Oak Ridge Reservation: Public Health Assessment Work Group
Public Health Assessment Work Group
December 16, 2002 - Meeting Minutes
ORRHES Members attending:
Bob Craig (Work Group Chair), Kowetha Davidson (ORRHES Chair), George Gartseff, David Johnson, James Lewis, and LC Manley
ATSDR Staff attending:
Jack Hanley, Karl Markiewicz, Bill Murray, and Lorine Spencer
- Minutes from December 2, 2002, meeting - Bob Craig
- Status of PHA - Jack Hanley
- Screening Current and Future Exposures (Surface Soil Pathway) - Karl Markiewicz
- New business – Bob Craig
Purpose: Bob Craig called the PHAWG meeting to order and attendance was noted for the record. He informed the group members that he would be leaving early and would turn the meeting over to Kowetha Davidson at that time.
Minutes from the December 2, 2002, Meeting
Bob Craig asked for comments. No one responded. Kowetha Davidson motioned to approve the minutes and LC Manley seconded the motion. The December 2, 2002, minutes were unanimously approved.
Update on the Public Health Assessment and Project PlanPresenter: Jack Hanley, ATSDR
Jack Hanley gave an update on the Uranium Public Health Assessment that was discussed at the previous PHAWG meeting. He informed the group that since that time, ATSDR has received internal comments from ATSDR’s management. In addition, DOE has reviewed the assessment and determined that it does not contain classified material. Also, he informed the PHAWG that they would receive the written version of the Uranium Public Health Assessment sometime in early January 2003.
Jack Hanley stated that the assessment would be presented at the second PHAWG meeting in January, which the group determined would be on Tuesday, January 21, 2003, due to the federal holiday on Monday, January 20, 2003. He told the PHAWG that ATSDR would like to receive their comments on the assessment during the January, 21, 2003, meeting. Jack Hanley informed the PHAWG that their recommendations and comments will be presented to the ORRHES in February. ORRHES can then consider the PHAWG’s comments before passing their own suggestions on to ATSDR.
Jack Hanley told the PHAWG that ATSDR’s next focus will be on mercury. He stated that ATSDR will begin concentrating on this chemical in January and will begin discussing mercury with the PHAWG at that time.
James Lewis asked if Jack Hanley was following the project plan that had been provided to the PHAWG. He stated that he was looking at items 151 and 153, but the items did not seem to coincide with Jack Hanley’s presentation. Jack Hanley stated that he was reading line item 152, regarding the Uranium Y-12 Draft Pubic Health Assessment, that would be presented to the PHAWG on January 21, 2003, and to the ORRHES in early to mid-February. Jack Hanley told James Lewis that the date of January 13, 2003, was incorrect on the plan and that the date was changed to January 21, 2003.
James Lewis voiced concern that the PHAWG needs to be provided periodically with current project plans and would like the meetings to follow the plans. Bob Craig agreed and suggested that the PHAWG receive up-to-date project plans once a month.
Radiation Screening Level
According to the Chair, at the previous ORRHES meeting, Kowetha Davidson requested that the PHAWG reconsider its approach to the radiation dose screening levels. Bob Craig led this discussion and requested that the PHAWG revisit the issue of radiation screening levels to ensure that the group was in agreement on this subject.
Bob Craig began by summarizing the information that was presented to the PHAWG in four previous meetings. Three different methods were considered for the screening levels; none of which received a two-thirds vote to pass. First, there was a 71 millirem per year (mrem/y) screening level that received a majority, but not a two-third, approval vote. Second, the group looked at a motion to allow ATSDR to determine what the screening levels should be. Third, a screening level of 14 mrem/y was evaluated, but failed to pass.
The Chair noted that none of these screening levels passed and assumed that ATSDR would establish minimum risk levels. Jack Hanley responded by saying that ATSDR will use a level that is one-third the annual background for the screening at Oak Ridge. At this time in the meeting, the Chair asked for any comments, motions, or other actions concerning radiation dose screening levels.
In response to the Chair’s question, James Lewis stated that he thinks that the ORRHES needs to be involved with this issue. He explained that he expects to receive challenges and finds that this issue is ... , “significant and the committee needs to weigh in on it.” He also commented that within the ORRHES, there are people with varying degrees of knowledge and expertise. He believes that the radiation dose screening needs to be summarized and presented in a way that is not difficult to understand.
The Chair responded by stating that the PHAWG has received several informative presentations on screening levels from ORRHES members Tony Malinauskas, Don Box, Herman Cember, and George Gartseff. The Chair did not believe that any expert would be able to tell the difference between 100, 71, and 14 mrem/y as far as a health risk level. As the PHAWG could not come to a consensus, the Chair believed that ATSDR should have the ability to proceed as the agency deems appropriate.
The Chair asked if the PHAWG could develop a resolution to deal with
the current situation. James Lewis responded by making a motion to reconsider
the 71 mg/year motion that failed originally. He requested that the motion,
originally submitted on October 22, 2002, be resubmitted to the ORRHES.
The motion requested that the radiation screening level of
71 mrem/y be reconsidered as a screening level by ORRHES. The motion also requested that a discussion, summary, and rationale of the discussion be included in the motion, as well as including all three screening levels previously mentioned.
The Chair commented that he believed it would be beneficial to allow ATSDR to determine the screening level. Following these comments, he motioned to vote on the motion for resubmittal. One person was opposed. The motion received a two-thirds majority from the PHAWG and passed. The PHAWG opted for Paul Charp (ATSDR) to draw up the motion and bring it to the next PHAWG meeting.
Kowetha Davidson suggested that the PHAWG provide feedback that will be universally understood. She stated that the work group will never be able to answer every question that arises. Instead, she explained that the PHAWG needs to adhere to a general rule of maintaining its focus of the group’s goals and intentions.
James Lewis expressed his concern that within the different work groups, subcommittee, and work sessions, there is a variety of people with various backgrounds. He used the subcommittee as an example, pointing out that within that group, there are persons with science backgrounds, technical expertise, and laymen as well. He suggested that the PHAWG compose and send out packets that provide persons who do not attend the meetings with information that is discussed, major recommendations, background summaries, and additional data as well.
Kowetha Davidson proposed that the ORRHES make an additional effort during presentations, such as making recommendations and providing feedback, to ensure that presenters provide all needed information and answer all questions. She believes that these extra efforts will help the members of the subcommittee to understand the issues.
Current and Future Exposures to Surface Soil PathwaysPresenter: Karl Markiewicz, ATSDR
Karl Markiewicz presented (1) background information on the chemical screening process, (2) detailed information on surface soil samples taken at ORR, and (3) the exposure dose calculations used by ATSDR.
Chemical Screening Process
Karl Markiewicz explained that the first step used by ATSDR in the chemical screening process is to look at chemicals in environmental media (e.g., biota). The second step is to conduct a preliminary screening. The third step is to evaluate the Environmental Media Evaluation Guide (EMEG) for a chemical. He stated that EMEGs are very conservative numbers that are media-specific and are based on maximum concentrations and maximum exposure levels.
Karl Markiewicz also detailed the aspects of a pathway evaluation used to determine the completed or potential pathways for exposure. He stated that ATSDR evaluates various pathways, including soil, water, air, and biota. He added that ATSDR also looks at different exposure scenarios, such as a worker or a child in a residential area, to formulate an accurate evaluation for each individual.
Karl Markiewicz reviewed aspects of boron that he had discussed in a previous PHAWG meeting. He emphasized that any change in the weight or quantity of media would change the exposure level. He presented an example where changing the body weight and quantity of soil altered the EMEG from 20 to 7,000 parts per million (ppm). He stated that the EMEG for a residential pica child for boron is 500 ppm. In addition, Karl Markiewicz showed that the U.S. Environmental Protection Agency (EPA) has an RfD of 0.09 milligram per kilogram per day (mg/kg/d) for the average US daily intake of boron, whereas ATSDR’s minimum risk level (MRL) is 0.01 mg/kg/day. The lowest-observed-adverse-effect level (LOAEL) for boron is between 10 and 100 mg/kg/day, showing that ATSDR’s MRL falls far below the LOAEL.
Summary Statistics on Surface Soil Samples
Karl Markiewicz presented the PHAWG with summary statistics that detailed the chemicals sampled in the surface soil at the Oak Ridge Reservation (ORR). First, there were 394 different chemicals sampled; 311 of these were sampled off site and 318 were sampled on site. Second, for 46 on-site and 58 off-site chemicals, the maximum concentration detected was above the comparison value (CV). These numbers did not include chemicals that were detected in less than 10 % of the samples because these were detected with such low frequency that people would not be exposed to them on a regular basis, if at all. Third, for 189 on-site and 211 off-site chemicals, the maximum concentration detected was below the CV. Fourth, 100 chemicals were detected in less than 10 % of the on-site samples and 101 chemicals were detected in less than 10 % of the off-site samples. Finally, 140 chemicals did not have CVs.
Karl Markiewicz elaborated on the chemicals that did not have CVs. He stated that if a chemical does not have a CV, then it does not have a screening value from ATSDR. In such cases, he stated that a “surrogate” chemical may be used, e.g., benzene for bromo-benzene). He mentioned that this could slow down the process at ORR, but that three-fourths of the chemicals without CVs can be screened out.
During his presentation, Karl Markiewicz provided the PHAWG with specific information on various surface soil samples taken at ORR. The following site-related chemicals were detailed: antimony, arsenic, lead, mercury, and trichlororethylene.
Karl Markiewicz informed the PHAWG that this chemical is found almost anywhere in the country and in several forms. He stated that 105 samples were collected off site and tested. Seventy-four (75 %) of the samples contained antimony. In addition, 225 of 410 samples (almost 50 %) taken on site detected antimony. He stated that the screening value, a Reference Dose Media Evaluation Guide (RMEG), is 20 ppm. Antimony was detected in on-site surface soil locations around K-25, one near Y-12, and in the far eastern area of the ORR.
Karl Markiewicz presented the results of arsenic surface soil samples at ORR. He stated that arsenic is both man-made and naturally occurring, and is consequently found everywhere. There were 607 on-site samples and 424 off-site samples taken. The concentrations detected ranged from less than 1.0 ppm to almost 200 ppm. According to Karl Markiewicz, the levels detected for arsenic at ORR are “low.” He explained that the Cancer Risk Evaluation Guide (CREG) for arsenic is 0.47 ppm. In addition, the background range for arsenic was listed from 2.3 to 655 ppm. Karl Markiewicz stated affirmatively that the 655 ppm could not be correct for the ORR background range and ascertained that the level should be 6.55 ppm. He said that he would throw this number out as a background level because it would skew the data.
Karl Markiewicz described to the PHAWG that lead levels have decreased significantly since the 1970s and 1980s because of the reduction of lead in gasoline, canned foods, and other products. The EPA’s guideline for lead in residential soil is 400 ppm. The EPA also has an emergency level for children of 1,500 ppm; if the level reaches this amount, the child is immediately removed. Karl Markiewicz demonstrated to the PHAWG on a map that lead detection levels exceeded the 400 ppm near the K-25, X-10, and Y-12 sites, and north of Y-12 also. He stated that the occurrence of lead in these areas may not be a result of the site, but that ATSDR will review the data because of children’s susceptibility to adverse health effects from lead. He also told the PHAWG that ATSDR defines elevated lead levels in children as levels that exceed 10 micrograms per deciliter (µg/dL). However, he said that 95 % of children will have a normal daily exposure to lead that is less than 10 µg/dL.
Karl Markiewicz reported that 2,716 on-site and 707 off-site surface soil samples were taken for mercury. He stated that 91 or 92 % of these samples had positive results for mercury. ATSDR used EPA’s soil screening value for methyl mercury of 20 ppm. He stated that the background levels detected at ORR (0.09 to 0.8 ppm) were “pretty normal.” In addition, he told the group that mercury releases will also be evident in other media, e.g., water), in that these samples were only representative of mercury releases in surface soil.
Karl Markiewicz informed the PHAWG that TCE was detected in 150 out of 896 on-site surface soil samples and in 14 out of 41 off-site samples. ATSDR used the EPA’s risk-based concentration screening value of 1.6 ppm. According to Karl Markiewicz, none of the off-site samples exceeded this screening value; however, one sample in Y-12 exceeded the screening value. In addition, he described how detections of volatile substances, such as TCE, are normally lower in soil because the substance will volatilize or break down in this type of media.
Exposure Dose Calculations
Karl Markiewicz discussed how ATSDR conducts exposure dose comparisons. Estimated exposure doses are calculated and then compared to ATSDR’s MRLs. He said that if the estimated levels exceed the MRLs, then these substances become contaminants of concern (COC), the chemicals are screened, and a public health assessment may be conducted. He also explained that an MRL is formulated by taking the weight of the compound in mg, dividing by the body weight in kg, and then dividing by day (mg/kg/d). He stated that ATSDR utilizes the MRL for evaluation purposes, whereas EPA uses a reference dose (RfD).
Karl Markiewicz showed the PHAWG the “standard formula” for exposure dose calculations. He stated that if a community was small and detailed information was known about each person, then site-specific information could be used for each person in the formula. However, this is not usually the case and thus, assumptions are used within the formula.
The formula, which is used by ATSDR and EPA, was presented as the following:
The terms in the formula are explained below.
The formula can change by varying the weight of evidence for certain compounds. ATSDR uses the 67th percentile for chemical concentrations which is one standard deviation from the mean. The standard deviation is used to account for different exposures, populations, and exposure assumptions. The formula is logarithmic in nature and will capture the majority of the higher-end concentrations.
The ingestion rate is measured in grams per day.
With regards to exposure frequency, Karl Markiewicz stated using 365 days is very unrealistic. ATSDR determines the days per year depending on the population that is being considered. For example, the exposure frequencies differ between a pica child, non-pica child, adult, and worker.
Different methods are used to measure exposure duration. For pica cases, the standard used is three years. For a non-pica child, the standard is six years. For an adult, the standard duration is 30 years.
The body weight changes depending on the population. However, standard assumptions are used to assess the weight.
The standard default assumption for averaging time over a lifetime for cancer is 70 years multiplied by 365 days. For non-cancer formulas, the averaging time is the exposure duration multiplied by 365.
Karl Markiewicz presented the PHAWG with thermometer graphs to demonstrate the relationship between doses and effects. The dose line presents the dose in order of magnitude and the effects are listed from right to left. He presented graphs for antimony, arsenic, and TCE. He compared groundwater ingestion levels to estimated exposure doses, using examples from the Paducah Gaseous Diffusion Plant (PGDP), in Paducah, Kentucky. Furthermore, he stated that it is critical to look at any detected level that exceeds the EPA level.
Karl Markiewicz detailed the various observed effects of long-term exposure from ingesting antimony. He stated that the LOAEL was 0.26 for animals, 0.5 for humans (acute oral), and 0.35 for rats. He discussed how 0.0004 mg/kg/d, which is the EPA chronic oral RfD, is normally used as the screening value for antimony. He used examples from the PGDP to demonstrate a case where the estimated total exposure dose for antimony was approximately 0.001 mg/kg/d above the chronic EPA oral RfD for drinking water in rats, but well below the LOAEL.
Karl Markiewicz also presented the health effects from long-term exposure via ingestion of arsenic. He showed that the LOAEL for animals was 50 mg/kg/d and the no observed adverse effect level (NOAEL) for animals was between about 2 and 10 mg/kg/d. He detailed how the cancer effect level in humans is between 0.01 and 0.1. However, he stated that there is a large range of cancer effects seen in humans. He explained that many studies have shown that within this range (0.01 and 0.1), the body continues to methylate arsenic and humans are often not affected. ATSDR has a chronic oral MRL of 0.0003 and a provisional acute MRL of 0.005. At PGDP, the estimated groundwater exposure dose was 0.0002 mg/kg/d for a pica child, 0.003 for an adult, and 0.007 for a child.
Karl Markiewicz went into detail on the long-term exposure health effects from ingesting TCE through groundwater. He explained that the LOAEL is 50 mg/kg/d for a mouse and that the ATSDR MRL for TCE is based on this mouse study. ATSDR’s acute MRL is 0.2 and the EPA RfD is 0.006. He stated that the estimated exposure dose for adults at PGDP fell below the acute MRL, but above the RfD.
Next Phase/Additional Information
Karl Markiewicz mentioned that the public health indications will be a useful tool for the public. He said that any chemical with elevated levels needs to be discussed in the public health indications section of the public health assessment and that it would include the levels seen in animals, what was found at the site, and the regulatory limits for each chemical.
Karl Markiewicz stated that by January he will have all of the exposure doses calculated. By looking at these, he said that he can determine what organic and inorganic chemicals get “pulled in” for both surface and subsurface soil. He also said that he will need to spend a lot of time focusing on the chemicals that do not have comparison values.
James Lewis asked whether ATSDR’s MRL or EPA’s RfD is more sensitive. Karl Markiewicz responded that ATSDR uses MRLs for screening and explained the hierarchy that ATSDR uses. He stated that ATSDR first looks at the MRL, then looks at EPA’s or other agency’s numbers, and, if a discrepancy exists, ATSDR uses the lower number. Jack Hanley responded to the question by stating that, even if an estimated dose exceeds the MRL or RfD, it does not mean that an adverse health effect will occur. In addition, the MRL is used solely for screening purposes - to help focus on “priority contaminants.”
Following Jack Hanley’s response, James Lewis asked if the EPA and ATSDR agree on the contaminant levels. Kowetha Davidson responded by stating that the EPA and ATSDR have different purposes for their established levels. She further explained that the EPA uses the RfD for risk assessment, regulatory purposes, and to establish clean-up levels. After these questions and comments, Jack Hanley summarized the discussion by stating that the RfD is used to define “safe” levels and for regulatory purposes. He noted that ATSDR is looking at the likelihood that a chemical could or could not cause a health effect.
George Gartseff inquired if the EMEG formula was always used with an oral ingestion rate. He used an example of examining soil contaminants where dermal exposure is of concern. Karl Markiewicz responded that there are no dermal rates for EMEGs. He explained that dermal exposures are evaluated by looking at models.
James Lewis requested that a list of assumptions be provided to the PHAWG and ORRHES. Karl Markiewicz suggested that assumptions be grouped into general areas (i.e., drinking water, rat dose). He stated that basic assumptions can be compiled. Kowetha Davidson suggested that only the major assumptions be listed because there was such a large quantity of them. Karl Markiewicz requested that the PHAWG assist and help him make the assumptions more clear.
James Lewis brought up a concern. He stated that in Scarboro (Oak Ridge neighborhood) the EPA and Department of Energy (DOE) went into the area to test for contaminants but the agencies sampled for different chemicals. He detailed how this caused confusion and concern in that neighborhood because the residents were not given a clear-cut picture of the situation. David Johnson agreed with James Lewis and showed concern that this same type of occurrence could take place at Oak Ridge if ATSDR and EPA used different criteria. It was suggested that details be written up to inform the community of the differences between EPA and ATSDR.
One meeting participant asked about thorium levels detected at or near the site. Karl Markiewicz responded that he thought the frequency of detection was very low. He said he would look at the data to confirm this.
Kowetha Davidson pointed out the differences in off-site and on-site detection on the maps provided to the PHAWG. Karl Markiewicz responded that some chemicals, such as lead, could come from different places other than the site, e.g., a gas station.
James Lewis asked if screening values change over the years or if they remain constant. Karl Markiewicz explained that if the values change at all, they typically are lowered or eliminated. James Lewis commented that he thinks further explanation is necessary on the levels. In response, Karl Markiewicz provided an example of how lead screening values have decreased over the years as lead has been examined for clinical and behavioral changes in children. Kowetha Davidson went into further detail regarding James Lewis’ question. She commented that unless high volume chemicals are involved, the levels do not receive much attention and as a result, would not be changed.
During the presentation on arsenic, one participant inquired about the possible benefits of this chemical in animals. Karl Markiewicz stated that this had not been proven yet, but it remains a large debate.
During the discussion on mercury, a meeting participant asked about the mercury in relation to coal mining. Karl Markiewicz stated that due to EPA’s “acid mine program,” mercury releases from coal mining are no longer an issue.
James Lewis suggested to the PHAWG that they look at a community in South Knoxville that is close to Oak Ridge. He stated that this neighborhood had well water that was contaminated, but for many years the residents were told that the water was safe to drink. He said that the water was now being cleaned up, but that the residents had lost confidence in authorities because of how the situation was handled.
In response to Karl Markiewicz’s question asking if he should present more detail to the ORRHES on exposure dose calculations, Kowetha Davidson stated that the full subcommittee may need more information than he provided. He agreed and stated that he thought it would be beneficial to present an “exposure dose 101” that could include more detail with the formulas to show the impact of rate and exposure changes in the formula. Kowetha Davidson agreed and thought it may also be helpful if he could change numbers on the screen to show how the formula would change with varying information.
James Lewis was concerned that nothing seems to get “cleared up.” Also, he suggested that Karl Markiewicz utilize recent data from Scarboro when he presents the information to the ORRHES. Kowetha Davidson disagreed and thought that Scarboro would not like to be singled out. However, James Lewis thought the community would not mind if their data were used for comparison purposes. Karl Markiewicz stated that he could present all of the data for Oak Ridge and then also show the results for Scarboro as a “rough comparison.”
Following Karl Markiewicz’s presentation, James Lewis requested that Paul Charp also use thermometer graphs in his future presentations. In addition, he requested that the minutes reflect the PHAWG’s questions and concerns so that the community will know what was asked by the public and the responses they received at the meetings. In response to James Lewis’ comment, Kowetha Davidson voiced that she did not think it was necessary to put all of the questions from the meetings into the Community Health Concerns database. She thought this would result in having too much included in the database. She stated that there needs to be “selectivity” involved in the database so people can recognize what is important. James Lewis expressed his concern that the technical audience may miss issues that are important to other community members.
Jack Hanley commented that Karl Markiewicz will not have to be as detailed in his future presentations, except for when he addresses the ORRHES on February 10, 2003. He stated that he would like Karl Markiewicz to provide the results, and to include additional information as well.
Kowetha Davidson asked the PHAWG if there were any additional issues. The group decided that the next PHAWG meeting would be held on January 6, 2003. Jack Hanley stated that epidemiology would be the topic at the next meeting. Kowetha Davidson asked the PHAWG for any new business. The PHAWG did not have any new business and she declared the meeting adjourned.