Automated milk fat extraction for the analyses of persistent organic pollutants.

We have utilized an automated acid hydrolysis technology, followed by an abbreviated Soxhlet extraction technique to obtain fat from whole milk for the determination of persistent organic pollutants, namely polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls. The process simply involves (1) pouring the liquid milk into the hydrolysis beaker with reagents and standards, (2) drying the obtained fat on a filter paper and (3) obtaining pure fat via the modified Soxhlet extraction using 100mL of hexane per sample. This technique is in contrast to traditional manually intense liquid-liquid extractions and avoids the preparatory step of freeze-drying the samples for pressurized liquid extractions. Along with these extraction improvements, analytical results closely agree between the methods, thus no quality has been compromised. The native spike (n=12) and internal standard (n=24) precision and accuracy results are within EPA Methods 1613 and 1668 limits. While the median (n=6) Toxic Equivalency Quotient (TEQ) for polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans and the concentration of the marker polychlorinated biphenyls show a percent difference of 1% and 12%, respectively, compared to 315 previously analyzed milk samples at the same laboratory using liquid-liquid extraction. During our feasibility studies, both egg and fish tissue show substantial promise using this technique as well.

Modeling and assaying dioxin-like biological effects for both dioxin-like and certain non-dioxin-like compounds.

13C NMR data have been correlated to Toxic Equivalency Factors (TEFs) of the 29 PCDDs, PCDFs, or PCBs for which non-zero TEFs have been defined. Such correlations are called quantitative spectrometric data-activity relationship (QSDAR) models. An improved QSDAR model predicted TEFs of 0.037 and 0.004, respectively, for 1,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 1,2,3,4,7-pentachlorodibenzo-p-dioxin (PeCDD), both among the 390 congeners for which zero value TEFs are assumed. A QSDAR model of Relative Potency (REP) values estimated the corresponding values as 0.115 and 0.020. Results from both models indicated that these two congeners may exhibit significant dioxin-like toxicity. If other such congeners have non-zero toxicity, TEF-based risk assessments of some dioxin-, furan-, or PCB-contaminated sites or foods may underestimate toxicity. Both models were extensively cross-validated and the TEF model was externally validated. We confirmed the predictions by an independent in vitro method, a luciferase gene expression assay based on mouse liver cells that found REPs of 0.027 and 0.013, respectively, for 1,3,7,8-TCDD and 1,2,3,4,7-PeCDD. The QSDAR-estimated and gene-expression assayed values agreed. The models were used to predict activity for an applicability domain including 108 non-2,3,7,8 dioxin, furan, or PCB congeners and 2,3,7,8-tetrachlorophenothiazine, a dioxin analog proposed as a drug candidate. This study showed that QSDAR prediction followed by a relatively inexpensive in vitro assay could be used to nominate a few candidates among hundreds for further investigation. It suggested that in silico and in vitro nomination protocols may facilitate practical risk assessment when chemical family members exhibit different degrees of toxicity operating via a common mechanism.

Dioxin and furan levels found in tampons.

BACKGROUND: Human exposure to dioxins and furans through diet and other sources has been of concern for many years. One specific concern, related to exposure in women's health, is the possible link to endometriosis. Although there are differences in opinion about this link, the concern from the public is real. Congressional interest has prompted investigations to determine the amounts of dioxins and furans present in feminine hygiene products available within the United States. METHODS: Tampon samples were analyzed via Gas Chromatography/High Resolution Mass Spectrometry (GC/HRMS) using a Micromass AutoSpec Ultima high resolution mass spectrometer at 10,000 mass resolution. As data were confirmed and quantified using direct isotope dilution, only the 17 2,3,7,8-chlorine-containing dioxin and furan concentrations were calculated from these analyses. RESULTS: A total toxic equivalence (TEQ), using the World Health Organization's toxic equivalency factor (TEF) values, was calculated for each sample. The calculated TEQs for samples were not statistically different from those of the calculated TEQs using the average limit of detection (LOD) values. CONCLUSIONS: Data show results similar to those reported by DeVito and Schecter (Environ Health Perspect 2002;110:23) in that most of the dioxins and furans were below the detection limit or estimated detection limits (EDLs).