Advisory Panel Meeting, October 11, 2011
Summary of Discussion
Contents
EHTB Program and Legislative Update ......................................................................... 2
East Metro Perfluorochemical Follow-up Study: Preliminary Results and Analysis ..... 2
Epidemiologic results.................................................................................................. 2
Discussion of data analysis and interpretation ............................................................ 4
Laboratory analysis and discussion ............................................................................ 5
Next steps for the PFC2 project .................................................................................. 6
Biomonitoring and Tracking Status Updates .................................................................. 6
Data Portal Demonstration .............................................................................................. 6
Discussion and questions ............................................................................................ 6
Strategic Planning for a Biomonitoring Program ........................................................... 8
Discussion ................................................................................................................... 8
New Business .................................................................................................................. 9
Adjourn ........................................................................................................................... 9
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Advisory Panel Meeting, October 11, 2011
Summary of Discussion
Members present: Bruce Alexander, Fred Anderson, Alan Bender, Jill Heins Nesvold,
Cathi Lyman-Onnka, Geary Olsen, Gregory Pratt, Cathy Villas-Horns, Lisa Yost.
EHTB Staff: Jean Johnson, Eric Hanson, Mary Jeanne Levitt, Barbara Scott Murdock,
Jessica Nelson, Leslie Schreier, Blair Sevcik, Dave Stewart, Chuck Stroebel
Panel Chair Bruce Alexander welcomed panel members. The summary below focuses
on the three presentations and the discussions that followed.
EHTB Program and Legislative Update
Jean Johnson gave an update on the Environmental Health Tracking and Biomonitoring
legislation. The original legislation supported the project with $1 million in Year 1, and $500,000
for FY 2010-11. After a proposed budget of $0 for the next biennium, the legislation that was
passed in the post-government shutdown special session provided $268,000 per year for FY
2011-12 and FY 2012-13. This was a one-time appropriation that would go to the MPCA. The
funds were designated for “transfer to the Department of Health to complete the
environmental health tracking and biomonitoring analysis related to perfluorochemicals and
mercury monitoring in Lake Superior and disseminate the results.”
Jean said that the strategic planning would thus be rolled into the mercury follow up. She also
pointed out that, because the funding amounts to a 40% cut from the expected support, state
tracking of Minnesota-specific issues will not happen in this biennium.
Noting that next year is an election year, Greg Pratt asked whether MDH would ask for support
in the next biennium. Assistant Commissioner Aggie Leitheiser answered that EHTB is on her
agenda, but the MDH budget request goes through a process and is submitted to the governor
before it goes forward [to the legislature]. She said that the EHTB program attracted a lot of
community interest and support in the special session.
East Metro Perfluorochemical Follow-up Study: Preliminary Results and Analysis
Jessica Nelson, EHTB staff epidemiologist, and Carin Huset, public health laboratory chemist,
reviewed the preliminary laboratory and data analyses. For clarity, this summary presents the
epidemiologic results first, then the laboratory results.
Epidemiologic results
Jessica explained that the serum samples for the PFC2 analysis came from 164 people who had
participated in the 2008 pilot project. The blood samples they provided in 2010 have undergone
both laboratory and data analysis in Phase I of the follow-up project. Phase II will entail an
analysis of questionnaire data gathered from the participants. Jessica asked the panel members
to consider the following questions as she and Carin presented their results:
Are additional analyses recommended for this Phase 1 analysis?
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How should MDH communicate to individual participants about whether differences
between their 2008 and 2010 concentrations are “real”? Should we incorporate
laboratory error into this assessment and, if so, how?
Please provide overall input on the interpretation and communication of results to
participants and the community.
Table 1 in the Advisory Panel book (AP book) shows evidence of decline in PFC levels in
participants’ blood, but participants’ levels are still higher than the latest NHANES findings for
PFC exposure in the US public. Differences by demographic factors persist: men had higher PFC
levels than women. Older people and people who had lived longer in area homes generally had
higher levels than younger participants and newer residents in the area (Table 2, AP book).
Of the 7 PFCs measured in this pilot project, three compounds were detected in all participants:
PFOS, PFOA, and PFHxS. The geometric mean (GM) for all participants showed that the levels
for these three PFCs had declined in this population between 2008 and 2010. The 4 other PFCs
(PFBS, PFBA, PFPeA, and PFHxA) were detected far less frequently in both 2008 and 2010 (Table
1, AP book). Some individuals, however, showed increased PFC levels in 2010. One person in
particular had a 1132% increase in PFHxS. But this participant’s 2010 level was still lower than
the GM of the other participants. In fact, as a figure Jessica presented later showed graphically,
the people with the lowest PFC levels in 2008 were more likely to either show little change in
PFC concentrations or show an increase in levels in 2010, compared to 2008.
Jessica then showed the panel two different tables that presented two different ways to
measure the decline in blood levels over the two-year period. The first table showed the 2010
and the 2008 geometric means for PFOS, PFOA, and PFHxS, and both the absolute change in
µg/L and percent change in the overall GMs. Both were presented as negative numbers to
indicate the drop in serum levels.
The second table presented the means of the individual changes in the PFOS, PFOA, and PFHxS
levels. Each of the 164 participants in 2010 was compared with the person’s own 2008 PFC
levels, and all of the paired changes were then averaged to produce both absolute change and
percent change in the group. As noted above, some individuals showed increased PFC levels in
2010. Because one person in particular had a 1132% increase in PFHxS, Jessica also showed a
table of the individual level analysis without this high value. The percent change in the group’s
PFHxS mean was higher, but because the individual’s absolute change was small, the mean
absolute change was basically the same.
The question she posed to the panel was, which approach was the best way to report the twoyear change in PFC levels: The first approach, which takes the change in overall GM? Or the
second approach, which averages the change between the 2008 and 2010 levels of the paired
samples of individuals? The second approach allows a t test. A related question, Jessica said, is
whether we should report absolute or percent change. It seems that percent change is more
accessible to the public.
Jessica also showed agreement plots which display the agreement between an individual’s 2008
and 2010 levels. The graphs make it clear that most peoples’ levels were lower in 2010, despite
the fact that some individuals had higher 2010 levels. These graphs also show that people
whose PFC levels rose in 2010 tended to have had lower levels in 2008.
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Discussion of data analysis and interpretation
In answer to Jessica’s question whether to use the change in the population geometric means or
the geomean of the paired individual results for reporting the overall 2 year population decline,
Bruce Alexander commented that it would be better to focus on the population data, not the
individual data. Both Greg Pratt and Alan Bender argued for using the means of the paired
individual results, in part because each participant acts as his/her own control. Greg Pratt said
that he liked presenting the change in individual levels as absolute changes because they
embody more information, and analysts need not worry about comparing populations and
distributional data issues.
In discussions about whether to use percent change versus absolute change for reporting
individual results, Greg and Bruce thought that using percent changes in reporting individual
levels to the participants would not be helpful and possibly misleading. Geary Olsen noted later
that he liked using the percent change, , because it actually reflects the rate of elimination of
the chemicals in each person.
Greg Pratt noted that the increase in PFCs in some people measured in 2010 is clearly a real
increase. Thus, he said, these people are going to want to know why. If PFCs in water have
gone down, is the exposure coming from another source, and what can I do to reduce it? Lisa
Yost commented that laboratory uncertainties, especially for these people whose
concentrations had risen, demonstrate that their results are still close to the geometric mean
and are, in fact, small absolute changes. In reporting individual results, especially to participants
whose levels increased, it’s important to graphically show when a person’s levels are still below
the 2010 project mean.
Potential reasons why some participants showed an increase in some PFCs range from analytical
uncertainty to individual behavior. Carin explained that small increases may stem from intrinsic
uncertainties in the laboratory measurements, and Jessica added that diet and contact with PFCcontaining products may explain larger increases in participants’ exposure. Other environmental
sources of exposure, such as fish from local lakes, may still exist. Finally, some people may
eliminate PFCs faster than others because of biological differences.
Jill Heins Nesvold suggested that perhaps the study questionnaire (to be analyzed in Phase II)
would answer questions about exposure or behaviors that might have led to higher levels of
people’s blood PFCs. She suggested providing clearer explanations of the laboratory uncertainty
to the participants. People whose PFC levels had risen might need a separate letter with the
message that they should not be alarmed if the change is small.
Jill also asked when efforts began to reduce drinking water exposures. Jessica answered that
mitigation began in 2006, and the first blood measurements were taken in 2008. No baseline
measurements were taken before remediation began in 2006. Carin said that the Oakdale
participants in the project were served by a community water supply, and the Cottage
Grove/Lake Elmo participants had private wells. The Phase II questionnaire analysis will involve
a more detailed look at participants’ water use and residential history.
Fred Anderson suggested sending a summary of the project along the letters to the participants.
Jessica agreed: the plan is to send a letter with an individual’s 2010 results compared to 2008
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levels and a summary report (with an overall message that levels have declined) in graphic form.
When Fred asked whether she could separate out the communities, she said that the outlier
issue and the fact that some people with private wells had switched to city water made that
difficult. Again, the Phase II analysis will look more thoroughly at some of these questions.
Alan Bender warned that she should anticipate more questions from people whose levels have
risen, and she’ll find much less interest from people whose levels declined. He suggested doing
pilot testing of the communications and letters before sending them to the participants and the
communities.
Geary Olsen pointed out that PFC data from various human studies show pharmacokinetic 1st
order serum elimination half-live curves of several years. If mitigation of the exposure has
occurred, this pharmacokinetic curve should be seen in these population samples. People with
the highest concentrations will clear greater amounts of PFCs than people with lower
concentrations. His back-of-the-envelope estimate shows the percent declines reported are
what one might expect to be in 2010 compared to 2008, based on these serum elimination halflives coupled with successful mitigation of exposure. Various exposure mitigation activities
were implemented a few years before the 2008 baseline sample collection (e.g., granular
activated carbon (GAC) filters in Oakdale municipal water; changing private well water to
municipal water).
Exposure to PFOA is a more difficult problem, he observed, because there are more ongoing
sources of PFOA, such as plastic water bottles with fluorinated surfaces, which can form PFOAlike compounds. Geary also pointed out that the fact that the 2010 levels are still above NHANES
is not surprising – given the elimination rates, this will be the case for many years.
Laboratory analysis and discussion
Carin Huset reviewed the laboratory analysis of the PFC2 samples. She pointed out that she
used the same analytes, standards, instruments, and calibrations in the PFC2 samples as she had
in the analysis of the first round of PFC samples taken in 2008.
Carin also discussed the elements of laboratory analytical uncertainty, which may partly explain
why some participants’ PFC levels seem to have increased. She explained that uncertainties in
the laboratory measurements arise from differences in sampling, storage conditions, the
instrument’s performance, and other standard laboratory procedures. For 2008, she tested a
batch of 18 unknown duplicate samples; for 2010, she tested a batch of 19 unknown duplicate
samples to get an estimate of the relative percent differences between each pair of samples. For
each year, she found a relative difference between paired samples of less than 20%, which
represents a small change in absolute sample to sample value.
The fact that some participants had large percent change increases between 2008 and 2010
prompted additional discussion about analytical precision and accuracy. Geary Olsen asked
whether Carin had re-analyzed the 2008 samples for these 2010 outliers. Carin said that, given
the results from her QA/QC, she saw no reason to suspect that the high percent change value
was strange because the result was within the normal range and, in fact, was below the mean of
the 2008 samples.
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Geary suggested that it would be good to re-run these 2008 stored samples, even if they are
within the calibration curve. But, he added, the analytical precision and uncertainty slide, which
documented the coefficient of variation, showed that one can’t say whether there is a
difference at the small end of the scale (e.g., an exposure of 2.0 µg/L in 2010 vs. 2.3 µg/L in
2008). It demonstrates that the ability to say whether something is different depends on the
scale of the difference. The numbers at the low end of the range of samples are within the
precision of the analytical method. For the most part, it is impossible to tell whether levels are
going up or going down at the low end of the scale. Thus, it’s important to explain that some of
the concentrations are in the low nanogram (ng) range, which is close to or in the lower range of
the laboratory instrument. He suggested that Carin, as an experienced analytical chemist, should
be able to choose the coefficients of variation of which she is most confident, perhaps for each
PFC.
Next steps for the PFC2 project
The PFC2 project staff will make a final analysis and interpretation of the results and will report
them to the participants by letter, including a short summary of the project findings.
Community meetings and meetings with healthcare providers and local public health officials
will follow the reports to the participants. Phase II analysis of the questionnaire data will begin
in 2012.
Biomonitoring and Tracking Status Updates
There were no questions from the panel regarding status updates provided in the meeting
materials.
Data Portal Demonstration
MN EPHT launched new interactive maps for asthma hospitalizations and childhood lead
poisoning in September, shortly before the AP meeting. Eric Hanson discussed and
demonstrated the maps he has developed to show how local public health professionals can use
the maps to compare county and state data for public health planning. He also demonstrated
new designs he is developing for some of the existing maps and charts. These include dot plots,
box plots, and bubble charts. One example is a dot plot graph of the percentage of children with
elevated blood lead levels by the percentage of children living in pre-1950s housing over time,
which allows users to see trends in the data. Eric also used the blood lead and housing data to
demonstrate bubble charts that use a Google API to create moving bubble graphics to illustrate
data changes over time. The technique is like the one that Swedish statistician Hans Rosling
uses in his Gap Minder demonstrations of changes in the environment and in human health and
social conditions (http://www.gapminder.org/).
Discussion and questions
Alan Bender suggesting using inter-census Minnesota population estimates rather than the
static data taken only during the national census years (e.g., 2000, 2010). Minnesota has intercensus data for every county in the state for each year, and the state demographer’s office can
supply these data. Inter-census data make data applications more accurate, while interpolating
major population shifts over time can create artifacts.
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Bruce Alexander asked how the Tracking staff made their decisions about what data to select
from the cancer registry maps. Staff answered that they were chosen for useful and interesting
patterns of nationally consistent data measures, or indicators. Staff talked with the Minnesota
Cancer Surveillance System, met with data users groups to learn about the available datasets,
and asked for their suggestions for cancers of interest. Al pointed out that, eventually,
Minnesota cancer data will be loaded into the University of Kentucky Cancer Registry, which is
now part of the National Cancer Institute's Surveillance Epidemiology and End Results (SEER).
He added that the [current cancer data] on the portal form a demonstration project. Eventually,
MN data from the Kentucky registry will be moved to this portal.
Bruce also suggested bringing in more partners, such as hospital associations, to display data on
a variety of health problems, such as trauma and occupational indicators. Jean Johnson replied
that part of the vision for Tracking is to display public health data from a variety of MDH
programs. Greg Pratt suggested looking at EPA’s environmental justice (EJ View) maps, which
allow users to select information that runs from hazardous waste sites to demographic
characteristics.
Jill Heins Nesvold added that hospital associations would be interested in data on
hospitalizations, and particularly on the three major readmissions to hospitals: asthma, heart
disease, and COPD (chronic obstructive pulmonary disease). She suggested mapping COPD
hospitalizations, saying that we need to raise awareness, not only of asthma, but of COPD,
which is both a known health effect of environmental tobacco smoke and a rising cause of death
in Minnesota and nationwide. Chuck said the portal will add county-level query data for COPD
in the next few months, and maps of COPD could be developed later, depending on Year 3
activities.
Lisa Yost raised a question about whether the EPHT portal controls or estimates quality
assurance (QA), saying that if we use data from other programs on our website, is there a QA
clearance? Or can we make the data consistent? Chuck Stroebel answered that QA is the
primary responsibility of each individual program that collects the data. He added that MN
EPHT develops How-To guides with specific instructions about to calculate data quality
measures so that the national tracking program can make the measures consistent across the
states.
Cathi Lyman-Onkka asked whether the tracking data could include diagnoses for health
outcomes, such as asthma. Alan answered that diagnoses are private data, so we use
hospitalizations, which represent events, not individuals. Chuck added that there are no perfect
indicators, but that the messaging on the portal helps to convey strengths and limitations of
hospital discharge data. MN EPHT is working with the national tracking network to develop
additional indicators for asthma based on emergency department visit data. Looking at multiple
indicators over time tells a story.
Finally, the discussion focused on messaging and handling external inquiries. Jill asked how the
tracking program planned to keep the data current, so it would continue to be usable. Chuck
acknowledged that, once the portal is built, we must maintain it, and said that the Advisory
Panel is critically important to doing so.
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Geary Olsen asked about cluster busters. Now that we have this transparent ability to look at
and use data, how will MDH handle public inquiries about it? Alan responded that messaging—
what we say about the diagrams and graphs—will be a bigger activity than the IT part of this
project. Greg Pratt and Chuck noted that agencies routinely deal with such questions and
requests for data, and Bruce said that journals have the same issue, but that the portal allows
the public to see the data online. Eric noted that anyone can access public data and create
maps with it, but that MDH does so responsibly.
Strategic Planning for a Biomonitoring Program
Barbara Scott Murdock presented recommendations for target populations garnered from 11
meetings with stakeholders during spring 2011 and then assessed several criteria for choosing a
target population for biomonitoring. Stakeholders had named young children, communities of
color, agricultural/rural communities, and pregnant women as key target populations most
frequently, with other important criteria being populations with exposure associated with
known, serious health implications (Table 3).
She reviewed several criteria for selecting a target population, focusing on pregnant women as a
test population for these criteria. Staff had decided to focus on pregnant women as a way to
learn about exposures to the youngest children possible, the highest priority for most
stakeholders. The criteria presented did not address analyte selection or study design, which will
be addressed in the feasibility assessment phase for selecting and planning a specific population
for a specific study.
Based on stakeholders’ recommendations, staff suggested that the Advisory Panel consider the
following primary criteria for selecting a target population:
Exposure factors:
Demographic and geographic diversity:
Public health policy impacts:
Information potential for individual results interpretation:
Discussion
Greg Pratt suggested vulnerability as a key criterion that is missing in this list. Even if pregnant
women are less exposed than others, they are more vulnerable, which argues for them as a
population for biomonitoring. Whether they are more exposed than others is unclear. But they
are vulnerable. Lisa Yost suggested adding a note about level of exposure, such as the dose of
Hg that can make someone vulnerable or not. The panel seemed to agree that adding
vulnerability criteria makes sense.
Alan Bender commented that we need to look within a subset and determine what is fundable,
based on the body politic. In response to Jill Heins’s question about how work by EHTB in this
population complements or duplicates the National Children’s Study, Alan suggested adding
criteria that address whether a study would add information vs. duplicating an existing study.
Bruce agreed, saying that you want to explicitly make sure you are not duplicating another
study.
Jill noted that different health outcomes are of different degrees: e.g., ETS exposure to an
infant could lead to asthma as an outcome vs. whereas Hg could lead to brain damage from
prenatal Hg exposure. Cathy Lyman-Onkka added that from a policy perspective, if a high
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exposure risk exists, there should be a policy opportunity for intervention. Lisa Yost addressed
criterion E1), saying that if it’s likely that exposure can cause health outcomes, is the exposure at
exposure levels that may be experienced?
Bruce Alexander said that feasibility isn't the next step, as we need to know more about which
population you will monitor and why. We can all agree that these are generally good ideas. But
unless you have a specific population in mind and why, it’s hard to give feedback on which
criteria to use. He wanted to know about the larger process: a hypothesis about why a
particular population is important, specific chemicals, and specific outcomes.
Cathy Lyman-Onkka suggested two approaches: 1) to look at the risk/reward balance in a
particular population & ask, what is the risk-reward in this particular population? 2) Identify
what the level of knowledge is about that population.
Alan added that feasibility needs to be on the front burner, so as not to waste money.
Greg Pratt commented that the stakeholders identified target populations that seem
reasonable, but how do you choose which population is most at risk? In other words, why
pregnant women? Why did they come to the top of the list? He agreed with Bruce that the
specifics of the population and what MDH intends to do are important in determining the
process. Given that there is an existing study (the NCS), why choose this population?
Barbara pointed out that stakeholders had recommended looking at “children, as young as
possible,” and that children in utero are as young as possible. Jean said that the stakeholders
had emphasized that we should be making decisions about which populations and chemicals to
monitor, as advised by the Advisory Panel, rather than having the legislature making decisions.
The legislators also told us that we want the Advisory Panel to say what we do going forward.
Therefore, are these criteria appropriate to guide the Advisory Panel?
Bruce said, presumably you would come forward with a slate of options for us to evaluate. Jill
Heins suggested looking at the most severe consequences of environmental exposures and then
figuring out how to measure and track those exposures in the population. Lisa Yost agreed,
saying that the presentation showed how in utero exposures could have devastating
consequences, so we should start with a problem. Jessica pointed out that MDH cannot do
statewide population exposure monitoring, so we have to identify target populations. Jean
Johnson asked for clarification whether the focus should be on the most severe consequences
experienced at environmental levels – the community levels, rather than occupational levels.
Greg Pratt agreed with Jill, and suggested that the program should list the health effects of
interest and then we would have information on which to compare populations.
New Business
Bruce Alexander asked the panel members for suggestions of new topics. Jill Heins suggested
that the panel might benefit from knowing more about the National Children’s Study and how
that might guide biomonitoring. Jean said that the panel would hear a report on the Lake
Superior Mercury in Newborns pilot in December.
Adjourn
Bruce Alexander adjourned the meeting.
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