Hair Analysis Panel Discussion:
Appendix C, LuAnn White
Hair Analysis: Exploring the State of the Science
LuAnn White, Chair
Overview/Perspective from the Panel Chair
The overriding question for the use of hair analysis in environmental public health is the need to find reliable methods for assessing chemical exposure of people living in communities near hazardous waste sites. Hair sampling is tantalizing because it is a biological material that is readily available, noninvasive, and easy to collect. However, much controversy exists regarding the use of hair samples as an indicator for environmental exposure, health status, or disease state. The use and misuse of results from hair sampling has stimulated debate and at times, cast a shadow over the issue.
Complex questions linger regarding three overarching issues: 1) accuracy and reliability because of laboratory methods; 2) toxicokinetics of compounds and the biological variability among individuals; and 3) the relationship of the results to exposure and/or potential disease. Within each of these issues, multiple questions arise that include, but are not limited to, the reliability and reproducibility of the analytical methods; interlaboratory variability; types of compounds suitable for hair analysis; baseline of elements and compounds found in hair—for an individual and/or populations; influence of distribution, metabolism, storage and excretion on incorporation of compounds and elements into hair; and duration and level of exposure. Even if all of the methodological and toxicological questions can be answered, there are still great gaps in our knowledge as to the relationship between the concentration of a compound/element in hair and environmental exposure, and then between exposure and disease or reduced health status. Indeed, a lack of knowledge of these complex interrelationships exists with any biological sample and prevents full answers to many questions.
While there is much we do not know, there is a body of knowledge on hair analysis. The challenge is to define the parameters whereby hair analysis can be a valuable tool to assist in exposure investigations, but to guard against overinterpretations beyond our knowledge and experiences. Perhaps, identifying the issues will open the door to stimulate research to answer questions and fill our knowledge gaps.