Media Contacts:
Dr. Jim Riviere, 919/513-6305
Greg Thomas, News Services, 919/515-3470

Nov. 12, 2003

Absorbing Research Leads to Advances in Human, Animal Health

FOR IMMEDIATE RELEASE

Every day humans and animals are exposed to dozens of chemical compounds – some harmful, others harmless. How those chemical compounds are absorbed by the skin and how they interact with one other is something Dr. Jim Riviere and his colleagues at North Carolina State University have been studying for years, with big dividends for both human and animal health.

It’s that kind of research that helped get Riviere elected this month to the Institute of Medicine of the National Academies. Election is considered one of the highest honors in the fields of medicine and health, and is awarded to those who have made major contributions to the advancement of the medical sciences, health care and public health.

Riviere is the Burroughs Wellcome Fund Distinguished Professor and Director of the Center for Chemical Toxicology Research and Pharmacokinetics at NC State’s College of Veterinary Medicine. He focuses his research on quantifying drug and chemical delivery across skin; his lab has developed several models for predicting absorption in humans.

Working with Riviere are Dr. Ronald E. Baynes, assistant professor of pharmacology and risk assessment; Dr. Nancy Monteiro-Riviere, professor of investigative dermatology and toxicology; Dr. Ronette Gehring, research assistant professor of pharmacology; Dr. Xin-Rui Xia, research lecturer; and a staff of 10 students and technicians.

Their work is one example of how basic and applied research at NC State’s College of Veterinary Medicine benefits human health as well as animal health.

“The outer layer of the skin is a dead protective barrier that’s meant to keep things out, but for some compounds it’s not a barrier at all, it’s a sponge, so depending on the kind of chemical and what the interactions are, some chemicals interact with skin and enhance the absorption of other chemicals. That’s the big area that’s the problem,” Riviere said.

Riviere hopes his research can help better define risk assessments. “What we’re really focusing on lately is that most chemicals and drugs are not exposed to people as single contaminants, they are exposed as complex mixtures. Fuel, for example, has a thousand components in it, so we’re looking at how you can predict the absorption of a mixture, as well as how other chemicals can affect the absorption of the fuel.”

Riviere’s research has uncovered cases where chemical absorption fears were unfounded. “There’s a group of environmental contaminants called nonylphenols that are found almost everywhere in the environment. They are the by-product of many manufacturing processes. There was a big concern with them, but it turns out that they are not absorbed. So now you can start to investigate if there are problems from eating or drinking them, for example.

“We’ve had funding from the Air Force for jet fuel absorption. We’ve looked at components in the fuel to see how additives affect the absorption of those compounds and we’ve looked at how fuel affects the absorption of totally unrelated things,” Riviere said.

The results of these studies will help determine how much exposure is too much. Experts will then have to decide how to regulate that exposure, but having quantified absorption models should help them in the decision-making process.

Riviere’s research on chemical absorption is funded by a grant from the U.S. Air Force and two grants from the National Institutes of Health. He also receives funding from the USDA for his work on the Food Animal Residue Avoidance Databank (FARAD), which makes up his other area of research.

FARAD is a collaborative project of NC State, the University of California and the University of Florida.

"Animals are exposed to things they shouldn’t be exposed to. Suppose your neighbor sprays his field with pesticides for West Nile virus and it sprays on to your cattle. Is there a concern? For some chemicals there isn’t, but for others there is. For some chemicals the concern might be that you just can’t drink the milk or market the animals until the chemicals clear through their bodies,” Riviere said.

FARAD maintains a database of information on chemical residues of every sort and has provided information to both veterinary and human health professionals. “We consulted back in the 1980s when the Chernobyl nuclear plant blew. The big question was what happens to all these people in Western Europe when clouds of radioactive stuff settle on their farmlands? Can you eat the meat or drink the milk? Those are some of the questions that needed to be answered,” Riviere said.

“It’s all the same kind of mathematical modeling, so we essentially can make predictions and determine when those chemicals are clear from the animal.

"You can’t test this stuff on humans, so you need to come up with models that will predict absorption,” Riviere said. Those models help regulatory agencies decide how much is too much.

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