Document KO7QV8wpNZdZNJGbnD0yq9rx

March 2 1 , 1938 Dr. Sam E* R oberta 1110 P r o f e s s io n a l B u ild in g Kans aa C ity , M issou ri Dear D octor Roberts*-. Ai. I have been somewhat tard y In Replying to your i e t t e r o f March 'Jth. by reaso n of my absence from th e la b o r a to r y f o r a tim e* i , ' The prcblem which you r a i s e in your l e t t e r concerning the production of deafness through the slow ab so rp tio n of le a d compounds i s one in which I would be I n te r e s te d * On the o th e r hand I am somewhat s k e p tic a l a s to the lik e lih o o d of the o ccu rren ce of deafness in a sso cia tio n with lead in to x ic a tio n , sin ce I hsive never seen any ev id en ce o f d eafn ess as a symptom of llead p o iso n in g . We would e x p e c t to fin d evid en ces of damage to h e a rin g among p la n t p op u latio n s In which th e re I s known to be s e rio u s and s i g n i f i c a n t lead exp o su re, and as v e t I h ave seen no evid en ce t h a t th is o c c u r s . On the o th e r hand one does n o t s e t out with, a p reco n cep tio n In e x p erim en tal work, and I f you have a means of stu d yin g t h is q u e s tio n , I should be q u ite w illin g to g iv e you as much a s s l s i a b c e as i s p o ssib le In view o f our own r a t h e r exten sive experim ental program# As t o th e lik e lih o o d of lead poisoning from food d is trib u te d in tin c a n s , I can a ssu re you t h a t the use of tin cans in the d is tr ib u tio n of food in the United Sta te s is not an Im portant f a c to r in lead p o iso n in g . 'We have stu d ie d t h i s problem q u ite e x te n s iv e ly in an i n d i r e c t way by fo llo w in g the lead c o n te n t of fo o d s, and b y stu d yin g th e d a i ly in tak e o f lead by persons on g e n e ra l d i e t s o f t h e i r own c h o ice * Tin cans a re m anufactured v e ry c a r e f u l l y in the U nited S ta te s and in g e n e ra l th e re is l i t t l e or no c o n ta c t o f food m a te r ia ls w ith the s o l d e r . This Is not tru e of c e rta in imported food m a te ria ls , but th ey do n ot c o n s t i t u t e an im p o rtan t f a c t o r In American d ie , so f a r as my e x p e rie n ce g o e s . We have o b tain ed v e ry good evidence over a period of y ears th a t the average American takes In about o n e-fo u rth of a m illig ram o f lead per day in h is fo o d . The a c tu a l q u a n titie s v a r y from t r a c e s up to somewhat in e x c e s s of one m illig ra m per d ay, h u t the average fig u re is around a q u arter of a m illigram . This is true a l l 2 over the c o u n try and th e r e is v ery good evid en ce th a t i t hass been the c a se f o r a long tim e* Indeed some s tu d ie s o f ours In a p rim itiv e community in which a l l the food was obtained l o c a l l y in d ic a te th a t the normal and n a tu ra l lead con ten t of food m a te ria ls is such th a t the average individual tak es in something more than a te n th o f a m illig ram from th is so u rce * From a la r g e s e r i e s of o b se rv a tio n s made In d i f f e r e n t f i e l d s , i t is q u ite c le a r th a t th ese q u a n titie s of lead In the d i e t do not produce a s t a t e in which lead in to x ic a tio n can be expected to occu r* This is not to In d icate th a t contam ination o f fo od s w ith lead Is an unim portant m a tte r* On the c o n tra ry th ere is evidence th a t s ig n if ic a n t contam ination occurs from a v a r i e t y of s o u r c e s . The most im p o rtan t of th e s e , so f a r as our observations go , are concerned with the contam ination of sm all fr u its w ith in s e c tic id e s , the contamination of sugar in the p ro cess of In v e r s io n , and th e use o f a number o f a cid s such a s Q i t r i c , f o r exam ple, which i s l i k e l y to be f a i r l y h ig h ly contam inated w ith l e a d , and which is l i k e l y to fin d I t s way in to food s t u f f s , I have n ever seen a case of lead poisoning from th is source b ut i t seems p ossib le th a t they * have o ccu rred h e re and t h e r e . Another p o te n tia l s o u rc e , of c o u rs e . Is in drinking w ater which in c e r ta in p a rts of the cou n try is handled through pipe system s which contain con sid erab le q u a n titie s of lead pipe* | I do not mean to go i n to any d i s s e r t a t i o n on th is s u b j e c t , b u t I do wish to p o in t out th a t th ere is a lread y a co n sid erab le amount of inform ation from which to a r r i v e a t c e r ta in te n ta tiv e con clu sion s* I t w ill be n e c e s s a r y , t h e r e f o r e , f p r you to 3 e t up a program f o r the study of p a tie n ts who have more than a h y p o th e tic a l le a d e x p o su re , I should he very g la d to know what you have in mind and to co o p e ra te w ith ybu i f i t seems f e a s i b l e . As to the in flu e n c e of the a d m in is tra tio n of " b a s i c m in e r a ls ", I am a f r a id you a re w alking In to a v e ry la r g e problem* M in eral m etabolism In gen eral has n ot been very adequately studied* This is a p e r f e c t l y enormous problem and a t the moment I see no nay of attack in g i t without very elab orate preparation fo r a prolonged and e x te n s iv e .s tu d y , I should be I n te r e s te d in knowing what you h ave In mind in th is c o n n e c tio n , I do n o t b e lie v e any exp erim en tal, work would answer the many q u estio n s th a t II unanswered in th is f ie ld w ithout a comprehensive study of the to t a l metabolism of these su b stan ces. Referring again to the question of jlead and d e a fn e s s , I may say th a t I f you have c a s e s of d eafn ess in which you s u s p e c t lead poison ing as an e t i o l o g l c f a c t o r , we should be glad to stu d y th e lead co n te n t o f th e b lo o d , the u rin e and the s p in a l f lu id in ord er to s e e w hether there are evidences of abnorm ality with resp ect to th e ir lead c o n te n t. We could do th is only In a lim ite d number of c a s e s and! we would wish to have com plete c l i n i c a l d a ta on th e c a s e s 3 fo r a l l such d ata Is of use to us in connection with our general s tu d ie s in th is f i e l d * I f we were t o do th is * i t would be n e ce s sa ry f o r us to supply you w ith con tain ers prepared in the lab o rato ry fo r the purpose of c o l l e c t i n g th e sam ples* and i t would be f u r t h e r n e c e s s a ry fo r the samples to be c o lle c te d in accordance w ith our p re c is e i n s t r u c t i o n s . I hope I may h e a r from you f u r t h e r as to your ideas in connection w ith th is work* .. Very tru ly yours* RAK i s R o b e rt"a V Kehoe* fcCJS*