The wonders of science

Imagine if you will your small son or daughter under the age of five dies from an insect borne disease. Whether the disease be typhus, malaria, or some other disease. The use of a pesticide DDT could have prevented it. It is believed that malaria afflicts between 300 and 500 million every year, causing up to 2.7 million deaths annually, mainly among children under five years. Mothers and fathers grieve. These deaths occur predominantly in Third World countries. They're people of color so maybe it matters less. Here the United States we have alternative methods of vector control. We send mosquito nets to Third World countries. The Nets don't seem to be enough do they? DDT was banned worldwide based largely on the alarm sounded by Rachel Carson in her book Silent Spring. Eagle eggs with thinning shells were blamed on the use of DDT and its metabolites DDD and DDE.

I will list a few of the findings from half a dozen or so different research efforts. The totality of the hundred plus studies clearly shows the DDT was not the cause of the Eagles malaise. Research was done on both humans, primates, and a variety of bird types. All were dosed in amounts varying from hundreds to in the case of primates more than 33,000 times the average daily human exposure. Many experiments on caged birds demonstrates the DDT and its metabolites do not cause serious egg shell thinning even at levels many hundreds of times greater than wild birds would ever accumulate. A myriad of other explanations for the egg shell thinning were identified. Lead has been associated with egg shell thinning. Mercury, stress from noise, fear or excitement and disease are all associated with egg shell thinning. Older birds produce thinner shells. Dehydration is associated with thinning in shells. Temperature extremes are associated with thinner eggshells. Decreased illumination is associated with thinner eggshells. Normal egg shells become 5% thinner as developing embryos withdraw calcium for bone development. Larger birds tend to produce thicker shelled eggs. Predator intrusion is associated with thinner egg shells. Phosphorus or calcium deficiency is associated with thinning shells.

Here's a couple more quick facts. Bald Eagles were reportedly threatened with extinction in 1921, 25 years before widespread use of DDT. Alaska paid over $100,000 in bounties for 115,000 bald eagles between 1917 and 1942. The bald eagle had vanished from New England by 1937. After 15 years of heavy and widespread usage of DDT, Audubon Society ornithologist counted 25% more eagles per observer in 1960 than during the pre-DDT 1941 bird census.

As stated earlier I have a complete compilation of studies done on DDT and its risk to humans and wildlife. I only scratched the surface of available information. It should be enough to make readers questioned certain claims. Hopefully it reminds us when someone sounds the alarm we need to ensure the evidence supports the claim. If not look at the harm that can be done.

A. C. Smithson