| Sponsored by: International
Society of Regulatory |
QUESTIONS FOR PANEL 2
MR. FESTA: Steve, here is a question you have gotten many times. When you look at EPA's risk assessment, risk characterization, they downplay the naturally-occurring ligands because they say they don't bioaccumulate, they have very short half lives. So, you know, they pooh-pooh it. DR. SAFE: I think that was mentioned this morning in Panel 1. You can pooh-pooh half lives all you want, but when you see serum levels, your argument on half lives just goes out the window. Serum is what delivers toxins and it is critically important. There are serum levels of these compounds, it is now widely recognized. They probably should consider that, but you know, it takes a while for things to sink through, maybe. They probably should consider it. MR. FESTA: I just have one quick question for Bob Scheuplein. Bob, it is not just EPA that is claiming dioxin is a known-human carcinogen, but HHS as well, and HHS is the parent agency of FDA. I don't know what FDA's position is, but if they disagree with this claim, can FDA espouse an independent position? DR. SCHEUPLEIN: It certainly can if it wants to. I don't know what their position is now either on dioxin, but it is certainly free to do so. MR. FESTA: So, they don't necessarily have to follow suit with the parent agency. DR. SCHEUPLEIN: No. MR. QUILL: Just a thought came to mind, Steve, when you were talking. You know, there has been a lot of talk recently about laboratory animal diets and how they may affect toxicity. Primarily the talk has been the amount of food lab animals eat. I am wondering if anybody has really thought about the amount of isoflavonoids and other antagonistic substances in the lab diet, and can we account for some of the differences that we apparently are observing in humans to that? DR. SAFE: People have not considered it as much for dioxin studies, but there are a lot of studies now going on. You know, this environmental endocrine disrupter stuff, everybody is paranoid about that. It is sort of like dioxin-II. A lot of people doing studies with those compounds or doing studies with isoflavonoids are really very careful now about their diets. If you are looking at genistein or quercetin in the diet and your chow contains tons of those compounds, you know, you can't do it. The chows now are very carefully looked at, particularly for studies on estrogens. You can get, I guess, a flavone-free diet and that is pretty important. It would be really interested to get a flavonoid-rich diet and do a long-term study with dioxin on a flavonoid-rich diet that would sort of mimic our diet versus a flavonoid deficient, or had none of it at all in the diet. I don't think it has been done. SARAH ARMSTRONG, Cambridge Environmental, Inc. I have a question for Dr. Barraj. I wonder if you could comment on the adequacy of the data base on concentrations of compounds in foods with respect to their dioxin-like PCBs. DR. BARRAJ: Basically, the reviews, as I said, they reviewed a lot of data. The beef, pork, poultry residue concentration data were derived from what are considered to be statistically representative samples of the food supply. I worked a lot with the dietary risk assessment. I don't know, for instance, they have two dairy cows included in their beef samples. I am not really sure whether they slaughter dairy cows and I am not sure if someone can answer -- maybe someone from USDA -- whether people do eat that. Also, it may not be a big impact, because the residues in those dairy cows were not so much higher than for the others. Basically, as I said, for beef, pork and poultry this is supposed to be a representative sample, a large enough number of observations, more or less, and from various regions, et cetera. For all the statisticians here, 84 samples is probably not always enough. You would like more. The more you get, the better estimates you could have and the variability if there are any regional or seasonal differences, you would like to see these. The data, I don't think, allows us to try to see anything like that. For the fish data, they have looked at a lot of information, as I said, but the numbers I have used are not necessarily representative, and I did refer to that. Especially the national consumption study which I think was for mostly the freshwater, these are older data and I don't think they are representative of what is going on. MR. ESTREICHER: I have a question for Barbara Schneeman. When the USDA sets up the pyramid, do they take into consideration the natural levels of toxicants or artificial toxicants in the particular food group when they set up the guidelines? DR. SCHNEEMAN: I mentioned the criteria that are used to set the food guide pyramid, which are really those looking at typical consumption patterns so that you are reflecting where Americans are getting their nutrients, meeting the RDAs and then, when the pyramid is explained, you can follow the dietary guidelines. So, obviously if it were known that there was a problem with a particular food, that might come out in the bulletin or the background, but it is really those three areas that are the most important criteria. One thing I forgot to mention at the end of my talk, another thing that the interagency working group has been involved with is encouraging a National Academy of Sciences study on some of the food safety issues. That is going forward. There have been discussions with IOM, the Institute of Medicine. The Food and Nutrition Board will take the lead in that study, but there are clearly several of the other boards that will be involved because of the nature of the issues. It will be sponsored primarily by FDA and USDA and will focus on some of these food safety issues. |