Document zb0EXDjDLobjeemBgeRkRNG70

6 90 W EST 6 5 T STREET CH I CAGO Fe b r u ar y 12, 19^2 Dr . Rober t Ke h o e n a t t e r in g La b o r a t o r y 'Uni'/ , o f Ci n c i n n a t i C i n c i n n a t i , On t o De a r Dr . Ke h o e : *- Thank you v e r y much fo r yo u r l e t t e r o f Fe b r u a r y y w n ich i s m ost r e a s s u r i n g s i n c e we \ ;oulvl n e ve r co n s id e r a package o f tooth p a ste in which lend con t a m in a t io n wer e 200 p .p -.m . o r m or e . It is of cour se p o ssib le t h a t such lead as is con t a in e d m ight r ea son ab ly be con ce n tr ate d a t the s u r fa ce so t h a t a ft e r a la r ge number o f le a d -fr e e b r u s h in g s , one b r u s h in g m igh t c o n t a in a s much as 1 m illigr am o f le a d . I t is a lso con ce iva b le t n a t t n is la s t br ushing con t a in in g 1 m illigr a m o f le a d m ight be swallowed in i t s e n t ir e t y or t h a t s u c h a cla im m ight be made. In t h i s l i g h t we h a ve a t fr e q u e n t i n t e r v a l s h e a r d s t o r i e s o f c h i l d r e n who h a ve s w a llo w e d an e n t i r e tube of tooth paste. You h a ve c i t e d a s a t y p i c a l c a s e t h e p o s s i b i l i t y o f a d a i l y a b s o r p t i o n o f 0.01+ m i ll i g r a m s o f -le a d fr o m t o o t h p a s t e . Le t us suppose t h a t due t o ir r e gu la r it y o f d is t r ib u t io n o f the le a d , no lead were a b s o r b e d f o r 29 d a ys o u t o f t h e m on t h , b u t t h a t on t h e 30t h d a y t h e f u l l 1 .2 m i l l i g r a m s w er e a b s o r b e d . Would t h i s a l t e r t h e p i c t u r e w i t h r e s p e c t t o p o t e n t i a l danger? Re p h r a s in g t h e q u e s t i o n w ou ld c l a r i f y my t h o u g h t i f p o s s i b le . I f t n e a ccu m u lat e d a b s o r p t io n o f 1 .2 ir .ill i gr am s o f le a d o v e r 30 d a ys i s t o l e r a b l e , w ou ld i t s t i l l be t o le r a b le i f t h is ab sor p tio n were concen t r a t e d i n t o on e d a y o u t o f t h e 30 w it h o u t i n c r e a s i n g t h e t o t a l a b s o r p t io n o v e r t h e J>0 d a y p e r io d ? Technical Dir e cto r Tiiii