Aluminum is a trivalent cation found in its ionic form in most kinds of animal and plant tissues and in natural waters everywhere. It is the third most prevalent element and the most abundant metal in the earth's crust, representing approximately 8% of total mineral components. Due to its reactivity, aluminum in nature is found only in combination with other elements.
The amount of aluminum in the human body ranges between 50 and 150 mg., with an average of about 65 mg. Most of this mineral is found in the lungs, brain, kidneys, liver, and thyroid. Our daily intake of aluminum may range from 10-110 mg., but the body will eliminate most of this in the feces and urine and some in the sweat. With decreased kidney function, more aluminum will be stored, particularly in the bones.
For most people, the greatest aluminum intake comes from food additives. Sodium aluminum phosphate is an emulsifier in processed cheese, potassium alum is used to whiten flour, and sodium silicoaluminate and/or aluminum calcium silicate are added to common table salt to help it run freely and not cake. In the average diet, 40-50 mg. a day may come from foods.
With use of aluminum pots and pans and aluminum foil, some aluminum leaches into food, especially with acid foods such as tomatoes or rhubarb. Cooking with fluoridated water in aluminum cookware increases the aluminum in the water and the food; still, the amounts we obtain in this manner are small in comparison with those from additives. Aluminum salts used in antiperspirants are not a major contaminant either, unless these products are overused. (Aerosol sprays, however, should be avoided for environmental toxicity reasons.) Antacids containing aluminum hydroxide can be a big source if they are taken regularly or abused, as antacids sometimes are. Some children’s aspirins have been found to contain aluminum as well.
Most studies on Al toxicity are performed with different media composition, Al concentration, and period of exposure. Also, there is a large variation between genotypes. This battery of nonharmonized experimental data needs caution during interpretation, mostly concerning generalizations of functional models. So, it would be important to uniform the experimental procedures in order to better comprehend the plant response to Al exposure and the mechanisms of Al tolerance.