Document v6NVBw7yMeXQpm92gBBMzOVKm

October 21 1938 Mr. Howard W* Ambruster W estfield New J e r se y , Dear Mr, Arabrusterj- This laboratory has not been d ir e c tly concerned with the study o f the problem o f spray r e s id u e s and con seq u en tly we have n ot p u b lish ed any a r t i c l e s which d ea l p rim a rily w ith t h is problem, I can not th e refo re send you any work on t h is q uestion* On the oth er hand I sun very glad to ex p ress ray own p o in t of view concerning t h is problem. Moreover during the p ast year and a h a lf I have been ca rry in g out some o b ser v a tio n s bn human s u b je c ts which w i l l serve to determine the fa te o f certa in sm all q u a n tities o f lead in g ested d a ily , I began t h i s work fo r the reason th at some ra th er e x te n s iv e o b ser v a tio n s in in d u stry lea d me to conclude th a t up to a c e r ta in p o in t o f le a d exposure the lead absorbed could be disposed of adequately by the normal human body. B riefly to sta te the situ a tio n as I see it our exp erien ce in in d u stry lea d s us to be f a ir ly c e r ta in that i f the lead con ten t o f the atmosphere breathed by workmen does not ex ceed 1 to 1 -1 /2 m illigram s per 10 cu b ic meters o f a ir , cases of lead poisoning do not occur, 2he exposure under th ese con d itions is such th a t one has resson to b e lie v e th a t t h e s e in d iv id u a ls may absorb in to the body as much a s 0*5 to 1 ,0 m illig ra m s d a i l y . I f , under th e s e c o n d itio n s , men are n ot p o ison ed . I t must he because the body is able to handle q u a n titie s of lead of th is order of magnitude. In view o f the fa c t that In d u stria l exposures are almost wholly resp iratory in o r ig in , th ese f a c t s do not perm it us to draw fa r reach in g b on clu sio n s w ith r e la t io n to the sw allow ing o f le a d . However we have seen over a period o f years th a t the average American ta k es in to h is body in h is food approxim ately 0*25 m illigram s o f lea d d a i l y , (lihe q u a n tity v a r ie s from tr a c e s up to some th in g more than a m illig ra m a day, b ut the mean v a lu e i s q u ite s t a b le up to a q uarter o f a m illig ra m per d a y ,) Lead pois'onlng def5.nlte ly does not occur under these conditions* Studies o f n o m a l in d iv id u a ls have shown q u ite c o n c lu s iv e ly th a t poisoning does not occur because there i s no p rogressive accumulation o f lead to any s ig n if ic a n t ex ten t w ithin the body, biiat is to sa y , .the lead output is eq u ivalen t to the lead intake over long periods of tim e, so that the 2 concentration of lead w ithin the tissu e s doss not m aterially Increase a fte r as equilibrium has been eistabllshed. , From in d ir e c t o b serv a tio n s I became convinced th a t the lead in ta k e of the normal human body could be in cr ea se d s e v e r a l tim es w ithou t danger of lead poisoning. I * therefore* began feed in g experimental subjects d e fin ite q u a n tities of lead w hile fo llo w in g c a r e fu lly t h e ir t o t a l lead in tak e and t h e ir t o t a l lead o u tp u t. As I a n tic ip a te d * th ere was an i n i t i a l com paratively sh ort period during which lead accumulated in the bodies of these su b jects rather r a p id ly . The rafco of lea d output in crea sed s t e a d ily , however* u n t il a t a c e r ta in p o in t output again became e q u iv a le n t to in ta k e . These experim ents are not com p le te d and they have n ot been p u b lish ed , but i am q u ite sure they are of g r-a t importance in connection with the problem o f the hazard o f spray r e s id u e s . I am d isp osed to b e lie v e th a t at th e p resen t time th ere i s no very g r e a t danger to the community in con n ection w ith sp ray r e s id u e s , I am fir m ly convinced th a t the a c t i v i t i e s of the Pure Food and Drugs Bureau should be m aintained and th a t every e f f o r t should be made to se e th a t fo o d s tu ffs - in general are kept w ithin the lim its s e t by the S ecreta ry of A gricu ltu re* I am n ot w h olly convinced that the the lead action of tolerance the to 0S.0e2c5r e tary grain in s re per c e n tly pound r a isin g was a . w ise move. On the o th er hand I do n o t view t h is change w ith any alarm , and I do not a n tic ip a te any d i f f i c u l t i e s as a consequence of t h is new regim e, moreover 'with the exp erim en tal work which i s now going on in t h is f i e l d , I think we s h a ll probably have a s e n s ib le answer w ith in a reasonably sh ort period of time as to what the toleran ce should b e. P re v io u sly we have had e it h e r no inform ation or inadequate inform ation o f a p h y s io lo g ic type on which to base these to lera n ces. I think every e ffo r t should be made to c a r e fu lly study the problem and to a r r iv e a t some c o n c lu s io n s . I t i s my very d e f i n i t e op inion th a t there has been much too much t a lk on both s id e s o f t h is q u estion and much too l i t t l e exp erim en tal work. For t h is reason I do not b e lie v e th ere i s very much p o in t in fu r th e r d is cu ssion of the problem u n t il there has been a great deal of enlightened experimental work. Very tru ly yours, R 'K*i s Robert A* Kshoe* i.I.D.