chemical addition(Chemical reaction in which one or more of the double bonds or triple bonds in an unsaturated compound is converted to a single bond by the addition of other atoms or groups)
addition polymer(A polymer formed by the chain addition of unsaturated monomer molecules, such as olefins, with one another without the formation of a by-product, as water; examples are polyethylene, polypropylene and polystyrene)
acceptable daily intake(The measurement of the amount of any chemical substance that can be safely consumed by a human being in a day. Calculations are usually based on the maximum level of a substance that can be fed to animals without producing any harmful effects. This is divided by a "safety factor" to allow for the differences between animals and humans and to take account of the variation in human diets)
adsorption(The physical or chemical bonding of molecules of gas, liquid or a dissolved substance to the external surface of a solid or the internal surface, if the material is porous, in a very thin layer)