CORRESPONDENCE/REBUTTAL pubs.acs.org/est
Reply to Comments on “Bisphenol A (BPA) in U.S. Food”
W
e respond to the letter submitted by Ackerman and Noonan 1 concerning our article, ”Bisphenol A (BPA) in U.S. Food”.2 The article described our study of BPA levels in a market basket survey of U.S. fresh, canned, and plastic contained food. We thank the authors for their comments, but we feel their letter fails to note that we stated our manuscript is the first peer reviewed publication measuring BPA levels in a single study in U.S. food for all three types of wrapping material or containers. The 11 articles cited by Ackerman and Noonan reflect literature where either one or two types of the food containers of interest have been measured for BPA levels in various countries, but these articles do not present data from U.S. food for BPA levels in food that is fresh, canned, and in plastic containers. The purpose of our market basket survey, one in a series of related studies,3 6 was to describe the levels of BPA found in a sample of common U.S. foods that can be purchased by members of the general public at common distribution sites (supermarkets). We realize that cans and other types of containers may vary in composition which may, at times, result in contamination. It was not our goal to evaluate technical details of food preparation or packaging in cans prepared in different ways and how this may affect BPA contamination of food. The idea that the concentrations of BPA in food may not be the same from different manufacturers or at different times is perfectly reasonable given the changing market conditions in the U.S. and variations in BPA levels that can occur over time and in different countries. Eurofins GfA GmbH is an accredited laboratory working in the field of environmental contaminants and human exposure for more than 25 years. All analyses performed need to fulfill specific QC/QA measures. For the determination of BPA, QC/QA included a multi point calibration curve, recalibration within each sequence of analysis with a minimum of one blank in each batch of a maximum of 10 samples, and duplicate analyses of >50% of positive samples. Nearly all positive samples were analyzed in triplicate. The percent CV indicates percent coefficient of variation; for the replicate/duplicate analysis of BPA in food samples, the CV percents were between 1.1 and 11.4% with an average of 6.01%. The laboratory blank level for BPA is 0.43 ng absolute (total amount of BPA per blank sample). (mean; n = 15) with SD: 0.12 ng abs and BPA: 0.05 ng/g ww (LOD) with 0.11 ng/g ww (LOQ) based on 15 g ww (sample intake).The limits of detection were 0.20 ng/g wet weight (ww). Accuracy of laboratory protocol and ability to reproduce results were determined by analyzing fortified (spiked) samples and included the freeze-drying process. The ratio between the assigned value and the determined value was in the range of 86% and 102% (average 92.1%; reproducibility variation coefficient of 9.59%; n = 6). Our report of correlation with pH and some BPA concentration in our article was simply a means of characterizing our findings. We did not suggest that this implied causality. In fact, we expressed considerable skepticism about the generalizability of this finding, including that it was unexpected, “may be due to chance or artifact,” and may reflect container types. Our use of r 2011 American Chemical Society
the word “curvilinear” does not refer to a quadratic model, but rather the results of our ANOVA, which we took to be a conservative way to test the pattern evident in the data, of increasing and then decreasing BPA levels as pH increased. The “single difference between the two most populous pH groups” to which the comment refers was the result of a posthoc comparison after this ANOVA, using the standard, conservative Bonferroni method of adjusting for multiple comparisons. By none of the possible interpretations of “non-detect frequency” that we considered was this equal to 44%. The “triplicate samples” were in fact three distinct samples of the same kind of food. We did not assert that it would not be appropriate to conduct another analysis including a random effect for food type in addition to the fixed effect of pH. Our goal was to present the first findings of BPA in U.S. food that is fresh, canned, and in plastic containers from a market basket survey. Studies by others on chemical composition of cans and changes in pH or BPA levels by preparation of the product for sale would make an interesting manuscript. However, that was not a goal of our research. We noted the percent of samples showing measurable levels of BPA and the types of food involved. These represent food purchased from U.S. stores at the time of collection. Arnold Schecter, Noor Malik, Darrah Haffner, Sarah Smith, and T. Robert Harris University of Texas School of Public Health, Dallas, Texas, United States
Olaf Paepke Eurofins GfA GmbH Laboratory, Hamburg, Germany
Linda Birnbaum National Cancer Institute, Bethesda, Maryland, United States, NIH, Research Park Triangle, North Carolina, United States
’ REFERENCES (1) Ackerman, L. K.; Noonan, G. O. Comment on “Bisphenol A (BPA) in U.S. Food. Environ. Sci. Technol. 2011, DOI: 10.1021/ es2002869. (2) Schecter, A.; Malik, N.; Haffner, D.; Smith, S.; Harris, T. R.; Paepke, O.; Birnbaum, L.; Bisphenol, A. (BPA) in U.S. Food. Environ. Sci. Technol. 2010, 44 (24), 9425–9430. (3) Schecter, A.; Colacino, J.; Patel, K.; Kannan, K.; Yun, S. H.; Haffner, D.; Harris, T. R.; Birnbaum, L. Polybrominated diphenyl ether levels in foodstuffs collected from three locations from the United States. Toxicol. Appl. Pharmacol. 2010, 243 (2), 217–224. (4) Schecter, A.; Colacino, J.; Haffner, D.; Patel, K.; Opel, M.; P€apke, O.; Birnbaum, L., Perfluorinated compounds, polychlorinated biphenyls, and organochlorine pesticide contamination in composite food samples from Dallas, Texas, USA. Environ. Health Perspect. 2010, 118 (6).
Published: March 23, 2011 3814
dx.doi.org/10.1021/es200613m | Environ. Sci. Technol. 2011, 45, 3814–3815
Environmental Science & Technology
CORRESPONDENCE/REBUTTAL
(5) Schecter, A.; Haffner, D.; Colacino, J.; Patel, K.; P€apke, O.; Opel, M.; Birnbaum, L., Polybrominated Diphenyl Ethers (PBDEs) and Hexabromocyclodecane (HBCD) in Composite U.S. Food Samples. Environ. Health Perspect. 2009, 118 (3). (6) Schecter, A.; P€apke, O.; Harris, T. R.; Tung, K. C.; Musumba, A.; Olson, J.; Birnbaum, L., Polybrominated diphenyl ether (PBDE) levels in an expanded market basket survey of U.S. food and estimated PBDE dietary intake by age and sex. Environ. Health Perspect. 2006, 114 (10).
3815
dx.doi.org/10.1021/es200613m |Environ. Sci. Technol. 2011, 45, 3814–3815
