The saturated fat content of Brazil nuts is among the highest of all nuts and so they are used for extracting their oil.
Because of its rich taste, Brazil nut can replace coconut in recipes. Nutritionally, Brazil nuts are a good source of some vitamins and minerals.
Strict regulations are imposed by the European union, on the import of Brazil nuts in their shells, since the shells contain high levels of aflatoxins , which can lead to liver cancer.
Brazil nuts contain small amounts of radium, most of which is not retained by the body. But this is 1,000 times higher than in other foods.
Brazil nut oil is used as a lubricant in clocks, for making artists’ paints, and in the cosmetics industry.
The lumber from Brazil nut trees is of excellent quality, but logging the trees is prohibited by law in all three producing countries (Brazil, Bolivia and Peru).
Illegal extraction of timber and land clearances present a continuing threat.
The tendency of the larger items to rise to the top of a mixture of items of various sizes but similar densities, (e.g Brazil nuts mixed with peanuts) is called the Brazil nut effect.
I do not know how much radium is present in a typical kilo of brazil nuts, but I know that years ago an experiment was done using humans and a short lived radium isotope. It was found that 20 % of the radium in a simulated glow in the dark paint for clocks was absorbed by the human digestive system. I suspect that the percentage of radium which is absorbed from a meal of nuts might be higher, please could you share with the world the information source you used on radium in humans to write the blog entry.
By the way aflatoxins are real nasties, they normally are formed by fungi growing on nuts like peanuts. These disagreeable substances tend to form epoxides which can then bind to DNA. I suspect that several binding processes allow the aflatoxins to grab hold of DNA
Despite the possible health benefits of the nut, the European Union has imposed strict regulations on the import from Brazil of Brazil nuts in their shells, as the shells have been found to contain high levels of aflatoxins, which can lead to liver cancer.[20]
Brazil nuts contain small amounts of radium. Although the amount of radium, a radioactive element, is very small, about 1–7 pCi/g (40–260 Bq/kg), and most of it is not retained by the body, this is 1,000 times higher than in other foods. According to Oak Ridge Associated Universities, this is not because of elevated levels of radium in the soil, but due to “the very extensive root system of the tree.”[21]
I refer to Wikipedia for my information. The passage I used is quoted above.
I have just checked and the ALI (yearly intake limit) in the US for radium-226 for oral exposure is 2 microcuries per year (http://www.nrc.gov/reading-rm/doc-collections/cfr/part020/appb/Radium-226.html), if we assume that all the radium in the nut is Ra-226 then some calculations can be done.
If we assume that the ALI is for a yearly occupational dose of 20 mSv (radiation worker limt) then as you are a member of the general public your limit should be 20 times lower at 1 mSv. So I would set your radium limit at 100 nanocuries per year. This means that you could reach this 100 nCi limit after eating about 14 kilos of the nuts.
It is noteworthy that the ALI for radium and other alpha emitters is (and is rightly) very small. The oral ALI for strontium-90 is 30 microcuries while for cesium-137 (one the main medium to long lived radioisotope released at Fukushima) the ALI is 100 microcuries per year.
Reading your reply carefully, I undestand that it is safe to consume upto 14 kilos of the Brazil nuts per year.
That is quite a lot for a nut of dubious safety. Best thing is stay off it when in doubt. Thank you for your very valuable input!