[ RadSafe ] Re: "Science" reports on background radiation and health

[Maury Siskel]

Many Radsafe readers would find the linked article in Science an 
intriguing account. But I agree that when you come to the section about 
"The Radiation Paradox", your ears will stand up -- Dog's did when I 
read it to him. <g>
Cheers,
Maury&Dog

====================
Muckerheide, James wrote:

> 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.
>