SECTION 5
TOXICOLOGIC CONSIDERATIONS
The panelists agreed that, in order to interpret hair analysis data in any meaningful way, scientists need a greater understanding of substance-specific relationships between levels in hair and other body compartments, including target tissues, and how those levels relate to adverse health outcomes. Much of the toxicology discussion, accordingly, centered around data gaps and research needs.
The panel chair stressed the importance of understanding to what extent a particular substance might enter the body, what could conceivably get into hair, and ultimately how such information can be used as an indicator of exposure and/or of possible clinical effects. Specific questions to consider included:
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What are the substance-specific pharmacokinetic factors (e.g., intake,
absorption, distribution, excretion) that can influence the biologic uptake
of specific substances and the concentration delivered and incorporated
into the hair? How should half-life and possible storage pools within
the body be considered? |
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What substances are transported to the hair, and by what mechanism are
they transported (e.g., how are environmental substances of interest incorporated
into the hair)? |
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What is the dose that causes effect at the target organ? If this is known,
how does it relate to the concentration in the hair matrix? |
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How do different patterns of exposure over time (e.g., as may be revealed by segmental analysis) help us understand possible acute versus long-term exposures, and how might these patterns correlate with potential health effects? |