Fw: Arsenic and Barium Peer Review

Chuck Miller rellim at MAILHOST.TCS.TULANE.EDU
Thu Jul 15 19:28:42 EST 1999

-----Original Message-----
From: Jacqueline Patterson <patterson at TERA.ORG>
To: TOXLIST at esc_server.syrres.com <TOXLIST at esc_server.syrres.com>
Date: Wednesday, July 14, 1999 6:52 PM
Subject: Arsenic and Barium Peer Review

>Independent Peer Review Meeting Discusses RfD for Barium and Research
>Program on the Teratogenicity of Arsenic
>An independent panel of expert scientists and risk assessors met on June
>14 and 15 at the University of Cincinnati College of Medicine in
>Cincinnati, Ohio.  The panel of experts reviewed a research program on
>the teratogenicity of arsenic and an oral reference dose (RfD) on
>barium.  Elf Atochem, North America, Inc. sponsored the arsenic review
>and Chemical Products Corporation of Cartersville, Georgia sponsored the
>RfD for barium.  The review meeting was organized by Toxicology
>Excellence for Risk Assessment (TERA).
>The review panel included: Dr. Kenneth Bailey, U.S. EPA (retired); Dr.
>Donald L. Bjerke, Procter & Gamble Company (arsenic only); Dr. Michael
>L. Dourson, TERA; Dr. Ernest C. Foulkes, Professor Emeritus at the
>University of Cincinnati, Department of Environmental Health (barium
>only); Dr. Edward Sidney Hunter, U.S. EPA, National Health and
>Environmental Effects Research Laboratory; Mr. Thomas Long, ChemRisk
>Division of McLaren/Hart; Dr. Benjamin K. Nelson, National Institute for
>Occupational Safety and Health (NIOSH) (arsenic only); Dr. Rebecca T.
>Parkin, George Washington University Medical Center, Division of
>Occupational and Environmental Medicine; Dr. Jennifer Seed, U.S. EPA,
>Office of Prevention, Pesticides and Toxic Substances (arsenic only);
>and, Dr. Calvin C. Willhite, California EPA, Department of Toxic
>Substances Control.   In addition, Dr. John Fawell of the Water Research
>Center and Dr. Robert Tardiff of The Sapphire Group were not able to
>attend the meeting, but provided written comments.
>Elf Atochem sponsored a review of the developmental toxicity literature
>on arsenic, and based on identified data gaps, supported a number of
>laboratory animal studies to evaluate the ability of inorganic arsenic
>to induce prenatal structural malformations.  The peer review panel
>reviewed these materials and evaluated whether ingestion or inhalation
>of inorganic arsenic causes structural malformations.  The review panel
>concluded that the existing human
> epidemiology studies were insufficient to make a determination on the
>ability of inorganic arsenic to induce birth defects in humans, due to
>weaknesses in characterization of exposures, lack of reporting of birth
>related outcomes, and control of confounders.  The panel concluded,
>based on the new, regulatory guideline-compliant studies of arsenic
>trioxide and arsenic acid in mice, rates, and rabbits, that repeated
>oral and inhalation exposures to these forms of inorganic arsenic did
>not induce structural malformations; even at doses that elicited frank
>maternal toxicity and lethality.
>Chemical Products Corporation developed an oral reference dose for
>barium and compounds based on kidney effects seen in the 1994 National
>Toxicology Program (NTP) drinking water studies of barium chloride
>dihydrate in rats and mice.  The peer review panel reached unanimous
>consensus that available human studies were of insufficient quality to
>serve as the basis for a RfD and that the 1994 NTP study was the most
>appropriate choice of critical study.  The panel also unanimously agreed
>that kidney effects, rather than cardiovascular effects, are the
>critical effect for barium and that the high dose in the male rat from
>the 2-year NTP study (60 mg Ba/kg/day) is the appropriate NOAEL from
>which to derive an oral RfD.  The panel approved using an uncertainty
>factor of 10 to account for human variability, but requested additional
>discussion and justification for factors accounting for interspecies
>extrapolation and database before approving a total composite
>uncertainty factor.  The final value of the oral RfD for barium will be
>determined after the panel reviews the additional uncertainty factor
>Toxicology Excellence for Risk Assessment (TERA) is a non-profit
>corporation dedicated to the best use of toxicity data for risk
>assessment.  The peer review panel was made up of experts from
>government, industry, consulting, and academia, creating a balanced
>panel, while carefully managing potential conflict of interest issues.
>The peer review meeting was open to the public and a summary of the
>discussions and recommendations will be made available later this summer
>on the Internet at http://www.tera.org/peer.  This site also provides
>more information about TERA and the peer review program.  Contact
>Jacqueline Patterson [(513) 521-7426 or email patterson at tera.org.]
>Jacqueline Patterson, M.En.
>Toxicology Excellence for Risk Assessment (TERA)
>1757 Chase Ave.
>Cincinnati, OH 45231
>Phone 513-521-7426
>Fax 513-521-7428
>Patterson at tera.org

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