Board defines C8 as “likely” carcinogen
By Callie Lyons
Without commenting on the probability or quantifying the potential risk of cancer, the Environmental Protection Agencys Science Advisory Board concluded Wednesday that C8 should be described as a likely human carcinogen.
The decision about the DuPont manufacturing chemical, known as PFOA or perfluorooctanoic acid, was made amidst intense discussion about the EPA process for deciding weight-of-evidence descriptors. Several of the independent scientists on the panel said more data was needed in order to be able to adequately quantify the risk of cancer to humans.
More likely than not, said Dr. Melvin Anderson, Director of Biomathematics and Physical Science, Centers for Health Research of Research Triangle Park, North Carolina, who said the decision to define C8 as a likely human carcinogen as opposed to a suggested human carcinogen was a critical issue.
Anderson said it should be made very clear that the panel was charged with finding an appropriate descriptor for PFOA, not quantifying the risk.
Representatives from DuPont and 3M presented scientific evidence to dispute the claim that PFOA is a human carcinogen.
Dr. Gerald Kennedy of DuPont Haskell Laboratories presented information about worker studies underway at the DuPont Washington Works plant located near Parkersburg. There are two studies in progress, one to examine the health of a cross section of workers and another to look at the well being of current employees and retirees who have had different assignments in the plant.
The overall population appears to be healthy, Kennedy said. Of 62 examinations, most were normal. None (of the health problems) were associated with PFOA in serum.
Kennedy said PFOA levels detected in the blood of DuPont workers range from .5 to 2 parts per million - with a few up to 10 parts per million. Of workers in the top 10 percent, statistics show a significant but unexplainable increase in cholesterol.
Cause and effect is not possible (to determine) from the cross section design, Kennedy said.
Dr. Geary Olsen of 3M took exception to the draft reports implication that cancer and heart disease can result from PFOA exposure.
Both DuPont and 3M stand by their claims that no ill effects have been noted in workers to suggest harm to the general population.
The Science Advisory Board draft report repeatedly expresses concern for some Mid-Ohio Valley residents who are believed to have some of the highest known levels of exposure.
The Panel notes there may be several distributions of exposed populations, some with much higher levels than indicated in the blood donor and pediatric populations. Besides the occupationally exposed (a group of unknown size) data presented at the meeting indicate high levels of PFOA have been detected in the serum of neighbors of the DuPont plant in West Virginia. The levels approach or at times exceed those found in worker populations . . . the sizes of more highly exposed populations remains unknown and this should be acknowledged, the draft concluded.
However, local water consumers will have to wait for additional studies to be performed before any definite conclusions characterizing the potential risk are formed.
There was not adequate and available data for the panel to estimate likelihood, said Dr. Ronald Melnick, Director of Special Programs in the Environmental Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina.
The EPA cautions that terms such as likely, when used as a weight-of-evidence descriptor, do not correspond to a quantifiable probability. The purpose of the panels meeting Wednesday was ultimately to get approval pending changes and move on with their final report.
It is not clear to us in many places whether the panel has actually reached consensus on an issue, said Dr. Jennifer Seed of the EPAs Office of Pollution Prevention and Toxics. We would greatly appreciate anything you could do to help clarify your recommendations.
Some members of the panel criticized the EPA for not reflecting the broad range of opinion reflected in the group, a difference of judgment that became apparent as members disputed their comfort with the draft report released last week.
The way the information is presented has an impact on how it is perceived, said Dr. Michael A. Kamrin, Professor Emeritus at the Institute of Environmental Toxicology, Michigan State University.
Kamrin said the emphasis was in the wrong place in some sections of the draft report and questioned the amount of space devoted to the conclusions as opposed to the amount of space devoted to the uncertainties.
I would like to see it again before I sign off on it, Kamrin said.
The EPA agreed to add more language indicating the range of opinion on each of the panels issues, but not everyone agreed with Kamrin.
I think bringing the uncertainties forward is very important, said Dr. Matthew P. Longnecker, MD ScD, Division of Intramural Research, National Institute of Environmental Health Sciences, Epidemiology Branch in Research Triangle Park, North Carolina.
All 16 Science Advisory Board members participated in the teleconference. All in all, more than 100 callers phoned in to listen in on the discussion, said Dr. Suhair Shallal, EPA Designated Federal Officer
The board will finalize their individual suggestions by July 20 in anticipation of releasing a revised draft in August. The report will be distributed to the Science Advisory Board panel members before the final draft is submitted to the EPA for consideration.
The Science Advisory Board holds public meetings to conduct their discussions in accordance with the Federal Advisory Committee Act. In order to maintain a proper balance of interests, a new formation process was designed for the selection of the PFOA Science Advisory Board. According to the new standards, the public has an opportunity to nominate individuals for participation; members must file a financial disclosure statement and participate in Science Advisory Board Ethics Training.