In one of the first studies to measure levels of bisphenol A (BPA) in humans after they’ve consumed canned foods, researchers at the Harvard School of Public Health have found that eating canned soup dramatically boosts urine concentrations of that controversial chemical.

The research, published Tuesday afternoon in the Journal of the American Medical Association, measured BPA in the urine of people who ate 12 ounces of canned vegetable soup daily for five days and that of people who ate the same amount of fresh vegetable soup. The BPA concentrations in the urine of the canned-soup eaters were an astounding 1,221 percent higher than those of the fresh-soup eaters.

BPA is an endocrine disrupter that’s found in many commercial products and is a byproduct of the epoxy resin lining used to protect the insides of food cans from corrosion, the study explains. Research has linked high levels of BPA in humans’ urine to cardiovascular disease, diabetes and other health conditions. The new research is part of an effort to identify the leading food sources of BPA in our diets. The researchers note that the increased levels of BPA in participants’ urine was temporary and that further study of the chemical’s longevity in the body is warranted.