http://www.scorecard.org/chemical-pr...ml/cobalt.html :
Quote:
Cobalt is found in the earth's crust at 0.001-0.002 percent and is found in cobalite, linnacite, smaltite, and erythrite (Merck, 1989). It is a by-product from nickel, copper, silver, lead, and iron ore refining. Green, leafy vegetables may contain concentrations as great as 0.5 milligrams per kilogram of dry weight (HSDB, 1991).
(Note: that's milligrams, not micrograms.)
http://www.coloradomining.org/materials.html :
Quote:
How might people be exposed to cobalt?
People are commonly exposed to small amounts of cobalt naturally present in the air they breathe, the water they drink, and the foods they eat. For example, leafy green vegetables are a natural source of cobalt in people’s diets. Industrial workers may breathe cobalt dust or fumes, or touch substances that contain cobalt.
http://www.thecdi.com/cdi/images/doc...nal%20food.pdf :
Quote:
What foods in Cobalt found in?
Research suggests that the top three food groups for Co in the human diet are: milk and dairy
products, which account for approximately 32% of the total Co intake; fish and crustaceans,
which account for approximately 20%, and condiments, sugar and oils, which account for
about 16%. One investigation of specific foods (Leblanc et al., 2004) found that chocolate
contains the highest level of Co, with molluscs and crustaceans, and dried fruit and nuts also
containing the high levels in comparison to other foods.
http://www.britannica.com/eb/article-1376 :
Quote:
Cobalt, though widely dispersed, makes up only 0.001 percent of the Earth's crust. It is found in small quantities in terrestrial and meteoritic native nickel-iron, in the Sun and stellar atmospheres, and combined with other elements in natural waters, in nodules beneath the oceans, in soils, in plants and animals, and in such minerals as cobaltite, linnaeite, skutterudite, smaltite, heterogenite, and erythrite. Traces of cobalt are present in many ores of iron, nickel, copper, silver, manganese, zinc, and arsenic, from which it is often recovered as a by-product.
http://www.championtrees.org/yarrow/tob12.htm :
Quote:
Mark Mead reports Mn, like nickel, forms B12 analogue, and is causing widespread soil depletion of cobalt.
From Vitamin B12 and cobalt
Quote:
THE B12-COBALT CONNECTION
by Mark Mead & John Mann
reprinted from SOLSTICE magazine #34, Feb. '90
B12 is the only vitamin synthesized solely by certain
microorganisms -- many of which are abundant in soil. And the only
vitamin containing a trace element: cobalt. B12 owes its chemical
name -- cobalamin -- to the cobalt at the center of its molecular
structure. Humans and all vertebrates require cobalt, though it's
assimilated only in the form of B12.
Cobalt is important in the plant world. Bacteria on root nodules
of legumes (beans, alfalfa, clover) require cobalt (and other trace
elements) to synthesize B12 and fix nitrogen from air. Soybeans grown
without cobalt are severely retarded in growth and exhibit severe
nitrogen deficiency, leading to death in about one of four plants.
Adding only a few ounces of cobalt per acre can resolve deficiency
symptoms in ten to 21 days.
Cobalt deficiency is far more dramatic in animals, particularly
ruminants (cattle, deer, camels, and sheep) grazing on deficient
pasture. These animals obtain all their B12 from their gut bacteria,
but only if bacteria are provided cobalt salts from pasture. Legumes
with less than 80 parts per billion (ppb) cobalt can't meet ruminant
B12 needs. Under deficient conditions, calves and lambs thrive and
grow normally for a few months as they draw on B12 reserves in liver
and other tissue, but soon exhibit gradual loss of appetite and
failure to grow, followed by anemia, rapid weight loss and finally
death. Marginally deficient pastures cause birth of weak lambs and
calves that don't survive long. These symptoms mirror B12 deficiency
in human infants.
To prevent or alleviate cobalt-B12 deficiency, farmers routinely
add cobalt to animal feeds or salt licks. Some fertilize pastures
with cobalt-enriched fertilizers; others opt for periodic quick- fix
B12 injections. With any of these measures, all symptoms are reversed
and B12 in milk and colostrum dramatically increases.
The implication for humans subsisting on vegetarian diets are
profound. B12 synthesis by indigenous bacteria is known to occur
naturally in the human small intestine, primary site of B12
absorption. As long as gut bacteria have cobalt and certain other
nutrients, they produce B12. In principle then, internal B12
synthesis could fufill our needs without any B12 provided by diet.
But if cobalt in our diet is on the wane, perhaps the problem
isn't so much lack of B12-synthesizing intestinal flora as lack of
cobalt, the element with which bacteria weave their magic. The
burning question then is: how cobalt deficient is our soil?
Stalking the Wild Cobalt
Investigating soil-cobalt links, we sought perspectives of two
researchers: an expert in agricultural chemistry, another in
nutrition.
Dan Reeter, chief researcher at Bio-Systems Labs in Salida, CO,
is creating one of the world's most comprehensive computer facilities
for soil biology testing. Reeter, whose lab has served agricultural
industry for over 40 years, told us:
"I can say with certainty there's a decline of soil cobalt.
Confirm this for yourself. Simply to pick any Ag magazine -- they all
push cobalt supplements, spurred by B12-poor condition of crops."
Reeter said soil bacteria, comprising 20 percent of soil biomass,
is destroyed or inactivated by ag chemicals, inhibiting uptake and
metabolism of cobalt and other trace elements. Reeter directly traces
this problem to increasing presence and proportion of B12 analogues
("false" B12). Reeter reports his extensive tests at Bio-Systems
demonstrate plants grown in organically managed soil make
significantly higher levels of usable B12.
Robert Kay, PhD candidate in nutrition at the Univ. of
Connecticut, emphasized uncertainties in B12 research, especially in
light of new methods to measure B12 and new insights these methods
made available. He also cautioned categorization of "true" vs.
"false" B12 may be too absolute. "We no longer talk about simply
TB12,' since we now know there's many varieties of cobalamins with
varied biological action (i.e., availability). There is no 'gold
standard' in this area."