Another chemical found to be harmful to boys.

Oct 31, 2008

Saillenfait AM, Sabatéa JP and F Gallissot. 2008. Diisobutyl phthalate impairs the androgen-dependent reproductive development of the male rat. Reproductive Toxicology 26(2):107-115.

Synopsis by Jennifer Adibi

Another chemical commonly found in the urine of U.S. residents was added to the list of those that are possibly contributing to the subtle feminization of boys.

Diisobutyl phthalate (DiBP) was shown in a recent study to cause similar defects in the male rat genitalia as does di-n-butyl phthalate (DnBP) when given during pregnancy. DiBP is used predominantly as a plasticizer in plastics, varnishes and adhesives and has been measured in the urine of most U.S. residents.

One published study reports a similar association of DiBP exposure in pregnant mothers with reduced AGD in their boy babies indicating that this finding may be relevant to humans.

The two chemicals are similar in their structure and in their uses. At a dose low enough not to cause harm to the mother (250 mg/kg day), when exposed in the womb  male rat pups had a smaller distance between the anus and genitalia (anogenital distance or AGD), making them more like females.

Researchers gave 4 doses of DiBP during the period in pregnancy when the male reproductive system is forming. The control group received only corn oil and another group received a comparable dose of DnBP. Other adverse effects were also caused by DiBP,  including the incorrect placement of the opening in the penis (hypospadias), undescended testes (cryportchidism) and defective sperm production.

Overall, DiBP caused similar effects as DnBP but at a slightly lower frequency.