Children exposed prenatally to high levels of phthalates — commonly used in plastics and scented products — have IQ levels seven points lower than those exposed to low levels, a new study finds.
The study is the first to find a connection between phthalate exposure during pregnancy and reduced IQ in children.
The 328 women and their children in the study were from low-income communities in New York City.
Researchers at Columbia University’s Mailman School of Public Health measured levels of four common phthalates, including di-n-butyl phthalate (DnBP) and di-isobutyl phthalate (DiBP), during pregnancy (Factor-Litvak et al., 2014).
The children were given an IQ test at 7-years-old.
The results, published in the journal PLoS ONE, showed that children who were in the top 25% for exposure to two particular phthalates (DnBP and DiBP) had IQs around 7 points lower than those who were in the bottom 25% for exposure.
Professor Robin Whyatt, one of the study’s senior authors, said:
“The magnitude of these IQ differences is troubling.
A six- or seven-point decline in IQ may have substantial consequences for academic achievement and occupational potential.”
The researchers controlled statistically for other factors that influence children’s IQ, such as maternal IQ and education as well as the home environment.
While it is impossible to avoid phthalates completely, they are found in these common products, amongst others:
- Plastic containers used for microwaving food.
- Air fresheners.
- Dryer sheets.
- Nail polish.
- Some soaps.
- Recycled plastics labelled 3,6 or 7.
About the author
Psychologist, Jeremy Dean, PhD is the founder and author of PsyBlog. He holds a doctorate in psychology from University College London and two other advanced degrees in psychology.
He has been writing about scientific research on PsyBlog since 2004. He is also the author of the book “Making Habits, Breaking Habits” (Da Capo, 2003) and several ebooks:
- Accept Yourself: How to feel a profound sense of warmth and self-compassion
- The Anxiety Plan: 42 Strategies For Worry, Phobias, OCD and Panic
- Spark: 17 Steps That Will Boost Your Motivation For Anything
- Activate: How To Find Joy Again By Changing What You Do
Dr. Pam Factor-Litvak, who led the study, said:
“Pregnant women across the United States are exposed to phthalates almost daily, many at levels similar to those that we found were associated with substantial reductions in the IQ of children.
While there has been some regulation to ban phthalates from toys of young children, there is no legislation governing exposure during pregnancy, which is likely the most sensitive period for brain development.
Indeed, phthalates are not required to be on product labeling.”