Working Group Meeting on Contaminant Candidate List Regulatory Determinations and the 6-Year Review of Existing Regulations, April 3-4, 2000

On April 3 and 4, 2000, the National Drinking Water Advisory Council (NDWAC) Working Group on Contaminant Candidate List (CCL) Regulatory Determinations and 6-Year Review of Existing Regulations, met at the Environmental Protection Agency in Washington DC to hold the second of three scheduled meetings, to discuss CCL Regulatory Determinations. The purpose and overall mission of this Working Group is to make recommendations to the full NDWAC regarding specific provisions of the Safe Drinking Water Act (SDWA) 1996 Amendments. The Working Group will recommend protocols for making regulatory determinations regarding current and future CCL contaminants, and for selecting existing National Primary Drinking Water Regulations for possible revision.

The meeting began with a review of the accomplishments of the three Subgroups formed at the March Working Group meeting. The three Subgroups were asked to focus their efforts on refining the proposed framework presented by the EPA, and discussed by the Working Group during the March meeting. The Subgroups were tasked with developing factors for consideration in addressing each statutory the statutory requirements (listed below) for the CCL as specified in the SDWA 1996 Amendments and to develop relative scoring and weighting tool for each factor identified. Statutory requirements:

• the contaminant may have an adverse effect on the health of persons;

• the contaminant is known to occur or there is a substantial likelihood that the contaminant will occur in public water systems with a frequency and at levels of public health concern; and

• in the sole judgment of the Administrator, regulation of such contaminant presents a meaningful opportunity for health risk reduction for persons served by public water systems.

As a starting point, the Microbial Subgroup presented a draft framework for making regulatory determinations for the microbial contaminants on the CCL. The full Working Group then discussed the factors for consideration in addressing each statutory question and provided the subgroup with some input on the practicality of developing a relative scoring and weighting tool for each factor identified.

Following the presentation by the microbial subgroup, the Working Group divided into two groups to further discuss protocols for Microbials and Chemicals, to work through outstanding issues and to address specific questions regarding priority factors, weighting, and methods of evaluating data. The balance of the first day was spent with the two groups refining the evaluation criteria and factors.

The chemical group focused mainly on statutory test 2 and 3 and the data ranges and the appropriate scoring and emphasis weighting associated with each of the data evaluation criteria. Statutory test 2 ("the contaminant is known or there is a substantial likelihood to occur in public water supplies at a frequency and at levels of public health concern") was subdivided into 4 areas for consideration (frequency, exposure, occurrence and distribution, and production and trend) and evaluation criterion for each of the factors was defined. It was agreed that some information, such as number and percentage of detections at any level above the minimum reporting level, although valuable in characterizing in contamination were not critical to addressing statutory test 2. So the group agreed that the information should be recorded and evaluated, but not included in the "scoring". Also included in the discussion of statutory test 2 was the presentation from the subgroup asked to address the issue of occurrence distribution. The subgroup proposed an approach that would look at the distribution of occurrence as it relates to watersheds rather than by state as had previously been suggested. The group agreed that the proposal was more appropriate and a better way of evaluating occurrence distribution. The issue of exposure was agreed by the group to be more appropriate in answering statutory test 3, and was therefore moved to address the question of meaningful opportunity for risk reduction.

Statutory test 3 ("a regulation of such contaminant provides a meaningful opportunity for health risk reduction") including the exposure factors moved from statutory test 2 were also discussed at length. Three factors were agreed upon for determining persistence, mobility, fate and transport but were thought to be more appropriately included in statutory test 2 as a means for characterizing "likely to occur". The group spent a good bit of time struggling with the issue of cancer vs. non-cancer health effects, and whether they should be address separately. No final decisions were made, but a subgroup of people would provide some additional thoughts on the issue and distribute it to the Working Group for comment prior to the next meeting.

The microbial breakout group was successful at developing and flow-charting a sequence and protocol for evaluating data. The microbial process presented is similar to that of the chemicals in that "scoring" factors for each of the statutory questions were identifies and given represented by a weighting factor. Consensus among the microbial breakout group on the underlying assumptions that would be made with regard to the data that would be used to answer the three statutory questions.

On the second day, the Working Group continued discussions on the development of recommended protocols for regulatory determination for CCL chemical and microbial contaminants refined during the prior day's breakout groups. Also as a group, members discussed issues related to the overall approach to applying the evaluation protocols being developed. The Working Group as a whole agreed that the scoring and weighting would not compare one contaminant to another, nor would the numbers be "totaled. Rather each number would represent a level of importance, not a score and would primarily serve to document and characterize the each factor considered in answering yes or no to each of the three SDWA criteria.

Finally the group and worked to assign individuals and additional subgroups address the outstanding issues related to the protocols and disburse them to the entire Working Group for review prior to the May 2 conference call. At that conference call, the Working Group plans to finalize the protocols for recommendation and to agree on a process for finalizing the Working Group' s recommended protocols for presentation to the full NDWAC in May. The next meeting will be held via conference call on Tuesday, May 2, 2000, from1:00 pm to 5:00 pm EST.

The following is a list of Working Group members: the * indicates members that were not in attendance at the April 3-4 meeting.

Safewater Home | About Our Office | Publications | Links | Office of Water | En Español | Questions and Answers

EPA Home | Privacy and Security Notice | Contact Us