Hair Analysis Panel Discussion: Section 5.0
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:
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?
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)?
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?
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?