Anogenital distance
Encyclopedia
Anogenital distance is the distance from the anus to the genitalia, the base of the penis
or vagina
. It is considered medically significant for a number of reasons, in both humans and animals. It is regulated by dihydrotestosterone
, which can be disrupted by phthalates common in plastics. Such endocrine disruption
may affect the development of the brain.
Yet another study, by Swan et al., has determined that the AGD is linked to fertility in males, not penis size.
An abnormally short male AGD (lower than the median around 52 mm (2 in) have seven times the chance of being sub-fertile as those with a longer AGD. It is linked to both semen volume and sperm count. Those with lower AGD than median also increases in the likelihood of undescended testes, and lowered sperm counts and testicular tumors in adulthood. Babies with high total exposure were ninety times more likely to have a short AGD, despite not every type of the 9 phthalates tested being correlated with shorter AGD.
Swan et al. also report that the levels of phthalates associated with significant AGD reductions are found in approximately one-quarter of Americans tested by the Centers for Disease Control and Prevention
(CDC) for phthalate body burdens.
Women who had high levels of phthalates in their urine during pregnancy gave birth to sons who were 10 times more likely to have shorter than expected AGDs.
are conditions which may be induced in males with short AGD.
Other problems in males include risk of testicular dysgenesis syndrome.
Experiments have demonstrated that in rodent studies this distance is shortened when the mother is exposed to chemicals that are anti-androgenic, such as dibutyl phthalate
(DBP) or benzylbutyl phthalate (BBzP).
Interestingly enough, bisphenol A
in certain doses increases the AGD of both genders of a study on mice.
Penis
The penis is a biological feature of male animals including both vertebrates and invertebrates...
or vagina
Vagina
The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...
. It is considered medically significant for a number of reasons, in both humans and animals. It is regulated by dihydrotestosterone
Dihydrotestosterone
Dihydrotestosterone is an androgen or male sex hormone. The enzyme 5α-reductase synthesises DHT in the prostate, testes, hair follicles, and adrenal glands...
, which can be disrupted by phthalates common in plastics. Such endocrine disruption
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...
may affect the development of the brain.
In humans
Studies show that the human perineum is twice as long in males as in females, but males have more variance. Measuring the anogenital distance in neonatal humans has been suggested as a noninvasive method to determine male feminisation and thereby predict neonatal and adult reproductive disorders.Yet another study, by Swan et al., has determined that the AGD is linked to fertility in males, not penis size.
An abnormally short male AGD (lower than the median around 52 mm (2 in) have seven times the chance of being sub-fertile as those with a longer AGD. It is linked to both semen volume and sperm count. Those with lower AGD than median also increases in the likelihood of undescended testes, and lowered sperm counts and testicular tumors in adulthood. Babies with high total exposure were ninety times more likely to have a short AGD, despite not every type of the 9 phthalates tested being correlated with shorter AGD.
Swan et al. also report that the levels of phthalates associated with significant AGD reductions are found in approximately one-quarter of Americans tested by the Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...
(CDC) for phthalate body burdens.
Women who had high levels of phthalates in their urine during pregnancy gave birth to sons who were 10 times more likely to have shorter than expected AGDs.
Conditions
Hypospadia and cryptorchidismCryptorchidism
Cryptorchidism is the absence of one or both testes from the scrotum. It is the most common birth defect regarding male genitalia. In unique cases, cryptorchidism can develop later in life, often as late as young adulthood. About 3% of full-term and 30% of premature infant boys are born with at...
are conditions which may be induced in males with short AGD.
Other problems in males include risk of testicular dysgenesis syndrome.
In animals
There have been extensive studies of AGD effects on animals. In some animals it is routinely measured to determine health.Experiments have demonstrated that in rodent studies this distance is shortened when the mother is exposed to chemicals that are anti-androgenic, such as dibutyl phthalate
Dibutyl phthalate
Dibutyl phthalate is a commonly used plasticizer. It is also used as an additive to adhesives or printing inks. It is soluble in various organic solvents, e.g. in alcohol, ether and benzene...
(DBP) or benzylbutyl phthalate (BBzP).
Interestingly enough, bisphenol A
Bisphenol A
Bisphenol A is an organic compound with two phenol functional groups. It is used to make polycarbonate plastic and epoxy resins, along with other applications....
in certain doses increases the AGD of both genders of a study on mice.