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
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 many 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
New Jersey Department of Environmental Protection
and Oregon Health & Science University
to calculate non-enforceable Health-Based Screening Levels (HBSLs). HBSLs were calculated for
contaminants that do not have USEPA Maximum Contaminant Levels.
A comprehensive update of the USGS Health-Based Screening Level (HBSL) database has been completed, effective February 28, 2012. As part of the update, the most current, peer-reviewed, publicly available human-health toxicity information from the U.S. Environmental Protection Agency was identified. The HBSL update resulted in revisions to HBSL values for 48 contaminants:
- New HBSL values are available for 17 contaminants that previously did not have HBSLs.
- HBSL values changed for 18 contaminants.
- HBSL values were removed for 6 contaminants.
- HBSL values were added for 7 isomers (such as cis- and trans- compounds). Previously, users were referred to the HBSL value for the mixed isomers.
The 48 contaminants with revisions to HBSL values are listed on the History of HBSL Revisions table on the Search for HBSL values page.
USGS authors: Please indicate the date that HBSL values were obtained from the HBSL website in your manuscripts. HBSL values downloaded between April 10, 2008 and February 28, 2012 were current as of April 10, 2008.
Toccalino, P.L., Norman, J.E., Booth, N.L, Thompson, J.L., and Zogorski, J.S., 2012, Health-based screening levels: benchmarks for evaluating water-quality data: U.S. Geological Survey, National Water-Quality Assessment Program, accessed [insert date], at http://water.usgs.gov/nawqa/HBSL/.