Oak Ridge Reservation: Public Health Assessment Work Group
Public Health Assessment Work Group
December 15, 2003 - Meeting Minutes
ORRHES Members attending:
Bob Craig (Chair), Susan Kaplan, Pete Malmquist, James Lewis, David Johnson, LC Manley, George Gartseff, Kowetha Davidson, and Tony Malinauskas
Public Members and Others:
Norman Mulvenon, Danny Sanders, Tim Joseph (DOE), Roger Macklin, Al Brooks, Gordon Blaylock, and Owen Hoffman
Bill Taylor, Paul Charp, Allan Susten, Melissa Fish, and Jack Hanley (telephone)
The purpose of the meeting was to present the basic purpose and components of the public health assessment and to differentiate between ATSDR’s Public Health Assessments and EPA’s site-specific Risk Assessments.
Susan Kaplan moved that the November 6th Draft PHAWG minutes be approved. LC Manley seconded the motion. The motion passed. The draft meeting minutes for November 6th were approved.
Allan Susten’s Presentation Regarding ATSDR’s Public Health Assessment and EPA’s Risk Assessment
All handouts used in this presentation are available in the Field Office with the meeting minutes.
Paul Charp introduced Allan Susten to the group and provided some background on the legal differences between a Risk Assessment and a Public Health Assessment.
Paul Charp said that ATSDR’s public health assessment is mandated under the Superfund act of 1986 under section 104(i) (6) and the EPA’s risk assessment regulations are under the same act under section 121, clean up standards.
Allan Susten is a board certified toxicologist and serves as the Assistant Director for Science in the Division of Health Assessment Consultation (DHAC) for ATSDR. One of Allan’s duties is to ensure that the best available science and scientific principles are consistently applied to the documents that DHAC produces. Allan Susten also serves on ATSDR’s Minimal Risk Level Work Group that develops the MRL values used within the agency. Before coming to ATSDR Allan worked for the Environmental Protection Agency (EPA), the National Institute for Occupational Safety and Health (NIOSH), and taught Pharmacology at the Kansas City College of Osteopathy. In addition to being a toxicologist Allan Susten is also a registered pharmacist and a Diplomat of the American Board of Toxicology.
PowerPoint Slide One- ATSDR Public Health Assessments
Allan Susten explained that his presentation would not be site specific. Rather, it would be a general overview of how ATSDR approaches public health assessments and what the differences are between public health assessments and risk assessments.
Allan Susten said that ATSDR is a public health agency and looks at health issues while EPA is a regulatory agency with regulatory mandates. EPA uses the numbers and has different approaches from ATSDR.
PowerPoint Slide Two-Objectives
Allan Susten told the group that he would review the basic purpose and components of the public health assessment and differentiate ATSDR’s public health assessments (PHA) from site-specific risk assessments (RA).
PowerPoint Slide Three-Approach
Allan Susten told the group that he would be taking the opportunity to perform a side-by-side comparison of the PHA to the RA by pointing out the similarities and differences and by pointing out the advantages and disadvantages of each from a public health perspective. In addition Allan would provide case examples and provide some perspective regarding both the PHA and RA. Allan added that the key message is that ATSDR’s PHA focus is qualitative and looks at the public health issues while EPA’s RA is more concerned with regulatory and clean up issues.
PowerPoint Slide Four-Definitions
Allan Susten explained that the PHA is a process used to evaluate exposure to chemicals (as well as radionuclides) in the environment and the impact on public health. The RA is an analysis that uses information—often the same information used in the PHA—about toxic substances at a site to estimate a theoretical level of risk for people. Allan said that the RA tends to be more quantitative than the PHA. The PHA is more narrative oriented that EPA’s RA.
PowerPoint Slide Five-PHA/RA Comparisons
Allan Susten compared the PHA to the RA. Allan said that the PHA tends to be a qualitative evaluation of exposure and health effects. The PHA defines likely exposure and populations by having the staff examine the real population to see who could be exposed. Allan added that just because someone lives in a community does not mean that they were exposed. Also, the PHA’s focus is on the past, present, and the future of exposed populations.
The RA is a quantitative evaluation that often does not require a specific population be identified. Because the RA is regulatory oriented, the RA’s focus is usually on the present and the future. It is typical for ATSDR’s PHA to look at the past but looking at the past is not a typical practice used in EPA’s RA.
Tim Joseph said that he disagreed with the statement that the PHA is qualitative while the RA is quantitative. Almost everything that ATSDR does for the PHA is based on a quantitative calculation. Tim does not want to see value taken from a PHA by saying that it is qualitative.
Allan Susten responded that ATSDR does use risk assessment methodology in the public health assessment. However, ATSDR’s PHAs are more qualitative.
Tim Joseph responded that the PHA is every bit as quantitative as the RA if not more so. The endpoint of both the PHA and the RA is based on quantitative information. Tim Joseph believes that it is important to not take anything from ATSDR by starting with a slide that lists the PHA as qualitative and the RA as quantitative. Do not give the RA more credit than the PHA-both products are quantitative.
Owen Hoffman said that ATSDR’s PHA has yet to embrace uncertainty analysis in their evaluation. Tim Joseph responded that uncertainty analysis is not a requirement to be considered quantitative.
Owen Hoffman said that he had been hired to perform a peer review of the EPA Human Health Risk Assessment for General Electric PCB’s released to the Housatonic River and a major criticism of the RA is that EPA is not addressing the attributes of specific populations within the context of its quantitative uncertainty analysis. Owen felt that because of the peer review process itself, EPA might be asked to do something similar to that of a PHA type of analysis, but that exposures and risks to reference individuals representative of specific population subgroups would be more fully characterized with respect to uncertainty.
Allan Susten responded that at the end of his presentation, he would answer questions relating to sediment levels.
PowerPoint Slide Six-PHA/RA Comparisons continued
Allan Susten compared the data and information used in the PHA to the data and information used in the RA. Allan said that the PHA and RA tend to use the same data in terms of toxicology and exposure. For example both the PHA and RA use environmental data such as sampling data. However, there are differences in the way environmental data are used by both agencies. When sampling data is not available ATSDR will use models. However, while models are useful, ATSDR will not use models as a decision tool while EPA may use a model as a decision tool.
Owen Hoffman said that the PHA at Hanford is entirely based on models. Allan Susten replied that he does not know very much about site specific PHAs and that he was speaking in general terms about the vast majority of ATSDR’s PHAs.
Owen Hoffman said that in order to investigate the past and to see what people were exposed to in the past, exposure is often based on models that are used as a type of decision tool. Allan Susten responded that he should reword his statement: at most places, ATSDR would not use models as a decision tool. However, there are some locations where ATSDR does use models as a decision tool. Allen Susten added that all models are wrong, some are useful and it is important to be careful about how models are discussed.
Allan Susten pointed out that another major difference between EPA and ATSDR is how each agency looks at soil data. For example, ATSDR is interested in the top two to three inches of soil and has asked EPA to sample the top two to three inches of soil because the topsoil is what people will be continually exposed to. EPA uses core samples that go from six to twelve or eighteen to twenty-four inches as a basis for clean up.
Allan Susten pointed out that both ATSDR and EPA look at standards and guidelines. But for ATSDR, the standards and guidelines are screening values that answer the question of whether or not ATSDR needs to look further at exposures, toxicity, and health effects data. EPA uses the standards and guidelines to basically say that if an area is cleaned up, a full-blown RA will not be necessary.
Regarding health outcome data, Allan Susten told the group that the PHA uses health outcome data while the RA generally does not consider health outcome data.
Allan Susten said that ATSDR actually walks around and talks with community members to learn important community information such as community concerns. The PHA is then often written in a way that will address the specific community concerns. The PHA has a community focus that is not normally found in the RA.
Concerning health effects data, Allan Susten said that ATSDR considers health effects data in a different way than EPA when EPA is developing standards and guidelines. ATSDR uses site-specific health effects data to learn what is known about the health of the community. ATSDR is thus considering the biological responses, dose responses, as well as how likely the biological responses are, and not just a single number.
Allan Susten told the group that the endpoint for the PHA is that ATSDR takes into consideration environmental data, standards and guidelines, health outcome data, community information, health effects data, and evaluation of exposures. The PHA will make a statement of hazard, which is based on the dose. The endpoint for the RA (especially as it relates to cancer) is that EPA will make a statement of the theoretical risk. Allan added that theoretical risk is not an actuarial risk although the public often gets confused. The theoretical risk is great for setting priorities and comparing against guidelines, but it will not tell the public about adverse health effects.
Al Brooks said that theoretical risk is not a good way to set priorities unless the theoretical risk is accurate.
Some discussion was started regarding theoretical risk but Allan Susten requested that further discussion be held off until the end of the presentation.
PowerPoint Slide Seven-PHA/RA Comparisons continued
Allan Susten described the outcomes that could result from a PHA and from an RA. Allan said that the outcomes from a PHA are generally public health actions while the outcomes from a RA are generally remedial alternatives.
The PHA outcomes might lead to health studies, health education, looking for additional information to fill data gaps, exposure registries, recommendations to cease or reduce exposure, address community concerns, and/or trying to leverage public and private partnerships. The RA outcomes might lead to meeting site-specific cleanup goals or site cleanup.
Owen Hoffman asked for how many federal facilities had ATSDR actually performed an epidemiological study. Allan Susten responded that he knew of several that had been done. Specific examples included Camp Lejeune, Fallon Nevada, and Kelly Air Force Base. Allan added that the studies are performed out of the Division of Health Studies at ATSDR, which is made up mostly of epidemiologists. The Division of Health Studies determines the feasibility of performing the study and then they carry out the study.
James Lewis asked if the sequence of events is important in helping the public understand the PHA findings. Allan Susten responded that he had not performed a PHA in a while and he deferred the question to Paul Charp or Jack Hanley who are presently writing a PHA. Allan added that ATSDR is always trying to get into the community, define exposure, and gather all available data. Although many events are laid out in a sequence format in the Guidance Manual, in reality, many events are performed in a parallel or simultaneous fashion.
Jack Hanley agreed with Allan Susten’s comments about PHA activities usually being performed in parallel with different teams working together.
Paul Charp added that several outcomes cannot be started until the PHA is completed (such as filling data gaps and starting exposure registries) and that certain activities do require a sequential order.
Susan Kaplan said that she had called the Centers for Disease Control and Prevention (CDC) when the Camp Lejeune study was going on and there being an automated phone system indicating which button to select if calling about Camp Lejeune or CDC. Susan asked if there has been any other effort like that attempted on a nation-wide basis at any DOE facility to track down a population that might have been exposed.
Paul Charp said that ATSDR has not made such an attempt but CDC and the National Center for Environmental Health (NCEH) has.
Allan Susten said that he could not answer the question for just federal sites and that he would try to find out about any nation-wide attempt to track down a population that might have been exposed at a DOE facility. Allan added that at the non-federal site of Libby, Montana there is currently an effort underway similar to what Susan Kaplan described.
Al Brooks asked if such an effort to track down a population would only occur if there were sufficient exposure to warrant it. Allan Susten responded that in the best of all worlds the answer would be yes. However, public pressure can be powerful.
PowerPoint Slide Eight-Primary Difference
Allan Susten explained the primary difference between the PHA and RA. PHAs make a determination about impact of sites on public health and identify pubic health actions. The PHA tries to answer the questions: Has my health been or will my health be affected? The RA makes a determination of acceptable or unacceptable risks with respect to regulatory requirements. The RA also identifies remedial options. The RA tries to answer the questions pertaining to theoretical risk of disease. Allan Susten presented a quote from EPA that stated that the actual risk might be less; the actual risk may be zero.
Allan Susten said that EPA has put in a lot of effort trying to communicate and explain what the risk numbers mean and do not mean. However, the message explaining the risk numbers often gets lost.
Tim Joseph asked what is meant by the actual risk might be less—less than what?
Allan Susten said that the risk numbers that EPA puts out are the upper bound of the 95% confidence interval. So the actual risk may be lower than that, in fact it might be zero. It is all in the assumptions that drew that line/that slope value.
Owen Hoffman said that Allan Susten was absolutely correct in terms of most chemicals-but for radiation that is not true. For radiation it is a central estimate of the slope, it is not the upper 95% bound. In the quantitative estimates of the uncertainty on radiation risk-there is no credence given to zero.
Tony Malinauskas attempted to get involved in the conversation but there was a lot of interruption by work group members and the conversation was deferred to the end of the presentation. Allan Susten reminded the group that the presentation was just a general overview and that he would get into specifics at the end of the presentation during question and answer time.
PowerPoint Slide Nine-Case Examples
Allan Susten provided two case examples of chemicals, one being DCE and the other chloroform.
PowerPoint Slide Ten-What to think about during these examples?
Allan Susten suggested that as the group reviews the examples of DCE and chloroform that they keep in mind the policy versus the science, what is known and not known, as well as the public health conclusions and recommendations.
PowerPoint Slide Eleven-DCE Case Example
Allan Susten told the group that the DCE case example he was providing was a real example. There was a groundwater plume affecting indoor air and the levels of DCE were found to be exceeding the acceptable cancer risk (as identified by EPA). Thus, the EPA made the public very aware of the risk. In EPA’s discussions with the community EPA said that they would create a sub-slab ventilation system for the homes that were above the plume because those homes exceeded the criteria risk number. Meanwhile EPA and other agencies throughout the world were re-looking at DCE and reevaluating the existing data. After reevaluating the existing data it was decided that there should not be a unit risk for DCE—that it was not going to pose an inhalation cancer risk. Next, EPA told the community that the DCE was no longer a risk for cancer and that the sub-slab ventilation would not be performed after all. Allan Susten said that occurred because the evaluation of more biology took away the cancer risk for this chemical.
PowerPoint Slide Twelve-DCE Case Example continued
Regarding the DCE case example, Allan Susten provided an example for oral drinking water and air inhalation.
Oral-drinking water: Allan Susten said that EPA at one time had a cancer risk number for DCE in oral drinking water. Once the cancer risk was eliminated from the drinking water, a new non-cancer value was developed for drinking water. EPA’s new reference dose value for DCE would be equal to a water concentration of 1700 parts per billion. (An RfD is an EPA estimated dose at which no health effects are expected, and which EPA uses as a criteria for cleanup.) The MCL is the enforceable water standard. For DCE, the MCL is 7 parts per billion.
Allan Susten explained that the difference between EPA’s MCL and reference dose is partly due to the fact that MCLs are not necessarily all health-based and the best available technologies are associated with the MCL.
Inhalation-air: Allan Susten said that the EPA at one time had a cancer risk number for DCE in air. Once the cancer risk was eliminated for DCE in the air, a new non-cancer value was developed. The new value is a reference concentration of 50 parts per billion. Thus, levels below the reference concentration are not going to cause adverse health effects. As a means of comparison, the American Conference of Governmental Industrial Hygiene has a worker value (8 hours per day, 40 hours per week, 40 years of lifetime exposure) of 5000 parts per billion.
Allan Susten reviewed the DCE case example and said that 1) EPA went in and told the community that there was a cancer risk and would be cleaning it up and 2) EPA came back and said that they reevaluated the information and it is not a cancer risk and it will not be cleaned up.
There was additional discussion regarding whether or not EPA had additional data when it reevaluated the cancer risk. Allan Susten said that EPA did not receive much new data. Instead, it reevaluated existing data using biology and mechanisms of action.
PowerPoint Slide Thirteen-Figure 2.1
Allan Susten explained that this figure is from ATSDR’s Toxicological Profile and shows the effects of DCE via inhalation in the male mouse kidney. Effects from DCE were seen in the male mouse kidney only—not in rats, female mice, or hamsters.
PowerPoint Slide Fourteen-Chloroform Case Example
Allan Susten provided the group with a chloroform case example. Allan pointed out that chloroform is a common groundwater contaminant, that there were cancer risk values for inhalation and oral (ingestion), and that the cancer risk usually drove the remediation process. Allan said that what he means is that EPA derives two types of numbers—they derive a cancer risk number (unit risk) and a non-cancer value (reference dose).
PowerPoint Slide Fifteen-Chloroform Case Example continued
Regarding the chloroform case example, Allan Susten provided an example for oral drinking water and air inhalation.
Oral-drinking water: Allan Susten said that EPA at one time had a cancer risk number for chloroform in drinking water because chloroform was considered a likely human carcinogen but not at levels that humans would likely get through environmental exposure. For the first time EPA was saying that yes, this is a likely carcinogen at an extremely high dose, but not under typical exposures. EPA dropped the cancer risk number because if humans and animals were protected from liver damage, then they would also be protected from cancer. Once the cancer risk was eliminated from the drinking water, a new non-cancer value was developed. EPA’s new reference dose (RfD) is a water concentration of 350 parts per billion. The MCL is the enforceable water standard for chloroform; the MCL for chloroform is 80 parts per billion as part of total trihalomethanes.
Owen Hoffman asked if EPA now uses the 350 parts per billion or the 80 parts per billion. Allan Susten responded that the MCL of 80 parts per billion is the legally enforceable standard for public water supplies.
Inhalation-air: Allan Susten said that the EPA at one time had a cancer risk number for inhalation of chloroform in air. The cancer risk was eliminated for chloroform in the air, but a new non-cancer value has not been developed. The American Conference of Governmental Industrial Hygiene has a threshold limit value for worker exposure (not the general community where there are children and pregnant women) of 10,000 parts per billion.
PowerPoint Slide Sixteen-Dose-Response Data—Gavage vs. Drinking Water
Allan Susten presented some of the dose-response data for chloroform. Allan pointed out the actual tumor response when chloroform was given by gavage. (A gavage is when a tube is inserted through the mouth directly into the stomach and all of a chemical or substance is administered at one time.) When chloroform was given to animals by gavage at the dose of 220 mg/kg/day and 350 mg/kg/day, tumors were observed. Chloroform is so soluble that it could be put into the drinking water of rats. But when chloroform was in the drinking water, the same percent of tumors were not observed. On the basis of this information and biological changes, EPA determined that chloroform does not pose a cancer risk under the conditions of exposure that most people would be exposed. If people are protected against liver damage they will also be protected against cancer.
Owen Hoffman said that the protective concentration for liver damage is well within the EPA concentrations that lead to the EPA acceptable cancer risk range of 10 to the minus 6, to 10 to the minus 4 (one in a million to one in ten thousand risk of cancer incidence). Thus, the use of a non-cancer health endpoint for decision-making in place of a health endpoint based on the risk of cancer is a moot issue, because the concentration that protects against a non-cancer health endpoint is also within the range of concentrations that would be considered by EPA to be protective of the risk of an excess cancer.
Allan Susten pointed out that the 350 parts per billion reference dose is not an effect level and is likely to be 30 to 40 times below an effect level.
PowerPoint Slide Seventeen-Dose-Response Assessment-Model Influence
Allan Susten said that the concept of risk is a theoretical estimate. Allan pointed out a data point, which was the bottom point of an actual experimental study, was the lowest value at which observable increases in cancer were seen. Every line extending down is a risk calculation that depends on the model that was chosen to extrapolate from that value. There is a range of 5 orders of magnitude in risk estimates, all using exactly the same data point. The model that is chosen, determines the theoretical risk.
Owen Hoffman said if the above information was taken in the present time, wouldn’t one use mechanisms of action to extrapolate below limits of epidemiological and experimental detection?
Allan Susten responded yes, absolutely; more biology and mechanisms of action are being used.
Al Brooks and Owen Hoffman stated that they have a difference of opinion with one another regarding this topic and neither of their conversations was audible.
PowerPoint Slide Eighteen-Dose-Response (Hormesis)
Allan Susten told the group that he left a few journal articles regarding the topic of hormesis with Bill Taylor and those articles will be available in the field office for those who are interested.
Allan Susten explained that for this slide he stylized the dose response curve to show the dose on the X-axis, and “adverse” and “beneficial” effects on the Y-axis. Marked on the dose-response curve are the lowest observed adverse effect level (LOAEL), the no observed adverse effect level (NOAEL), and screening values (RfD and MRL). There is also a “control” dose-response line, showing no adverse or beneficial effects. The NOAEL is plotted near the control. Allan added that it is never known exactly where the NOAEL is because it is not an exact number; the NOAEL varies depending on which experiment was performed, which animal studies were performed, and the way the study was performed, etc.
Both EPA and ATSDR develop their non-cancer values through a process using either the LOAEL or the NOAEL (often there is not a NOAEL or there are numerous LOAELs). The process leads to the development of a reference dose or the minimal risk level. These levels are then considered to be “safe.”
Allan Susten said that as lower doses of certain chemicals are studied, people are learning that for many chemicals there is an adaptive response/positive effect (some work group members prefer one term over the other). This is called hormesis. Allan added that the adaptive response phenomenon is certainly the case for essential elements including iron, copper, zinc, and selenium. Allan added that for essential elements, some is good but more is not necessarily better. (Low doses show beneficial effects, higher doses show adverse effects.)
Owen Hoffman asked what does this mean if the reference dose or the minimal risk level is clearly below a range at which beneficial effects will occur? Are we robbing the public of an opportunity for better health?
Allan Susten replied that EPA and other agencies could not figure out how to incorporate this into [at this point the rest of Allan’s statement was inaudible].
Owen Hoffman asked how ATSDR handles this type of (hormesis) situation when performing its public health studies. Allan Susten responded that except for essential elements, ATSDR tends to try to not talk about it because ATSDR does not know how to deal with it.
Allen Susten told the group that male rats that received 0.001 micrograms of dioxin did not respond. But female rats that received the 0.001 micrograms of dioxin lived longer than the control rats and had fewer tumors. But what do you do with those data? How can you tell people that a little bit of dioxin is good for you?
Owen Hoffman said that there seems to be a fundamental issue when you have such data, but rely instead on multiple safety factors to derive a reference dose or minimal risk level from a lowest observed adverse effects level or a no observed adverse effects level. Without properly accounting for uncertainty, reference doses and minimum risk levels that are presented as a single value or point estimate may lead to bad decisions designed to be protective of public health and the environment.
Allan Susten said that there are more studies looking into the issue of hormesis.
PowerPoint Slide Nineteen-Environmental and Clinical Perspectives
Allen Susten said this slide was prepared for clinicians who are familiar with pharmaceutical doses but less familiar with environmental exposures. This slide presents the relative magnitude of toxic doses, effective doses, and no observed effect levels (NOELs) for pharmaceuticals, and lethal doses, LOAELs, NOAELs, and regulatory or screening values for environmental substances (such as EPA’s reference dose and ATSDR’s minimal risk level).
In medicine, the ratio of a lethal dose to the dose intended to be given to humans is called the therapeutic index (TI). The range of the TI is typically 10 to 20, but it may be as small as 1, such as for the drug digitalis. In that case, the therapy is literally the titration of a toxic dose to strengthen the heart for a short period of time. For drugs, the range of the ratio between the effective dose and the dose where you don’t see anything at all (in studies of humans and animals) is about an order of magnitude. For environmental exposures the range of the ratio of the lethal dose to the lowest observed adverse effect level (LOAEL) and the range of the ratio of the LOAEL to the dose where no adverse effect is seen (NOAEL) are both about an order of magnitude.
Owen Hoffman asked how often ATSDR’s minimal risk level is different from EPA’s reference dose.
Allan Susten said that sometimes ATSDR’s minimal risk level is different than EPA’s reference dose because one agency has looked at a more recent study or both agencies have used the same study but used different uncertainty factors or considerations. However, most of the time the agencies (MRL and RfD) are within a factor of two or three. Given the uncertainties in a factor of two to three there is little to no difference. Allan stressed that regulatory values and screening values are not threshold values, they are regulatory screening levels—they are not threshold values!
PowerPoint Slide Twenty-Esophageal Tumors from NDEA in Male Rats
Allan Susten told the group that he had left a copy of an article “A Pharmacologist’s View of Risk Assessment” with Bill Taylor, and that the article would be available in the Field Office for people who were interested.
This slide (from Dr. William J. Waddell’s presentation) shows a different way of looking at dose-response. The data (esophageal tumors in male rats) were plotted (not calculated) as “Percent of animals with tumors” on the y-axis, and numbers of “Molecules of N-nitrosodiethylamine /kg/day” (in units of log-rhythmic, or powers of 10 molecules per kilogram body weight per day) on the x-axis. There is an almost-horizontal line at zero percent animals with tumors on the y-axis stretching from 1 molecule to about 10 to the 17 molecules/kg/day on the x-axis, at which point the curve rises abruptly to 100 percent animals with tumors between 1017 and 1018 molecules/kg/day. These data are plotted; there is no extrapolation or mathematical conversion. At 1017 molecules/kg/day you see essentially a NOAEL. Dr. Waddell did not consider whether there is a hormetic response.
Al Brooks said that data can be taken as y = x and make the transformations that Waddell made or the range of data that he made and with exactly the same progression of scale at the upper end and make a straight line out of anything.
Allan Susten said that these data are plotted.
Al Brooks said he didn’t care if they were plotted or calculated. If they are plotted accurately they are the same as calculated, and you can take any arbitrary function and squeeze it up and make it do that. Al Brooks said he would send Allan Susten an example.
Kowetha Davidson said that for this data, you would not look at the straight line; you would look at the R-value.
Power Point Slide Twenty One-Summary
Allan Susten said that ATSDR likes to use dose-based conclusions and an integrated evaluation of exposure and health information, mechanism of action, and site-specific approach because the question we are asking is a different one from that of EPA. Allan pointed out that risk values can change even when data do not change. Allan also said that the message delivery does not have to change regardless of what risk values change because if what is known and what is not known is discussed and put into perspective—then the narrative and doses can be discussed without having the theoretical risk being perceived as actual risk.
Owen Hoffman asked if this means that in the public health assessments for chemicals, ATSDR does not show or mention what the risk is? Allan Susten said that he did not say that ATSDR does not mention risk—he did not say that at all.
Owen Hoffman said that he believes he has seen public health assessments for chemicals where the ATSDR official has shown what the risk is.
Allan Susten replied that Owen was correct and that some states have regulatory requirements to include risk—therefore they have to be consistent with those requirements. Also, some health assessors include risk because EPA is used to seeing “risk” as well as other communities and members of the public are used to seeing “risk”. But ATSDR does not make decisions based on risk—it is only one factor that goes into the decision.
Owen Hoffman said that one of the reasons that he took the time to attend the meeting was because of the perception that in the radiation area ATSDR has problems with EPA risk; yet in the public health assessments ATSDR will sometimes disclose what the risk is for chemicals. But in the radiation area where we have not only quantifiable risk but also quantifiable uncertainty in the risk—ATSDR refuses, and it is on record that Paul Charp has said that he has been told to not show risk for radiation. Owen Hoffman finds this position to be without merit and posed the question, why engage in censorship of information?
Allan Susten responded that he does not believe that ATSDR is censoring information. ATSDR does prefer to not talk about quantitative risk because risk is theoretical, is misread, and that the way that it is presented by most people gives a false sense of precision that it does not deserve. I am sorry but the uncertainty bounds and uncertainty things that you do are all quantitative, they go over my head very often, I understand the big picture and the quantitative risk really does not add anything. Allan believes that if ATSDR provides adequate narrative, ATSDR has a better chance at helping the community understand their hazards. For example, this way, each individual can see if they were a part of the actual exposure pathway.
Al Brooks said that EPA takes animal studies (highly sensitive animals) and develops a number, then applies an uncertainty factor/safety factor of 10 to get from the specific animal to humans, and then another factor of 10 to get from humans to sensitive humans. What this results in is an estimate for animals (such as a rat) with a safety factor of 1000.
Owen Hoffman said that safety factors account for extrapolation from animals to humans.
Al Brooks and Allen Susten said that the assumption is that humans are more sensitive than animals.
Al Brooks said that there is a list of pharmaceuticals that would never have made the market if they were tested on animals such as rats. Some of today’s pharmaceuticals are absolutely lethal to some species of animals. Allan Susten said that aspirin and penicillin are two examples.
Kowetha Davidson said that there are basic assumptions that have been used for safety factors. One assumption is that humans are always more sensitive than animals—and we know that is not always the case [at this point Kowetha was interrupted by several work group members and the rest of her statement could not be heard].
In her attempt to finish her statement, Kowetha Davidson said that it is important to remember (and she was told this by a person in EPA) that uncertainty factors and safety factors within EPA do not have a basis in science. Uncertainty factors and safety factors within EPA are policy and EPA is now trying to develop a scientific basis for applying uncertainty factors. The policy came first, but now because of all of the questioning about using a ten-fold uncertainty factor, EPA is trying to come up with a scientific basis for applying the ten-fold uncertainty—but now it is all default.
Owen Hoffman said that a community like Oak Ridge is not a lay audience; there is a considerable amount of expertise that exists within the Oak Ridge community. Thus, the strengths and weaknesses of the various safety factors should be discussed openly. Owen added and that to the extent that there is potential for risk below epidemiological limits of detection, shouldn’t that potential also be discussed? Owen said that he would be interested to see what would result if radiation was treated (through the same process, as indicated on slide 18) as a non-carcinogen instead of a carcinogen.
Kowetha Davidson said that Owen’s suggestion probably could be performed because with radiation we are assuming that there is no radiation dose that does not present a cancer risk. But also in that assumption, it is not true that there is no repair. Because the only way that you could make that assumption [At this point Kowetha was interrupted by a work group member and the rest of her statement could not be heard].
Al Brooks said that he could make any assumption that he wanted as long as I have the assumption as part of a policy.
Kowetha Davidson continued saying that with some chemical carcinogens the assumption that is often made is that there is never a case of 100% repair. But we know that our bodies have a really great ability to repair damage.
Owen Hoffman said that at low doses, repair mechanisms are always taking place. It is the infrequent occurrence of misrepair that is important. The frequency of repair is never 100% and the frequency of misrepair is never 0%, even at background levels of exposure.
Nevertheless, Owen Hoffman emphasized that he was not talking about extrapolating down to zero dose nor was he talking about linear no-threshold dose-response effects. Owen was talking about consistency in the methods used by ATSDR, starting with the lowest observed effect level and extrapolating from there to the no observed effect level and then from there to a level that would be appropriate as a screening level for ATSDR public health assessments.
Owen Hoffman said he feels that limits of epidemiological detection are being used directly by ATSDR as a surrogate for a threshold of concern for the special case of radiation released from federal facilities. He is very concerned that the ATSDR use of the limits of epidemiological detection as a screening limit for evaluation of past radiation exposure is very likely to lead to false negative conclusions. The margin of safety inherent with this approach is inadequate and inconsistent with approaches used elsewhere by ATSDR for screening of exposures to toxic substances.
Additional Conversation Regarding Presentation
Owen Hoffman went on to say that the reason that ATSDR is here, in Oak Ridge is because of a strong objection to ATSDR’s Y-12 Uranium PHA raised by the Office of Radiation and Indoor Air. Requests have been made by some people in Oak Ridge for EPA to come to Oak Ridge to disclose whether or not the ATSDR’s answers to their questions have been responsive. Yet, there seems to be political pressure to keep EPA out.
Kowetha Davidson stressed that EPA—the Office of Radiation and Indoor Air—has been invited and they are not here by their own decision. Kowetha added that she had not received any response from EPA.
Paul Charp said that ATSDR called the Office and spoke to Bonnie Gitlin and her response was that EPA did not want to talk to ATSDR about the discrepancies if members of the public are present.
Owen Hoffman said that if what Paul is saying is true, then EPA is engaging in an act of censorship.
Paul Charp explained that ATSDR has requested [the rest of Paul’s comment could not be heard because he was interrupted].
Owen Hoffman asked if he personally calls EPA and asks them why they have not come to Oak Ridge and if Owen receives a different answer than what ATSDR provided, ATSDR will allow Owen to let everyone know.
Paul Charp said that would be fine with him. Paul added that ATSDR told EPA that they wanted some members of ORRHES involved in the telephone conversations and EPA said that they would not discuss these issues with members of the public on the call.
James Lewis said that he felt Allan Susten provided an excellent presentation and that he did not understand why it took so long to have a detailed discussion regarding the issue of risk assessment and public health assessment. James said that this presentation would have been very helpful two years ago and would have helped people understand the direction that ATSDR and ORRHES were headed. ATSDR needs to do a better job of getting adequate information out to the general public at the beginning of the various processes. If not, ATSDR will have ineffective message delivery. James felt that the presentation that Allan provided should have been made at the beginning of the public health assessment process and in a format that both ORRHES and the general public can understand.
Referring to the slide that stated, “message delivery does not have to change if clear narratives and perspective are presented”—assuming that ATSDR does not have a “cracker jack” health education program that is being applied in a timely manner and in such a way that the public will understand what ORRHES and ATSDR are doing—the community finds themselves in a dilemma associated with the aura of decision versus the aura of confusion.
Tim Joseph said that it is important to talk about the ATSDR process in a simple and educated way so that the public can understand the process. It is absolutely critical that ATSDR present and explain the process and not just provide the results of the public health assessment.
Paul Charp pointed out that there has been discussion about presenting the information in Allan’s presentation as well as the conclusion categories up front at the very beginning of the ATSDR PHA process.
Jack Hanley said that he understands what James Lewis is talking about. Jack said that he thinks James is mainly referring to communication with the broader public. Jack told the group that Allan Susten has been working with Region IV EPA to develop a document comparing the public health assessment and the risk assessment. This document was distributed at the December ORRHES meeting and is available to the public.
Allan Susten said that he believes the document comparing the PHA to the RA is supporting material, but he believes that James Lewis has made a strong point and that a recommendation should be made about presenting certain information up front to various audiences, at the beginning of the ATSDR PHA process. James Lewis added that it is important that an effective communicator is brought in to present the information.
Al Brooks said that he feels the statement made by EPA that “conservatism in the face of uncertainty is wisdom” would be better stated as “conservatism in the face of uncertainty is stupidity”. Al Brooks disagrees that what EPA does is suitable for allocation of priorities. Al added that unless you know from empirical data, the relative sensitivity, you do not know enough to extrapolate.
Allan Susten said that EPA’s process is to measure the amount of a substance in sediment and then model where it will go, etc. ATSDR does not care how much of a substance is in the sediment, ATSDR will look at the fish and perhaps measure levels of the substance in the bodies of fishermen. EPA would clean up a groundwater contamination even if people were not drinking it. ATSDR would not consider the groundwater a public health hazard if people do not drink it. From the standpoint of sediment standards, ATSDR is interested in a completed exposure pathway.
Owen Hoffman said that from the standpoint of a professional risk assessor, reasonable assumptions are used in terms of exposure frequency and exposure duration. And where the maximum exposure has been categorized, they clearly state their assumptions. Owen said that he is concerned with ATSDR’s practice of using limits of epidemiological detection as thresholds for risk. Owen would like to see more rationale for taking information below the limits of epidemiological detection in order to derive a screening level of concern for use in a PHA.
Allan Susten asked what information Owen was referring to. Owen Hoffman replied that he was referring to mechanisms of biological action and information from other studies besides epidemiology. Owen added that his concerns are more in the radiological area. Owen said that he has not found the same type of consistency in approach with respect to how the health effects of chemicals are evaluated and the radiation effects. Owen sees an attempt to use the limits of epidemiological detection in radiation to determine threshold levels of concern.
Kowetha Davidson said that once you are below the limit of detection, then everything is just theoretical. If you are below the limit of detection you need some sort of dose or else it is just theory and extrapolation.
Owen Hoffman said that all he is asking for is that ATSDR use all available evidence and that there is careful consideration for what is done in the area of radioactivity. Owen added that he feels there is political incentive to keep the thresholds of concern at the highest level possible.
Paul Charp said that Dr. Falk had an expert panel meet to discuss some radiological issues. The findings of that panel will be distributed to ORRHES members in a report form.
Owen Hoffman asked if the panel was open or closed.
Regarding the expert panel, Paul Charp said that Dr. Falk selected the panel and that the Division of Health Assessment and Consultation did not have input as far as the actual panel selection.
In response to Owen’s question of who was on the panel, Paul Charp said that the panel included Charles Miller, Tom Mason, Bob Spengler, and David Kleinbaum.
Regarding mixtures and combined exposures, Allan Susten said that it is known that there are interactions between substances. Where studies have been performed at the no observed adverse effect level of each component, it is difficult to find any effect from the mixture let alone super effects. Most environmental exposures are hundreds to thousands times below the no observed adverse effect level for individual compounds. Allan said although everything is not known, the empirical data suggests that in general when levels are well below (100 fold) the no observed adverse effect level, all compounds combined will not show any effects.
Gordon Blaylock asked Allan Susten how many studies he had regarding synergistic effects. Allan Susten replied that he has not seen any studies for environmental chemical synergistic effects but has seen them for pharmacological synergistic effects.
Kowetha Davidson said that mixtures encompass the range where hormesis would have been observed, but undoubtedly they did not see hormesis. Perhaps hormesis is an artifact of a single exposure. When there is multiple exposures it all depends on the mechanisms [the audio was inaudible at this point]. Some chemicals are not toxic when taken alone, but may become toxic when they are metabolized in the liver or vise versa. Toxification and detoxification can be either increased or decreased.
James Lewis said that the community understands risk. If ATSDR elects to not present risk data, how will ATSDR be effective when the world is used to looking at risk data? When ATSDR leaves Oak Ridge, the Oak Ridge community will still have the same questions if data is not presented in a way that the general public can understand.
Allan Susten said that communication is the key and that the environmental science agencies have created problems by using terminology that is not clearly understood by the general public. It is important that ATSDR identify what is known and put it in the proper perspective.
Owen Hoffman said that the “Making Choices: Screening for Thyroid Disease” document includes estimates of risk and its uncertainty and is not a regulatory document and was put together by the National Cancer Institute and not by EPA. The “Making Choices” document is a public health message, which contains risk as part of the message. Owen Hoffman’s point is that full disclosure of information should include risk and risk does not necessarily have to be a regulatory value.
James Lewis said that he is not asking ATSDR to make a call based on risk. Instead, James is suggesting that ATSDR use risk as one way of communicating with the public, especially for those who do not understand dose.
Kowetha Davidson said that risk is impossible to define and does not tell an individual if they are safer. Risk provides an individual with a calculated number but does not tell them if they will get a disease. People need to understand that when it comes down to it, risk really does not provide an answer or tell the individual anything.
At this point everyone was talking at once and the meeting was adjourned at 7:45 PM.
Votes/Specific Actions Taken in the Meeting
The draft meeting minutes for the November 6th PHAWG meeting was approved.
Allan Susten said that he would try to find out about any nationwide attempt to track down a population that might have been exposed at a DOE facility.
Allan Susten said that he would carry the message back to Atlanta about the need for additional information regarding the risk assessment versus public health assessment process to be provided to the communities at the beginning of the ATSDR PHA process.
Al Brooks said that he would provide an example to Allen Susten of other data that would reproduce Dr. Waddell’s dose-response plots.