Study traces obesity to infamous pesticide

A pesticide banned in 1973 might contribute to obesity, according to a study led by MSU professor Janet Osuch.

Osuch’s study focused on the levels of DDE — a form of the pesticide DDT — in mothers who consumed fish from and lived near Lake Michigan. Those levels were then used to estimate the levels of DDE their daughters were exposed to in the womb, Osuch said.

DDT is an endocrine disrupter and interferes with the metabolism of sex-steroid hormones, such as estrogen, Osuch said.

“(The findings) didn’t actually surprise us because we know that women who are deficient in estrogen gain more weight and DDE — the chemical — interferes with estrogen metabolism,” Osuch said.

DDT is a pesticide that was used widely in the earlier part of the 20th century.

“It was the major insecticide used by farmers for years,” said Jim Bingen, professor of community, food and agriculture.

One of the characteristics of DDT is that it bioaccumulates, Bingen said. Bioaccumulation refers to the buildup of a substance, such as DDT, in an organism, said Christine Flaga, a toxicologist with the Remediation and Redevelopment Division within the Department of Environmental Quality.

“That means that organism is going to absorb the material at a rate faster that it can excrete it,” Flaga said.

Although DDT was outlawed decades ago, it can still be found in the soil and in the waters of the lake, Osuch said.

“DDT was outlawed but unfortunately, DDE — its breakdown product — persists,” Osuch said. “It gets in the soil and into the water and then any animal with any fat will bioaccumlate it.”

Obesity isn’t the only side effect DDE exposure in the womb has been linked to. Young girls may get their periods early, may get pregnant more often and may be less likely to be able to breastfeed, Osuch said.

To limit exposure, Osuch suggests eating two or less servings of fish a week and trimming the fat from any meat, since DDT accumulates in fatty tissues.

Doctors aren’t able to test a person to see if exposure to DDE in the womb contributed to their obesity, she said. The next phase of the study will involve studying males and grandchildren in addition to daughters.

“You know that old nature versus nurture argument? Now we’re realizing that it’s both,” Osuch said.