Study reports hints of phthalate threat to boys' IQs
You may have a hard time spelling phthalates, but there’s no avoiding them. They’re in the air you breathe, water you drink and foods you eat. And this ubiquity may carry a price, particularly for young boys, emerging data suggest. Including a drop in their IQ.
A new study examines cognitive risks from phthalates. The study wasn't big — including just 667 third- and fourth-graders. But it does cover a broad and nationally representative cross-section of South Korea's youngsters. Moreover, whatever changes occurred in these kids might well develop elsewhere. And that's because residues of diethylhexyl phthalate, or DEHP — the phthalate that appeared most neurotoxic to these children — show up in people throughout the developed world, including the United States.
Soo-Churl Cho and Hee-Jung Yoo of Seoul National University College of Medicine and their colleagues recruited participants from nine grade schools. These drew from vastly different communities: Seoul, a metro area with 10 million people; Incheon, an industrial center with close to 3 million inhabitants; Ulsan, an industrial region about one-third Incheon’s size; Seongnam, a suburban home to some million residents; and a rural region covering land mass comparable to Seoul’s metro region, but inhabited by a mere 50,000 people.
Each child took the Korean version of a widely accepted IQ test known as the Wechsler Intelligence Scale for Children, or WISC. So did the kids' moms, which offered the researchers — from four Korean medical schools — a gauge for the genetic component to each child’s IQ.
DEHP metabolites, or breakdown products, ranged from a minimum of 0.5 micrograms per liter to 445 µg/l. Two DEHP metabolites were measured and summed for each child. Then the kids were split into four groups on the basis of these metabolites. In an upcoming issue of Environmental Health Perspectives published online, ahead of print, the researchers report finding that as the amount of DEHP's breakdown products in urine climbed, a child’s IQ fell a small amount.