Nails: concern over their use in lead exposure assessment

Non-invasive procedures for determination of lead exposure such as nails or hair are an attractive alternative to more invasive procedures, such as blood sampling, especially for infants. In spite of rigorous sample preparation and use of high precision lead isotope measurements, data obtained for fingernails and toenails of a subject serially sampled for over 6 months and in several other subjects exhibit such variability as to preclude nails as a reliable lead exposure indicator.