About the HBSL Project
When contaminants are detected in water resources, it
is important to describe what the occurrence of these contaminants may mean to
human health. The U.S. Geological Survey
(USGS)
began an interagency pilot effort in 1998 to communicate the potential relevance
of the water-quality findings of its National Water-Quality Assessment
(NAWQA) Program in a human-health context. Many ground-water
resources sampled by USGS are used as drinking-water sources, and water-quality
conditions historically have been assessed, where appropriate, by comparing
measured contaminant concentrations with drinking-water standards and
guidelines. Drinking-water standards and
guidelines are not available, however, for about two thirds of the contaminants
measured in water by the NAWQA Program and other USGS studies. To
supplement existing Federal drinking-water standards and guidelines, USGS began
a collaborative project with the U.S. Environmental Protection Agency
(USEPA),
New Jersey Department of Environmental Protection
(NJDEP),
and Oregon Health & Science University
(OHSU)
to calculate Health-Based Screening Levels (HBSLs). HBSLs were calculated for
contaminants that do not have USEPA Maximum Contaminant Levels.
Suggested Citation
Toccalino, P.L., Norman, J.E., Booth, N.L, and Zogorski, J.S., 2008, Health-based screening levels: A tool for evaluating what water-quality data may mean to human health: U.S. Geological Survey, National Water-Quality Assessment Program, accessed [insert date], at http://water.usgs.gov/nawqa/HBSL/.