A recent letter to the U-B advocated the use of DDT for mosquito control. It claimed using DDT would save millions of lives worldwide by reducing malaria.
It stated that in 1971 an EPA judge concluded that DDT was not a hazard to man and does not have deleterious effects on fish, other aquatic life or wildlife. Nonetheless, the EPA banned its use in the U.S. in 1972.
I Googled the effects of DDT on birds. Over 440,000 articles were identified. A few indicated that DDT was not harmful, but the majority implicated DDT in the decline of many predatory birds including eagles, hawks, pelicans, and fish-eating birds. While direct mortality was not found, it was shown that DDT and other chlorinated hydrocarbon pesticides affected reproduction — most notably egg shell thinning. As a result, populations declined and many species were listed as threatened or endangered.
With reduced use of such pesticides, populations of predaceous birds have rebounded so well that now terns, cormorants, gulls, pelicans, and other fish-eating birds eat 10s of millions of juvenile Columbia River salmon. Other links showed DDT caused direct death of some types of fish, affected reproduction of others, and killed aquatic organisms like crayfish, aquatic insects and shrimp without which fish would starve.
The U.S. was not the first country to ban DDT. European nations banned it from the 1960s through the 1980s.
However, DDT is still produced and used by many Third World countries. DDT can take up to 30 years to break down, and then it becomes DDE which is equally toxic in the environment. Even if we no longer use such pesticides, they are still in our environment and we take them into our bodies.
NOAA Fisheries and the EPA recently banned more pesticides because they affect the immune systems and reproduction of salmon. Given new studies about the delayed effects of pesticides, antibiotics and other chemicals developed to solve disease or pest problems, we should not be hasty in removing bans on DDT or other harmful chemicals.
We all have DDT stored in our fat, and contrary to the author’s claim, it has been implicated in human health issues — namely diabetes. In addition to adverse effects in our environment, levels that cause problems in humans are often low or unknown so I am not anxious to add to them by reinstituting use of harmful chemicals like DDT.