Exposure to the pesticide DDT can genetic impact linking to obesity, WSU researchers found.

Michael Skinner, founder of the Center for Reproductive Biology, has been looking into the effects of environmental toxicants on pregnant females and their descendants for 15 years. He first began investigating DDT about four years ago to learn about the unknown long-term effects.

Skinner and his lab started this research when the World Health Organization pushed for a lift on the ban of DDT. As an effective mosquito-killer, DDT is used to help treat malaria in Africa. Many countries in Africa and some in Europe started to use DDT once the ban was lifted.

Elizabeth Houser, an undergraduate research assistant, said the lab looked at the long-term effects of the drug across family lines. The lab also investigated how characteristics of exposure may be inherited if an ancestor had contact with DDT. They will use this information to promote more responsible use of the pesticide, she said.

Skinner tested the effects of DDT by exposing gestating rats to the chemical in a critical stage of their embryo’s development. He discovered that the exposure to DDT causes a change in DNA methylation, a chemical mark on the DNA.

Because the pesticide causes a change in the DNA structure of exposed rats, they transmit the effects to their offspring.

“These become permanently programmed and sperm or eggs pass it to the next generation,” Skinner said.

Eric Nelson, a graduate research assistant, said the lab discovered the transmittable connection to obesity unintentionally.

“Over the course of following the rats as they got older, we noticed that out of our DDT ancestrally treated group an awful lot of them were pretty chunky,” he said.

The lab then found that the first generation of rats born from the pregnant ones did not appear to show an obesity trend. However, in the third generation, over 50 percent of males and females showed obesity.

“(What) it really came down to was keeping our eyes open trying to see what happened as the third generation rats got older,” Nelson said.

The concept, known as transgenerational epigenetic inheritance, means that the effects are not observable for at least three generations, he said.

Obesity was not the only condition potentially connected to DDT. Kidney, ovarian and testes disease were also found in the third generation. However, all these conditions are commonly associated with obesity, Skinner said.

Nelson said though human testing has not occurred yet, this same effect could cause obesity in people.

“If something like this can occur for rats, it could occur for humans too,” Nelson said. “Exposure to environmental toxicants can have an effect not just on you, but several generations to follow.”