Aluminum food chain

Some metals used as metallic coatings are considered nontoxic, such as aluminum, magnesium, iron, tin, indium, molybdenum, tungsten, titanium, tantalum, niobium, bismuth, and the precious metals such as gold, platinum, rhodium, and palladium. However, some of the most important poUutants are metallic contaminants of these metals. Metals that can be bioconcentrated to harmful levels, especially in predators at the top of the food chain, such as mercury, cadmium, and lead are especially problematic. Other metals such as silver, copper, nickel, zinc, and chromium in the hexavalent oxidation state are highly toxic to aquatic Hfe (37,57—60). 

The movement of fluoride through the atmosphere and into a food chain illustrates an air-water interaction at the local scale (<100 km) (3). Industrial sources of fluoride include phosphate fertilizer, aluminum, and glass manufacturing plants. Domestic livestock in the vicinity of substantial fluoride sources are exposed to fluoride by ingestion of forage crops. Fluoride released into the air by industry is deposited and accumulated in vegetation. Its concentration is sufficient to cause damage to the teeth and bone structure of the animals that consume the crops. 

The soils of humid regions are commonly low in calcium thus, ground limestone usually is applied tu add the clement, reduce the toxicity uf aluminum and manganese, and correct soil acidity. The soils of dry areas are frequently rich in calcium. There is little evidence to indicate a strung relationship between human nutrition and calcium excesses or deficiencies in the soil. Even wiih farm livestock, most calcium deficiencies are not related to levels of av ailable calcium in the sail. The reason for this anomaly is evident when one examines some of the controls over the movement of calcium in Ihe food chain. 

Transfer coefficients of 0.0002 (kg-day)"1 for uptake into milk and 0.0015 (kg-day) 1 for uptake into beef tissue have been reported (Baes et al. 1984). The transfer coefficients represent the fraction of daily aluminum intake in feed that is transferred to a kilogram of milk or beef muscle. Based upon the above values, aluminum is not transferred to beef muscle or milk from feed to any appreciable extent and therefore would not be expected to bioaccumulate in terrestrial food chains. 

Jackson ML, Huang PM. 1983. Aluminum of acid soils in the food chain and senility. Sci Total Environ 28 269-276. 

The increasing content of fluorides and aluminum in food chains has raised the possibility that the near future will supply us with much more data about the neurotoxic effects of aluminum plus fluoride on humans. 

Recently, we can witness many discussions about the benefits and risks of the fluoride supplementation. Also the question of aluminum toxicity in men has been discussed. The understanding of the mechanisms of their synergistic action could allow us to explain numerous observations about the effects of increased load of fluoride and aluminum in the environment and to reevaluate their widespread use. Understanding the role of phosphate and G-proteins in cell signaling forces us to accept the fact that aluminum in the environment, water, and food chains followed by fluoride ions could evoke various and multiple pathological symptoms. 

Selenium enters the food chain mainly as selenomethionine from plants that take the element up from the soil but do not appear to use it. The soil content of selenium is highly variable and can be low in volcanic soils when soluble salts are leached out by ground water. Soils in parts of China and New Zealand are particularly low in selenium. Acid soils, where insoluble selenium complexes can be formed with iron and aluminum, occur in some parts of Europe, resulting in low available soil selenium. The geographical source of plant and animal foodstuffs determines the level of dietary intake. In the United States and Canada, wheat and other cereal products are a good source of selenium average intakes in North America range from 80 to 220 fig Se per day, whereas in the UK dietary intake is about 30 to 60 Llg/day. Intakes in China are as low as 11 lg/day and in New Zealand 28 fig/day. ... 

Some epidemiological studies report data from populations exposed to selenium in the food chain in areas with high selenium levels in soil. It is likely that selenite, selenate, and the selenium found in food and in dietary supplements comprise the majority of selenium compounds to which oral, off-site selenium exposures will occur at or near hazardous waste sites. Aside from the variation in effective dose, the health effects from exposure to selenate, selenite, and dietary selenium are not expected to differ greatly. However, oral exposures to many other compounds of selenium could occur (primarily through soil or edible plant ingestion) if those compounds were deposited at the site, or if local environmental conditions greatly favor transformation to those forms. Heavy metal selenides, aluminum selenide, tungsten diselenides, and cadmium selenide are used in industry and may end up in waste sites. 

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