srs, without getting too deep into geochemistry, I'll first say that your point about salts is a good one from the standpoint that it points out an important distinction, and that is the difference between naturally occurring "minerals" and "man made carcinogenic compounds". Salts don't "break down" into different compounds like man-made products, but are a problem in water. In water, salts change to different ionic states and dissolve to lower concentrations. Then when the water is evaporated, salts are re-concentrated and appear as solids. Salts, like other substances, don't just disappear, they change forms. Salts can also accumulate in blood and effect kidney functions and raise blood pressure. Aquatic organism are just as, if not more sensitive to, salt cancentrations as humans. But man-made petroleum distillates such as TCE (trichloroethylene) are a completely different class of pollutants. First, they are man-made compounds, which in the environment break down into "daughter products". TCE and the daughter products are all cancer causing. Second, these compounds can "bioaccumulate". Which addresses your comment about how can a little WD-40 hurt. It's not that a little can hurt, it's all about 250 million people in our country, and major industries, all saying "oh, a little bit can hurt". TCE accumulates in the environment, and in the blood, and effects the central nervous system, liver, kidney functions, and can cause cancer. I can hardly pick up a water quality analysis any more without seeing some level of man made compound present. And not just in water collected from industrial sites. I mean in water from place you would think should have really nice clean water. All it takes is just one person deciding to empty a little left over something along side the road or in the back yard and bam, it's there, for decades. If we all just go on saying a little bit won't hurt, it will hurt.
