Document mBXvG63oV1dXVXKwvQxBnYB5B

Monsanto Ii t i n M i s 4w [ v o c ^ i'O * * * d * t i December 1A, 1982 ft^^icr U ' *i Dept, of Medicine 8t Environmental Health r T T . . ' .. A H __________________ - G-J. Levinska s . G2WF fA-ftRftg) ee R.T. Berendt, E2ND T.M. Bistline, E2ND G. Roush, Jr., M.D, G2WG DRfi to RTfi & 12/13/82 - TO D.R. Bishop, A3NB Dr. Roush and 1 had discussed the earlier and the present draft of your statement. He asked me to convey our comments to you. A copy of the draft is being returned with some suggested changes and comments. A few of these are highlighted and discussed below. The numbers correspond to the circled numbers noted on your last draft- l p.l (1) Mention should be made of chlorophenols, since those also have contributed to our knowledge of dioxin. p.2 (2) TCDD is highly toxic to all animal species studied so far, despite the wide range in toxicity. Data is lacking for all isomers. The di- and octa-dioxins may be quite harmless, but hexaisomers probably are poisons in the statutory sense. p.3 (3) No such examples come readily to mind. p.4 (A) Somehow, the concept that one part per billion may be fatal or harmful has to be overcome since this leads to the implication that one part per billion .in the soil also is fatal or harmful. The attached insert is an attempt to address this. alw attachment George J. Levinskas * IN-10M ( R E V . 2/78] CONFIDENTIAL C06241 - INSERT - To avoid confusion, some comments should be made about terms used by medical scientists. It is well recognized that the dose, i.e., the amount of aspirin needed to relieve pain varies between adults and children. Most adults take two aspirin tablets. Children are usually given one-half tablet up to the adult dose, depending on their age or weight. These differences can be standardized by expressing them as a dosage, i.e., the amount of aspirin per unit of body weight. Since the average aspirin tablet contains about one onehundredth of an ounce of aspirin, a 150-pound adult taking two tablets gets a dosage of 13 hundred thousandths of an ounce per pound of body weight. Simi larly, a 40-pound youngster given one-half tablet gets approximately the same amount per pound of body weight. In animal feeding studies, standardized dosages are calculated to permit com parisons between different animal species. While parts per trillion in the diet refers to the ratio of the weight of TCDD to the weight of the animals' feed, it can be converted to a dosage. For example, a 16 parts per billion diet would be achieved by mixing 16 ounces (one pound) of TCDD with 1 trillion ounces (31,250,000) tons of food. Animals given that diet would be getting 16 parts TCDD for every billion parts of food they ate. If desired, the dosage, i.e., the amount of TCDD eaten per unit of body weight could be calculated from the weight of the animal, the amount of feed consumed, and the concentra tion of the test substance in the diet. Dosages are used in a similar manner to express lethality. For TCDD, the dosage lethal to guinea pigs is about 16 billionths of an ounce per pound of body weight. While the ratio of TCDD to the body weight of the guinea pig is one to one billion, it is incorrect and misleading to refer to the lethal dose as one part per billion. The example of aspirin can be used to illustrate this. The average tablet has about 85% aspirin. Another way to express this is to say that the tablets have 850 million parts per billion of aspirin. It would be meaningless to say someone should take 850 million parts per billion of aspirin. It is equally meaningless to say one part per billion of TCDD is lethal to guinea pigs, or that low parts per trillion causes cancer in rodents, without specifying additional information. GJL 12/14/82