Hair Analysis: Exploring the State of the Science. (Meeting Report)

Article excerpt

On 12-13 June 2001, the Agency for Toxic Substances and Disease Registry (ATSDR) convened a seven-member panel in Atlanta, Georgia, to review and discuss the current state of the science related to hair analysis, specifically its use in assessing environmental exposures in support of the agency's public health assessment activities. ATSDR invited scientific experts in the fields of hair analysis, toxicology, and medicine to participate in a discussion of such topics as analytical methods, factors affecting the interpretation of analytical results, toxicologic considerations, and data gaps and research needs. The goal of the panel was to determine the overall utility of hair analysis as a tool to evaluate exposure at hazardous waste sites. The principal lesson learned from the meeting was that, for most substances, data are insufficient to predict health effects from the concentration of the substance in hair. The presence of a substance in hair may indicate exposure (both internal and external) but does not necessarily indicate the source of exposure. Thus, before hair analysis can be considered a valid tool for assessing exposure and health impact of a particular substance, research is needed to establish standardized reference ranges, gain a better understanding of biologic variations of hair growth with age, gender, race and ethnicity, and pharmacokinetics, and further explore possible dose-response relationships. ATSDR intends to use the findings of this panel to develop educational materials to support its site work and to encourage researchers to continue to develop methods that may facilitate reliable exposure assessments. Key words: analytical methods, arsenic, data gaps, environmental contamination, exposure assessment, limitations, methyl mercury, reference ranges.

**********

Recently, the Agency for Toxic Substances and Disease Registry (ATSDR) explored human hair analysis as a potential additional tool to assess exposure. Hair analysis may have useful applications in forensic investigations for trace elements (Fletcher 1982), in screening for the use of illicit drugs (Valente et al. 1981), and in exposure assessment for some occupational settings (Foo et al. 1993; Taylor 1986). However, the general utility of hair analysis to assess environmental exposures (Bencko 1995; Frisch and Schwartz 2002; Hammer et al. 1971; Hindmarsh 2002; Manson and Zlotkin 1985), especially those that might occur because of exposure to contaminants from hazardous waste sites, remains largely unproven (Esteban et al. 1999).

In this report, we summarize the deliberations of an ATSDR-sponsored expert panel that met in June 2001 in Atlanta, Georgia, to discuss the state of the science related to hair analysis for environmental substances found at hazardous waste sites (ATSDR 2001). The panel consisted of individuals representing state and federal government agencies, academia, and the private sector and whose expertise, interests, and experience covered a wide range of technical disciplines critical to the issues being discussed. This report highlights the lessons ATSDR learned from the panel deliberations about the utility of hair analysis to assess exposure to contaminants.

ATSDR's recent interest in hair analysis is 2-fold. First, the agency is seeking and using more direct and specific measures of exposure rather than relying on default exposure assumptions to strengthen and support its public health assessments and recommended public health actions. Among the measures being used are biologic measures of exposure (typically target substances or metabolites in blood and urine), point-of-contact environmental measures (e.g., personal air samplers), geographic information systems (GIS) integrated with fate and transport models, and direct observations made by the health assessment team during site visits. Integrating these techniques has increased our capacity to assess exposure, both qualitatively and quantitatively. …