Document Rab3dOGx0derdYxgN2Y5ojLXk

Ju n e Ik, 1939 Dr. E lsto n L. Belknap 231 V/. W isconsin Avenue Milwaukee, W isconsin Dear D octor Belknapi I b e lie v e th e f ig u r e s Which y o u 'h a v e q u o te d , g iv in g th e l i m i t s o f .OS to 1 mgs. p e r 24 hours o f u rin ary ex cretio n a re our fig u re s and were probably talien from our a r t i c l e in th e Jo u rn al o f I n d u s t r i a l H ygiene f o r Septem ber 1933* On th e o th e r hand you a re q u i t e r i g h t in sa y in g t h a t we r e f e r to th e u rin a ry lead ex cretio n in term s o f co n cen tratio n f o r th e moot p a r t . In some o f o u r w ork,w here th e o p p o r t u n i t y h a s p r e s e n te d i t s e l f , we have d e te rm in e d th e r e s u lts b o th on a tw en ty -fo u r hour b a s is and'on th e c o n c e n tr a tio n b a s is * You w i l l f in d such f ig u r e s , r e f e r r e d to in t h e g re e n book w hich I s e n t you on "I-loiuai A b so rp tio n and E xcretion of Lead" rep rin ted 'fro m the Jo u rn al o f the American M ed ical A s s o c ia tio n - Volume IQ**- - P ag es 9 0 -9 2 , ( a c t u a l l y pa^e 3 o f th e r e p r i n t in th e b o o k ). 3-onera l l y speaking, however, i t I s not p o ssib le in in d u stry to ob tain tw e n ty -f o u r h o u r sam p les o f u r in e in th e Case o f men who are working. I t i s our p ra c tic e not to c o lle c t such . sam ples in th e p la n t b u t to o b ta in them a t th e men*a homes where th e o p p o rtu n itie s f o r co n tam in atio n arepresu m ab ly c o n s id e r a b ly l e s s . In t h i s ty p e o f work we o b ta in from two and a h a l f to fo u r l i t e r s * o f u r in e , c o l l e c t e d w ith o u t r e s p e c t t o tim e , and we e x p r e s s th e re s u lts in term s of m illigram s p er liter.*.- I t has been w e ll e s ta b lis h e d by our work th a t th e u rin a ry le a d con c e n tra tio n v a rie s w ith the magnitude o f th e exposure, but th a t I t a lso v aries w ith the w ater output p e riu n it tim e. Our purpose in o b ta in in g la rg e sam ples is to iron out th e l a tte r v a ria tio n s and to o b tain a re s u lt in term s o f co n cen tratio n which w ill express th e gen eral le a d co n ten t o f th e body o f the in d iv id u a l In a compara t iv e way. The le a d o u tp u t p e r day depends a ls o upon th e w a te r e x c r e te d p e r day and we have shown t h a t w here th e in tak e is h ig h , the le ad ex cretio n is Increased; and where i t la lo**, th e r e i s a c o rre sp o n d in g ly low le a d o u tp u t. F or t h i s r e a s o n , i t i s q u ite a p p a re n t th a t. some c a re m ust be u se d in e x p re s sin g th e r e s u l t s e i t h e r on a c o n c e n tr a tio n o r on a tim e b a s i s . What we have a t tem pted to do i s to show th e ran g e o f v a lu e s which o ccu r in normal in d iv id u a ls by e i th e r method o f e x p re ssio n . I t i s , th e re fo re , a very good 2 as to w hether th e r e s u lts in a given case are expressed on a c o n c e n tra tio n b a s is o r on a tim e b a s is . However, sin c e, as I sta te d above, i t is freq u en tly im possible to o b ta in th e r e s u l t s on a tim e b a s is , i t i s more p r a c tic a b le and more u s e fu l to ex p ress them on a concen tr a ti o n b a s is . In making use o f t h i s l a t t e r form o f e x p re ssio n , however, i t must be remembered th a t the sm aller th e sample o b ta in e d , th e la rg e r is th e range of v ariab ility of resu lts. ~ I tr u s t th e above answers your q u e s tio n b u t i f i t does n o t, p le a s e do n o t h e s ita t e to w rite ae fu rth er, "' 1 . The p a p e r w hich I p re s e n te d In C leveland w ill n o t be p u b lish ed in th e form in which I gave i t . However i t w i l l be p u b lish ed in th e n o t too d is ta n t fu tu re In another form , and I s h a ll be pleased to sen d you r e p r i n t s when th e y a r e a v a i l a b l e . What 1 a tte m p te d to dd was to show th e range o f norm al v a lu es fo r the blood, the u rin e and th e tis s u e s , and also to show in term s o f blood le v e l s and u r in a r y e x c re to ry le v e ls th e p o in t o f -d is tin c tio n between hazardous and n o n -h azard o u s le a d e x p o s u re . We have now- s tu d ie d a s u f f ic ie n t number o f in d u s trie s by both c lin ic a l and a n a l y t i c a l m ethods so t h a t we a r e a b le to e x p re s s th e th resh o ld o f hazard in terms o f these d a ta . C ordially yours, PAKiis Robert A. Kehpe, M.D. 0019862