of the body, especially the bones.
The metabolic behavior of Ra in the body is similar to that of Ca. For this reason, an appreciable fraction is preferentially deposited in the bones and teethes. Its
amount in the bones decreases with time from the exposure, generally dropping
below 10% in a few months, to 1% and less in few years. Release from the bone is
slow, so a portion of inhaled and ingested Ra will remain in the bones throughout a
person’s lifetime. Although ingestion is the most common means of Ra entry into the
body, risk coefficients for that exposure route are lower than for inhalation (Argonne
2007).
Radium has been shown to cause adverse health effects, such as anemia, cataracts, fractured teeth, cancer, and death. The relationship between the amount of
Ra that the man is exposed to and the amount of time necessary to produce these
effects is not known. Although there is some uncertainty as to how much exposure
to Ra increases chances of developing a harmful health effect, the greater the total
amount of exposure to Ra, the more likely to develop one of these diseases (ATSDR
1990a).
Radium is currently used in brachytherapy to treat various types of cancer.
Brachytherapy is a method of radiation treatment, in which sealed sources are used
to deliver a radiation dose, at a distance of up to a few centimeters, by surface, intracavitary, or interstitial application (Argonne 2007).