Document OJBQZmyxzV48enNQNygGEZNaL

A pr i l 7, 1938 Mr* P. A, Combelic . V/ aahington St at e A gri cult ure Ass in. Spray Residue Committee Dear Si r :- > Tour l et t er of March 2Jrd r ai se's a question t o which, in ray opinion, there i s no answer* The problem of spray residues on f r u i t and,more p ar t i cu l ar l y, on l eaf y green veget ables i s an important problem in public healt h* Much has been w ri t t en on both si des of t h i s quest ion h ut , un for t un at ely, not much experiment al work has been done to j u st i f y a sound opinion as to the fact s* 1 per son ally do not f eel t hat the posit ion of the al ar m i st s i s well taken* On the other hand I do not f eel t hat t here i s any avai l ab l e evidence which would j u st i f y the Bureau of Pure Pood and Drugs in the Department of A gri cult ure i n .r ai si n g these tolerances for ei t h er lead or ar sen i c. The t ole ran ees, as they now ex i st , have no ver y sound sc i en t i f i c or physiologic background. On the other hand 1 f eel t hat i f t h i s Bureau i s to be In er r or , i t should er r on the si de of saf et y. Moreover, with a l l due respect to Dr* I r a Car d i f f , with whom I have t al k ed , I do not b el i eve t hat h i s posi t ion i s w el l taken when he says t hat i t i s up t o t h i s governmental agency t o prove the correct ness of i t s posi t ion with regard to lead and ar sen ic t olerances* i t I s r at h er up to the indust ry to prove t hat the t olerances est abli sh ed by t h i s department are incorrect As a m at t er of f act these t olerances are set by the Department af t er consult at ion with quit e a number of men Who are presumed t o be au t h or i t i es in t h ei r f i el d * These men express the combined judgment of experim ent al workers who know t hat both lead and ar sen ic are t pxic subst ances and t hat t h ei r presence in food f o r general consumption should be l i m i t ed . I per son ally disagree with some of the experiment al evidence on which t h ei r conclusions were reached. However, in the st r i c t sci en t i f i c sense, and from the point of view of the public h eal t h , t h i s i s unimportant and I f I were responsible for the adm inist rat ion of t h i s Bureau, I would not change the t oleran ces upward except on the b asi s of ver y sound evidence that t hey were unreasonable and unnecessary. Moreover with excel l en t sc i en t i f i c evidence at hand as to the l ev el of lead and ar sen i c int ake;which could be endured without i n ju r y to human beings, I should s t i l l want a large safet y fact or in view of the f act t hat children and si ck people have to be thought oif in connection with general V2 d i et ar y problems* What I have sai d above would seem to in dicat e t hat I l ack sympathy f o r the fruit**growing indust ry* This i s not the case. I recognize the d i f f i c u l t i es of t h ei r si t u at i o n , and I am st r on gl y 'sympathetic with t h ei r problem when I r eal i ze t hat they must in a measure choose between a l oss of t h ei r f r u i t because of i n sect s and damage to t h ei r f r u i t by various t ypes of washing operat ions* On the other hand i t should not be necessary f o r the ordinary ci t i zen to have to consider whether or not the food by which he l i v es i s l i k el y to poison him. Wholesome food should be avai l ab l e to him without the exer ci se of pr eci se precaut ionary m easu r es . , With regard to the act ual dangers of sp. ray, r esldues,. I .may. say t hat in aimost f i f t een years of experience, I have not seen a case of lead poisoning or of ar sen ic poisoning derived from the ingesfci.cn of f r u i t contaminated with spray residues* Moreover I should be disposed to f eel t hat t he statement of the t w en t y-five ph ysi ci an s, r efer r ed to in your l et t er , t hat they " have never observed or t reat ed a case of ar sen i c or ler-'d poison-ng et c* " i s truer. I have not found any other physician who has seen or t r eat ed such cases although the numerous publicat ion s of C, !i, 1'eyers (who Is not a physician) and h i s associ at es would in dicat e t hat they have seen numerous examples of ``sub-el in l eal * ' lead and ar sen ic poisoninJigs .* Ju st what, i s meant, by "sub-cl in l eal " in t oxi cat i on i s not quit e cl ear t o me, and from some of the an al yt i cal data supplied by those men, I can nc fc f eel t hat i t i s very cl ear to them. However t h i s w i l l in dicat e t hat t here i s a d i ffer en ce of opinion on t h i s su bject which o f f i c i al agencies have to take int o account. A ll of the negat ive evidence has to be regarded with some skept icism si n ce the r eal i ssu e has to do with whether the qu an t i t i es of lead and ar sen i c involved are such as to produce cases in various part s of the country which, f o r a var i et y of reasons, may not have been recognised. Those of us who have, st udied t h i s problem in indust ry know t hat t here are shfe l evel s of lead and ar sen i c I n t ak e, Hpwever in i n dust ry exposure i s mainly through i n h alat ion * I f t hese m at er i al s are i n gest ed, the problem i s wholly d i f f er en t , and i t seems quit e cer t ai n t hat neit her lead or ar sen i c adm inist ered by mouth are as t oxi c ,as when in h aled. The reasons f o r this_ are quite apparent since i t lias been shown t hat a considerable pro port ion of ingest ed lead t r aver ses the alim ent ary t r act upabaorbed. We have found;, f o r example, t hat even when lfifele Iffihd sal t s, in sol u t i on , are administered t o human mbJedfcs:, t hat a very l ar ge proport ion of the lead passes li''p alim ent ary t r act 'without absorpt ion. I t i s probable, and in f act i t i s almost cer t ai n , t hat a much l ar ger proportion of lead arsenat e i s unabsorbed than i s the case with these soluble sal t s* The f i r st problem, t h er efor e, from an exper i mental point of v i e, with, r ef er 'n ee to lead arsenat e spr ays, has t o do with the ext ent pf t h ei r act u al absorpt ion int o the V -3 deal to do with the magnitud of the t o x i ci t y of t his substance* The next quest ion i s the ext ent t o which absorpt ion from the alim ent ary t r act i s taken up by the l i v er and promptly excret ed from the body* Ho doubt numerous fact or s influence the f at e of such absorbed l ead , and obviously persons wit h l i v er damage w i l l not behave so well in t h i s regard as w i l l normal persons. You w i l l be i n t er est ed in knowing t h at a ver y considerable amount of animal experimentation i s under way at t h i s time* Rather ext ensive work i s being car r i ed out by the United St at es Public Health Ser vi ce under the d i r ect i on of Dr* R. H. , Sayer s, in an ef f o r t t o determine the ext ent of lead absorpt ion by experiment al anim als. I t w i l l I s some time before the data on t h i s study are avai l ab l e, but the r esu l t s should be ver y i n t er est i n g and quit e important in r el at i on t o t h i s problem. On the other hand i t I s quit e cl ear t hat they w i l l not answer the quest ion of the r eact ion of the human being to t hese poisonous m at er i al s* In my opinion I t w i l l not be possible t o ar r i ve at sound conclusions as to the safet y fact or In lead and ar sen ic int ake by mouth u n t i l ext ensive human experimentation has been car r i ed out . I t hink some ext remely valu abl e information could be obtained by f i el d st u di es in the orchard sect ion s during the apple picking season. One would fin d here largo groups of people eat ing unwashed f r u i t , and I t would be possible to, study t h ei r physical condit ion and al so the magnitude of t h ei r lead absorpt ion and lead excr et i on . In t h i s way one could obtain data which could be compared, with t hat obtained in indust ry under condition's of known exposure, and from such information one could determine f ai r l y sat i sf act o r i l y the magnitude of the hazard. You have asked my opinion as to the maximal quant it y of lead ar senat e which might be in gr at ed without harmful offeet o* Anything which 1 might say on t his subject would be pure guess work since t here I s no information on which to go. I can say, however, from our experiment al obser vat ion s, t hat i f the. t ot al lead int ake per day by mouth does not exceed 1- 1/ 2 M i lligr am s, cases of lead poisoning w i l l not occur among normal persons. What w i l l happen to i n fan t s and si ck people under these con dit ion s, I am unable to say* I would be in clin ed to expect t hat nothing would occur, but t h i s i s a guess based on numerous I n d i r ect obser vat ion s. . You might be i n t er est ed fu r t h er In knowing that the lead int ake over a per iod-of t went y-four hours among average American adult s var i es from approximately one-t ent h of a m illigram to 2 m illigram s per day under present condit ions of food consumption and d i st r i bu t i on * Only r ar el y does the t went y-four ftouf food intake contain as much as a m illigram of l ead . The average fi gu r e, however, i s V / approximately O.25 m illigram s per day. Xh l ar ger qu an t i t i es which, I r epeat , occur i n fr equ en t l y, u su al l y coincide wit h the in gest ion of more than usual quan t i t i es of salads and f r u i t . We have seen no in dicat ion in our own dat a t hat lead Intake has increased during the period of the past ten year s, I should guess, however, t hat i f unwashed f r u i t were gen er al ly d i st r i b u t ed over the United St at es, the average lead int ake would he considerably in cr eased, I t hink i t might perhaps be increased by as much as four* t ines I t s present magnitude without gr eat danger, On the ot her hand, I can assure you t hat I would not wish to be respon sible f o r any si t u at i on which brought about such an incresl.se. Frankly X would not even experiment with human subject s on Increased lead int ake except as I could maintain a cont inual medical supervision of t h ei r m et abolic response, &ven under condit ions in which I am adm inist ering one m illigram a day as a soluble sal t , I am m aint aining a d'aiiy check on the lead int ake and output, I am carryin g out complete physical examine-felons onca a week, and I am watching the blood d ai l y fbr microscopic changes i n d i cat i ve of increased lead absorpt ion. This w i l l serve to show you t hat in my opinion the quest ion of increased lead absorpt ion I s considerably more than iHaiadeittiC''''';o n e i* : ... ' 1 t r u st t hat in t h i s -somewhat lengt hy'-discussion X have given you a general idea- Of my point of view which 1& , perhaps, con ser vat ive, hut in my opinion conservat ism i s f u l l y j u st i f i ed in r el at i on to t h i s public healt h problem* Very t r u l y yours, RAKsls RobeFtTMn""Eehoe, M.f). \ ( 0015112