Dichlorodiphenyldichloroethylene

Toxicity

DDE has been shown to be toxic to rats at 79.6 mg/kg. DDE and its parent, DDT, are reproductive toxicants for certain birds species, and major reasons for the decline of the bald eagle, brown pelican peregrine falcon, and osprey. These compounds cause egg shell thinning in susceptible species, which leads to the birds' crushing their eggs instead of incubating them, due to the latter's lack of resistance. Birds of prey, waterfowl, and song birds are more susceptible to eggshell thinning than chickens and related species, and DDE appears to be more potent than DDT.

Research shows that an elevated blood levels of DDEs (also of other toxic molecule from nonstick cookware, and fire retardants) have been tied to an increased risk for celiac disease in young people. DDE has also been shown to be present in increased concentrations in the tumors of patients with primary hyperparathyroidism.

Mechanism

The biological mechanism for the thinning is not entirely known, but it is believed that p,p'-DDE impairs the hen's gland's ability to excrete calcium carbonate onto the developing egg. Multiple mechanisms may be at work, or different mechanisms may operate in different species. Some studies have shown that although DDE levels have fallen dramatically, eggshell thickness remains 10–12 percent thinner than before DDT was first used.

Some studies have indicated that DDE is an endocrine disruptor. However, human exposure to DDE is not associated with breast cancer. What is more clear is that DDE is a weak androgen receptor antagonist and can produce male genital tract abnormalities.