ABSTRACT
A second important characteristic in determining the degree of toxicity a chemical will produce is how well it dissolves in different solvents. In particular, compounds are divided into those that are soluble in waterlike (or polar) solvents and those that are soluble in fat-(oily)-like (or nonpolar) solvents. This difference is very important in determining how easily a chemical can enter the body, how it is distributed inside the body, and how easily it can be excreted. An example of a polar compound (one which dissolves in polar solvents) is table salt. An example of a nonpolar compound (one which dissolves in nonpolar solvents) is DDT. Since the human body is most efficient at excreting polar compounds, there are chemicals in the body that are designed to convert foreign nonpolar compounds into polar variants so that they can be removed from the body. Unfortunately, they cannot alter the characteristics of all nonpolar compounds, and so some, like DDT, are difficult to excrete and can remain in the body for long periods of time. Briefly put, this one difference in character-polarity or nonpolarity-can have a very significant impact on the toxicity of a particular chemical.
