The findings were published online ahead of print in the journal Environmental Health Perspectives today.
BPA is used in certain packaging materials such as polycarbonates for baby food bottles. It is also used in epoxy resins for internal protective linings for canned food, infant formula and metal lids.
The US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) have declared BPA safe based, in part, on the assumption that it was excreted quickly from the body.
The authors of the study looked at levels of the chemical in the urine of 1,469 US adults who took part in Center for Disease Control's National Health and Nutrition Examination Survey (NHANES).
While it had been thought that BPA was rapidly eliminated from the body through urine, this study found people who had fasted for even a whole day still had significant levels of the chemical.
The researchers said this suggested BPA may linger in the body longer than previously known or that it may get into the body through sources other than just food, such as tap water or house dust.
They added that BPA may get into fat tissue, from where it might be released more slowly.
A recent study by a team of UK researchers found that higher concentrations of the chemical in urine were linked with heart disease, type 2 diabetes and liver enzyme abnormalities, while the US National Toxicology Programme (NTP) said that effects on reproductive development from BPA in packaging cannot be ruled out.
There is growing interest in the exposure of BPA to young children via food stored in BPA-containing packaging, as it is not clear the exposure levels in developing foetuses and newborns.