Are people's PBDE uptake patterns changing?
Researchers don't know why the PBDE uptake patterns in Spanish infant placentas resemble those from electronics recycling workers—and not those of their parents' blood.
In 2002, Maria José González of the Spanish National Research Council (CSIC) was asked by the Province of Madrid's Public Health Authority to assess the population's exposure to persistent organic pollutants (POPs). Experts agree that her findings about the uptake of PBDE flame retardants by the citizens of central Spain, published in ES&T (DOI: 10.1021/es0714484), are intriguing.
One reason the findings are interesting is because of the study's design, which, González says, inspired her to take on the project. The samples were taken from newborn babies and both of their parents. In all, 391 samples of maternal blood serum, paternal serum, umbilical serum, placental serum, and human milk were collected between October 2003 and May 2004. Researchers from Spain's Institute of Health Carlos III also collaborated on the project.
González and her colleagues looked for 15 PBDE compounds, or congeners, in the samples, including the heaviest BDE-209 molecules associated with the Deca formulation used in electronics products. The majority of human-milk PBDE studies conducted to date haven't measured BDE-209, points out Åke Bergman, chair of Stockholm University's environmental chemistry department. Data on BDE-209 in umbilical and placental serum are also lacking, he adds.
The study population's overall concentrations of PBDEs were similar to those found elsewhere in Europe—where levels tend to be an order of magnitude lower than those in North America. But the Spanish researchers were surprised to find that the dominant congeners varied within the sample set. As is typical for samples from Europe and North America, the predominant congener in the maternal, paternal, and umbilical-cord samples was BDE-47, which is found in the Penta and Octa formulations banned by the EU in August 2004. However, BDE-209 was the dominant congener in the placental serum and breast milk samples. In the past, this pattern has been seen mainly in people who work in electronics recycling.
The only study to report similar findings was conducted by Adrian Covaci of the University of Antwerp (Belgium), who reported dominant concentrations of BDE-209 in pooled Belgian umbilical serum. More data on the toxicokinetics of BDE-209 are needed to explain these findings, he stresses.
The new research also provides data for the ongoing debate over whether different PBDE congeners cross the placenta at varying rates. However, "in contrast to most previous studies, maternal serum and cord serum [were] not sampled simultaneously," points out Kristina Jakobsson, a physician and senior consultant at Lund University Hospital (Sweden). "This is not likely to affect the levels of the low–medium [weight] PBDEs, which have a long half-life (years), as much as it might affect levels of BDE-209, which [has] an apparent half-life as short as 14 days. . . . Thus, from a theoretical standpoint, a steady state cannot be assumed, taking into account also the numerous sources of exposure (indoor air and dust, diet)."
Janna Koppe, an emeritus professor of neonatology at the University of Amsterdam, made the same observation. The new paper raises questions about whether hospitals could be a significant source of the infants' BDE-209, she adds.
