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C8 Science Panel Newsletter

C8 Science Panel Quarterly Newsletter #3

January, 2011


1. Science Panel studies update
2. Press and publicity
3. New publications
4. Quarterly focus

1. Science Panel studies update

Now that 2010 has come to an end, we enter the final phase of the Science Panel Community Study. Nearly all the data on health and exposure have now been collected and the teams led by the three members of C8 Science Panel are working on the large amount of data we have assembled. We are still awaiting some more information, for example, the validation of medical records for new diseases reported in the telephone interviews and the last round of the Half-life Study, which is charting the speed of clearance of PFOA from people’s blood. This information will be collected in the first half of this year.

During the last 3 months, data collection was completed in Phase 2 of the Short Term Follow-up Study of C8 and Immune, Liver, Kidney and Endocrine Function, the Community Follow-up Study and is nearly closed in the Worker Follow-up Study. A member of the Science Panel held a press conference in Parkersburg in late November, asking the press to alert the community to the imminent end date for completing interviews. This was very successful, prompting a rush which improved the completeness of participation rates.

This year we shall enter the evaluation phase of the Science Panel work; when we have sufficient evidence to hand we will determine if there are probable links between C8 exposure and various diseases. As we are looking at a number of different diseases, and the evidence from different studies is coming in at different times, this will take some time. Our work plan is to issue the first probable link finding in the middle of 2011 and complete these probable link evaluations by mid-2012.

2. Press and publicity

Dr. Kyle Steenland, member of the C8 Science Panel, visited Parkersburg on Monday, November 30 to make one final plea for participants who wished to be part of the C8 follow-up study to complete their 2nd round interviews. The second round of interviews for two follow-up studies ended December 7. The Science Panel is conducting two interview studies, one of the community and one of workers in the DuPont plant. Both studies have been going well. The first involves about 30,000 people and the second about 6,000 people. Excluding people the Science Panel has not been able to contact, about 90% of people contacted have participated. That’s over 35,000 interviews completed for these two studies.

Dr. Steenland’s appeal for last minute participation was in local newspapers and on TV, and was accompanied by a last minute reminder letter in mid-November. As a result of these efforts, participation doubled in the last two weeks. About 1000 interviews were completed in the last two weeks compared to about 500 a week previously. High participation is important for the successful completion of these studies. From the interviews the Science Panel will know what diseases people have had, and can determine whether or not those who have had more C8 exposure have a higher disease rate. The Science Panel is also asking those who report disease to send in permission to review their medical records to confirm their disease via their doctors.

3. New publications

The following journal articles are publications on C8 with input from C8 Science Panelists appearing in journals (online or in print) in the last 3 months.

Private drinking water wells as a source of exposure to PFOA in communities surrounding a fluoropolymer production facility.
Hoffman K, Webster TF, Bartell SM, Weisskopf MG, Fletcher T, Vieira VM.
Environ Health Perspect. 2011 Jan;119(1):92-7. Epub 2010 Oct 4
doi: 10.1289/ehp.1002503
Now in print and full text available at: http://dx.doi.org/10.1289/ehp.1002503

The above is an article from the Science Panel looking at correlations between water concentrations of C8 in private wells and levels in the blood of people drinking the well water and has just been published in the journal Environmental Health Perspectives (EHP). Kellyn S. Betts, writing for the journal, has summarised some issues from the article in the following report, which they have kindly agreed to allow us to reproduce. Both her report and the full article are freely available on the web at the following links:

A Measure of Community Exposure: PFOA in Well Water Correlates with Serum Levels*
Betts KS.
Environ Health Perspect 119(1):A35 (2011)
Full text available at: http://dx.doi.org/10.1289/ehp.119-a35a

By Kellyn S. Betts

The first detailed investigation into contamination of private wells with perfluorooctanoic acid (PFOA) and levels of the compound in human blood serum suggests that drinking water was the dominant source of exposure to PFOA in a community industrially exposed to the compound [EHP 119(1):92–97; Hoffman et al.]. The study, conducted in 2005 and 2006, included only people who obtained their drinking water from private wells. The results showed that each 1-µg/L increase of the compound in the participants’ water supply was associated with a 141.5-µg/L increase in people’s serum PFOA concentrations.

The participants lived around DuPont’s Washington Works facility in Parkersburg, West Virginia, where PFOA (also known as C8) is used in the manufacture of Teflon® nonstick polymers. PFOA has been shown to increase risk of cancer, reproductive problems, and liver damage in laboratory animals, although human health effects are less clear. Many of the water monitoring data used in this study were collected as part of an agreement between DuPont and the U.S. Environmental Protection Agency (EPA) to conduct a human health risk assessment for PFOA.

The groundwater in the Parkersburg area had been contaminated by DuPont’s releases of PFOA into the nearby Ohio River. A second source of contamination was PFOA that was released into the atmosphere and deposited onto soils, which then leached into the groundwater.

Previous research in this study area linked drinking water supplied by six local water districts and consumption of home-grown vegetables to PFOA levels in participants’ serum [EHP 118(8):1100–1108; Steenland et al.]. The new study provides a quantitative estimate of the relationship between drinking water and serum PFOA levels based on exposure to a wider range of PFOA levels in drinking water from 62 wells. It also corroborates the earlier finding about consumption of home-grown vegetables.

Many of the wells in the study had PFOA concentrations that exceeded the EPA’s 0.4-µg/L advisory level, although the median concentration in the well water samples was half that level. The concentrations of PFOA in participants’ serum ranged from 0.9 to 4,751 µg/L, with a median of 75.7 µg/L, approximately 20 times the average level in the U.S. general population.

The association between PFOA in drinking water and serum was similar for both shorter- and longer-term residents of the area. The researchers found the associations held after excluding participants who reported drinking bottled water and those who worked at the DuPont facility. Compared with other factors (including age, sex, body weight, cigarette smoking, and alcohol consumption), drinking water was consistently the strongest predictor of serum PFOA levels.

The 141.5:1 ratio estimated for drinking water to serum PFOA concentrations is close to the 114:1 ratio predicted by a steady-state pharmacokinetic model employed by the authors. These findings may be useful in developing drinking water guidelines and studying other communities where PFOA is manufactured.

* Reprinted with kind permission of EHP and the author.

Accumulation and clearance of PFOA in current and former residents of an exposed community.
Seals R, Bartell SM, Steenland K.
Environ Health Perspect. 2011 Jan;119(1):119-24. Epub 2010 Sep 22
doi: 10.1289/ehp.1002346
Now in print and full text available at: http://dx.doi.org/10.1289/ehp.1002346

4. Quarterly focus

The C8 Science Panel “Half-life” Study – Learning About the Rate of Clearance of PFOA from the Human Body

From Scott Bartell:

The C8 Science Panel studies of potential health effects from PFOA (i.e. C8) exposures rely, in part, on classifying Mid-Ohio Valley residents according to how much PFOA was present in their bodies during various parts of their lives. Although any person’s exposure history is largely determined by his or her residential history and how much contaminated water was consumed, the rate at which PFOA is removed from the body is also an important factor.

If PFOA is cleared slowly, higher exposures that occurred earlier in life stay in the body longer, thus contributing to longer-term exposure to PFOA in the blood and other body tissues. If PFOA is cleared quickly, then the measured PFOA levels in blood samples taken in 2005 and 2006 could only reflect recent exposures. We need to know the PFOA removal rates to estimate the past patterns of PFOA levels in people, and we need to know the PFOA levels at different times in relation to when people got sick, to help determine whether or not PFOA exposures may have played a role in those health conditions.

When the C8 Science Panel began its work little was known about the rate of PFOA clearance for humans. One of the ways in which this rate can be summarized is by the “half-life,” the amount of time it takes for the amount of PFOA in the body to decrease by half after exposure has ceased. Prior to the C8 Science Panel studies, the best available estimate of the half-life for PFOA was about 3.8 years, based on a single study of 26 retired fluorochemical production workers from Alabama. However, this was not representative of the Ohio Valley general population: there were few women among these study participants, only older retirees and nobody with recent PFOA exposures.

In mid-2007 we began a study to determine the half-life of PFOA in 200 volunteers served by Little Hocking Water Association and Lubeck Public Service District — two PFOA contaminated public water supplies in the Mid-Ohio Valley. During 2007 both water districts began to remove the PFOA from the water supply using granular activated carbon (GAC) — the same material used in many popular home water filtration systems. This treatment is highly effective when the GAC is changed often enough, leading to substantial decreases in PFOA blood levels over time for our volunteers.

Up to 6 blood samples were collected from each participant during the first year of the study, so we could follow trends in blood PFOA levels soon after the public water supply was cleaned. Two additional rounds of blood samples were scheduled for 2 years and 4 years after water treatment in order to determine long-term trends in blood PFOA levels.

We fixed appointments by telephone, including a short interview on exposure related questions like how much water they drink and whether they eat locally grown vegetables. Our trained phlebotomists then drove around to peoples’ homes to draw the blood samples (about 1 teaspoon at each visit). Participation has been excellent: of the 200 who signed up 192 are still enrolled after 3 years, which is an excellent level of participation, much higher than many community surveys. We are very grateful for the commitment of our participants.

In the first year of our study our volunteers experienced a more rapid decline in blood PFOA levels than was reported in the smaller Alabama study, resulting in an estimated average half-life for PFOA of just 2.3 years. This indicates that PFOA clears more quickly from the body than had been thought before. There was no difference in the half-life between men and women or across age groups, but PFOA levels did not decline as quickly among people reporting eating home-grown vegetables, suggesting that they may have some ongoing PFOA exposures by that route. A detailed scientific report describing these results is publicly available online at http://www.ncbi.nlm.nih.gov/sites/ppmc/articles/PMC2831921/.

We are still studying the data from the second year of measurements, but first results suggest that PFOA removal rates slowed in the second year compared to the first year. The half-life in the second year is about 3-4 years. This range is consistent with the previously reported 3.8 year half-life for the Alabama workers, suggesting that the half-life for PFOA may actually change over time, with quicker clearance during the first year after exposure stops and slower rates of clearance in later years.

Our PFOA half-life estimates are already being incorporated into the exposure predictions for participants in the other C8 Science Panel Studies. We will ask our volunteers for one more round of blood samples in mid-2011, which will allow us to estimate more precisely the longer term removal rate.