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Occurrence & Contaminant Selection Working Group
EXECUTIVE SUMMARY
National Drinking Water Advisory Council
Occurrence & Contaminant Selection Working Group
April 3 & 4, 1997
Washington, D.C.
1. Attendance: absent - Walter Bishop, alternate (for Joye Emmens)
- Greg Grunenfelder, all other Working Group Members in attendance.
2. Issues Discussed: The purpose of the meeting was to develop
recommendations for the Agency in developing the first Candidate List.
The Candidate List as mandated by the Safe Drinking Water Act amendments
of August 6, 1996, must be published by February 6, 1998 and every 5 years
thereafter. The Candidate List will serve as the source of priority contaminants
not currently regulated from which drinking research, monitoring, guidance
development and selection for determination of whether or not to regulate
will be drawn. A draft Candidate List is expected to be published in the
Federal Register in August 1997. The discussion included contaminants
to be included on the first Candidate List as well as criteria considered
to be important for choosing contaminants for the Candidate List.
3. Issues Resolved: An initial Candidate List was developed by
identifying contaminants from a starting list prepared by the Agency of
approximately 370 contaminants. The contaminants identified for the Candidate
List include those which had data indicating concentrations in water from
the STORET (Storage & Retrieval) database exceeded the
health effect level as calculated from IRIS (Integrated Risk Information
System), and those found in US Geological Survey's National Water Quality
Assessment (NAWQA) program in 25% or more of the samples (e.g., MTBE,
and several pesticides). STORET database houses occurrence data on contaminants
found in ambient ground and surface water, and includes some drinking
water data. IRIS includes reference dose & cancer quantification values
developed and agreed upon by various Agency programs.
Additional contaminants (e.g., aluminum, zinc) were identified from the
1991 Drinking Water Priority List which the Working Group felt may be
of concern to drinking water, but where additional data evaluation is
necessary. Recommendations for microorganisms will be developed after
consultation from a number of experts in the field of microbiology. Sulfate,
nickel, and aldicarbs were also included; sulfate as it is required by
the 1996 Amendments to be one of the 5 or more contaminants for which
a determination is made by 2001, and aldicarbs and nickel due to their
respective incomplete regulatory status prior to 1996 Amendments.
In addition to the initial Candidate List, a set of criteria was developed
which would be used to evaluate the remaining contaminants on EPA's starting
list of approximately 370. The purpose of applying the criteria which
is an assessment of occurrence & health effects to gauge risk, is
to identify any additional compounds that may warrant consideration. The
criteria developed is very similar to what was presented in a working
draft document prepared by the Agency last November, but with more specificity.
4. Next Steps: The next meeting of the Working Group will be June
3. At that time the results of applying the criteria to the remainder
of EPA's starting list, and recommendations for microorganisms will be
discussed. A draft Candidate List will be provided as a recommendation
to the National Drinking Water Advisory Council in June.
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