Oak Ridge Reservation: Public Health Assessment Work Group

Public Health Assessment Work Group

July 19, 2001 - Meeting Minutes

Agenda

1. General status of WG activities - Bill Pardue
   
2. Statistical issues of dose reconstruction - Ed Frome
   
3. Status report on PHA process flow diagram - James Lewis
   
4. Epidemiology 102 course - Bill Pardue
   
5. Iodine-131 public health assessment - Michael Grayson
   
6. Sources of exposure - Burt Cooper
   
7. Other issues?

Attendees

Members attending: Bill Pardue, Chair, Susan Kaplan, James Lewis, David Johnson, LC Manley, Ed Frome, Al Brooks, Bob Craig, Bob Eklund (teleconference), Kowetha Davidson, Chairperson, ORRHES (teleconference).

Members of public attending: Cristina Carbajo, Owen Hoffman, Walter Coin, Timothy Joseph, Linda Gass.

ATSDR staff attending: Burt Cooper, Michael Grayson, Karl Markiewicz (teleconference), Bill Murray.

Summary

The meeting was called to order by the chair at 5:35 pm. Minutes for the June 28, 2001, meeting were available. A brief summary of each topic follows.

1. Status of PHA WG activities - Bill Pardue said he was anxious to complete the WG discussions on I-131 and use this task as a model for addressing the other contaminants of concern (COCs). He thinks the best way to proceed is to have a small group focus on the issues and draft recommendations for the WG for their consideration. The WG would revise the draft recommendations as needed and forward them as formal recommendations with a justification/rationale to ORRHES. The WG would then move on to the next COC and follow the same process.


2. PHA process flow diagram - James Lewis presented a new draft of the flow diagram with the changes suggested by the WG at the last meeting. The WG voted to submit the diagram to ORRHES as a recommendation.


3. Epidemiology 102 course - Bill Pardue talked about the follow-up course in principles of epidemiology that Lucy Peipins will give at the September ORRHES meeting. The Mangano report should not be used as the paper for the educational exercise of critically reviewing an epi study. No report has been selected yet for the exercise but a nitrate study in Iowa was proposed. Owen Hoffman suggested using the Hanford thyroid disease study (HTDS). However, it was decided that the HTDS was not appropriate since it might be difficult to separate from the emotion of the topic (I-131). Lucy will use her best judgment is selecting the study for review.

Bill Pardue thought both reports could be reviewed at the same meeting. Bill Murray will contact Lucy to get her opinion and to discuss the timing of the epi 102 talk to the WG.

4. Sources of contaminants - The WG questioned whether ATSDR would consider contaminants released from sites other the Oak Ridge Reservation (ORR) in the Public Health Assessment (PHA). Burt Cooper said that environmental samples have a composite of contaminants and it is difficult, if not impossible, to determine the source of the contaminant. Under the Toxic Substances Control Act (TSCA), such contaminants are included in the PHA. No environmental data are collected from other sites and, in the PHA, it would be stated that the contaminant could have been released from another site.


5. Probability and statistics - Ed Frome talked about probability distributions and how the sample data fit into such a distribution. He showed through an example the range in which 90% of the data points fall and, consequently, the values above and below this range comprise 10% of the values (5% at each end). The central (50%) value, at which most data points occur in a normal (Gaussian) distribution, is the mean, median and the mode. He also mentioned that the standard deviation is a measure of the spread of the data points. He showed an example of what the distribution of lifetime radiation doses looks like. It is a bimodal distribution with a large percent of the values at zero (27.9%), and the remainder of the data fitting a normal distribution. A lognormal distribution is often used with radiation dose and other exposure data because of the large number of data points at or near zero.


6. ATSDR PHA - Bill Murray introduced this discussion, reviewing briefly the talks at the June 2001 ORRHES meeting. Michael Grayson discussed the PHA in more detail, focusing on iodine-131 (I-131). The purpose of the PHA is to evaluate the potential for adverse health effects (past, present and future) to occur in people exposed to I-131. Currently, past exposures to I-131 are being reviewed and evaluated. ATSDR will use the following approach to evaluate past exposures to I-131 in the PHA:

• Determine whether the Oak Ridge Reservation Dose Reconstruction (ORRDR) study is usable in the PHA - the technical reviewers determined that the study overall is adequate for public health decision-making;


• Assess the potential for adverse health effects using dose estimates from the ORRDR; and,


• Determine whether follow-up public health activities or research is needed

In the PHA, both non-carcinogenic and carcinogenic health effects will be considered. For the non-carcinogenic effects, the thyroid-specific organ doses will be used to determine ATSDR's Public Health Hazard Category. For this portion of the PHA, ATSDR will use recent findings of the Institute of Medicine and National Research Council's "Exposure of the American People to Iodine-131 from Nevada Nuclear Bomb Tests, Review of the National Cancer Institute Report and Public Health Implications."

For carcinogenic health effects, the effective dose to the whole body will be used to determine compared to ATSDR's Public Health Hazard Category. For this portion of the PHA, ATSDR will use recommendations from the International Commission on Radiological Protection Report # 60, "1990 Recommendations of the International Commission or Radiological Protection," and the National Council on Radiation Protection and Measurements Report No. 116, "Limitation of Exposure to Ionizing Radiation."

Several questions were raised and comments and suggestions were made.

• Walter Coin asked what is the difference between ORRDR and the Hanford Dose Reconstruction study. Owen Hoffman replied that there are no major differences; there are minor differences in the variables selected.


• LC Manley asked why are people born in 1952 at highest risk. Owen Hoffman replied that babies born in 1952 would have the highest I-131 dose.


• Bob Eklund suggested that the I-131 releases need to be reevaluated to include the 20,000 curies released from the graphite reactor, as reported by Owen Hoffman.


• Al Brooks suggested that the I-131 releases should be compared to standards in effect at time of release, in addition to present standards.


• Owen Hoffman asked why the I-131 thyroid doses will be converted to whole body doses. Michael Grayson said that ATSDR only has carcinogenic risk estimates for whole body.


• Owen Hoffman suggested comparing the data for thyroid cancer at ORR to that for the Hanford site.


• Al Brooks asked what value should be used for the most probable dose. Michael Grayson replied that the mode is the most probable dose.

Bill Pardue asked the WG to transmit any individual recommendations to Bill Murray at the Oak Ridge Field Office (Phone - 865/220-0295; fax - 865/220-0457; email - wem2@cdc.gov). The recommendations should be submitted by August 3, 2001. The recommendations will be considered at the next PHA WG meeting. Those considered appropriate by the PHA WG will be forwarded to the full subcommittee for consideration as recommendations to ATSDR.

The next PHA WG meeting is scheduled for Monday, August 6, 2001, from 5:30 pm to 7:30 pm at the Oak Ridge Field Office.

The meeting adjourned at 7:45 pm.

Addendum 1

Email
To: William E. Murray
From: Owen Hoffman
Date: July, 27, 2001
Re: Comments on draft minutes of July 19, 2001, PHA WG meeting

Bill,

I'm on vacation today but wanted to forward to you my comments on the draft meeting minutes of the last PHA WG meeting.

Note, that the HHES was cancelled at the last minute, so the discussion about added doses from local and NTS + global I-131 never took place.

The Oak Ridge Dose Reconstruction is the first and only location to have formally included both NTS and local exposures.

Attached are my comments on your draft minutes.

Sincerely,

Owen Hoffman

President and Director
SENES Oak Ridge, Inc.
Center for Risk Analysis
Oak Ridge, TN 37830

865-483-6111 ph
865-481-0060 fx
senesor@senes.com (e-mail)
www.senes.com

Attachment

Attachment from Owen Hoffman with comments on minutes of July 19, 2001, meeting

The Public Health Assessment Work Group (PHA WG) met on Thursday, July 19, 2001 at the Oak Ridge Field Office.

Members attending: Bill Pardue, Chair, Susan Kaplan, James Lewis, David Johnson, LC Manley, Ed Frome, Al Brooks, Bob Craig, Bob Eklund (teleconference), Kowetha Davidson, Chairperson, ORRHES (teleconference).

Members of public attending: Cristina Carbajo, Owen Hoffman, Walter Coin, Timothy Joseph, Linda Gass.

ATSDR staff attending: Burt Cooper, Michael Grayson, Karl Markiewicz (teleconference), Bill Murray.

The meeting was called to order by The Chair at 5:35 pm. Minutes for the June 28, 2001, meeting were available. A brief summary of each topic follows.

• Status of PHA WG activities - Bill Pardue said he was anxious to complete the WG discussions on I-131 and use this task as a model for addressing the other contaminants of concern (COCs). He thinks the best way to proceed is to have a small group focus on the issues and draft recommendations for the WG for their consideration. The WG would revise the draft recommendations as needed and forward them as formal recommendations with a justification/rationale to ORRHES. The WG would then move on to the next COC and follow the same process.


• PHA process flow diagram - James Lewis presented a new draft of the flow diagram with the changes suggested by the WG at the last meeting. The WG voted to submit the diagram to ORRHES as a recommendation.


• Epidemiology 102 course - Bill Pardue talked about the follow-up course in principles of epidemiology that Lucy Peipins will give at the September ORRHES meeting. The Mangano report should not be used as the paper for the educational exercise of critically reviewing an epi study. No report has been selected yet for the exercise but a nitrate study in Iowa was proposed. Owen Hoffman suggested using the Hanford thyroid disease study. Bill Pardue thought both reports could be reviewed at the same meeting. Bill Murray will contact Lucy to get her opinion.


• Sources of contaminants - The WG questioned whether ATSDR would consider contaminants released from sites other the Oak Ridge Reservation (ORR) in the Public Health Assessment (PHA). Burt Cooper said that environmental samples have a composite of contaminants and it is difficult, if not impossible, to determine the source of the contaminant. Under the Toxic Substances Control Act (TSCA), such contaminants are included in the PHA. No environmental data are collected from other sites and, in the PHA, it would be stated that the contaminant could have been released from another site. Al Brooks mentioned that short-lived contaminants like I-31 came from sources outside the ORR but such a record would not be found in soil.


• Probability and statistics - Ed Frome talked about probability distributions and how the sample data fit into such a distribution. He showed through an example the range in which 90% of the data points fall and, consequently, the values above and below this range comprise 10% of the values (5% at each end). The central (50%) value, at which most data points occur in a normal (Gaussian) distribution, is the mean, median and the mode. He also mentioned that the standard deviation is a measure of the spread of the data points. He showed an example of what the distribution of lifetime radiation doses looks like. It is a bimodal distribution with a large percent of the values at zero (27.9%), and the remainder of the data fitting a normal distribution. A lognormal distribution is often used with radiation dose and other exposure data because of the large number of data points at or near zero. No, it is because the data are dispersed over one order of magnitude. The lognormal is bounded by, but does not include zero. Using a logarithmic, instead of an arithmetic scale, will produce a distribution that is symmetrically bell shaped with the mode, median, and mean of logarithms coinciding at the same location.


• ATSDR PHA - Bill Murray introduced this discussion, reviewing briefly the talks at the June 2001 ORRHES meeting. Michael Grayson discussed the PHA in more detail, focusing on iodine-131 (I-131). The purpose of the PHA is to evaluate the potential for adverse health effects (past, present and future) to occur in people exposed to I-131. ATSDR will use the following approach in the PHA:


• Determine whether the Oak Ridge Reservation Dose Reconstruction (ORRDR) study is usable in the PHA - the technical reviewers determined that the study overall is good quality and can be used for public health decision-making;


• Use the dose estimates from the ORRDR to assess the potential for adverse health effects; and,


• Determine if follow-up public health activities or research is needed.

In the PHA, both non-carcinogenic and carcinogenic health effects will be considered. For the non-carcinogenic effects, the thyroid-specific organ doses will be used. For carcinogenic health effects, risk estimates taken from the International Commission or Radiological Protection Report # 60, "1990 Recommendations of the International Commission or Radiological Protection," and the National Council on Radiation Protection and Measurements Report No. 116, "need title," will be used. This decision should be revisited. The values in both the above reports are specific to chronic low LET exposure to the whole body. They are not specific for exposure of the thyroid gland for gender and specific ages at time of exposure (nor specific for members of groups of common ethnic origin).

Several questions were raised and comments and suggestions were made.

1. Walter Coin asked what is the difference between ORRDR and the Hanford Dose Reconstruction study. Owen Hoffman replied that there are no major differences; there are minor differences in the variables selected.


2. Walter Coin (I believe that this was Mr. LC Manning who asked the question) asked why are people born in 1952 at highest risk. Owen Hoffman replied that babies born in 1952 would have the highest I-131 dose. Not necessarily the highest dose, but the highest risk as the result of their exposure.


3. Bob Eklund suggested that the I-131 releases need to be reevaluated to include the 20,000 curies released from the graphite reactor. The issue here is not the graphite reactor per se but the completeness of the Task 1 ORDR report in terms of the likelihood that there were other sources of I-131 release in addition to RaLa. Among these were: THOREX, plutonium production, and fuel ruptures at the Graphite Reactor.


4. Al Brooks suggested that the I-131 releases should be compared to standards in effect at time of release, not only to present standards.


5. Owen Hoffman asked why the I-131 thyroid doses will be converted to whole body doses. Michael Grayson said that ATSDR only has carcinogenic risk estimates for whole body. This should be checked with Dr. Robert Spengler at ATSDR. ATSDR should contact NCI for the most recent risk values for I-131 exposure to the thyroid gland of various ages, gender, and ethnic groups. The Task 1 ORDR report represents our state of knowledge as of November 1998.


6. Owen Hoffman suggested comparing the ORR dose estimates to data ATSDR developed for evaluating the risk of thyroid cancer at ORR to that for the Hanford site. Again, Dr. Robert Spengler was suggested as the appropriate contact person.


7. Al Brooks asked what value should be used for the most probable dose. Michael Grayson replied that the mode is the most probable dose. See correspondence from Owen Hoffman on this issue. The mode of a lognormal distribution would occur with less frequency than values outside a 90% confidence interval, and thus is not very "probable". Owen Hoffman maintains that the full uncertainty range should be given more emphasis than central values.

Bill Pardue asked the WG to transmit any individual recommendations to Bill Murray at the Oak Ridge Field Office (Phone - 865/220-0295; fax - 865/220-0457; email - wem2@cdc.gov). The recommendations will be considered at the next PHA WG meeting which is scheduled for Monday, August 6, 2001, from 5:30 pm to 7:30 pm at the Oak Ridge Field Office.

The meeting adjourned at 7:45 pm.

From Michael Grayson for minutes of PHA WG meeting on July 19, 2001:

The Public Health Assessment Work Group (PHA WG) met on Thursday, July 19, 2001 at the Oak Ridge Field Office.

I began discussion of ATSDR's assessment of I-131 by stating that I was interested in engaging the WG to obtain insight into their input, interests, and needs. I believed this interaction will also reflect the desired input, interests, and needs of the full health effects subcommittee. This feedback will help to guide my discussions with the WG and subcommittee as well as my presentations to them.

I stated the purpose of the PHA is to evaluate the potential for adverse health effects (past, present and future) to occur in people exposed to I-131.

ATSDR is currently focusing on past off-site exposures to I-131 that was released from the Oak Ridge Reservation (ORR). A dose reconstruction was conducted to determine the past level of I-131 exposure community members experienced from the ORR facility. This dose reconstruction represents a major effort to estimate past I-131 doses to ORR residents in off-site areas.

I described "ATSDR's Approach for Assessing Potential Adverse Health Effects due to Past I-131 Exposures" in the ORR area. There are three steps.

• Step 1 is to the determine the usability of the I-131 dose reconstruction for the purposes of the ORR Public Health Assessment.


• Step 2 is to use dose estimates in the dose reconstruction to assess the potential for adverse health effects in nearby ORR communities.


• Step 3 is to determine whether follow up public health activities or research are needed in the nearby ORR communities.

I characterized Step 1 as completed, Step 2 as the area in which ATSDR is focusing its current efforts, and Step 3 as a stage which ATSDR will work on in the future.

I stated that ATSDR considered Step 1 completed because we had the I-131 dose reconstruction document technically reviewed by four scientist for:

• quality,


• completeness, and


• adequateness of the document to serve as a foundation to base follow up public health activities.

The reviewers thought that the dose reconstruction achieved three things:

• the I-131 dose reconstruction meets current dose reconstruction standards,


• the I-131 dose reconstruction covers all aspects of dose reconstruction, and


• generally, the I-131 dose reconstruction generates reasonable outcomes.

Because of that, ATSDR believes the dose reconstruction is appropriate for use in the ORR Public Health Assessment and plans to use the report's dose estimates to assess potential adverse health effects due to past I-131 exposures in the ORR Public Health Assessment.

I stated that ATSDR will evaluate the potential for noncarcinogenic and carcinogenic health effects.

I explained the ATSDR plans to use the following general approach to assess potential noncarcinogenic health effects from I-131 exposure

• noncarcinogenic health endpoints will be based on organ-specific doses


• use thyroid-specific doses and recent findings of the Institute of Medicine and National Research Council's "Exposure of the American People to Iodine-131 from Nevada Nuclear Bomb Tests, Review of the National Cancer Institute Report and Public Health Implications" to determine the appropriate Public Health Hazard Category

I explained the ATSDR plans to use the following general approach to assess potential carcinogenic health effects from I-131 exposure

• carcinogenic health endpoints will be based on whole body doses (i.e., convert thyroid specific doses to whole body doses)


• use recommendations from The International Commission on Radiological Protection Report # 60, "1990 Recommendations of the International Commission or Radiological Protection," and the National Council on Radiation Protection and Measurements Report No. 116, "Limitation of Exposure to Ionizing Radiation" to calculate effective doses (i.e., whole body doses) and radiation protection risk estimates


• compare effective doses (i.e., whole body doses) to recommended public dose limits


• use ATSDR qualitative phrases to describe the risk estimates


• use doses and risks to determine the appropriate Public Health Hazard Category