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By Jen Christensen

Women who had a high amount of the chemicals called di-n-butyl phthalate and di-isobutyl phthalate in their bodies during pregnancy gave birth to children who had markedly lower IQ scores, according to a new study running in the journal PLOS One.

The study found that by the age of 7, children exposed to more of these chemicals had IQ’s that were more than six points lower than children exposed to lower levels of the chemicals.

Phthalates make plastics more flexible and harder to break. These plasticizers are also good at helping chemicals carry a particular scent.

The material is found in a wide variety of things people use every day, like the containers you use to store food or heat it up in the microwave. Phthalates are also in air freshners, dryer sheets, shampoos, cosmetics and many other things you’d find around your house.

The Environmental Protection Agency estimates over 470 million pounds of phthalates are produced each year.

Phthalate exposure is widespread in the United States, according to research done in 2009 in the Fourth National Report on Human Exposure to Environmental Chemicals. Women had much higher rates of exposure. That’s because they used more products with phthalates — products like soaps, shampoos, cosmetics and body washes.

Phthalates then can wind up in your body after you eat or drink food that has been in any contact with the plasticizer. You can also breathe it in from vapors or dust that contain phthalate particles.

“In recent years phthalates have come under greater scrutiny,” said the study’s lead author Pam Factor-Litvak. The associate professor of epidemiology works at the Mailman School of Public Health at Columbia University. She has been looking generally at the biological relationships between environmental exposures and development. “This is the first study that followed prenatal exposure.”

Prior studies have focused on the negative health impact phthalates may have on the male reproductive system. Other studies have shown associations between exposure to phthalates and human health, although no causal link has been established.

This latest study focused on the health of 328 inner-city moms and their children. The scientists measured the chemical by looking at the amount of phthalates that was in a mother’s urine in the third trimester.

IQ tests were given to the children when they turned 7. The tests evaluate how quickly a child processed information, how they used their perceptional reasoning, how the child used their working memory, and it tested their verbal comprehension.

The researchers screened out for elements that already have a negative impact on a child’s IQ.

Those elements include the mother’s education level, her perception of hardship and the access she has to proper food and clothing as well as her satisfaction with her living conditions.

Researchers also screened for a child’s environment and their exposure to tobacco smoke, and other demographic details.

Even after screening out for those factors researchers saw the IQ difference.

Scientists don’t know why there may be this link between chemicals and IQ. Phalates can impact the way a person’s hormones work. During development hormones impact brain and other organ development. The study though doesn’t show definitively that the chemicals damaged the brain.

The results from this study were not entirely what the authors expected.

“We are a little surprised at the magnitude of the IQ drop,” Factor-Litvak said. A drop in IQ can change a child’s potential for success at school and on the job. “We are not happy about the finding since phthalates are very ubiquitious in the environment.”

“These findings further suggest a potential role for phthalates on neurodevelopment,” said Dr. Maida P. Galvez who did not work on the study but has a specialty in environmental pediatrics. The associate professor is in the Department of Preventive Medicine and Pediatrics at the Icahn School of Medicine at Mount Sinai. “While this requires replication in other study populations for confirmation, it underscores the fact that chemicals used in everyday products need to be rigorously evaluated for their full potential of human health impacts before they are made widely available in the marketplace.”

Phthalates have been banned from toys and children’s products. In Europe low phthalates are also banned from cosmetics. No such effort has been made to reduce pregnant women’s exposure to the chemical.

Factor-Litvak and her fellow authors suggest that pregnant women should do what they can to minimize their exposure to phthalates. That means using unscented lotions and laundry detergents; microwaving food in glass containers rather than plastic; using cleaning supplies without scent; avoiding air freshners and plastics labeled as No. 3, No. 6 and No. 7, since these products use phthalates.

Factor-Livak hopes the study will encourage other research in this area.