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Procedures for Detection and Quantitation

Policy Workgroup

Federal Advisory Committee on Detection and Quantitation Approaches and Uses in Clean Water Act (CWA) Programs

Summary of Policy Work Group Conference Call #21
November 01, 2006
1:00 – 3:00 p.m. EST

Calls will be held from 1:00 to 3:00 PM, Eastern Time, on the following dates: November 9, 15, 17 and 29, 2006.

The call in number is 1-866-299-3188, and the access code is 202-566-1000#.

Action Items

A subgroup on data quality objectives (DQOs) (Mary Smith/Brian Englert, John Phillips, Jim Pletl) was tasked with reviewing an initial list of fundamental questions related to DQOs and developing a product for the PWG to develop a recommendation around this issue. Michael Murray, Dave Akers, Tom Mugan and Nan Thomey all offered to review a draft product before sending to the PWG, but said their availability to participate in the development of a product was limited.

Triangle will:

Welcome and Introductions

Facilitator Alice Shorett convened the conference call at 1:00 PM ET and called the roll of participants. She briefly reviewed the agenda with participants, saying she wanted to get right into the discussion of measurements quality objectives (MQOs). She suggested holding the discussion of the draft summary from the October 26 meeting until the end of the meeting.

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Discussion of Recommendations on Measurement Quality Objectives

Alice Shorett said that Mary Smith had the opportunity to connect with Jim Pletl on the issue of setting MQOs. Mary Smith said that she wanted to hear Mr. Pletl's perspective on setting MQOs in light of the sample spreadsheets EPA assembled reflecting results for a couple of existing analytical methods.

Jim Pletl said that since he was one of the earliest proponents in the process of establishing MQOs he wanted to spend a few minutes describing his point of view. He hoped that he could clarify his belief of how the PWG and committee should proceed on the issue.

Ideally, the committee will develop recommendations around an acceptable precision and accuracy for the quantitation limit (QL) and an acceptable false positive and false negative rate for the detection limit (DL). In a broader context, he hoped the committee could develop recommendations that EPA could put into guidance on a level of error that is acceptable to make a decision for a given analytical method. If that acceptable level of error is not met, an analyst in a lab could mitigate - through MQOs, uncertainty, analytical processes or some other measure - that level of error for decision-making. For example, to adjust for uncertainty from the perspective of sampling (i.e. sample size), a permittee could reduce uncertainty by collecting more samples or using more data.

Mr. Pletl said this was just a suggestion to illustrate his main point, which is to focus the committee more globally on the issue of setting some data quality objectives around analytical methods. He said he was not originally advocating that the committee should seek consensus on numbers for specific MQOs.

The PWG discussed for a moment Mr. Pletl's vision for addressing the issue of MQOs. Initially, there was some confusion of how committee recommendations on the subject could translate into EPA guidance if the committee did not agree to specific numbers. Mr. Pletl suggested that his approach does not prohibit the committee from seeking consensus on numbers. However, the fundamental issue that first needs to be addressed is to say that limits need to be established with accuracy and precision taken into account, not that we just need better precision and accuracy.

Nan Thomey used the example, to illuminate Mr. Pletl's thinking, of a lab that reports a number with its associated accuracy. However, many times that number is treated as though it is 100% accurate, which is almost never the case. Guidance from the committee may simply be text that says bias has to be taken into account in the decision-making process, and may even go as far as systematically relating decision-making to levels of accuracy or bias.

The group generally agreed with the suggested approach. Instead of spending time trying to reach consensus around specific numbers for the four MQOs, the committee's time will be better spent trying to address the issue more holistically, from a data quality objective perspective. MQOs then become a subset of this larger issue.

The group spent some time trying to identify some of the fundamental questions that might be addressed by the committee. They came up with the following list.

A subgroup was then assigned the task of sifting through this initial list and developing a product for the PWG to send to the committee for its December meeting. The subgroup consists of Mary Smith and Brian Englert, John Phillips and Jim Pletl. Tom Mugan, Nan Thomey, Michael Murray and Dave Akers also volunteered to review the product before it is sent to the PWG, but said they would have very little time to participate in the preceding discussion and development of the product. Alice Shorett said Triangle would pull together the initial list of fundamental questions and circulate that to the subgroup to get it started.

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Meeting Summary Review and Approval

Ms. Shorett asked for comments to the draft summary from the October 26 PWG meeting. Chris Hornback made a few suggestions for minor revisions that were accepted by the group.

Michael Murray asked to add some language to the summary about the discussion of the Great Lakes Initiative that took place at the end of the last meeting.

Ms. Shorett said Triangle would revise the summary. Given that the group would need to see the revisions again before approving the draft summary, she suggested the group review two summaries (from 10/26 and from this meeting) at the November 9 meeting. The group agreed to that approach.

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Updates on Outstanding Assignments

Ms. Shorett reviewed with the group the outstanding assignments. She identified the following:

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Wrap Up and Adjourn

Alice Shorett briefly summarized the meeting and said the next meeting is scheduled for Thursday, November 9 from 1:00 - 3:00 PM, ET. She also suggested adding an additional meeting to the schedule to finalize details before the December committee meeting. The group agreed to add a conference call on Friday, November 17 from 2:00 - 4:00 PM, ET.

Ms. Shorett reviewed the schedule of remaining calls with the group. She said it was important to come to each meeting prepared to move forward in an effort to develop products that could be distributed to the committee well before the December meeting. Ms. Shorett thanked all for their participation and concluded the call at 2:55 PM (ET).

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