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01-25-2007 09:25 AM |
ESTIMATES OF ABUNDANCE IN EARTH'S CRUST VARY FROM 2 TO 10 PPM. NATURAL ISOTOPES: 9 (100%); RADIOACTIVE ISOTOPES (MASS NUMBERS): 6-8; 10-12. FOUND IN PHENACITE, CHRYSOBERYL PRECIOUS FORMS OF BERYL: EMERALD, AQUAMARINE. Beryllium is concentrated in silicate minerals relative to sulfides. In common crystalline rocks, the element is enriched in the feldspar minerals relative to ferromagnesium minerals and apparently replace the silicon ion; 85-95% of the total crystal beryllium may be bound in the feldspar structures. The greatest known concentrations of beryllium are found in certain pegmatite bodies, where crystals of beryl account for a few percent of the total pegmatite volume, and may be found in several of the strata of zoned dykes. The element is sometimes concentrated in hydrothermal veins, and some granitic rocks contain sufficient amounts to permit the crystallization of small amounts of beryl. CERTAIN FOSSIL FUELS CONTAIN BERYLLIUM CMPD, ACCOUNTING FOR THE PRESENCE OF BERYLLIUM IN SOME COMMUNITY AIR SAMPLES AND TISSUES OF CITY RESIDENTS. Ceramic artists can be exposed to many hazardous materials, generally related to dry clays, glazes and kiln use. Glazes can contain lead, antimony, arsenic, barium, beryllium, boron, chromium, cobalt, cadmium, copper, vanadium and other materials which all have potential toxic effects. Beryllium enters the environment principally from coal combustion. Be contents in the ashes from a Czechoslovakian power plant were determined (coarse (> 20 mm) and fine (2.0 to 0.2 mm) fraction from dump, and fine (0.2 mm) fraction from electrostatic precipitators). Acidic and alkali aqueous extracts of these ashes contained various concentrations of Be (1 to 17% of total concentrations). Wastewater showned 3.15 and 3.4 ug Be/l. Thus, secondary long term beryllium pollution emerges from the slag and ash dumps. Soil concn generally range from 0.1-40 ppm, with the average around 6 ppm. Beryllium concentrations (dry weight) of 0.08 mg/kg in polished rice, 0.12 mg/kg in toasted bread, 0.17 mg/kg in potatoes, 0.24 mg/kg in tomatoes, and 0.33 mg/kg in head lettuce. Beryllium levels (ppm in ash) for different foodstuffs were: beans, 0.01; cabbage, 0.05; hen eggs (yolk) 0.01; milk, 0.02; mushrooms, 0.12; nuts, 0.01- 0.47; tomatos, 0.02; and baker's yeast, 0.02. In birch, aspen and willow beryllium content may rise as high as 3 mg/kg. Potatoes contain 0.17 mg/kg dry substance, tomatoes 0.24 mg/kg and head lettuce 0.33 mg/kg. Beryllium in root, stem, and leaf tissues of tobacco (Nicotiana tabacum L Md-609) plants grown in McMurtrey's nutrient solution with addition of 0.3, 1.0 and 3.0 mg/l Be were determined by gas chromatography-mass spectrometric analysis using m/l 246 of beryllium trifluoroacetylacetonate chelates. The method was sensitive to about 4 pg of Be. The majority of Be was associated with tobacco roots (0.3, 1.0 and 3.0 mg/l of Be were added to the solution were associated with 374, 427 and 4280 ug Be/g dry wt of tissue, respectively; leaves were associated with 2.14, 2.36 and 81.4 ug Be/g dry wt tissue respectively. ACCORDING TO STUDIES ON COWS WITH RADIOACTIVE BERYLLIUM, LESS THAN 0.002% OF INJECTED ACTIVITY WAS RECOVERED IN MILK. BIOLOGICAL HALF-LIFE IN MILK WAS 19 HR. Beryllium level reported in milk, 0.02 ppm in ash. FOOD NOT SIGNIFICANT SOURCE OF HUMAN EXPOSURE NO EVIDENCE THAT BERYLLIUM IS MOVING FROM SOILS INTO FOOD OR FEED PLANTS IN AMOUNTS DETRIMENTAL. Humans: total body burden: 36 ug Beryllium; 24 ug Beryllium in soft tissue. Humans: Kidney; 0.2 ug beryllium/kg: liver; 1.6 ug beryllium/kg: muscle; 0.75 ug beryllium/kg: bone; 3.0 ug beryllium/kg: hair; 6.0-20.0 ug beryllium/kg Human: blood: 0.01 ug beryllium/l Humans: lung: 1x10 2 to 1x10 5 ug beryllium/l: blood: 0.02-3.0 ug beryllium/l: urine: 0.02-3.0 ug beryllium. The soft tissue burden of an adult is likely to be less than 20 ug and the skeletal burden about 30 ug.
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