Actinides in the environment

Elements with atomic numbers greater than 94 do not exist naturally on Earth, and must be produced in a nuclear reactor.

[2] However, certain isotopes of elements up to californium (atomic number 98) still have practical applications which take advantage of their radioactive properties.

[9] Generally, ingested insoluble actinide compounds, such as uranium dioxide and mixed oxide (MOX) fuel, will pass through the digestive tract with little effect since they have long half-lives, and cannot dissolve and be absorbed into the bloodstream.

Actinium can be found naturally in traces in uranium ore as 227Ac, an α and β emitter with half-life 21.773 years.

The residents of this area are exposed to a naturally occurring radiation dose ten times higher than the worldwide average.

It is present in almost all soils and it is more plentiful than antimony, beryllium, cadmium, gold, mercury, silver, or tungsten, and is about as abundant as arsenic or molybdenum.

Significant concentrations of uranium occur in some substances such as phosphate rock deposits, and minerals such as lignite, and monazite sands in uranium-rich ores (it is recovered commercially from these sources).

[15] However, it is relatively mobile over the long term, and diffusion of neptunium-237 in groundwater is a major issue in designing a deep geological repository for permanent storage of spent nuclear fuel.

[17] In 1999, a truck transporting 900 smoke detectors in France was reported to have caught fire; it is claimed that this led to a release of americium into the environment.

[18] In the U.S., the "Radioactive Boy Scout" David Hahn was able to buy thousands of smoke detectors at remainder prices and concentrate the americium from them.

The worst case was that of Harold McCluskey, who was exposed to an extremely high dose of americium-241 after an accident involving a glove box.

It is likely that the medical care which he was given saved his life; despite similar biodistribution and toxicity to plutonium, the two radioactive elements have different solution-state chemistries.

Chaplin et al. reported advances in the diffusive gradients in thin films technique, which have provided a method to measure labile bioavailable americium in soils, as well as in freshwater and seawater.

[23] Atmospheric curium compounds are poorly soluble in common solvents and mostly adhere to soil particles.