Dear Henry --

Last weekend I was fortunate enough to spend time at the beach in Dana Point.  One of the pleasures I experienced was watching the beautiful pelicans that now appear in increasing numbers on our coastal areas.  When I moved here from New York in 1973, these birds were on the verge of extinction, but their resurgence is one of the major success stories of our efforts to clean our environment of toxic chemicals.  In this case, the culprit was the infamous DDT, an insecticide that was used extensively by the agricultural interests in our state to prevent damage to the crops.  The DDT permeated its way through the food chain where it eventually was washed out into the ocean and wound up contaminating the fish that provided the diet for the pelicans.  As the DDT levels in the birds rose it effected them in a very unique way.  They didn't die from damage to their internal organs.  What happened was a failure to be able to reproduce due to the ability of the DDT to selectively combine with the calcium in their bodies thus making this critical element unavailable to be incorporated into the shells of their eggs. 

The net result of the calcium deprivation was that the shells lacked the strength to literally support the weight of the nesting mothers, thus causing the eggs to crack open, which resulted in the death of the embryonic birds.  DDT was banned from use in the early 1970s and within a few years, biologists were starting to note that more and more eggs were being hatched to completion and that the egg shells were more durable.  It was then that the relationship between the chelating effects of DDT binding the calcium and making it unavailable for use in egg shell formation was realized.  Today these birds are off the endangered species lists and are thriving.

The principle of chelation also has its positive sides.  A common anti-coagulant, EDTA, is used in the little purple-topped tubes that blood is collected in prior to its analysis at the laboratory.  Calcium is an element that facilitates the clotting process but the EDTA binds to it and makes it unavailable for this purpose and allows the blood to remain in a liquid state.  What is even more amazing, is the fact that the same EDTA is used as the primary treatment for lead poisoning.  As much as the EDTA likes to combine with calcium, it has an even greater affinity for combining with lead.  When a patient is diagnosed with lead poisoning, calcium EDTA is administered, whereupon the calcium is jettisoned by the EDTA in favor of its more attractive partner, the offending lead.  The lead EDTA combination is than harmlessly excreted via the urinary tract.

Chelation!  Who knew?