Actinium
Actinium is a silvery
radioactive metallic element. Actinium glows in the dark due to its intense
radioactivity with a blue light.
Actinium was
discovered in 1899 by André-Louis Debierne, a French chemist, who separated it
from pitchblende. Friedrich Otto Giesel independently discovered Actinium in
1902. The chemical behavior of Actinium is similar to that of the rare earth
Lanthanum.
The word Actinium comes from the Greek aktis,
aktinos, meaning beam or ray.
Applications
It is about
150 times as radioactive as Radium, making it valuable as a neutron
source. Otherwise it has no significant industrial applications.
Actinium-225 is used in medicine to produce Bi-213 in
a reusable generator or can be used alone as an agent for radio-immunotherapy.
Actinium in the environment
It is found
only in traces in Uranium ores as 227-Ac, an α and β emitter with a
half-life of 21.773 years. One ton of Uranium ore
contains about a tenth of a gram of Actinium. Actinium is found in trace
amounts in Uranium ore, but more commonly is made in milligram amounts
by the neutron irradiation of 226-Ra in a nuclear reactor. Actinium
metal has been prepared by the reduction of Actinium fluoride with
lithium vapor at about 1100 to 1300-degrees C.
Naturally occurring
Actinium is composed of 1 radioactive isotope; with 227-Ac being the most
abundant (100% natural abundance). 27 radioisotopes have been characterized with
the most stable being 227-Ac with a half-life of 21.773 years, 225-Ac with a
half-life of 10 days, and 226-Ac with a half-life of 29.37 hours. All of the
remaining radioactive isotopes have half-life's that are less than 10 hours and
the majority of these have half life's that are less than 1 minute. This element
also has 2 meta states.
Purified Actinium-227 comes into equilibrium with its
decay products at the end of 185 days, and then decays according to its
21.773-year half-life.
The isotopes of
Actinium range in atomic weight from 206 amu (206-Actinium) to 234 amu
(234-Actinium).
Actinium-227 is
extremely radioactive, and in terms of its potential for radiation induced
Health effects, Actinium-227 is about as dangerous as Plutonium. Ingesting even
small amounts of Actinium-227 would represent a serious health hazard.
The greatest threat of radioactivity to life as we know it is damage to
the gene pool, the genetic make-up of all living species. Genetic damage from
radiation exposure is cumulative over lifetimes and generations.
Even low-dose exposures are carcinogenic after extended
exposure. The current generation, the one in uterus, and all that follow
may suffer cancers, immune system damage, leukemia, miscarriages,
stillbirths, deformities, and fertility problems. While many of these
health problems are on the rise, individuals cannot prove either
increase in "background" radiation or specific exposure as the cause.
Only epidemiological evidence is scientifically acceptable to impute
cause. Perhaps the most extreme outcome over time would be simply the
wholesale cessation of the ability to reproduce. Radiation is a known
cause of sterility.
The development of nuclear technology has been accompanied by gross as
well as minute releases of radioactivity into the atmosphere, the soil, the
oceans, seas, and water table, showing up worldwide in animal, vegetable, and
inert matter. Radiation crosses species and concentrates through the food chain,
subjecting other animals and humans to its damaging effects.
Actinium-227
is extremely radioactive. Radioactivity damages the gene pool not only
of humans, but of all living creatures, causing
cancers, immune system damage, leukemia, miscarriages, stillbirths,
deformities, and fertility problems. Furthermore, genetic damage from
radiation exposure is cumulative over lifetimes and generations.
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