When is it appropriate/inappropriate to consider hair analysis in assessing human exposures to environmental contamination?
While scalp hair growth rates are generally cited as being approximately 12 cm/year or about 1 cm/month, actual rates may vary between 0.6 and 3.6 cm/month (Harkey 1993). Because of this variability, the panel concluded that hair analysis is not generally useful for evaluating recent exposures or those occurring more than 1 year ago. Segmental analysis of hair (i.e., looking at concentration trends along the length of the hair) could have a role in documenting exposures over time (e.g., identification of a high-dose, acute exposure). However, this type of hair analysis would need to be considered on an individual-, substance-, and situationspecific basis. Conclusions. Because of the growth rate of human hair, hair analysis is not generally useful for evaluating recent exposures or those occurring more than 1 year ago. Segmental analyses of hair could have a role in documenting exposure over time under very specific circumstances. What data gaps exist that limit the interpretation and u
