Dichlorodiphenyldichloroethylene
Encyclopedia
Dichlorodiphenyldichloroethylene (DDE) is a chemical compound
formed by the loss of hydrogen chloride
(dehydrohalogenation
) from DDT
, of which it is one of the more common breakdown products. DDE is fat soluble which tends to build up in the fat of animals. Due to its stability in fat, DDE is rarely excreted from the body, and body levels tend to increase throughout life. The major exception is the excretion of DDE in breast milk, which delivers a substantial portion of the mother's DDE burden to the young animal or child.
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.
The biological mechanism for the thinning is not entirely known, but it is believed that p,p'-DDE impairs the shell 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
and contributes to breast cancer
, but more recent studies provide strong evidence that there is no relationship between DDE exposure and breast cancer. What is more clear is that DDE is a weak antiandrogen.
Animal studies show that organochlorine pesticides—such as DDE—are neurotoxic, cause oxidative stress, and damage the brain's dopaminergic system.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
formed by the loss of hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...
(dehydrohalogenation
Dehydrohalogenation
Dehydrohalogenation is an organic reaction from which an alkene is obtained from an alkyl halide . It is also called a β-Elimination reaction and is a type of elimination reaction....
) from DDT
DDT
DDT is one of the most well-known synthetic insecticides. It is a chemical with a long, unique, and controversial history....
, of which it is one of the more common breakdown products. DDE is fat soluble which tends to build up in the fat of animals. Due to its stability in fat, DDE is rarely excreted from the body, and body levels tend to increase throughout life. The major exception is the excretion of DDE in breast milk, which delivers a substantial portion of the mother's DDE burden to the young animal or child.
DDE and its parent, DDT, are reproductive toxicants for certain birds species, and major reasons for the decline of the bald eagle
Bald Eagle
The Bald Eagle is a bird of prey found in North America. It is the national bird and symbol of the United States of America. This sea eagle has two known sub-species and forms a species pair with the White-tailed Eagle...
, brown pelican
Brown Pelican
The Brown Pelican is the smallest of the eight species of pelican, although it is a large bird in nearly every other regard. It is in length, weighs from and has a wingspan from .-Range and habits:...
peregrine falcon
Peregrine Falcon
The Peregrine Falcon , also known as the Peregrine, and historically as the Duck Hawk in North America, is a widespread bird of prey in the family Falconidae. A large, crow-sized falcon, it has a blue-gray back, barred white underparts, and a black head and "moustache"...
, and osprey
Osprey
The Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...
. 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
Waterfowl
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....
, and song birds
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
are more susceptible to eggshell thinning than chickens and related species
Galliformes
Galliformes are an order of heavy-bodied ground-feeding domestic or game bird, containing turkey, grouse, chicken, New and Old World Quail, ptarmigan, partridge, pheasant, and the Cracidae. Common names are gamefowl or gamebirds, landfowl, gallinaceous birds or galliforms...
, and DDE appears to be more potent than DDT.
The biological mechanism for the thinning is not entirely known, but it is believed that p,p'-DDE impairs the shell gland's ability to excrete calcium carbonate
Calcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
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
Endocrine disruptor
Endocrine disruptors are chemicals that interfere with endocrine in animals, including humans. These disruptions can cause cancerous tumors, birth defects, and other developmental disorders...
and contributes to breast cancer
Breast cancer
Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...
, but more recent studies provide strong evidence that there is no relationship between DDE exposure and breast cancer. What is more clear is that DDE is a weak antiandrogen.
Animal studies show that organochlorine pesticides—such as DDE—are neurotoxic, cause oxidative stress, and damage the brain's dopaminergic system.