|
Appendix B
Charge to the Panel
Section 1 1.1
Background Hair Analysis: Exploring the State of the
Science
The Agency for Toxic Substances and Disease Registry (ATSDR)
is holding a panel discussion to review and discuss the current
state of the science related to hair analysis. ATSDR has invited
a cross section of scientific experts in the fields of hair analysis,
toxicology, and medicine to participate in 1½ days of discussions
on a variety of topics, including analytical methods, factors affecting
the interpretation of analytical results, toxicologic considerations,
and data gaps/research needs. The panel will discuss whether hair
analysis is a useful tool in evaluating exposures to hazardous substances
present in the environment. The agency will use the input received
during the discussions to develop a framework for determining when
measuring contaminant levels in hair can help support scientifically
defensible public health evaluations.
Background
ATSDR conducts public health assessments to evaluate possible public health implications of contaminants associated with hazardous waste sites and other environmental releases. An important step in ATSDR's assessment process is examining exposures to contaminants under site-specific conditions and determining whether people are being exposed to contaminants at harmful levels. In most of the agency's evaluations, the environmental concentration serves as a surrogate for "exposure."
Exposure concentrations, or estimated doses based on exposure
concentrations, however, represent only one factor in a continuum
of events that ultimately determine whether exposures will result
in illness. Other factors include exposure conditions and various
pharmacokinetic/pharmacodynamic events (e.g., absorption, metabolism,
excretion), as well as individual variability and susceptibility
in the exposed population. To a large extent, ATSDR evaluates these
factors qualitatively in its public health assessments.
To refine its assessments and/or to fill data gaps, ATSDR sometimes
identifies ways to more precisely quantify exposures, such as measuring
body burdens of a particular contaminant or its metabolites (e.g.,
lead in blood). On a site-by-site basis, ATSDR evaluates what additional
exposure data might be practical and useful to obtain to further
support public health evaluations and ultimately to help determine
the disease potential of a particular exposure. ATSDR seeks
to determine the overall utility of hair analysis as one such exposure
assessment tool.
Charge to Panel Members
General Questions
ATSDR's overall goal is to receive expert opinion on the following four general questions related to hair analysis. Panelists should keep these questions in mind when answering the specific charge questions that follow.
Specific Charge Questions
Discussions on the first day of the meeting will focus on answering questions that pertain to Topics #1, #2, and #3 below. In asking these questions, ATSDR seeks a critical review and assessment of the state of the science pertaining to hair analysis. The second day of the meeting will be devoted to identifying critical data gaps and research needs, and also identifying scenarios for which hair analysis should/should not be considered in light of limitations in analyzing and interpreting hair data (Topics #4 and #5).
Topic #1: Analytical Methods.
Discuss/review basic sampling and laboratory methodology used in
hair analysis.
Topic #2: Factors Influencing the Interpretation of Analytical Results. Discuss to what extent (qualitatively and/or quantitatively) the following factors influence the interpretation of hair analysis data. Provide substance-specific examples. Note any additional factors not highlighted below that are critical to or limit the interpretation of hair analysis data.
Topic #3: Toxicologic Considerations. Discuss to what extent hair analysis data can be used to predict adverse health outcomes. Cite specific examples/substances for which information is available.
Topic #4: Data Gaps and Research Needs. In light of Topics #1–#3, provide recommendations to fill data gaps and overcome/clarify limitations in hair analysis and interpretation.
Topic #5: Identifying Scenarios for Which Hair Analysis May Be Appropriate. Considering the factors identified in the matrix below, and in light of issues identified under Topics #1–#4, discuss when hair analysis may or may not be appropriate for evaluating exposures to environmental contaminants. This matrix will assist ATSDR in developing a framework or decision logic for determining when to conduct hair analysis.
Exposure Scenario |
Chemical/ |
Exposure Chronology |
Exposure Duration |
Measurable Health Effects (Y/N) |
- Individual |
E.g., ingesting lead in soils |
- Past |
- Acute |
- Specify |
Reference Materials
When addressing the charge questions, please provide citations for references that ATSDR should consider when evaluating hair analysis issues. ATSDR has developed a bibliography for your review (primarily post-1985). Please identify additional key studies or papers.
The following journal articles and papers have been provided for panelist review and consideration. ATSDR selected these papers to represent the breadth of the issues to be discussed by the panel. Their selection does not indicate ATSDR's position on any particular issue. ATSDR recognizes that these only represent a sampling of the many peer-reviewed papers on the subject of hair analysis. The purpose of reviewing these papers is to help stimulate thought and discussion related to the charge questions.