Document DMGq360M72RNzv9dkaRKmXgEQ

3vm 15, 1937 r.Ken n eth D. Blaekfan arvar d Medical Sch ool Ch ildren (s H ospital 300 Longwood Avenue Boston Maas* Bear Doctor Black fan 1 I have a t presen t a con siderable mass of d at a which h ave been accum ulatin g over a period of a year or more and which I am now ready t o work u p* When I have completed the study of th ese data I sh all be able to answer th e qu estion in your l e t t e r o f June 7th more accu r at ely than X can do offh and As t o the le ad con cen tration s in th e blood o f normal p er son s and in person s exposed t o lead X am surfe sh a ll be ab le t o giv e you very s a t i s fa c t o r y figu r e s X am n ot q u it e so o e r t ain in the c ase of the sp in a l fl u id fo r we have n ot st u d ied enough e it h e r normals or exposed to be q u it e su re of th e range of v a r ia h ility The blood le v e ls of normal person a ran ge from 01 t o *05 m illigm m s per 100 gr cas o f blood The mean i s somewhere between *02 and *033 (Some time ago we pu blish ed figu r e s sl ig h t l y h igh er than t h ese but sin ce we h ave been st u d yin g sam ples obtain ed on ly by ou r selves and an alysed in a lab or at or y which i s fr e e o f o u t sid e atm osph eric a i r we have found th e figu r e s t o be sl i g h t l y low er} We have a la r ge enough se r ie s o f r e su lt s h ere th at any slig h t e r r o r s in an a ly sis can cel each ot h er so t h at th ere can be no qu estion as t o the aocuraoy o f th ese r e su l t s* During th e p ast 6 months we have been doin g an aly ses on blood by two methods oper at in g in p a r a lle l th e one our Spectrograph lo Method as d escr ib ed by Cholakand th e oth er * m od ificat ion o f th e Dith lson e Method as o r ig in a lly d escr ib ed by Fisch e r and Leopoldl* We have seen lead in the b lood in v ar io u s types o f plumbism In con cen t r t Ions exten din g from sl ig h t l y in excess o f a m illigr am per 100 grams of ^ blood down to one ten th o f a m illigram per 100 grama o f n ^ <-, r? b lood * In ge n e r al two fa c t o r s appear t o determ in e thn- il u 4 4 / h eigh t of the le ad con cen tration } one the se v e r it y of exposu re} and two th e time in t e r v a l between the c e ssa t io n of exposure and th e t ak in g o f the blood sample Gen er ally, th e se v e r it y of th e symptoms c o r r e lat e with th e h eigh t of the lead con cen tration , hut t h is Is not always tru e* I th in k i t I s q u it e sa fe t o say t h at th e presen ce of one ten th of a m illigram of lead per 100 grams o f h lood la In d icat ive of a r ecen t sig n ific a n t exposure t o lead and alth ough symptoms may not be pr esen t a t t h is con cen t r at ion , th e e xist en ce of symptoms resem blin g th ose of plumbism may be adequ ately explain ed I sh ould be In clin ed at presen t to r egar d valu es un der one ten th of a m illigr am of blood as slgn lflo a n t on ly I f repeated ob ser vation s confirm t h is as the b asic le v e l of le ad con cen tration r ath er than a chance h igh valu e, The le ad valu es in th e sp in a l flu id ar e much low er. From our pr esen t data which ar e In complete X am d isp osed to r egar d valu es in excess of 01 m illigr am s per 100 co o f sp in al flu id as d ou b t fu lly Sign ific a n t ) valu es In excess of 02 m illigr am s per 100 co of sp in al fl u i d as alm ost c e r t a in ly sig n ific a n t ) and valu es above ,02 as d e fin it e ly In d icative of recen t sig n ific a n t le ad exposu r e* X b e lie v e when we have si ft e d the t h in g as c a r e fu lly In the case of sp in a l!flu id as we have in the case o f blood we sh a ll probably fin d the normal , valu es to ran ge between 001 and *01 m illigr am s per 100 cc. In acu t e le ad coses we h ave found valu e a s h igh a s 1 ' m illigram s per 100 cc* X b elieve without r e fer r in g a t . t h is time to, my r ecor d s t h at t h is occurred in only one case in which th e d iagn o sis was a t no time a m atter of con jecture Th is w ill r equ ir e con fir m ation th rough observation s on sim ila r oases sin ce you w ill r e a liz e X am su r e th at th ere ar e numerous o p p o r t u n it ies fo r s l i g h t con tam in ation , p a r t ic u la r ly a t th e b e d sid e * 4s a m att er o f fa c t we stake i t is p oin t a t p r esen t n ot t o make an aly ses o f sp in a l flu id or o f blood e it h e r u n le ss the sam ples ar e c o lle c t e d by means.o f ou r own n eedles, In t o our own con t ain er s and by a tech n ique which we d e scr ib e in d e t a i l * The u se of th e ordin ary h o sp it a l sp in al flu id : n eedle i s alm ost c e r t a in t o r e su lt In contamina t ion slnCo the con st r u ct ion o f th e n eedle Is such, th at the flu id may come l a oon taet with lc&dVbearing m at e r ial* X t r u st t h is w ill give you th e form ation you r e q u ir e and X sh a ll be p leased t o give su any a d d it io n al in form ation a s a refin emen t of t h i s in I h ave com pleted th e study of our d a t a . . Cor d ially yours RAKiis Robert "A# kekoe~^H.D* P* C