Document 5L8Mpawo66ggLQQMzDkJZKmJR

Jtu 15# 193? D r.K ennehh D* Bl&ckfan H arvard Medical School C hildren*s H ospital 500 Longwood AvenUe B osto n , Mass* y . Dear D octor BlAekfan* r I have a t present a considerable mass of d a ta which have been accum ulating over a p eriod of a y e a r o r m ore, and w hich I am non read y t o work up*. When I have completed th e stu d y of th ese d a ta , I sh a ll be able to answer th e qu estio n In your l e t t e r o f June 7 ^ .wore a c c u ra te ly than I can do offhand* As to th e le a d c o n c e n tr a tio n s in the blood o f normal p erso n s, and in persons exposed to l e a d , I am su re I s h a l l b e a b le t o g iv e you v ery s a t i s f a c t o r y f ig u r e s * X am n o t quit so c e r t a i n in th e c a s e of th e s p in a l f l u i d f o r 0. .have- n o t s tu d ie d enough e i t h e r normals or exposed to be q u ite sure of th e range of v a ria b ility * The b lo o d l e v e l s o f norm al persons range from *01 to * 05 m illig ia m s per 100 gr?ms of blood* The mean is somewhere betw een *02 and *055# ( Soa tim e ago we p u b lis h e d f i g u r e s s l i g h t l y h ig h e r th a n t h e s e , b u t s in c e we h a v e been s tu d y in g sam ples o b ta in e d only by ourselves and analysed in a la b o ra to ry which Is fre e of ou tsid e atm ospheric a i r , ue have found the fig u res t o be s l i g h t l y lo w er* ) W have a la r g e enough s e r i e s o f re s u lts here th a t any s lig h t erro rs in an aly sis cancel each o th e r, so th a t th e re can be no question as to the a c c u ra c y o f th e s e r e s u l t s * D uring th e p a s t 6 m o n th s, w have been doing a n a ly se s on blood b y two methods o p e ra tin g in p a r a l l e l , th e one our Spectrograph! Method as d e sc rib e d by C holak,and th e o th e r a m o d ific a tio n o f th e D ith izo n e Method as o rig in a lly described by P isoher and Leopold!. We have s e e n le a d in th e b lo o d in v a r io u s ty p e s o f plumb ism In c o n c e n tra tio n s e x te n d in g from s li g h tly In excess o f a m illig ram p er 100 grams of b lo o d down to one t e n t h o f a m illig ra m p e r 100 grams of bloo d * Xn g e n e r a l , two f a c t o r s ' a p p e a r t o d e te rm in e the height of the le a d concentration} one, the s e v e rity of exposure} and two, the tim e in te rv a l between the -cessatio n of exposure and th e ta k in g o f th e blood sample* G en erally , KS 0020095 2- th s e v e r ity o f th e symptoms c o r r e la te w ith th e h e ig h t of the le a d eonee n tr a "Ion* h u t th is is s o t always true# I th in k i t is q u ite sa fe to say th a t th e presence of one ten th , of' a m illig ra m o f le a d p e r 100 grams o f b lo o d i s in d ic a tiv e of a recen t s ig n ific a n t exposure to lead# . and a lth o u g h symptoms may n o t be p r e s e n t a t t h i s c o n c e n tra tio n * th e e x is te n c e of symptoms re se m b lin g th o se o f plumbism may be adequately explained* X should be inclined* a t present* to regard, values under o n e,ten th of a m illigram of blood as s ig n ific a n t only if repeated observations confirm th is as the b asic le v e l of lead con cen tratio n ra th e r than a chance h ig h .value... .. " -1: . ' The le a d v a lu e s in th e s p i m i f l u i d a r e much low er* Prom o u r p r e s e n t d ata* w hich a r e Incom plete* I am d is p o s e d to r e g a r d v a lu e s in e x c e ss o f 01 m illig ram s per 100 oc of s p in a l f lu id as d o u b tfu lly s i g n i f i c a n t i v a lu e s In ex cess o f *02 m illig ra m s p e r 100 cc of sp in a l f lu id as alm ost c e rta in ly s ig n ific a n ti and v a lu e s above *03 a s d e f i n i t e l y i n d i c a t i v e o f r e c e n t s i g n i f i c a n t le a d e x p o s u re . I b e l ie v e when we have s i f t e d th e th in g as c a r e f u l l y in th e c a se o f s p in a l., f l u i d a s we have i n th e c a s e o f blo o d * we s h a l l p ro b a b ly f in d th e no u s a i v a lu e s to ran g e betw een *001 and *01 m illig ra m s p er 100 cc* I n a c u te le a d c a s e s , we h a v e found v a lu e s a s h ig h as .1 m illigram s per 100 cc* I believ e* w ithout re fe rrin g a t t h i s tim e t o my re c o rd s* t h a t t h i s o c c u rre d in o n ly one case in which th e d ia g n o s is was a t no tim e a m a tte r of c o n je c tu re * T his w ill re q u ire c o n firm a tio n through o b se rv a tio n s on s im ila r oases* s in c e you w i l l r e a l iz e * I am s u r e * t h a t th e re a r e numerous o p p o rtu n itie s f o r s l i g h t contam ination* p a r tic u la r ly a t th b e d s id e * As a m a tte r o f f a c t* w mali i t a p o in t a t p re s e n t n o t to make a n a ly se s o f s p in a l f lu id * o r o f blood e ith e r * u n le s s th e sam ples ar c o lle c te d by means of our own n e e d le s* i n t o o u r own c o n ta in e rs * and by a te c h n iq u e w hich we d e s c r ib e in d e t a i l . The us o f th e q r d in a r y h o s p i t a l s p i h a l f l u i d n e e d le 1i s alm o st c e r t a i n t o r e s u l t in con tam ina tio n since the co n stru ctio n of the needle is such th at the f l u i d may come in c o n t a c t w ith le a d - b e a r in g m a te r ia l* . X t r u s t th is w ill g iv e you the info rm atio n you req u ire * and I s h a ll be p leased to g iv e you eny a d d i t i o n a l i n f o rm ati on a s a re fin e m e n t o f t h i s when I have co m pleted th e stu d y of our d a ta * . ` C ordially yours* ' RAKiis ' '. 'Robert..'A* Kehoe* M.D*