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Tuesday, January 10, 2006, 12:00 a.m. EDT
NIEHS to Put More Emphasis on Systematically Assessing the Health Risks of Toxicants; Christopher Portier, Ph.D. Named Associate Director for Risk Assessment
Christopher Portier, Ph.D., will assume a new leadership role as Associate Director for Risk Assessment at the National Institute of Environmental Health Sciences (NIEHS), one of the National Institutes of Health. Dr. Portier will oversee and coordinate risk assessment activities within the NIEHS and apply the results of toxicological studies to national and international efforts dedicated to assessing the human health risks of chemical, drugs, and physical agents. The new position is in line with the Institute's renewed interest in using environmental health sciences to understand human disease and improve human health, according to the NIEHS Director, Dr. David A. Schwartz.
"We are very excited that Dr. Portier will lead this important effort," said Dr. Schwartz. "Dr. Portier has done an extraordinary job in overseeing the activities of the National Toxicology Program, and has developed strong relationships with scientists all over the world. This new NIEHS leadership role will allow him an opportunity to merge the fields of toxicology and environmental health sciences and prepare the world for tomorrow's health challenges."
Dr. Portier has served in many prominent positions within NIEHS since his arrival as a post doctoral student in 1981. Most recently he has served as the Associate Director of the National Toxicology Program, the Director of the Environmental Toxicology Program, and the Head, Environmental Systems Biology, Laboratory of Molecular Toxicology at the NIEHS.
It was in 2001 when he was appointed to the prestigious position of the Associate Director of the National Toxicology Program (NTP). The NTP is an interagency program whose mission is to coordinate, conduct, and communicate toxicological research across the U.S. government. The NTP is administratively housed at the NIEHS.
The culmination of Dr. Portier's efforts at the NTP is exemplified by his role in developing the landmark document "A National Toxicology Program for the 21st Century: A Roadmap for the Future," which was released in 2005 as part of the NTP 25th Anniversary Celebration in Washington, D.C. The NTP Roadmap outlines a framework by which the NTP will modify, adapt, and improve its programs to better address its mandate in providing scientific information for protection of public health.
"The NIEHS remains fully committed to promoting the goals set forth in the NTP Roadmap," said Dr. Schwartz. "The NTP has an extremely talented and dedicated staff that will keep the important work that the NTP does going strong."
Some of the many other accomplishments achieved by Dr. Portier while at the NTP include developing the first ever evaluation guideline for non-cancer endpoints as part of the NTP's Center for the Evaluation of Risks to Human Reproduction. The NTP has also played a lead role in developing a High Throughput Screening Initiative, which will enable large numbers of environmental substances to be screened for potential health hazards. Dr. Portier has authored more than 150 peer-reviewed publications; 50 book chapters, reports and agency publications in statistics, risk assessment and cancer research.
"Closely linking risk assessment processes to NIEHS research will improve the Nation's ability to make informed public health decisions," said Dr. Portier. "We will be better poised to answer the basic questions inherent to risk assessment, including: Is it possible that this substance poses a hazard to humans? If yes, how much is dangerous? Are humans exposed to this substance and in what ways? Given human exposures and knowing how much is dangerous, what levels would be safe? These are exciting times in health research and being able to focus on bringing cutting edge research into the risk assessment arena will be a challenging new role for me at NIEHS."
Allen Dearry Ph.D., who most recently served as the Director of the Institute's Division of Research, Coordination, Planning and Translation, will act as the Interim Associate Director of the NTP. Dr. Dearry will work closely with other leaders in the NTP during this time of transition. Dr. Dearry served in a variety of high profile science positions while at NIEHS, including the Chief of the Chemical Exposure and Molecular Biology Branch, within the Division of Extramural Research and Training. A national search for a permanent NTP Associate Director will begin in the next three to six months.
Component in Soy Products Causes Reproductive Problems in Laboratory Mice
Genistein, a major component of soy, was found to disrupt the development of the ovaries in newborn female mice that were given the product. This study adds to a growing body of literature demonstrating the potentially adverse consequences of genistein on the reproductive system.
"Although we are not entirely certain about how these animal studies on genistein translate to the human population, there is some reason to be cautious," said Dr. David A. Schwartz, Director of the National Institute of Environmental Health Sciences (NIEHS). "More clinical studies are needed to determine how exposure during critical windows of development can impact human health."
Genistein is the primary naturally occurring estrogen in plants (called phytoestrogens) and can mimic the effects of estrogen in the body. Genistein can be found in foods containing soy such as soy-based infant formulas as well as over-the-counter dietary supplements.
The results of this study conducted by researchers at the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health, in collaboration with an investigator at Syracuse University, are published in the January issue of Biology of Reproduction.
The NIEHS researchers previously showed that mice given genistein immediately after birth had irregular menstrual cycles, problems with ovulation, and problems with fertility as they reached adulthood. The new study looks at the direct effects of genistein on the ovaries during early development.
"We knew genistein was linked to reproductive problems later in life, but we wanted to find out when the damage occurs," said Retha R. Newbold, MS, a developmental endocrinologist at NIEHS and an author on the study. "The study showed that genistein caused alterations to the ovaries during early development, which is partly responsible for the reproductive problems found in adult mice."
Female mice were injected with three different doses of genistein during their first five days of life. The genistein given to the mice was comparable to what human infants might receive in a soy-based formula, which is approximately 6-9 mg/kg per day. The researchers examined the effects on days 2 through 6.
The researchers found effects at all levels. Mice treated with the high dose (Gen 50 mg/kg) were infertile and mice treated with lower doses were subfertile, meaning they had fewer pups in each litter, and fewer pregnancies. Mice receiving the highest level of genistein, 50 mg/kg per day, had a high percentage of egg cells that remain in clusters, unable to separate and therefore develop abnormally. The researchers explain that oocytes that remain in clusters are less likely to become fertilized based on previous research. The largest difference between the genistein treated and normal mice was found at six days of age where 57 percent of the egg cells in the non-treated ovaries were single or unclustered; and only 36 percent in the genistein treated group were single.
We think genistein inhibits the oocytes or egg cells from separating apart," said Wendy Jefferson, Ph.D. of NIEHS and lead researcher on the paper. "Since there are many egg cells in the same follicle instead of just one, the resources from the surrounding cells are spread too thin and they can't get the support they need to become a mature functioning egg cell."
"You need at least one good healthy single oocyte that is ovulated and fertilized by a sperm to get a healthy baby. Genistein seems to have a way of making this task very difficult," said Newbold.
"I don't think we can dismiss the possibility that these phytoestrogens are having an effect on the human population," said Dr. Jefferson. "They may not show their effects or be detected until later in life, but chances are they are having an effect."
NOTE: The National Toxicology Program, Center for the Evaluation of Risks to Human Reproduction (CERHR) will hold an independent expert panel meeting on "Genistein and Soy Formula" on March 15-17, 2006, at the Radisson Hotel Old Town, Alexandria, VA. The NTP is an interagency program headquartered at NIEHS.
W Jefferson, E Padilla-Banks, R Newbold and M Pepling. Neonatal genistein treatment alters ovarian differentiation in the mouse: Inhibition of oocyte nest breakdown and increased oocyte survival. Biology of Reproduction, January 2006.
W Jefferson, E Padilla-Banks and R Newbold. Adverse Effects on Female Development and Reproduction in CD-1 Mice Following Neonatal Exposure to the Phytoestrogen Genistein at Environmentally Relevant Doses. Biology of Reproduction 73(4):798-806, 2005. Epub Jun 1, 2005.
About the National Institute of Environmental Health Sciences (NIEHS): NIEHS supports research to understand the effects of the environment on human health and is part of the National Institutes of Health. For more information on NIEHS or environmental health topics, visit www.niehs.nih.gov or subscribe to a news list.
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