Environmental Health & Engineering, Inc.
Newton, Massachusetts

Interpreting PCB, Dioxin, and Furan Congener Testing Results
Chafee Social Science Center

May 1, 2001

Background
Congener Identification
Results
Concept of Toxic Equivalency
Interpreting Chafee Dioxin Results
Next Steps
Table 1: Dust Sample Results
Table 2: Building Material Results
Table 3: Sampling Results

Background: Environmental Health and Engineering (EH&E) has received and reviewed the results of additional congener testing as part of the process to characterize the source of PCB contamination observed in Chafee Social Sciences Building (Chafee). Nine building material samples were identified as having elevated levels of PCBs, based on data from Phase II screening and testing in February. These materials and ten dust samples collected from several locations throughout the building were sent to Triangle Laboratories (Durham, NC) to assess the PCB congener profile (EPA Method Modified 1668A) in the samples. This latest round of testing focused on materials that were collected during the Phase II testing when EH&E collected samples of building materials from various locations within Chafee to determine PCB content. In contrast, the goal of Phase II screening sampling phase was to quantify the level of PCBs in a variety of building materials that may be the source of the PCB residues found in the building during the Phase I sampling effort. By comparison, the goals of this testing was to quantify concentrations of specific PCB congeners that will be used in the ongoing risk assessment and source apportionment. The source apportionment analysis of the results from this latest testing will help map out the distribution of congeners found in samples and material samples that can be identified and matched as possible sources of PCBs found in earlier dust and air samples.

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Congener Identification: Prior to analysis, EH&E reviewed the literature on specific congeners that constitute the Aroclor 1254 mixture. EH&E chose the Aroclor 1254 pattern for analysis because all of the air and dust samples from prior sampling have only detected measurable amounts of Aroclor 1254 versus other Aroclor mixtures that were tested. EH&E focused the analysis on a limited list of specific congeners that represents 60-70% of Aroclor 1254 by weight, and included 14 congeners that are listed by the World Health Organization (WHO) as PCB congeners suspected or known to pose adverse health effects on humans in the analysis. In addition, the National Oceanographic Atmospheric Administration (NOAA) maintains a list of 24 PCB congeners that are commonly analyzed and this list was also included as part of this testing. The combination of these three target analyte lists resulted in a total list of 34 distinct congeners that were analyzed. The analyzed samples will provide measured concentrations of these congeners that will be used in the risk analysis.

In addition to testing specific PCB congeners, EH&E also had four samples analyzed for dioxins and furans (EPA Method 8290) at the request of the Chafee Hall Advisory Committee. Dioxins and furans are generally released from emissions due to incineration processes and were also historically found in herbicides and pesticides. It is thought that dioxins and furans transported from outside sources over the course of the building history may pose a contributing health hazard. In order to address the possible dioxin and furan congener contamination, standard testing of seven dioxin congeners and 10 furan congeners were conducted, in accordance with the latest list recommended by the WHO.

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Results: The elevated levels of PCBs in the tested materials were consistent with PCB mixture levels measured in materials that had been analyzed in the Phase II screening testing. The results are presented in the following tables. Caulking material appeared to contain the highest levels of PCBs as observed in previous testing. More importantly, Levels of the most toxic congeners were much lower or not detected in the samples. In addition, specific congeners found in the dust samples correlated well with congeners found the tested materials. This appears to support the idea that building materials are the source of contamination. These results support the hypothesis that gradual degradation of building materials are the sources to measurable amounts of PCBs found in air and dust samples. It should also be noted that the dust samples that were taken were from the interior areas of unit ventilators or air returns, areas where it is unlikely that occupants have direct exposure.

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Concept of Toxic Equivalency: One of the primary purposes of this third round of testing is to provide specific congener concentrations that can be used in the risk assessment. For the purposes of risk assessment, the EPA has developed a process to estimate toxicity of specific dioxins and PCB dioxin-like congeners relative to a reference toxicity value. The reference congener used is 2,3,7,8 TCDD, which is given a Toxicity Equivalency Factor (TEF) value of 1.0, being the most toxic dioxin congener. All other congeners (dioxins, furans, and dioxin-like PCBs) have values that are either equivalent to this reference value or lower (equivalent to or less toxic than 2,3,7,8- TCDD). The next step of the process involves the multiplication of the congener specific TEF value by the actual measured concentration of each individual congener. A congener with a TEF less than 1.0, will have an adjusted concentration that is lower than the actual level measured in the analysis.

After all of the congeners are adjusted by their respective TEFs, the adjusted concentrations are summed to arrive at a Toxic Equivalency (TEQ) for the total mixture for dioxins and furans, and PCB dioxin-like congeners. The total TEQ value is then used in the risk analysis, and can be compared to other TEQ values to assess the relative potencies of various mixtures of PCBs, dioxins, and furans.

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Interpreting Chafee Dioxin Results: None of the samples had high levels for the more toxic dioxin-like congeners, although less toxic congeners were found in the samples. There are no data available for dioxin and furan levels in dust and in the building environment. The four samples taken from Chafee reported non-detect values for the congeners with the highest toxic equivalent factors. Measured concentrations for the least toxic dioxins were higher, but these values are still much lower than measured PCB values. Additionally, comparisons of the dioxin and furan analysis can be made to the PCB congeners through the use of TEQs to determine relative toxicity. Based on the data analyzed, the dioxin and furan TEQs are much lower than the observed PCB concentrations. These results indicate that the PCB concentrations present that are the main component of risk within Chafee. As a result of the clean-up for PCBs, dioxin concentrations will also be reduced since the clean-up will also result in the clean-up of residual amounts of dioxin.

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Next Steps: Clean-up of PCBs will also result in the clean-up of the dioxin and furans. Clean-up plans are also in progress that will capture materials with higher than accepted levels of PCBs found within them. In addition, data from the congener analysis will be used in current risk assessment for Chafee Hall. As part of the risk assessment, additional air samples will be taken to characterize specific PCB congeners that are found in the air.

Table 1: Dust Sample Results Taken from sampling on February 16th and 17th, 2001 PCB Concentration of WHO listed congeners (ppm)
 
High Rise
Low rise
Lecture Hall
IUPAC Number
Sample 37121
Sample 37122
Sample 37124
Sample 37125
Sample 37126
Sample 37127
Sample 37128
Sample 37129
Sample 37130
Sample 37132
UV, Rm 514
UV, Rm 801
UV, Rm 606
UV, Rm 413
UV, Rm 419
UV, Rm 312
UV, Rm 228
HU, Rm 223
AR, Rm 271
AR, Rm 277
77
0.032
0.003
0.018
0.040
0.027
0.037
0.052
0.015
0.015
0.021
81
0.016
0.002
0.009
0.008
0.016
0.016
0.041
0.003
ND
0.002
105
0.963
0.129
0.652
0.987
0.96
0.602
3.04
0.077
0.061
0.053
114
0.127
0.014
0.074
0.125
0.128
0.079
0.425
0.009
0.008
0.007
118
3.57
0.38
1.36
3.44
3.56
1.97
4.52
0.207
0.161
0.121
123
0.734
0.084
0.443
0.76
0.762
0.49
2.22
0.049
0.041
0.032
126
ND
ND
0.002
ND
ND
ND
0.007
0.0004
ND
0.0004
156
0.172
0.021
0.114
0.22
0.139
0.096
0.982
0.008
0.009
0.007
157
0.049
0.005
0.03
0.050
0.035
0.019
0.244
0.002
ND
0.001
167
0.129
0.012
0.07
0.138
0.086
0.050
0.51
0.005
ND
0.004
169
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
170
0.108
0.025
0.083
0.1
0.153
0.123
0.821
0.022
0.034
0.044
180
0.099
0.018
0.064
0.082
0.134
0.11
0.521
0.019
0.031
0.041
189
ND
0.001
0.002
ND
0.003
ND
0.014
0.001
ND
0.001
Total WHO PCBs (n=14)
6.0
0.7
2.9
5.9
6.0
3.6
13.4
0.4
0.4
0.3
Total Tested PCBs (n=34)
18.1
2.9
9.9
19.7
22.2
23.9
35.0
2.3
3.3
4.1
Adjusted Total PCBs* (n=34)
36.2
5.8
19.8
39.4
44.4
27.8
70.0
4.6
6.6
8.2
* To compare levels of congener specific data with total PCBs, as an Aroclor. The total congener PCB amount must be multiplied by a factor of two. This convention has been established as a way to estimate total PCBs from congener data to account for the likely presence of unmeasured congeners in the analysis.
ND- Non detectable with limits of detection
UV- Unit ventilator
HU- Heating unit
AR- Air return

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Table 2: Building Material Results from Sampling on February 16th and 17th, 2001 PCB Concentration of WHO listed congeners (ppm)
IUPAC Number
 
Sample 37565
Sample 37566
Sample 37566 B
Sample 37567
Sample 37568
Sample 37569
Sample 37570
Sample 37571
Sample 37576
Exterior window glazing
Lighter Cg
Darker Cg
Cg
Grout from Rm 145
Cg
Mastic from UV
Puff foam from UV
Ribbed gasket material
77
2.150
14.400
14.500
5.150
ND
16.550
0.249
0.094
0.479
81
ND
15.470
18.990
6.750
ND
19.580
0.084
ND
0.578
105
21.570
433.340
1,251.7
306.760
0.005
1,335.8
1.390
0.879
16.420
114
ND
113.210
111.810
53.400
ND
127.370
0.209
0.089
2.180
118
59.910
583.630
3,926.4
436.190
0.016
4,485.1
4.710
2.520
62.130
123
ND
528.650
726.810
271.570
0.004
794.540
1.590
0.588
ND
126
ND
1.670
ND
0.669
ND
ND
ND
ND
ND
156
2.670
262.310
208.910
101.320
ND
275.610
0.101
0.120
1.190
157
ND
75.970
64.000
29.540
ND
64.730
0.016
0.030
0.311
167
ND
161.060
133.490
74.590
ND
148.320
0.075
0.054
0.853
169
ND
ND
ND
ND
ND
ND
ND
ND
ND
170
1.400
145.510
160.960
62.060
0.001
176.000
0.058
0.094
0.709
180
0.950
78.030
82.270
39.280
0.001
114.530
0.063
0.066
0.433
189
ND
1.430
ND
0.936
ND
4.660
ND
ND
ND
Total WHO PCBs (n=14)
88.7
2,414.7
6,699.8
1,388.2
0.03
7,562.8
8.5
4.5
85.3
Total Tested PCBs (n=34)
243
6,182
17,051
4,066
0.2
18,438
31
19
861
Adjusted Total PCBs* (n=34)
486
12,364
34,102
8,172
0.4
36,876
62
38
1,722
Phase II Result (Aroclor 1254)
630
10,000
10,000
10,000
N/A
33,000
63
36
4,300
* To compare levels of congener specific data with total PCBs, as an Aroclor. The total congener PCB amount must be multiplied by a factor of two. This convention has been established as a way to estimate total PCBs from congener data to account for the likely presence of unmeasured congeners in the analysis
ND- Non detectable with limits of detection
Cg- Caulking Material found between window frame and brick
UV- Unit ventilator

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Table 3: Sampling Results from samples taken on February 16th and 17th, 2001 Dioxin and Furan congeners (ppb) Different from Table 1 & 2.
 
Sample 37568
Sample 37126
Sample 37128
Sample 37130
Grout from room 145 Dust from unit ventilator, room 419 Dust from unit ventilator, room 228 low-rise Dust from air return, room 271 lecture hall
Dioxins
2,3,7,8-TCDD
ND
ND
ND
ND
1,2,3,7,8-PeCDD
ND
ND
ND
ND
1,2,3,4,7,8-HxCDD
ND
ND
0.049
ND
1,2,3,6,7,8-HxCDD
0.179
0.144
0.79
0.080
1,2,3,7,8,9-HxCDD
0.054
0.083
0.203
0.048
1,2,3,4,6,7,8-HpCDD
0.426
2.87
140.44
1.66
1,2,3,4,6,7,8,9-OCDD
1.84
19.05
586.22
11.73
Furans
2,3,7,8-TCDF
0.007
0.083
0.040
0.009
1,2,3,7,8-PeCDF
ND
0.058
0.018
ND
2,3,4,7,8-PeCDF
0.003
0.044
0.030
0.02
1,2,3,4,7,8-HxCDF
0.012
0.112
0.090
0.065
1,2,3,6,7,8-HxCDF
0.004
ND
0.037
0.029
2,3,4,6,7,8-HxCDF
0.009
0.049
0.055
0.051
1,2,3,7,8,9-HxCDF
ND
ND
0.007
0.011
1,2,3,4,6,7,8-HpCDF
0.047
0.47
1.17
0.503
1,2,3,4,7,8,9-HpCDF
ND
ND
0.097
ND
1,2,3,4,6,7,8,9-OCDF
0.022
0.42
1.76
0.507
ND- Non detectable with limits of detection

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