ABSTRACT
Methyl mercury (MeHg) is a well-known fi sh contaminant and potential developmental neurotoxin, for which exposure standards are still under debate (1-3). Several ongoing projects aim to determine the effects of low-level MeHg exposure from fi sh diet during pregnancy and their impact on the unborn child’s neurodevelopment (4). In most studies maternal hair has been used as an indicator of mercury fetal exposure (1,4). However, there is ongoing controversy whether hair or whole blood serve as a better indicator of MeHg exposure. The choice of the indicator medium for epidemiologic and clinical studies depends on several factors, such as the concentration measured, the access to the medium, and its ability to predict levels in the target tissue. Human hair as a biomonitoring medium and has several well-established advantages: noninvasive sampling, easy collection, sample stability during storage, accessibility, and most importantly long-term recapitulation of the history of past exposure (5). Nondestructive physical methods, such as X-ray fl uorescent spectrometry, are now available that can measure mercury in single strands of hair, and the difference in mercury levels between each strand has been shown to be less than the analytic variance (6). Although some data have indicated that certain hair treatments might remove mercury or possibly add mercury as a contaminant (7,8), a large population study found no evidence of any effect of hair treatment on hair mercury levels (9).
