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MICHIGAN DIOXIN EXPOSURE STUDY IMPACT OF THE CHANGES IN WHO TEF VALUES FROM 1998 TO 2005 ON THE TOTAL TEQ VALUES IN SERUM, HOUSEHOLD DUST AND SOIL Hong B1, Hedgeman E1, Gillespie BW2, Chen Q2, Lee S-Y2, Chang C-W1, Zwical L1, Knutson K1, Towey T3, Olson K4, Sima C2, Luksemburg W5, Maier M5, Adriaens P3, Demond A3, Lepkowski J4, Franzblau A1, Garabrant D1 1Department of Environmental Health Sciences, University of Michigan School of Public Health, 109 S Observatory, Ann Arbor, MI 48109; 2Department of Biostatistics, University of Michigan School of Public Health, 109 S Observatory, Ann Arbor, MI 48109; 3Department of Environmental and Water Resources Engineering, University of Michigan College of Engineering, Ann Arbor, Michigan 48109 USA; 4Survey Research Center, Institute for Social Research, University of Michigan, 426 Thompson Street, Ann Arbor, Michigan 48104; 5Vista Analytical Lab, 1100 Windfield Way, El Dorado Hills, CA 95762. Abstract The University of Michigan Dioxin Exposure Study (UMDES) previously calculated the toxic equivalency (TEQ) values based on the World Health Organization (WHO) 1998 consensus toxicity equivalency factors (TEFs),1 in serum, household dust and soil from a sample of adults in Michigan, USA. In June 2005, the TEFs were reevaluated in a WHO expert meeting in Geneva, Switzerland and new WHO 2005 TEFs were presented.2 All the TEQ values in the study samples have been recalculated based on the 2005 TEFs. Compared to the 1998 TEFs, the overall median TEQ values decreased 26% in serum samples, 6% in dust samples, and 6% in soil house perimeter samples; the percent contribution of polychlorinated dibenzodioxins (PCDDs) to the serum TEQ increased about 16%, polychlorinated dibenzofurans (PCDFs) slightly decreased about 0.4%, and polychlorinated biphenyls (PCBs) decreased about 16%. Among the seven congeners (2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 2,3,4,7,8PeCDF, PCB-118, PCB-126 and PCB-156) that had the highest contribution to the serum TEQ using 1998 TEFs in the studied blood samples, PCB-118 and PCB-156 together contributed only 3% and were not among the top 7 contributed congeners to TEQ using 2005 TEFs. Introduction The University of Michigan Dioxin Exposure Study (UMDES) was designed to assess exposures to polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in adults in 5 counties of Michigan, USA, and to identify factors that explain variation in serum dioxin levels. 3 All TEQ values for serum, household dust and soil samples in the study, originally calculated based on WHO 1998 TEF values, were recalculated based on the WHO 2005 TEFs (See Appendix 1). The goal of this report is to present the changes in the total TEQ levels of serum, household dust and soil samples, after implementation of 2005 TEFs. Materials and Methods The study included Michigan populations who live in Midland County, Saginaw County, and part of Bay County, both in and out of the Tittabawassee River flood plain (Midland/Saginaw), and who live in Jackson and Calhoun Counties (Jackson/Calhoun), which represent a referent county with no appreciable industrial sources of dioxins. The studied populations were sampled using a two-stage area probability household sample design,4 and the statistical analyses were sample weighted to reflect the population from which the sample was selected. To contribute a blood sample, participants had to be at least age 18 years, have lived in the current residence for 5 years or more, and be capable of safely donating 80 milliliters of blood. All serum results were lipid adjusted. To contribute dust or soil samples, participants had to also be the owner of their property. For soil samples, this report only shows the results for the top 1 inch house perimeter samples. Full details on the study are posted on the website (www.umdioxin.org). Results below the limit of detection (LOD) were substituted with LOD/2 for analysis. All statistical analyses were performed using SAS version 9.1. Organohalogen Compounds Vol 69 (2007) O-050 218 MICHIGAN DIOXIN EXPOSURE STUDY Results and Discussion A total of 946 serum samples, 764 household dust samples and 766 soil samples from around participant homes were collected. Table 1 presents descriptive statistics (Minimum, Mean, Median, 75th percentile, and Maximum) for both TEQ-1998 and TEQ-2005 values for the serum, dust, and soil house perimeter top 1 inch (Soil HP1) samples in our study. Results are shown in Table 1 for all samples in the entire studied area (Overall), samples from the combined geographic area Midland/Saginaw (M/S), and samples from the referent county Jackson/Calhoun (J/C). There are two major findings from Table 1: 1. In general, the TEQ-2005 values are lower than the TEQ-1998 values across serum, household dust and Soil HP1 samples. For serum samples, the overall median TEQ-2005 value (19.6 ppt) decreased 26% compared to the overall median TEQ-1998 value (26.4 ppt). For household dust samples, the overall median TEQ-2005 value (16.2 ppt) decreased 6% compared to the overall median TEQ-1998 value (17.3 ppt). For Soil house perimeter samples, the over median TEQ-2005 value (4.5 ppt) decreased 6% compared to the overall median TEQ-1998 value (4.8 ppt). 2. Regarding the comparison between the TEQ levels in Midland/Saginaw and Jackson/Calhoun, the following relationships remain the same for both TEQ-1998 and TEQ-2005: People who lived in Midland/Saginaw had higher levels of serum dioxins than people in Jackson/Calhoun, with the median TEQ value about 2 ppt higher. For household dust samples, the mean TEQ level is higher in Jackson/Calhoun, while the median level is higher in Midland/Saginaw. For soil house perimeter samples, the median TEQ levels are about 2 to 3 ppt higher in Midland/Saginaw compared to Jackson/Calhoun. Table 1: Descriptive statistics for UMDES samples (unit: Parts Per Trillion) TEQ calculated from 1998 TEFs TEQ calculated from 2005 TEFs Samples Region N Min Mean Median P75* Max Min Mean Median Serum Overall 946 4.7 32.4 26.4 39.9 238 3.8 23.9 19.6 M/S+ 695 4.7 35.2 27.3 44.1 238 3.8 26.5 20.7 J/C 251 5.2 29.7 24.8 36.2 150.4 4.7 21.3 18.5 Overall 764 1.5 41.9 17.3 33.1 1746 1.4 36.7 16.2 Dust M/S+ 566 1.5 38.2 19.0 31.5 1746 1.4 34.9 17.6 J/C 198 2.2 46.0 14.4 35.3 1080 2.1 38.8 13.8 Overall 766 0.4 16.6 4.8 11.7 3056 0.4 14.3 4.5 Soil HP1** M/S+ 572 0.9 24.9 6.4 19.2 3056 0.8 21.6 6.0 J/C 194 0.4 8.3 3.6 8.5 329.7 0.4 6.9 3.6 P75*: 75th percentile; Soil HP1**: Soil House Perimeter Top 1 inch; M/S+: Midland/Saginaw; J/C: Jackson/Calhoun. P75* 29.2 32.3 25.3 29.7 29.0 32.2 10.3 17.2 7.6 Max 210.7 210.7 109 1749 1749 1114 2300 2300 186.2 Previously, most statistical analyses focused on the TEQ and the seven specific congeners that had the highest contribution to the serum TEQ-1998: 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, PCB126, PCB-118, and PCB-156. We have recalculated the percent contribution of each congener to the total serum TEQ-2005. The results show that the top 7 congeners contributing to the serum TEQ-2005 are 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,7,8,9-HxCDD, 2,3,4,7,8-PeCDF, PCB-126, and PCB-169. PCB-118 and PCB-156 together contribute only 3% and are not among the top 7 congeners contributing to the serum TEQ2005. Organohalogen Compounds Vol 69 (2007) O-050 219 MICHIGAN DIOXIN EXPOSURE STUDY Across blood, household dust and soil house perimeter samples, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,6,7,8HxCDD, 2,3,4,7,8-PeCDF and PCB-126 remain among the top 7 congeners for the total TEQ-2005, and are the top 5 congener contributors for serum TEQ-2005. Among these five congeners, the TEF only changed for 2,3,4,7,8PeCDF: 1998 TEF=0.5 vs. 2005 TEF=0.3. Table 2 shows details of their percent contributions to the total TEQ using 1998 and 2005 TEFs. For serum samples, these five congeners contributed more in TEQ-2005 (about 76% to the total TEQ), compared to 62% in TEQ-1998. For household dust, they contributed a similar percent to both TEQ-1998 and TEQ-2005, about 41%-42%. For soil house perimeter, they contributed a similar percent to both TEQ-1998 and TEQ-2005, about 60%-62%. Table 2: Percent contribution to total TEQ in UMDES samples (Numbers in the table are the average percent contribution over all eligible samples) Serum Household Dust Soil House Perimeter Percent contribution TEQ- TEQ- TEQ- TEQ- TEQ- TEQ- to total TEQ (%) 1998 2005 1998 2005 1998 2005 2,3,7,8-TCDD 7.25 9.58 4.19 4.49 14.56 15.4 1,2,3,7,8-PeCDD 20.59 27.29 9.16 9.75 14.37 15.37 1,2,3,6,7,8-HxCDD 14.63 19.49 9.31 9.84 4.53 4.83 2,3,4,7,8-PeCDF 10.86 8.69 6.39 4.24 18.02 12.28 PCB-126 8.6 11.41 12.07 14.07 10.93 12.24 Sum 61.93 76.46 41.12 42.39 62.41 60.12 Table 3 presents the percent contribution of PCDDs, PCDFs, and PCBs to total TEQ-1998 and TEQ-2005. The percent contribution of PCDD increased about 16% for serum, 7% for dust, and 5% for soil house perimeter, after implementation of 2005 TEFs. The percent contribution of PCDFs decreased about 1% to 4% after implementation of the 2005 TEFs. The percent contribution of PCBs decreased about 16% for serum, 6% for dust and 1% for Soil house perimeter, after implementation of 2005 TEFs. Table 3: percent contribution to total TEQ for PCDDs, PCDFs, and PCBs Percent Contribution to the TEQ (%) 1998 TEFs 2005 TEFs Changes in % by using 2005 TEFs Serum PCDDs PCDFs PCBs 48.65 16.83 34.53 64.72 16.43 18.85 Increases 16% Decreases <1% Decreases 16% PCDDs 59.51 66.79 Dust PCDFs 16.95 15.62 PCBs 23.54 17.59 Increases 7% Decreases 1% Decreases 6% PCDDs Soil HP1** PCDFs PCBs 49.44 36.20 14.36 54.35 32.07 13.58 Increases 5% Decreases 4% Decreases 1% Soil HP1**: Soil House Perimeter Top 1 inch Acknowledgments Financial support for this study comes from the Dow Chemical Company through an unrestricted grant to the University of Michigan. The authors acknowledge Ms. Sharyn Vantine for her continued assistance and Drs. Linda Organohalogen Compounds Vol 69 (2007) O-050 220 MICHIGAN DIOXIN EXPOSURE STUDY Birnbaum, Ron Hites, Paolo Boffetta and Marie Haring Sweeney for their guidance as members of our Scientific Advisory Board. References 1. Van den Berg M, Birnbaum L, Bosveld ATC, Brunstrom B, Cook P, Feeley M, Giesy JP, Hanberg A, Hasegawa R, Kennedy SW, Kubiak T, Larsen JC, Van Leeuwen FXR, Liem AKD, Nolt C, Peterson RE, Poellinger L, Safe S, Schrenk D, Tillitt D, Tysklind M, Younes M, Waern F, Zacharewski T. Environmental Health Perspectives 1998; 106:775. 2. Van den Berg M, Birnbaum L, Denison M, De Vito M, Farland W, Feeley M, Fiedler H, Hakansson H, Hanberg A, Haws L, Rose M, Safe S, Schrenk D, Tohyama C, Tritscher A, Tuomisto J, Tysklind M, Walker N, Peterson RE. Toxicological Sciences 2006; 93: 223. 3. Franzblau A, Garabrant D, Adriaens P, Gillespie BW, Demond A, Olson K, Ward B, Hedgeman E, Knutson K, Zwica L, Towey T, Chen Q, Ladronka K, Sinibaldi J, Chang S-C, Lee S-Y, Gwinn D, Sima C, Swan S, Lepkowski J. Organohalogen Comp 2006; 68:205 4. Lepkowski J, Olson K, Ward B, Ladronka K, Sinibaldi J, Franzblau A, Adriaens P, Gillespie BW, Chang SC, Chen Q, Demond A, Gwinn D, Hedgeman E, Knutson K, Lee S-Y, Sima C, Swan S, Towey T, Zwica L, Garabrant D. Organohalogen Comp 2006; 68:209 Appendix 1: Summary of WHO 1998 and WHO 2005 TEF values Compound WHO 1998 TEF WHO 2005 TEF* chlorinated dibenzo-p-dioxins 2,3,7,8-TCDD 11 1,2,3,7,8-PeCDD 11 1,2,3,4,7,8-HxCDD 0.1 0.1 1,2,3,6,7,8-HxCDD 0.1 0.1 1,2,3,7,8,9-HxCDD 0.1 0.1 1,2,3,4,6,7,8-HpCDD 0.01 0.01 OCDD 0.0001 0.0003 chlorinated dibenzofurans 2,3,7,8-TCDF 0.1 0.1 1,2,3,7,8-PeCDF 0.05 0.03 2,3,4,7,8-PeCDF 0.5 0.3 1,2,3,4,7,8-HxCDF 0.1 0.1 1,2,3,6,7,8-HxCDF 0.1 0.1 1,2,3,7,8,9-HxCDF 0.1 0.1 2,3,4,6,7,8-HxCDF 0.1 0.1 1,2,3,4,6,7,8-HpCDF 0.01 0.01 1,2,3,6,7,8,9-HpCDF 0.01 0.01 OCDF 0.0001 0.0003 non-ortho substituted PCBs PCB 77 0.0001 0.0001 PCB 81 0.0001 0.0003 PCB 126 0.1 0.1 PCB 169 0.01 0.03 mono-ortho substituted PCBs PCB 105 0.0001 0.00003 PCB 114 0.0005 0.00003 PCB 118 0.0001 0.00003 PCB 123 0.0001 0.00003 PCB 156 0.0005 0.00003 PCB 157 0.0005 0.00003 PCB 167 0.00001 0.00003 PCB 189 0.0001 0.00003 * numbers in bold indicate a change in TEF Organohalogen Compounds Vol 69 (2007) O-050 221