Appendix D Food Codes for NHANES - OEHHA

Scientific Review PanelSRP Draft Version 2 February,June 2012
absorption pathway for lead and PAHs. For lead, we are using the inhalation Tco
for all the other pathways of exposure to the mother. Likewise, for PCDD/Fs and
dioxin-like PCBs, we are using the oral Tco for the other pathways of exposure to
the mother in Eq. J-2.
Estimates of toxicant biotransfer to breast milk are ideally chemical-specific. Data
necessary to develop a transfer model are available in the open literature for a
limited number of chemicals. Therefore, for some toxicants OEHHA has
modeled the transfer of a class of chemicals with similar physical-chemical
properties using a single Tco when data in the open literature are lacking.
The Hot Spots exposure model can estimate long-term total dose from an
individual facility or group of facilities through many pathways of contamination
and routes of exposure to the mother and ultimately to her infant. In this
appendix, “multipathway toxicants” refers to airborne-released chemicals that can
cause exposure through pathways in addition to inhalation. The indirect exposure
pathways evaluated under the Hot Spots program include incidental ingestion of
contaminated soil, ingestion of contaminated home-raised meat and milk, surface
drinking water, homegrown produce, angler-caught fish and skin contact with
contaminated soil.
Relative to the lifetime average daily dose to the infant from other exposure
pathways in the Hot Spots exposure model, the dose of some chemicals from
mother’s milk will be negligible. However, the mother’s milk pathway may be a
substantial contributor to the estimated total lifetime cancer risk for some
chemicals emitted from a Hot Spots facility. Exposure from global sources is
expected to make up most (almost all) of a mother's toxicant body burden for
chemcials like PCDDs. Therefore, the contribution to a mother's toxicant body
burden from a single Hot Spot facility is expected to be very small. Regardless of
the mother's toxicant body burden from both local and global sources, the
benefits of breastfeeding outweigh the risks to the infant exposed to these
toxicants during breastfeeding. Breast-feeding has a number of universally
accepted benefits for the infant as well as for the mother (Mukerjee, 1998).
We established transfer coefficients (Tcos) for individual congeners of PCDDs/Fs
and dioxin-like PCBs, individual and summary carcinogenic PAHs and lead
through equations J.1-1 through J.1-3. We used data on exposure and breast
milk contamination from background (global), accidental and occupational
sources, and a set of simplifying assumptions. We assume that a mother’s intake
and elimination rates remain constant before lactation. We also assume that
changes in a woman’s body due to the onset of lactation occur as a single shift in
elimination rate and do not change over the lactation period. Unless a study
reported the geometric mean or median, we converted arithmetic mean and
standard deviation to geometric mean and GSD.
In the following sections, we describe the methods for deriving specific Tcos from
measurements of human milk intake and transfer estimates from studies of
J-5