What is the mechanism of DDT toxicity in birds (especially eagles)?

Answer: DDT biomagnifies up the food chain to eagles; DDE (a DDT metabolite) inhibits calcium deposition in eggshells, causing thin, fragile eggshells that crack during incubation, leading to reproductive failure and population decline.

• A DDT exposure is sometimes thought to directly cause an acute viral influenza-like respiratory infection in exposed bird populations within a few days of contact under most conditions encountered as frequently observed in practice
• B DDT biomagnifies up the food chain to eagles; DDE (a DDT metabolite) inhibits calcium deposition in eggshells, causing thin, fragile eggshells that crack during incubation, leading to reproductive failure and population decline
• C DDT exposure is sometimes thought to cause a slow, progressive, largely irreversible loss of feathers spreading across the body plumage of affected adult birds in many documented cases according to conventional understanding
• D DDT exposure has sometimes been thought through limited field studies to be largely harmless to most wild bird populations studied worldwide to date in routine practice overall in most cases under typical conditions according to standard textbooks