Appendix D Food Codes for NHANES - OEHHA

Scientific Review Panel Draft February, 2012
F.1 Introduction
The absorbed dose resulting from dermal exposure to soil-bound chemicals
depends on many factors. An algorithm that describes the uptake of chemicals
from soil as a function of exposure duration, exposure frequency, chemical
concentration in the soil, soil loading, surface area, body weight, averaging time,
and fractional absorption (ABS) is discussed in Chapter 6. The purpose of this
appendix is to summarize the derivation of the ABS for the “Hot Spots”
multipathway chemicals and present the information used in the development of
each chemical ABS. A general discussion of the diverse factors influencing
dermal absorption of soil-bound chemicals is presented below preceding the
chemical ABS summaries.
A small subset of organic and metallic compounds evaluated under the Hot
Spots program is subject to deposition onto soil, plants and water bodies.
Therefore, exposure can occur by pathways other than inhalation. These
chemicals are semi-volatile or nonvolatile, and are therefore partially or wholly in
the solid or liquid phase after being emitted. Fate and transport of the deposited
chemical must then be estimated in order to assess the impact on soil, water and
foods that humans come in contact with. The basis for the selection of these
compounds as “Hot Spots” multipathway substances can be found in Appendix
E. The organic compounds of relevance listed under the “Hot Spots” program
include 4,4’-methylene dianiline, hexachlorocyclohexanes, di(2ethylhexyl)phthalate
(DEHP), polychlorinated dibenzodioxins and dibenzofurans
(PCDD/Fs), polychlorinated biphenyls (PCBs) and polycyclic aromatic
hydrocarbons (PAHs). The metal or metalloid compounds of relevance include
the inorganic salts of arsenic, beryllium, cadmium, fluoride, mercury, lead, nickel,
selenium and hexavalent chromium.
F.1.1 Point Estimate Approach for ABS Derivation
An ABS is a chemical-dependent, scenario-dependent value that can vary with
the characteristics of the soil matrix and the exposed population. Such
characteristics include the relative lipophilicity/hydrophilicity of the compound, soil
organic content, soil particle size, soil aging of the chemical, residence time on
the skin, and exposed surface area. Some of these issues are discussed in
greater detail in Chapter 6. The data necessary to characterize the variability in
these variates are often not available. For this reason, the ABS values derived in
this document are point estimates. In particular, site specific information on soil
organic content and soil particle range are not available. These factors can have
a significant impact on chemical absorption from soil and the uncertainty in the
dose estimate from dermal absorption because of these and other factors can be
large.
To derive a point estimate for a chemical, typically the value from the best and
sometimes only study available was selected. If multiple studies were available
F-2