Appendix D Food Codes for NHANES - OEHHA

Scientific Review PanelSRP Draft Version 2 February,June 2012
percent body fat of older adults) in addition to accounting for the substantial
variability between individual congeners of PCDDs, PCDFs and dioxin-like PCBs.
To calculate oral Tcos, OEHHA used adjusted reference half-lives for the
chemicals in the adult human body derived from dietary and occupational
exposures. OEHHA estimated oral Tcos for these chemicals from estimates of
body weight reported in Chapter 10 of this document, the steady-state equation
developed by Smith (1987) and reference half-lives reported in Milbrath et al
(2009). Milbrath et al (2009) adjusted reference half-lives for age, body fat,
smoking habits and breast-feeding status as these factors were all strong
determinants of half-life in humans.
A carryover rate > 1 would suggest that dioxins and dioxin-like compounds could
accumulate in body fat and transfer to the fat in mother’s milk. An average dioxin
Tco of 3.7 d/kg indicates that 370% of the daily intake from ingested sources
transfers to mother’s milk. This high transfer-value suggests that some
accumulation of carcinogenic dioxins and dioxin-like compounds occurs in the
mother’s body. For individual congeners, an oral Tco less than one (e.g.
1,2,3,4,7,8-HxCDF and 2,3,4,6,7,8-HxCDF) suggests that some metabolism
occurs in the mother’s body.
J.5.2 PAHs
Based on the estimated intake of 16 measured PAHs in simulated smoking
studies and the PAHs found in breast milk from long-time smoking mothers
(Zanieri et al. 2007), OEHHA was able to estimate transfer coefficients (Tco) with
a modified version of Equation J-1.
The key assumption underlying the development of these Tcos is that the
variability in an individual PAHs Tcos is sufficiently small to justify the use of an
average value for individual PAH congeners. This approach appears to be the
best available given the available studies.
OEHHA calculated oral Tcos for each individual PAH by Equation J-8. The
average Tco for carcinogenic and PAHs without cancer potency factors was
calculated as the sum of the Tco values over the total number of PAHs
evaluated. Similar Tco values are obtained for both groups of PAHs (0.46 d/kg)
and 0.31 d/kg, respectively). This finding suggests that, on average, the PAHs
with cancer potency factors as a whole transfer to mother’s milk with about the
same efficiency as some of the most common PAHs without cancer potency
factors that are taken in through the diet. Therefore, summary Tcos were
calculated by pooling across individual PAH-Tcos from both groups (see Table
J.3-7).
J-48