What is an appropriate geometric standard deviation (GSD) for my site?
The GSD blood lead (PbB) for a population is a measure of inter-individual variability of observed blood lead levels. Factors that may contribute to variability in a population include: • occupational exposure • exposure history • socioeconomic and ethnic characteristics • activity patterns • degree of urbanization • geographic location • sources of lead A homogeneous population (i.e., expected to have a low GSD) may have similar characteristics and exposure histories, and live within a small geographic area; there may be a single dominant source of lead exposure (e.g., an ethnically and culturally homogeneous population living in a small town). By contrast, individuals with diverse backgrounds, who are exposed to multiple sources of lead within an urban community, may be considered a heterogeneous population. In the absence of information that would indicate whether the population is homogeneous or heterogenous, an appropriate geometric standard deviation (GSD) value would be based on
