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The research comes from the School of Nursing and Health Sciences at Boston's Simmons College. The researchers tested the breast milk of 27 women and the urine of 31 infants. The infants were between three months and 15 months old, and they were screened for environmental exposure to BPA sources. The infants tested had no known BPA environmental exposure.
The tests analyzed the levels of unconjugated or free BPA as well as total BPA levels – including conjugated BPA. The researchers used solid-phase extraction along with liquid chromatography-isotope dilution with mass spectrometry to determine the levels with accuracy.
The testing found that 93% of the children had significant total BPA levels – averaging from 1.2 to 4.4 micrograms per liter.
The testing also found that 75% of the mothers' breast milk had detectable amounts of total BPA – in the range of 0.4 to 1.4 micrograms per liter.
The researchers found that levels of free BPA - considered more harmful – were lower than total BPA levels.
The researchers checked the feeding habits of the children to determine whether there was a relationship between their diet and their BPA levels, but found no relationship. Surprisingly, they also could not find a significant relationship between the amount of BPA in the mother's breast milk and the BPA levels of her baby's urine.
Research published last month from the German Institute for Prevention and Occupational Medicine confirmed similar results from urine and plasma samples taken among the German population between 1995 and 2009. Analyzing 600 urine and plasma samples, the researchers found that total BPA was detectable in over 96% of the samples tested. The BPA concentrations averaged 1.49 micrograms per liter and high levels (in the 95th percentile) averaged 7.37 micrograms per liter.
The researchers found that unconjugated BPA made up the bulk of the BPA found. This indicates environmental exposure. The researchers also concluded, "total BPA in urine as the most appropriate and robust marker for BPA exposure assessment."
The researchers did not find a significant increase or decrease in overall BPA levels between 1995 and 2009 among the samples.
This of course confirms what science has discovered among so many marine mammals and fish – that BPA tends to bioaccumulate gradually within the tissues and migrates up through the food chain. And marine researchers are finding increasing BPA levels among sea-life as microplastics are accumulating in the oceans.
These studies also confirm research done in October by the U.S. Centers for Disease Control and Prevention that showed children between three and eleven years of age are accumulating BPA and seven other toxins.
In another study out this year, Swedish researchers tested BPA levels among 100 women and correlated those levels with their exposure to BPA from their diets. They found that the most prevalent BPA sources were from fish, meat, potatoes, and dairy products. This study also indicated the women's primary source of exposure is through the diet, a direct result of animals bioaccumulating BPA and this accumulation effect finding its way up the food chain to humans. In this study, 76% of the women had detectable levels of BPA in their blood.