[ RadSafe ] "Science" reports (again) on background radiation and health

[Muckerheide, James]

Friends,

 

An essay on 'medical geology' in the current Science magazine includes the
following section.  The article is at:

http://www.sciencemag.org/cgi/content/full/309/5736/883 

 

Let me know if you need the PDF for review.

 

Please consider writing a letter to Science stating that better health at
high background levels is not a 'paradox' but is consistent with the
voluminous evidence  that low doses of radiation are essential to biological
functions and supplemental radiation above the lowest levels of natural
background enhance immunological and other functions to enhance health and
longevity.

 

Regards, Jim Muckerheide

===================

 

The Radiation Paradox
Natural radioactivity on Earth has been in existence since the planet formed,
and there are about 60 radionuclides present in nature. These are found in
air, water, soil, rocks and minerals, and food. About 82% of this
environmental radiation is from natural sources, the largest of which is
radon. 

Some areas of the world, called high background radiation areas (HBRAs), have
anomalously high levels of background radiation. In such terrains, the
geology and geochemistry of the rocks and minerals have the greatest
influence in determining where the high natural radiation shows up. Extreme
HBRAs are found in Guarapari (Brazil), southwest France, Ramsar (Iran), parts
of China, and the Kerala coast (India). Of these, most are found in tropical,
arid, and semiarid areas. In certain beaches in Brazil, monazite sand
deposits are abundant. The external radiation levels on these black beach
sands range up to 5 mrad/hour, which is nearly 400 times the normal
background level in the United States. The Brazilian coastal sands have
several radioactive minerals, among them monazite, zircon, thorianite, and
niobate-tantalate, as well as nonradioactive minerals, including ilmenite,
rutile, pyrochlore, and cassiterite. 

In India, along the 570-km-long coastline of Kerala, there are major deposits
of monazite-rich mineral sands with very high natural radiation. The monazite
deposits are larger than those in Brazil, and the dose from external
radiation is, on average, similar to those reported in Brazil.

 

Ramsar, a city in northern Iran, has one of the highest natural-radiation
levels in the world. In some locations at Ramsar, the radiation level is 55
to 200 times higher than the background level. Exposures as high as 260
mGy/year have been recorded in Ramsar. The unit of ionizing radiation here,
grays per year, corresponds to 1 J of energy imparted to 1 kg of tissue (the
milligray, mGy, which is one-thousandth of a gray, is more commonly used).
Whole-body exposure to a uniform dose of 3 to 5 Gy would kill 50% of those
exposed within 1 or 2 months. 

The most interesting feature in all these cases is that the people living in
these HBRAs do not appear to suffer any adverse health effects as a result of
their high exposures to radiation. On the contrary, in some cases the
individuals living in these HBRAs appear to be even healthier and to live
longer than those living in control areas that are not classified as HBRAs.
These phenomena pose many intriguing questions for medical geologists.