The average daily dose of dichlorodiphenyltrichloroethane, 3.7 mg. (3.5 mg. given in the feeding study + 0.2 mg., the average daily intake in food), was substituted for I in Eq. 4. The assumption was thus tacitly made that all of the administered pesticide was actually absorbed. The mean content of pesticide found in body fat, 613 mg., was taken to represent the body total, since other work showed that over 95 of body dichlorodiphenyltrichloroethane is dissolved in the fat (8).
To estimate the degree of accumulation of pesticides in the general population, it was assumed that administration occurs with meals, three times a day. R was calculated by Eq. 11, using a value of 1/3 day for 7 and the values for ?I/, given in Table I. The values of R, also shown in Table I, indicate that the degree of accumulation of the organochlorine pesticides is indeed high. In the case of dieldrin, for example, repeated dosing causes the average body level to rise to 1600 times the value that would result after a single dose.
The pesticides treated in this study have been widely used in agriculture. Although toxic effects have not been demonstrated in volunteers receiving doses many times higher than those to which the general population is at present exposed, the safety of these chemicals in humans is still open to question. Organochlorine pesticides have been shown to elicit pharmacological effects in animals and are blamed for decreases in the population of several species, including the bald eagle. In a sense, widespread use of persistent pesticides represents an uncontrolled experiment on man and other animals. The extremely long half-lives of these materials and their consequent accumulation in man, coupled with their slow degradation in the environment, make us extremely vulnerable if it should turn out that they are not as safe in man as their proponents would have us believe.
REFERENCES
(1) J. Robinson, Ann. Rev. Pharmacol., 10, 353(1970).