Document 1gzOxBBxm7GqNR5dmY0O244e5

F eb ru ary 8* 1938 D r, Sonne fci B lack fan C hildren*s H ospital 300 longwood Avenue Boston* Mass, Dear. Doctor? Blacfcfan?-* In accordance w ith the r e q u e s t in your l e t t e r o f F e b ru a ry 2nd* I am se n d in g you two papers from, th e la b o ra to ry * one of which g iv e s th e d e t a i l s of our d ith tz o n e method, and the o th e r g iv es a r a t h f d e t a i l e d ecsnparisan o f th e d lfch iso n e and th e spec* tr o g r a p h ic m ethods*' You w i l l n o te from th e l a t t e r p ap er t h a t th e r e s u l t s o b ta in e d from th e two m ethods a re sub* s t a n t i a l i y the same* l a f a c t the accu racy of th e method of an a ly sis, is c o n sid erab ly more than th e accuracy of our phys i o l o g l c a l . i n t e r p r e t a t i on of th e r e s u l t s , T h is* I believe* w ill serve to answer your question as to whether th e u se o f th e d ith i s o n e method has m o d ifie d my o p in io n as to th e norm al blood le v e ls * The f i g u r e s w hich I gave' you In my l e t t e r o f l a s t June are* th e r e f o r e * s u b s t a n t i a l l y c o r r e c t* I may say t h a t in sane r e c e n t d a t a on two e x p e r i m ental su b je c ts follow ed over a p erio d of months under la b o ra to ry c o n d itio n s* th e mean r e s u l t in th e blood was 0*032 mgs, p er 100 grams of blood* w ith v a r ia tio n s ex ten d in g from:: 0 * 01''t.;0:#ot*. h is * I b e lie v e * : f a i r l y ..re p re s e n ts th e normal range of v a lu e s. Perhaps I should poio.t out to you* however* th a t i t is e a s ie r to re c o g n ise abnormal fin d in g s in the u r in e than i t is in th e blood* F or example* we have r e c e n t l y s tu d ie d s e v e r a l groups of workmen in le a d tra d e s In which th e le a d exposure was r e l a t i v e l y s ita ll* These groups could r e a d ily be d if f e r e n tia te d from each other on-the b a s is of the u rin a ry fin d in g s* b u t one did n o t fin d a s ig n if ic a n t s t a t i s t i c a l d iffe re n c e in the groups on the b a s i s o f t h e i r mean b lo o d l e v e l s . To be s t i l l more s p e c if ic * an unexpoaed group had a mean blood le a d le v e l of 0*038 mgs. p er 100 grams o f blood and a u r in a r y l e v e l o f ab o u t 00l|. m gs. per l i t e r . A very' s lig h tly exposed group had a corresponding blood le a d l e v e l o f O.Ol^ and a c o rre sp o n d in g u r i n a r y l e v e l of 0. 08. The d if f e r e n c e s in th e u r in a r y v a lu e s were s t a t i s t i c a l l y s ig n ific a n t w hile the d iffe re n c e s between the blood le v e ls were no t s t a t i s t i c a l l y s i g n i f i c a n t * ' and' th e re fo r e p ro v id ed no b a s i s f o r d i f f e r e n t i a t i o n . As a m a tte r of f a c t , we have found uniform ly th a t where u rin e samples can be c o lle c te d in such a way as to avoid any p o ssib le c o n ta m in a tio n , they 2> are more u s e fu l f o r d ia g n o s tic purposes than any o th e r type of b io lo g ic m aterial* I have always f e l t I t necessary to be cautious in the acceptance of the d iag n o stic sig n ifican ce of any av jaly tlcal r e s u lts of a b o rd e rlin e type* Thus, I f the blood fin d in g s are in excess of a te n th of a m illigram per ICO grams of blood* one can be f a i r l y su re o f s i g n i f i c a n t e x p o s u re . By th e same to k e n , I f u r in a r y r e s u l t s a re c o r r e s p o n d in g ly h ig h , th e i n t e r p r e t a t i o n i s n o t d i f f i c u l t . My only p o in t Is th a t the u rin a ry r e s u lt s in a given case are more l i k e l y to be d e f i n i t e l y abnoratal than a re the blood fin d in g s I am n o t q u ite c e r t a i n as to th e p h y s io lo g ic I n t e r p r e t a t i o n o f th is f a c t, b u t th a t I t is a f a c t is w ith o u t doubt* I p e rso n a lly lik e to have both blood sam ples and u rin e samples f o r a n a ly sis In most e a s e s , and in come in s t a n c e s , e s p e c i a l l y th o se w ith r e c e n t e x p o s u re , I l i k e t o h ave f e c a l sam ples a ls o * The l a t t e r a r e , of c o u rse , th e l e a s t u s e fu l In m o st'c a se s sin c e i t is v ery d if f ic u lt to In te rp re t the r e s u lts of a sin g le fe c a l an aly sis on acco u n t of th e ex trem e v a r i a b i l i t y of th e le a d c o n te n t o f th e food m a te r ia l* In th e c a se of c h i l d r e n , how ever, on s e v e r a l occasions a d ia g n o sis h as been made p o ssib le by the d isc o v ery of p a in t-c o v e r rd fragm ents of wooden o b je c ts in the sto o l* In c id e n ta lly , b efo re concluding,- I should p o in t out th a t In our experience, th ere is very l i t t l e d iffe re n ce in the r a te of lead ex cretio n of children as .compared to a d u lts , w hether under normal co n d itio n s o r under c o n d itio n s o f le a d ex p o su re* I am n o t p re p a re d to say t h a t t h i s i s always th e c a s e , b u t so f a r we a r e n o t j u s t i f i e d in d if f e r e n tia tin g ch ild ren from ad u lts w ith re sp e c t to ra te -of le a d e x c re tio n * ' : Sincerely yours, , RAIijis ` R o b e rt "XT"'Kehoe,''M".'Q. KH 0020008