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Dichlorodiphenyldichloroethylene (DDE) is a
/ref> A 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.
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
formed by the loss of hydrogen chloride
The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chlorid ...
( dehydrohalogenation) from DDT, of which it is one of the more common breakdown products. Due to DDT's massive prevalence in society and agriculture
Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
during the mid 20th century, DDT and DDE are still widely seen in animal tissue samples. DDE is particularly dangerous because it is fat-soluble like other organochlorines
An organochloride, organochlorine compound, chlorocarbon, or chlorinated hydrocarbon is an organic compound containing at least one covalently bonded atom of chlorine. The chloroalkane class (alkanes with one or more hydrogens substituted by chlo ...
; thus, it is rarely excreted from the body, and concentrations tend to increase throughout life. The major exception is the excretion of DDE in breast milk
Breast milk (sometimes spelled as breastmilk) or mother's milk is milk produced by mammary glands located in the breast of a human female. Breast milk is the primary source of nutrition for newborns, containing fat, protein, carbohydrates ( la ...
, which transfers a substantial portion of the mother's DDE burden to the young animal or child. Along with accumulation over an organism's lifetime, this stability leads to bioaccumulation in the environment, which amplifies DDE's negative effects.
Synthesis
DDE is created by dehydrohalogenation of DDT. The loss of HCl results in adouble bond
In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betwee ...
on the central (previously quaternary) carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon ma ...
atoms.
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 thebald eagle
The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche as ...
, brown pelican
The brown pelican (''Pelecanus occidentalis'') is a bird of the pelican family, Pelecanidae, one of three species found in the Americas and one of two that feed by diving into water. It is found on the Atlantic Coast from New Jersey to the mout ...
peregrine falcon
The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a cosmopolitan bird of prey (raptor) in the family Falconidae. A large, crow-sized falcon, it has a blue-grey bac ...
, and osprey
The osprey (''Pandion haliaetus''), , also called sea hawk, river hawk, and fish hawk, is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor reaching more than in length and across the wings. It is brown o ...
. 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
Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predat ...
, waterfowl
Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which ...
, and song birds
A songbird is a bird belonging to the suborder Passeri of the perching birds (Passerine, Passeriformes). Another name that is sometimes seen as the scientific or vernacular name is Oscines, from Latin ''oscen'', "songbird". The Passeriformes co ...
are more susceptible to eggshell thinning than chickens and related species, and DDE appears to be more potent than DDT.ATSDR - Toxicological Profile: DDT, DDE, DDD/ref> A 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 mother bird's glands 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 anendocrine disruptor
Endocrine disruptors, sometimes also referred to as hormonally active agents, endocrine disrupting chemicals, or endocrine disrupting compounds are chemicals that can interfere with endocrine (or hormonal) systems. These disruptions can cause ...
and contributes to breast cancer
Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or ...
, 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 androgen receptor
The androgen receptor (AR), also known as NR3C4 (nuclear receptor subfamily 3, group C, member 4), is a type of nuclear receptor that is activated by binding any of the androgenic hormones, including testosterone and dihydrotestosterone in ...
antagonist
An antagonist is a character in a story who is presented as the chief foe of the protagonist.
Etymology
The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, ri ...
and can produce male genital tract abnormalities.
See also
*Insecticide
Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed t ...
References