This study measured levels of PBDEs, PCBs, and OCPs in paired whole blood and serum samples from three subjects to estimate whole blood-to-serum conversion factors. The chemicals were extracted from the samples using liquid-liquid extraction and analyzed using GC-MS/MS. Conversion factors ranged from 0.46-1.96 with PBDE-47 closest to the theoretical value for complete serum partitioning. PCBs 74 and 99 had conversion factors above 1.1, indicating they partition more into cellular components than serum. Larger studies are needed to accurately quantify average population conversion factors.

1. INTRODUCTION
METHODS
ACKNOWLEDGEMENTS & DISCLAIMER
A variety of biospecimens have been used to assess exposure to PBDEs, including
serum (plasma with clotting factors removed), plasma, and whole blood; however,
the partitioning of PBDEs between blood components is not well described.
Studies have observed variation in PCB partitioning between blood components
based on chlorination and PBDE partitioning may likewise depend on the extent of
bromination.
As part of the California Childhood Leukemia Study, we previously measured
PBDEs in the whole blood of 191 children. For the purposes of inter-study
comparisons, here, we estimate whole blood-to-serum conversion factors (η) for
PBDEs, PCBs and OCPs. Since PBDEs are largely nonpolar, they are expected to
partition preferentially along with lipids into the serum layer of whole blood.
• Six 1mL aliquots of serum and three 1mL aliquots of whole blood obtained from each of three
subjects
• Blood/Serum sample preparation:
• Internal standards added to each 1mL sample
• 4 liquid-liquid extractions
• Silica gel column chromatography
• Injection standards added
• PBDEs, PCBs and OC Pesticides analyzed with gas chromatography-triple quadrupole mass
spectrometry (GC-MS/MS)
• Compared to NIST 1958 certified values, the average percentage error in replicate samples was
less than 20% for all PBDEs.
This work was supported in part by the National Institute of Environmental Health Sciences (NIEHS, grant numbers R01ES009137, R01ES015899, P42ES0470518, and
P01ES018172); by the Intramural Research Program of the National Cancer Institute (NCI), National Institute of Health (Subcontracts 7590-S-04, 7590-S-01); by the NCI (Contract
N02-CP-11015); and by the Environmental Protection Agency (EPA, grant number RD83451101). We thank the CCLS staff for their effort and dedication and specifically acknowledge
Mr. Praphopphat Adhatamsoontra for preparing the blood samples for chemical analysis. The opinions given by the authors are not necessarily those of the California Department of
Toxics Substances Control (DTSC), the California Environmental Protection Agency (Cal-EPA), the NIEHS, or the NCI. Mention of any product or organization does not constitute an
endorsement by DTSC, Cal-EPA, NIEHS, or NCI
Non-polar
Polar
Column Chromatography
GC-QQQMS
Serum ~55%
Centrifugation
Whole
blood
Serum
~45%
Cellular
Components
Vortex
Blood
Draw
RESULTS
Table 2. Whole blood-to-serum conversion factors (η)
and 95% confidence intervals for selected PBDEs,
PCBs, and OC pesticides
Table 1. Summary statistics for selected PBDEs, PCBs, and OC pesticides.
Notes:
• Reported as
𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑊ℎ𝑜𝑙𝑒 𝐵𝑙𝑜𝑜𝑑
𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑆𝑒𝑟𝑢𝑚
Individuals Subject 1 Subject 2 Subject 3
PBDE-47
0.54
(0.43,0.66)
0.46
(0.37,0.53)
0.86
(0.45,1.18)
PBDE-99
0.57
(0.10,1.44)
0.46
(0.33,0.61)
1.96
(0.68,3.24)
PBDE-153
0.76
(0.50,1.12)
1.63
(0.47,11.34)
0.68
(0.35,1.22)
HCB
0.72
(0.60,0.82)
0.84
(0.53,1.09)
1.26
(0.76,2.91)
p,p'-DDE
0.47
(0.44,0.52)
0.40
(0.36,0.45)
0.76
(0.46,1.72)
PCB-74
1.35
(0.72,2.42)
1.26
(0.67,1.92)
1.11
(0.63,2.55)
PCB-99
1.17
(0.33,2.67)
1.75
(0.73,3.64)
1.17
(0.65,3.58)
PCB-118
0.60
(0.41,0.85)
0.74
(0.60,0.91)
0.98
(0.62,2.05)
PCB-138
0.63
(0.42,0.92)
0.54
(0.42,0.66)
0.69
(0.37,1.39)
PCB-153
0.62
(0.50,0.72)
0.51
(0.45,0.58)
0.77
(0.43,1.67)
PCB-180
0.54
(0.29,1.18)
0.55
(0.44,0.79)
0.76
(0.45,1.74)
REFERENCES
DISCUSSION
• We observed substantial variation in η between subjects, which may be explained by
underlying variation in the proportion of the cellular component comprised in the whole
blood [range of 40-54% in adult males (1)].
• Assuming a cellular component equal to the average value of 45%:
• The median η for PBDE-47 is η = 0.54, which corresponds closely to the
theoretical η-value for a chemical that completely partitions into serum (η=0.55)
• In concordance with another study (2), the median η for PCBs 74 and 99 are
η > 1.1, which means they partition more into the cellular component phase
than serum and suggests that normalization by serum lipid content may not be
appropriate for these chemicals.
• Assuming a cellular component equal to the maximum value of 54% yields a
theoretical minimum of η = 0.46, yet we observed individual η-values below that
threshold, possibly due to measurement error.
• Larger number of subjects needed for more accurate quantification of population average
η-values
• To estimate subject-specific η-values, it may be necessary to adjust for the proportion of
the cellular component comprised in the whole blood.
0.55 < η < 1.1
η = 0.55
η > 1.1
η = 1.1
Figure 1a. Whole blood-to-serum conversion factors (η) and 95% confidence intervals for
selected PBDEs, PCBs, and OC pesticides
1. Billett HH. Hemoglobin and Hematocrit. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory
Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 151. Available from: http://www.ncbi.nlm.nih.gov/books/NBK259/
2. J. Mes , L. Marchand , D. Turton , P. Y. Lau & P. R. Ganz (1992) The Determination of Polychlorinated Biphenyl Congeners and Other
Chlorinated Hydrocarbon Residues in Human Blood, Serum and Plasma. A Comparative Study, International Journal of Environmental
Analytical Chemistry, 48:3-4, 175-186, DOI: 10.1080/03067319208027398
Chemical
partitions
more into
serum
Chemical
partitions
more into
cellular
components
Chemical
partitions
completely
into serum
Chemical
partitions equally
into serum and
cellular
components
CONCENTRATIONS OF PBDES, PCBs and OCPs IN PAIRED
WHOLE BLOOD AND SERUM SAMPLES
Warren Li1, Todd P. Whitehead1, Sabrina Crispo Smith2,3, June-Soo Park2, Stephen M. Rappaport1, Catherine Metayer1, Myrto X. Petreas2,
1UC Berkeley School of Public Health; 2California Department of Toxic Substances Control, Environmental Chemistry Laboratory; 3Sequoia Foundation
wentaii@berkeley.edu
When whole blood
is left undisturbed,
distinct layers will
form as follows:
Figure 1b. Theoretical η-values
for different types of partitioning.
Colored regions correspond with
Figure 1a.
Notes:
• Calculations assume a 45% cellular
component in whole blood
region: η < 0.55 represents a
theoretically undefined region
Red region
Tan region
Liquid-Liquid Extraction
*Extends to 11.34
Above Method
Detection Limit
Above Method
Detection Limit
% Minimum Medium Maximum % Minimum Medium Maximum
PBDE-47 100 0.014 0.080 0.042 100 0.021 0.147 0.178
PBDE-99 78 0.001 0.006 0.013 72 0.002 0.011 0.029
PBDE-153 89 0.013 0.026 0.066 100 0.003 0.026 0.119
HCB 100 0.016 0.020 0.042 100 0.006 0.021 0.063
p,p'-DDE 100 0.151 0.429 0.607 100 0.188 1.081 1.230
PCB-74 100 0.003 0.006 0.008 100 0.002 0.005 0.008
PCB-99 100 0.001 0.003 0.006 100 0.001 0.002 0.005
PCB-118 100 0.005 0.009 0.013 100 0.007 0.012 0.014
PCB-138 100 0.004 0.010 0.017 100 0.007 0.017 0.020
PCB-153 100 0.008 0.017 0.039 100 0.013 0.033 0.039
PCB-180 100 0.002 0.010 0.033 100 0.004 0.020 0.034
Congener
Serum
Concentration, ng/g wet weightConcentration, ng/g wet weight
Whole Blood
Whole Blood
(Green Top
Na-Heparin Tube)
Whole Blood
(Red Top Tube)