Lead poisoning: hair analysis shows the calendar of events.

A woman was given frequent oral doses of lead nitrate over an extended time period. Diagnosis was finally made about 6 months after the first symptoms appeared. Analysis of hair taken at 2 different times was used as evidence in court. The hair lead concentrations exhibited rapid changes and normalised shortly after chelation treatment had been instituted. This finding suggests that the hair lead level may reflect a current absorption level rather than the lead content of whole blood which, in this case, changed much more slowly. Despite the extremely high blood lead levels and the severe clinical lead poisoning, lead concentrations in hair were relatively low in comparison to the concentrations found in hair of workers exposed to high levels of airborne lead. This observation suggests that a large proportion of the lead content of hair from individuals with respiratory lead exposure may be exogenous.