Their study involved more than 2,800 children ages 6 through 19, who took the survey in the years 2003 through 2008. They compared BPA levels in their urine to their weight, and divided them into four groups based on BPA amounts.
The key finding: About 22 percent of the children with highest levels of BPA were obese, compared to just 10 percent of kids with the lowest levels.
Was the reverse true? Did the heaviest kids have more BPA in their urine, and the thinnest kids less? Yes, Trasande said. But he did not include those numbers in his study, and declined to provide them.
The study raised more questions than it answered:
All this means is that the study raises some interesting questions, but at this point it's impossible to say BPA causes childhood obesity, said Linda Birnbaum, director of the National Institute of Environmental Health Sciences, a federal agency involved in research on BPA.
"It's a hypothesis that needs further exploration," she said.
The American Chemistry Council, which represents chemical manufacturers, called the study speculative and noted lab animal studies that found no evidence that BPA causes obesity.
"Attempts to link our national obesity problem to minute exposures to chemicals found in common, everyday products are a distraction from the real efforts under way to address this important national health issue," the organization said in a statement.