CHICAGO, July 20 (Xinhua) -- Male and female rats exposed in the womb and during lactation to plasticizing chemicals known as phthalates had significantly fewer neurons and synapses than those that were not exposed, researchers at the University of Illinois reported in a study.

Moreover, the phthalate-exposed rats had reductions in the size of their medial prefrontal cortex, a brain region that regulates behavior, and showed deficits in cognitive flexibility.

The researchers assigned pregnant rats in the study to one of three groups: two of which were exposed to differing concentrations of phthalates during pregnancy and lactation; and one, a control group that was not exposed at all. They then tested how well the offspring learned to use visual and textural cues to navigate a maze, and examined the relative development of their brains once they reached adulthood.

"We found that there was an appreciable reduction in the number of neurons, the number of synapses and the size of the medial prefrontal cortex in the phthalate-exposed rats," said UI psychology professor Janice Juraska, who led the study. "They also showed a deficit in what we call cognitive flexibility. They made significantly more errors when navigating the mazes than rats that had not been exposed."

The negative effects of perinatal exposure to phthalates were seen at both doses of the phthalate mixture, the researchers said, which were "presumably within the range of the estimated daily intakes of humans."

The variety of phthalates and quantities used in the study were environmentally relevant to human exposures, Juraska said.

"Phthalates are used as plasticizers in a variety of consumer goods, including plastics, personal care products, fragrances, pharmaceuticals, clothing and building materials," she said. "Contact with these products can lead to exposure through the skin, digestion or lungs."

Several studies in humans suggest that prenatal phthalate exposure may negatively affect children's behavior, their ability to regulate their own actions and the incidence of neuropsychiatric disorders.

The study was posted on UI website on July 18. Enditem