The accurate chemical determination of lead in the body or in the environment is a critical factor in assessing human exposure limits and in identifying sites where remediation is required. To compare and evaluate data from laboratory studies or to determine when and where expensive abatement procedures must be employed, chemical analysis data must be tied to an accepted system of measurement accuracy.
The need for comparability and traceability of chemical analysis data is becoming recognized world-wide. Efforts are now underway by the International Committee for Weights and Measures (CIPM) through its laboratory, the International Bureau of Weights and Measures (BIPM) to link chemical measurements to the International System of Units (SI) at the highest levels of national systems of measurement. As the U.S. member of the CIPM, the National Institute of Standards and Technology (NIST) is responsible for providing the link between chemical measurements in the U.S. and the SI units of the kilogram and the mole. NIST provides this traceability for measurements through a highly leveraged system of key Standard Reference Materials (SRMs)and primary methods. The design, development, and application of these SRMs and primary methods for use in secondary reference material and reference methods development will be described. In addition, the role that SRMs and primary methods are intended to play in ensuring traceability to the national system of measurement will be outlined.