Document 85DZNbgD88OLEkedq2oYxxJ0d
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Laad Aboorrtlon Verona l.*ad P oioon ln r
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T'obcrt A, :>ho<t, H, "i*
Tr a n &h<* Cot t or in ?; h a b o r a t o r y o f An e lim i ih y fs i o lo r y In t h t o l l e r i ? f ' O l e i n e i f The tin ir c r a ity o f Cin e i n a s t i .
O eaptie th a v a ila b l : t t y o f gom d and v o l i
notrxbllsjbMBd methods f o r r*eo& siiti? and preventinr? ifUMistr-ou
otcapA^l-mal load eirposttre*
io a t l l l an im naoeaim rily
' ir'h in cid o n o ot le a d palaon^n^ e*?? in d u s t r ia i w orh ers.
Moreoxrer* d e e p ite th ostitono* o t sa n e r a i l y r e ila b i
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d i fra o a tie O ri to r io * a auspriainri: tiene o f cortfneion and
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xm eortA inty o r to e n to r in to th oonal:;OT*?,tion o f n m topeetea
oaao rf :d u b b ie vfteth er th q u e stio n n% tasu* ia Ih* proper
oaro o f a a io li :ian* th hyglflB lo ta to * i f e r lo n t* th r r n n t-
i a rr q * q
ion* or th
? l i t t a n t i<n# :'or thona
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r n aona orni ;vay. >>** l u a t i f io d in r e s t a t in e o e r t in f'-ch s vr !c.h
nona t o r^-qulr^enpfta ia * 'v.i a bna'irnro-,-nd fo r a E r e t i c a i
(lM ttia io o o f c s r t n in nth3ds o f ;--rooduro
th eir aiqniflonnoo
In in u a telA l hyrieoe# .
"hr C?har--otr and lig n ific a n o o f n-sr-rtl ? *"a .' >>-! >a:-..
I t vou ld sema oltont a p i a t i t i s i * H>y tn s t a t o ,
no *4 i*crre c r i t i c i s m i fo r doinf? in l'JH?* fchat *th* peeaenc*. a f
lim a in human s e c r e t a and bona tlo a u eo * no w e il - a in l i v i n g
argcniasa in general*. la nn i n w i t t b l consequence ->f l i f e on n le a d -b e a r in g p la n e t* , w ith ou t it in*? th e extm oive e v id e n c e I n s u p p o r t o f t h i s o t a t c w n t * t h e r e fo r e * t a t ust ~ v l v tne f a c t In ao f a r . ? tM y concern th e avcrare normcl h e a lth y Anar loon ad ult* Ho in v e s t* w ith h is fla tly fo o d and d rin k q u a n t it ie s o f l ^ d varying fro a 0*0*3 arjo.* r a r e ly * to eonewhAt room, than 3*0*> n#a* o c c a s io n a lly * the noon quantity over a period o f nonthe being approxirately
0.33 fa^ss* Ho take in t o h is body by In h a la tio n w ith th e a i r '
he breathe a assail and r e la t iv e ly in s t^ n tfle a n t q u an tity *
vhloh probably r a r e ly exceed. 0*10 sw-sa p#r 2^ hour* and o f
vhloh only a portion fismbtlesa a v a ria b le bat otherw ise un p r e d ic ta b le p o rtio n - * la r e ta in e d by th e r e s p ir a to r y Bumfertmee and ev e n tu a lly absorbed in to the tissu e * the remainder being e i t h e r erhA led o r trapped. In th e upper m n p lr a to r y t r a c t e.nd
/
su b seq u en tly wallowed* ( `The q u a n tity absorbed 1st m s n a il as
n ot to be oprren t In prolonged stu d io in whieh the t o t a l load ou tp ut la b&l&aood a g a in s t Ic e d in ta k e by in stvetlon only* Con oid a r i m; th e prarptne and th e mgriitude o f %imoratory resp o n se under oondlttcos- o f oooupatlnnal load absorption fron in h a letlo one any ooaolude th a t under averar.e nororxl co n d itio n s t h i s ty p e o f load absorption la indeed nintite*) L ittle in siste d lead i s . a c tu a lly absorbed in to the body* A very la r g e pro a r t ion o f i t tr a v e r s e `th e a h ia en tn ry t r a c t unabsorbed and. arpenre In the
f e c e s . Cone p o rtio n 1 absorbed and c a r r ie d t o the liv e r * ia
pidrtly excreted w ith the b ile bsck in to the allrsentory tract*
and i 3 soon l o s t f r o th e body w ith the face* The r e s u l t o f
t h e s e and p erh ap s o t h e r aven u es of, s e c r e t io n in t o th e
*< 7
. '
a lim en t a r y t r a c t is t o m ike' th e d a ily feo &l le a d ou tp u t o ld e s t
'
e q u iv a le n t t o t h e t o t a l. , In t&ke b y l o c a t i o n . l s em a il q u a n t it y
eac&pe# r or sova l by t h e l i v e r sa d 1 c a r r ie d In th e b lo v i fnora
wh ich I t la lo s t b o t h t o t h e ' tla-m ie# an a t o t h e e x c r e t io n s .
"o co n t o h so r TAt lo n s wool is t o show thr.t t h e b lo o d .1 in .
.
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e q u ilib r ia , w it h t h e t is s u e s ' o f t b s body- a s a
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with r esp eot
t o I t s lo a d co n t en t In a n y a&ae lostd 1 c o n s t a n t ly fou n d in t h e
b lo o d and in t h e `u r la e la c u o n t it i fiu b jo e t t o b u t m in or
v a r ia t io n ," ^ hua t h e whale b lood o f n ortsal h e a lt h y ^ wr lo&n a d u lt s
u s u a lly con es In s fiw r O , ! ' to ft, 05 sa p er Ihh gn u * w it h a
:ao*n va lu e o f a p p r o xim a t e ly 0 *0 3 nw* p e r in o prams* (Co n e e n t r n t io n s
a s h igh m 0 .0 7 is? p e r 10 0 grams a r e o c c a s io n a lly fou n d )* Va r y
l i t t l e .of t h i s i s In t h e p la s m * 95, p e r ce n t o r r o r e b e in g foun d
in th e s e lla * n aln ly# / preq^ ?sably0 in t h e e r yt h r o cyt e s . head is
fou n d n orrs.nll y in t h e u r in e in q u a n t it ie s va r y ire? fr o 0 ,0 1 nqn /
t o 0*011 agoi p e r l i t e r w it h a aan n va lu e a l l la s t ly In e xe e o s o f
0 *0 3 regc p e r l i t e r . The esaaa u r in a r y le n d aon cerr &r r.tlan a ? bo
.
s
,
a r e a t o n p p r oxlsi&te on e t e n t h o f t h a t' in t h e b lo o d ,
lord la
t h e t i s s u e s - *e *la t r ib u t o d in c o o e r ^ n c e w it h a d e f i n i t e }' it e m *
*7i t i i t h e m a jor p o r t io n in t h e s k e le t o n a n d 'w it h a 'H igh er con cen
t r a t io n In su ch lo n g bones n s th e f^ rrur, u t w it h a e n s u r t Ab le
an d f a i r l y co n st a n t q u a n t it ie s in th e o t h e r t is s u e s awmi? wh ich
th e liv e r * kid n ey* sp leen and b r a in ar e sp ecia lly n oteworth y*
The a ver a ge g r o s s q u a n t it y O f le a d p r e se n t in the bod y o f th e
n o r a a l h ym n a d u lt i s ocmrwlmt In d o u b t * b eca u se o f t h e s c a r c i t y
o f d a t a * h u t I t I s p r o b a b ly n ot lo a n th an 10 0 rag, n o r r-o^e th a n
t h r e e t o fo u r t i a e s t h i s q u a n t it y* w it h d u e r e ga r d to- v a r ia t io n #
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In body w eigh t. Barth b eliev ed h i# data on th e s k e le ta l lead content pointed to a p rogressive in crease In the consent ration with a g e , b u t th e d iff e r e n c e In youth and o ld age were to o a lig h t and too ir r e g u la r to be con vin cin g. Calvary has drawn th e unwarranted ooncluaion th a t Tonpaett* r e s u lt s on th e lea d co n c e n tr a tio n in v a r io u s p a rt# o f th e human s k e le to n (B ootland) dem onstrate a p r o g r e s s iv e accum ulation t h r o u ^ o u t human l i f e . There i s ad m itted ly a s t a t i s t i c a l l y s i g o lf lea n t degree o f p o sitiv e c o r r e la tio n between th e ages and the lead co n cen tra tio n s in th e faau r and th e t i b i a o f Toaspeett* o a ses Tnrt th e r e a re alm ost as la rg e v a r ia tio n s w ith in narrow age groups as can be found in
r e la t io n t o extrem es o f a g e , M oreover, Calvary* 11 assum ption
that the tis s u e s o f persons w ith sig n ifica n t occupational or in cid en tal lead exposure sh ortly before death has not been in
*
eluded in th e se a n a ly se s I s J u s t if ie d n e ith e r by Tompstta sta tem en ts nor h i s d a ta . One may p ro p erly s u s p e c t , t h e r e f o r e , that v a ria b le environm ental fa cto rs (d ieta ry and o th erw ise), w ith variab le individual lend in ta k e, serve b etter to explain d iffer en ce s between normal in d iv id u a ls w ith resp ect to th e lea d
. 's
content o f th e ir b o d ies, than can the v a r ia b ility in the duration o f an e s s e n t i a l l y common and c o n sta n t le a d in ta k e , The in d ir e c t evidence a gain st th e in d e fin ite ly p rogressive accum ulation of lead in th e tis s u e s o f parsons exposed to f a ir ly constant en viron m en tal c o n d itio n i s much t o o g r e a t to b e ig n o red .
I t has been demonstrated clea rly that the urinary lead ex c re tio n o f In d iv id u a ls and o f groups o f persons v a r ie s w ith th e magnitude o f t h e ir current lead absorption* and th at an abrupt change in the le v e l o f le a d latah e r e s u lt s In a ( 3 1 'do 10) f a i r l y prompt e x c r e to r y r e sp o n se , d ecen t o b se r v a tio n s show { B XI) th a t t h is resp o n se to a known and co n sta n t magnitude o f In creased lea d Intake i s not Immediately aaxia*.;* but th at i t gradually b u ild s up to a l e v e l which Is dependent p rim a rily upon th e q u a n tity o f lea d which has been absorbed and r e ta in e d In the body, w ithin the U n it s which have been stu d ied I t does not continue In d e fin ite ly to lnoreane but reaches a le v e l which Is m aintained so long m the lead intake remains at a constant le v e l* These f a c t s are In com plete harmony w ith th e in form ation
s
( iilid e 12 ) obtained, on groups o f workmen w ith p rolonged exposure to f a i r l y
co n sta n t and a p p a ren tly s a f e o c c u p a tio n a l c o n d itio n s . The u rin ary le a d e x c r e tio n of r e p r e s e n t a t iv e workmen c l e a r ly d e f in e s the magnitude o f the lea d exposure not only o f an Industry as a whole* but o f c h a r a c t e r is t ic and w e ll I s o la t e d o cc u p a tio n a l groups w ith in the Indu stry. Moreover* th e group le v e ls o f u rin ary load
(Jlid e 13) e x c r e tio n d<ewie4 in c r e a s e p r o g r e s s iv e ly b u t remain s u b s ta n tia l) 7
" lfc) con stan t over long periods o f time (years) durm g which l i t t l e or no change occurs in p la n t c o n d itio n s . Such o b se r v a tio n s combined w ith the fa c t s obtained in the study o f nlru?le In d iv id u el can hardly be exp lain ed exoept on the b a sis th a t the r a te o f urina lead excretion la determined c h ie fly by the gross lead content of the body as an organ ic w hole, and th a t the m aintenance o f a con sta o r n e a r ly co n sta n t r a t e e f u rin a ry le a d e x c r e tio n I s e v id e n c e o f im
e s s e n tia l" :/ co n sta n t q u a n tity o f 1or, . in th e body, There la adeguate f a c t u a l tmefcep'oand* th e r e fo r e fo r tri# con cept th a t w ith in c e r ta in U n i t e o f le a d intake* a Mtat^of dynorAe equilibrium la m aintain ed w ith in th e b-^aisn body whereby iem l Intake and output ar e bal anced over l eni ? per i oda of t l e# and pr or - pr esai v aeeusm1at ion in the tissu e does not occur.
ihe i&pdWic o f the co n sid era tio n s o u tlin ed in cose d e ta il in the foregoing paragraphs cannot he overemphasised in t h e ir r e la t io n to the problems o f n u b ile and in d u s tr ia l hygiene th a t a r ia e from th e uae o f lo a d ocirconda* ~*ince le a d la an I n e v ita b le c o n s titu e n t o f haaan tiea u eo and ex c re tio n s i y i e q u ite obvious th a t th ere are c e r ta in norsml and p h y s io lo g ic a l meoh/mlena in to vhioh t h is lesjent e n te r s whether in cid en t a l l y
*
or u s e f u lly * Thero orua be no doubt th a t le a d can be in trodu ced in to th e h nan ^ o & f/w ith o u t p reju d ic e to th e normal h e a lth and dov^-lo c u t o f the organs sa and t h a t ft t o x ic e f f e c t o n the p a rt o f t h i s Q lm m n t an w e ll a s o f an y-oth er la a n a tte r o f oon-- c e n t r a t i on* The d eg ree o f c o n tr o l o f ; ubi io and in d u s t r ia l lead
' . \ exposure which Is nsceaen ry to ovoid h s i n h&atard th-r~i'frr--, la n o t to be d e^ sea in ed on the h.nsia -.>t th e praurjnatto avoid ance o f t h e w orst e f f e c t s o f t h e ab sorp tion o f m t I n t r in s ic a lly ninonous element but on p ree lee inform ation ns to the lira!ta o f load ex oomire and ab sorp tion vM ch orq unattended by any to x lo nani fe e tat.ione* or which in o th e r verde ore p h y sio lo g ica l*
fhe ^ ld en co g ,.o f,.i^ < ^ p im a nal. head..AbsorptjUiu , The e t i e t e n o s o f o c c u p a tio n a l len d exposure
can u s u a lly be reco g n ised by a survey o f th e n e t c r i d s and m o tiv iti in an indue t r i a l p la n t , '`.'ll rrenm1 arder o f u agnituds
ot th
-f-.ir? orm ho oetirsetert by ih 4eteraInntioi o?* th
Xm& c o n t o n t ;>f t h a g n o o p t a r e o f vorkin ;-'- s p r e e a * b y t!\ u o f
n e t h o d * wh ioh iavo baors so v a l i d e s o r ib e d and r e no a n t le fa e t w r y
f a r t h i r :.m r p oae t fa n t s h a y a e e n o t b * r lv a n .oo*- t h a n p a n a lo *:
n e n t t o o h-ore* o a t an si: opim a! se t h fa c t t h a t Ziiron rh t h e lr
a d e gu a t o an d c a n s ia t e n t u n e* i t la p a -ibi t o d a n a r r in e t h
ddi^ peo :>f t h e o c u p a t lo n - a l it a .s*r d an d t h o t t o n i: .*? t h n or d f a r
p r e ve n t ive ami p r co a u tto n a r y Bea eu ra o, Sadeed l i th lu n d con ten ti
o ? t h a t m e p h c r e o f tforkaroon in t h Xead t m d e ii fr e n e r a i l y ver
a a in te. Ine! v it h n . t h 1 l o t t a now ~ of*nle c s enf* in fo n e t i c o *
o o c t m t ia n .n l a t t o r n io , fr e s i s a ? o t h ^ r tlv an h o e t e n t e *.n l a n t
o p e r e t t e *, vm ild ceno t o ooou r * H oafever, so lon rr a t h
' a s a r e o f n a n y p i a n t a a r e 'n o* o n d a r a e h c o n t r o l , an d ao lon f?
a# o p r ja r t u n t t le f a r a c c i d e n t e ! a n d L n a d yo r t e n t l o r d Tpoap.sr
o x l a t in in h n n t r r * I t v i l i b n eoe-sear*? i o t r a via r e d i g e !
rm-'^r-rvln V>n . h ich i l i ho on th Alarti fa r fh a a r llp a t alane
a f a t e n t i a i ;; tlanpora.*3 lo s -a n b a o r p t i > n . / ;r.h p h yn lo l a r i c e !
/ l.*cn co o -`f Xe n i Ab n e r a t i a > -*-ove t h a o r n a ! l e v a i n h m r . h e
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* y o io*
fcaat aueh evidencea do not n eoesaarily alim i fy o s is i Inrj or
>i;>erhUnrr la n ci i n t o r i s e t i o n , !end a b a o r p t io n io n o t n yn on an otto w i t
la n d o le o n in a * Xho a b e o r p t lo n arici e x e r e t i o n o f p u a n t .it tee o f
c o n a lle r & it ly in eroeaa o f t h noti.! an d b o r a s i I n v e la la v h o lly
oon patibl v i t h n on !
h a o i t h y h :o ji U f o ait. A C t i v l t y * a n d i f
o e r t n ln U n i t a e r o n o t oacoeeded* no in t o v ie n t lo n In t a he o n t le i*
. iitod*
I
e a r lie s t sig n of elev a ted lead ahfflorpion, and on v h ich fo r tu n a te ly , l e o p a c ifie fo r land a lo n e , le found lu an In crea sed r a ts o f u rin a ry le a d ex c r e tio n * The deaonefcrat ion o f a n m ll loorM-JS req u ire* cars f ill procedures for the c o lle c tio n ' o f onjsplee and Km d e t a ile d knowledge o f th e p h y s io lo g ic a l fa c to r coiiQcrnsd w ith the urinary exorct ion o f lead Various pub lish ed tatasicBV s lmv* .q eared to th e e f f e c t tmtjth u rin a ry le a d f a i l * frequently to reveal the extent of lend absorption, that the
r s u lt a o b ta in ed 0 u rin e staples- are too v a r ia b le and th a t th e
b lo o d , "ore c o n sta n t aa t o i t # le a d c o n te n t, should be used f o r ob tain in g a n a ly tic a l information* These conclusions here sprung " fro.o lnexpe-rlacto* or frets the u se o f inadequate method* fo r th e c o l l e c t i o n and g fin ly si* o f aarsulea* I t la tr u e th a t u rin ary cample o f m &li valuta* obtij Inod a t random a re s u b je c t to co n n i.lern b l* v a ria tio n in th e ir lend con ten t. In In dividu al ens4# tbb la t t e r v a ries c h ie fly v lth the v o ter output o f the period o f t&eir c o l l e c t ! o n , l * e . I f th e u rin e i* co n cen tra ted th e le a d cone!'* ' t m t lo n 1# r e l a t i v e l y h ig h , i f d i l u t e from hl^h w ater iota be or d iu r e s is th e le a d co n cen tra tio n la r e la t iv e ly low* T his fa c to r can bo enntraj.^pd - in th e oaae o f o a a ll volum e*, by p~o~^r aela d tio ? o f th * t la * o f sam pling ao o s 'to a void e s tr o n e s o f u w ter in to it* . and ou tp u t i I t can be e lim in a te d aXtc& ether by o o lV o tta fs s e v e r a l l i t e r * o f u r in e , atla** cu re t h a t no umtteual u s tI t i c e o f liq u i d a re taken to speed up the c o l le c t io n o f tas srselo* "cual y ir p o rta n t I s th avoidance o f con ta m in a tio n of u rin a ry annr l e e , and th e sm a ller i!ie sample th e frrenter m*et be th e c a r e In t h i s ~apot. U sine ample* c e l l s otad In th e-u su a l types o f vashronae o r m edical q u arters In manufncturinr: p la n t s , or o b ta in ed by
oustooary c a p i t a l procdures* or* in faot* aucured by any o th sr
tlu r n >y p r c i s s e t h o d # e o n t r o l l e d b y t h e ^ r saisin er * .ara n o t o n ly
v lu clo$ .;8 b u t jfjr oa sily n jis le &iU a n 1 s a t o fch s lr Xe& c o n t e n t * L d
i u biqraifcou s* on& t t la d i f f i o u l t ursdor t h c n o s t fa vo r n b l# c i r
e u s e tar tes# t o n vo id a i l s o u r o s a o f con tas ! n a t io n . Uum ercus o s a *
r e p o r t a in eu r r en p a u m a is ir se iu d o r m a ly t i o a l d &t s on th u r i n *
u M o h b y t s a r s in s p e c t io n oen b is s m r d s d a crr on coti *. In son #
t o a t n n o im tb # t ia a t ifcls # fou rn i "bm * a * r e la t i o n t o t h s c o n d it io n *
-of e x .o s a m Pn ovn o r M i o v a l t o h a ve e x is t e d * ami in o t h e r # t J y
a r e e n t i r e l y b e yo n d t ls e imxiift&X H a l t s o f u r i n a r y l e a d e x c r e t i o n .
In t h i s co n n ectio n i t should be p o in te d ou t th a t a u rin a ry Xcd
c o n c e n tr a tio n .in e x c e s s o f 0*5 *3 p e r l i t e r Is a very g r e s t
r a r it y * th a t oanesntrafclans h ig h e r t h a a 0 ,3 s&a p er l i t e r are '*
a sso c ia ted only w ith |p o#3ly dangerous con d ition s o f load expo# re
a n d a b s o r p t io n * wi4 l@ 4&lu e s ea wsed ln f 0* 00
/1
p er l i t o r can n ot
occu r w ithout a d e f in i t e and s ifjn lfle a n t a ^ o sa r o to load, each as
i s .^ e c la te d w ith th e adm ittedly hazardous lead tr a d e s, ih-olon^ed
expocure lit d o u b tfu l,y hft#ardou# o ccu p a tio n s h a s -m t* in _pur
e*:f;*s in n o e * in d u co d s u ch m * e s o f u r i n a r y lo a d o x e r e t l- > n .
At***-*. 1P.3 for<a-rfolnr dlaousalon* t `-i* depc*pcnoa on
r e c u it* oxprecacd ir* to r :a *3 f y f i o-. 'p/ ie !; cone entm t. to 1 r a th e r
on
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ex creto ry ro t* in t!ui tin ##nse Is not alw ays f e a s ib le , Moreover*
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IX
to o p in io n s and vnritton statem ent o f many* la in d ic a t iv e o f le a d in to x ic a tio n * Both occu r In: e n t ir e ly h e a lth y person* ex cep t th a t th e le a d IX.'' floe* not appear w ith ou t b a c t e r ia l in vad o? o f the g in g iv a l tissu es* i* e . aone degree o f g ln g iv itla Is neeeonsrj fo r It a develercwnt*
Punctate basophilia* or "ctlppiln#* o f the erythrocyi** w ithin certa in lim its la o f norsml occurrence in th e huntm b cud, In xjusinlng th e b lood o f one thousand* o f apparently norm 1 h ea lth y ad ult free o f ecou-pet ton al le a d exposure, '.!o hnv*> found naoii e r y th r o c y te s l a nwrsbera ran gin g fro n one o r tic up t o na h igh co s i r thousand, per j a illt o a e r y th ro c y te s* Skr*ar 6 par c e n t i f th e cprou? Showed one tbouanM o r acre per m illion , eryth rocyte* w h ile th e neon fig u r e f o r 7Sb persona im 539*1 * ?*73 per m illio n erythrocytes* She m a b tr o f such stip p led , ery th ro cy te# In th e blood She** l i t t l e or no change w ith e ll ) Incrosienta o f in creased le a d Irtish*, but a t h ig h er l e v e l s o f 7 exposure and ab sorp tion t h e ir nusiber In th e c ir c u la t in g blood ten d s to in c r e a s e . Consider1.,ble v a r ia t io n in the d eg ree o f ' in d iv id u a l resp onse i s observed* and f a i r l y wide v a r ia tio n s o ccu r fro.-i day to flay* but w ith in c r e a s in g ly se v e r e o a n d ltio tic o f le a d exposure there la a d e f i n i t e tren d toward in c r e a s in g &`jaberc o f a tin .c lo d e r y th r o c y te s in th e b lood o f expocod worteaea* i f cor* rorinone are baaed on groups rather than in d ivid u al reactions*
The fa c ta a re rneponeible both fo r the ueefulnece o f regular sio ro a co v io exsalnnttone o f the blood of worfcswn a* a neona o f e c t i : t i n g th e s ig n if ic a n c e o f t h e ir o c c u p a tio n a l le a d oxpeaure* nnd f o r th e InadCi^oacies o f such neaeurec fo r d io rn o a tio purposes in indlvidTjal ca se . -Hxffloc '
12
It* in th is n ecessarily lim ited d iscu ssion , to point out,
th a t hazardous exposure t o le a d oosxpdunds i s a s s o c ia t e d w ith
th e appearance o f d e f i n i t e l y abnormal numbers o f b a s o p h ilic
erythrocytes in the blood of a considerable proportion o f exposed
workmen, w h ile th e absence o f such ery th ro cy tes in a su sp ected
or a lleg ed ease o f lead p oison in g, during the period o f a ctiv e
in to x ic a tio n , i s very n early co n clu siv e evidence that the toxemia
i s due t o some fa c to r o th e r than le a d .
A "lead lin e " may appear in gum margins which
are somewhat inflammed by b a c t e r ia l in v a sio n whenever th e lea d
content of the Involved tissu e s i s s u ffic ie n tly elevated . have observed th e appearance o f a fa in t b lu e lin e in an
We
in fe o te d gum p o ck et in one person whose b lo o d co n ta in ed le a d
to th e e x te n t o f 0.05 mgs p er 100 grams. Thre i s l i t t l e doubt
s
th a t e a s i l y i d e n t i f i e d le a d l i n e s s i g n i f y somewhat h ig h e r l e v e l s
/>
o f lead absorption. N evertheless obvious d ep o sits o f lead sulphide
are seen in th e gums o f p erso n s w ith no dem onstrable symptoms o r s ig n s o f in t o x ic a t io n . They must be d if f e r e n t i a t e d from s im ila r
d e p o sits r e s u ltin g from th e p r e c ip ita tio n o fs other m e ta llic ~
su lp h id e s, n otab ly o f bism uth, and th ey must not be confused w ith
the normal pigment o f negroes and correspondingly dark-skinned
p e o p le s . The form er d i f f e r e n t i a t i o n i s som etim es p rovid ed by
th e m ed ical h is t o r y o f th e p erson in q u e s tio n , but may re q u ir e
an alyses o f the blood or urine or both; the la t t e r can u su a lly be
made by c a r e f u l stu d y o f th e lo c u s and appearance o f th e pigm ent.
The n a tu r a l pigment i s r a r e ly , i f e v e r , found in the gum t i s s u e
on th e lin g u a l s i d e , w h ile , d e s p ite the sca n t a tte n tio n g iv e n
the fa ct by c lin ic ia n s in gen eral, a favored s it e for th e f ir s t appearance o f lead lin e i s in the extreme lin g u a l edge o f the
- 13 -
gum o p p o s ite th e b ic u sp id s and low er m olars. The b lu is h p u rp le l i n e o f g in g iv a l co n g e stio n may be tak en f o r le a d l i n e by t h e in e x p e r ie n c e d , and e s p e c ia ll y i f no exam ination i s made a f t e r ex p ressio n o f th e blood by means o f a tran sparen t a p p lica t o r (su c h a s a g la s s s l i d e ) . More commonly, th e s t a in e d o r discolored surface o f a tooth Just v is ib le beneath a thin layer o f gum t i s s u e la c a l le d a le a d l i n e . The d i f f e r e n t i a t io n i s not always ea sy and r e s o r t must sometimes be had to the u se o f a hand le n s , or even to biopsy follow ed by alcroohem ical or b etter by speotrographic a n a ly sis.
The R ecognition o f Dangerous Lead Exposure Time does not perm it a u s e f u l o r adequate
d e s o r ip tio n o f th e symptoms and o l i n l c a l s ig n s o f t o x i c le a d a b so r p tio n , nor i s i t ay-purpose to do more than t o s t r e s s th e n e c e ssity fo r b asin g the reco g n itio n o f such absorption on the
)
a c tu a l occu rren ce o f i l l n e s s w hich i s com p atib le w ith th e known c l i n i c a l p ie tu r e o f satu rn ism , or upon se q u e lla e which can a t le a s t be a ttrib u ted p la u sib ly to th e e ffe c ts o f such absorption. I t w ill be ob jected th a tr th is p oin t o f view le a v e s the m atter to th e judgment o f th e c l i n i c i a n and tak es i t ou t o f th e realm o f c o n c lu sio n s which can be reached by methods and instrum ents o f s c i e n t i f i c p r e c is io n . One can o n ly answer t h i s o b je c tio n by reminding the properly en th u sia stic proponents o f laboratory methods in in d u s t r ia l h y g ie n e , th a t t h e ir moat s ig n if ic a n t fu n ctio n i s to chart the co n d itio n s under which illn e s s i s lik e ly to develop and t o p o in t th e way fo r th e id e n t if ic a t io n o f such c o n d itio n s . The dem onstration o f s ig n s o f le a d ab sorp tion above th e normal
le v e l c o n s titu te s a u s e fu l e x e r c ise o f t h is fu n c tio n . The actu al
f t & i 01 608
- 14- -
r e c o g n itio n and I d e n tific a tio n o f i l l n e s s i s a fu n otion la r g e ly and l o g i c a l l y re ser v ed t o th e p h y sicia n * One may confidently an ticip ate that the further correlation of the sig n s o f le a d a b so rp tio n w ith d e t a ile d c l i n i c a l data on th e types of to x ic response and th e ir frequencies o f occurrence, w ill d e lin e a te dangerous lead, exposure in q u a n tita tiv e terms oo e x p l i c i t as to compel i t s r e c o g n itio n and e lim in a tio n .
) /