Document baOpner7v259NDx9ae0jnMXO6

May 17, 1954 . . . . . - ,. . '. Mr. R. R. Fulton Industrial H ygiene D epartm ent W orkmen's C om pensation Board V ancouver, B ritish Colum bia Canada ' .. : - . . ! . .. ; . . ,; ;; , . D ear M r. Fulton: The general p rincip les concerned in the control of the hazards ol the lead trad es and the view point which I hold concerning the problem s involved in them , is ex p ressed fa ir ly com p letely in the chapter in the second volum e of P atty's book "Industrial H ygiene and T oxicology, " to which no doubt you have a c c e s s . I r efer you to th is chapter, th erefo re, and in the factual sen se add h ere only such com m ent a s m ay be required to extend the know ledge of the su b ject beyond the date of that p u b lication . It is not fe a s ib le , oth erw ise, to answ er your questions within reasonable lim its of tim e and space. . ... . . I refer you further to the booklet "Occupational L ead E xposure and Lead P oisoning, " a report prepared by the C om m ittee on Lead Poisoning of the Industrial H ygiene Section of the A m erican P u b lic H ealth A sso cia tio n in 1943, of w hich I had the honor to be the chairm an. This co v er s the p rin cip les and the fa cts of the m atter adequately, with certain exceptions w hich I sh a ll attem pt to rem edy by further rem arks-. Xsh a ll not refer to the treatm en t of lead poisoning, w hich is not d ealt w ith en tirely sa tisfa cto rily in th is booklet, in view of later-d evelop m en ts. The booklet is availab le at a co st of 75 cents in this o ff ic e of th e A . P . H. A . , 1790 B ro a d w a y , N ew Y ork 19, N ew Y ork . It is not p o ssib le to d escrib e a sa tisfa cto ry m ed ical regim en in the form of ; dogm atic rules sin ce there is no substitute for a sound.understanding of ;; - th e p r o b le m s involved-on: th e p a r t o f th e r e s p o n s ib le p h y sic ia n . A ny p h y sic ia n * who is aw are of his resp o n sib ilities w ill acquire the n ecessa ry knowledge to . do his job satisfactorily, and if he does not do so , no set of rules w ill avail. . y 0r e3Calttp ie ; th e 'fr e q u e n c y o f -exam in ation, is in o t , and cannot reasonab ly b e , a m atter of ru le, sin ce both the frequency and the character of the exam ination m ust depend on the quantitative extent of the hazard that e x ists. The p rescrip tion of m onthly or quarterly, or sem i-ann ual exam inations, is m ean in gless, reg a rd less o f it s sou rce or the ^apparent reason s for it. Such ru les m erely perpetuate the irrelev a n ce of m any o f the p resen t regulations on the subject, . and th e-failure of resp on sib le peoplej to acq u ire a genuine understahding of th ei# r e s p o n sib ilitie s . The R otation of w orkm en, is a lik e situ ation .. It can be !. . i - - i . - . * . * Ke t OiSei g *. - M r. B. B. F lton - (2) - M ay 17, 1954 \ done in telligen tly only on the b a sis of p r e cise knowledge of the extent of the lead absorption of m en who are em ployed in sp ecific job s. It is not good technique or good m orals to deal with risk s of this type on the b a sis of guessw ork, now that we have exact m ethods for arriving at the fa cts. S p ecifica lly , the th resh old lim its for sa fety , on the part of m en engaged in the lead tr a c e s, as e x p ressed in term s of p h ysiological evid en ces of absorption, m ay be expressed as follow s: 1. The lead le v e ls in the blood sh a ll not be p erm itted to reach 0. 08 m g, per 100 gram a of w hole bipod, and m en who reach this le v e l should not be perm itted to continue under conditions of exp osu re. (The m atter of an alytical p r e c is io n h e r e is ox the u tm o st im p o r ta n c e . The b e s t m eth o d s a v a ila b le h a v e an in trin sic e rr o r (va ria b ility in reproduction) of ap p roxim ately G.01 m g. p er 100 g fa m s when quantities of blood ranging from 0 to 20 m l. a re taken fo r a n a ly s is . Thus a s in g le a n a ly tic a l v a lu e of 0 .0 3 m a y a c tu a lly be O'.,,09 o r 0 .0 7 . Many of the m ethods yield m uch la rg er e r r o r s, and th erefore one m ay not p r e sc r ib e a th resh old Value without linking it to the p r e c isio n of the m ethod u sed . I speak above of valu es obtained by m ethods com parable in p recisio n to th ose em ployed in th is L aboratory, knowing that such p recision is not generally achieved. ) .. 2. The m ean u rinary value which corresp on d s to that of the blood given above v a r ie s fr o m 0. 12 to 0. 14 m g. p er liter,d ep en d in g on the m ethod of sam p lin g the u rin e. Spot sam p les of urine, taken during work, yield higher m ean valu es - by app roxim ately 0 .0 2 m g. per lite r - than do sa m p les of la rg e volum e of the urine of the sa m e individuals obtained during, hours of le is u r e . M oreover, co rrect interpretation of the resu lt obtained on a sin gle spot sa m p le o f a -single ind ividu al is quite im p o ssib le . It is n e c e s s a r y to obtain m u ltip le sa m p les from, the sam e individual, a n d /o r to obtain individual sa m p les of the urine of a fa ir ly la r g e group of m en w orking at th e sam e kind of job, in o rd er to a p p ra ise the ap p roxim ate le v e l of th e le.ad ab sorp tion of the individual o r group. A num ber o f su b terfu ges have been em ployed by variou s p erso n s to co rrect for the consequences of the p h ysiological variab ility of the urinary lead ex cretio n - such a s , for. exam ple, using a co rrectio n factor based on the sp ecific gravity. T hese are a ll un satisfactory. The only procedure that w orks is that of m ultiple sam pling or the collection of sam ples of large volum e under suitable conditions . ; We s o lv e 'tliis p r o b le m , in rgulai* d e te r m in a tio n s o f the sta tu s of in d iv id u a ls or groups , b y obtaining sam p les of blood and sam p les of urine (spot sam p les of urine taken under the su p ervision of a resp on sib le person to prevent contam ina tion). Study of the com bined resu lts provides us with en tirely sa tisfa cto ry inform ation on w hich to recom m end or to take appropriate action. The m atter of obtaining sa tisfa cto ry sam p les of urine for a n a ly sis is exacting S s5r &9 a *o+ &;s PS ob ^d , sP ulton - (3) - May 17, 1954 and trou b lesom e. U n less this is done with m eticu lou s ca re, th resu lts obtained are not only u s e le s s but g r o ssly m isleadin g. I send you copies of the instructions which we follow and require of o th ers. When m en a r e at too, high a le v e l of ab sorp tion , as shown by th e se r e s u lts , they are rem oved from exp osu re, until they return to le v e ls w ell within norm al lim its. T his, of course, is not a m atter of rule, but of observed facts. With r e s p e c t to the p ro ced u reso f co n tro l b a sed on h e m a to lo g ica l fin d in g s, o r those based on the m easurem ents of coproporphyria excretion , have only this to say. if the lead expo su re of workm en is kept within safe lim its by m eans of adequate environm ental control, th ese m ethods w ill appear to be sa tisfa cto ry , and can be em ployed in p ractice as w ell as any oth ers. If, . how ever, the m en are actu ally exposed to dangerous conditions, from tim e to tim e or irreg u la rly , within a plant, i, e. if the m easu res of environm ental . control a re u n sa tisfa cto ry or irreg u la r in th eir application, dependence upon the h eiratclogical or b io ch em ica l findings fporphyrins) w ill resu lt in failu re to p r e v e n t le a d p o iso n in g ; .. T h e se m ethods, a r e la c k in g both in s p e c if ic it y and in quantitative relev a n cy , with r esp ect to lea d absorption , and they re'd ep lorab ly poor tools for the intended pu rp ose. They w ill in crease, the batting average of th e p h y sicia n to so m e slig h t ex ten t, in picking up in cip ien t c a s e s of lead, in toxication before th ey reach the stage of sev e r e illn e ss and d isa b ility , but they a re not, str ictly speaking, preventive m ea su res. They d eserv e to be condem ned, for the reason, that they rep resen t traditionally sanctioned m ake shifts which we w ere ju stified in using for preventive purposes before we had adequate m ethods. At p resen t, they se r v e to dem on strate the ch a ra cteristic inertia of the hum an m ind, w hich finds it e a sie r to cling to the com fortable past than to exert its e lf to understand the p resen t. I do not speak here of the sign ifican ce of th ese m atters in relation to the diagnosis of lead poisoning, or m ore im portantly, of the p h ysiological m ech an ism s of which they are a m anifestation w ell worthy of further investigation. Rather, am talking of the relative value of proced ures in the field of preventive m ed icin e. H ere they a re poor su b stitu tes fo r 3 aural p r o ced u res. . I r e a lise fu lly, of co u rse, that a governm ental agency, in its attem pt to m iti gate the ev ils of inadequate control of ind ustrial h azard s, including th ose of occupational lead absorption, fe e ls the n e c e ssity of adopting regulations w hich, g en era lly applied, w ill tend to e x e r c ise som e d egree of control in the right d irectio n . find it d ifficu lt to v isu a liz e any approach to this m atter that w ill be even reasonably sa tisfa cto ry , except that based on m echanism s {governm ental or oth erw ise) of c r itic a l in sp ection of in d u strial plan ts, im plem ented by the com petent investigation that w ill esta b lish the fa c ts, law s that fix resp o n sib ilities where they belong, and p rovision s fo r the educational efforts which w ill provide the resp o n sib le people with the know ledge w hich they .require to handle th eir ow n r e s p o n s ib ilit ie s . A m e r ic a n in d u str y , to a c o n s id e r a b le d e g r e e , 3 im m a tu r e in its handling of th ese m a tters, and A m erican p h ysician s, as w ell as m ed ical ed u cators, are ju st beginning to rea lize th eir resp o n sib ilities to industry for com petent m edical serv ice and adequate p rofession al training. I su sp ect, with M r. R. R. Fulton - (4) - M ay 17, 1954 o that your p o sitio n and that of your a s so c ia te s in the govern m ent, in this m atter, is not e sp ec ia lly happy. I would not w ish to 3eem unsym pathetic th erefore. I only ex p ress the b elief, b ased on m any y ears of exp erien ce, that there is no panacea, no rule of thumb, and no short cut, which can have m ore than a m od erate p a llia tiv e effect in the handling of this situation. C ordially yours, Robert A. Kehoe, M. D. RAX ef D ictated but not read. Xnc. Instructions for taking blood, spot urine and large urine sam p les. i. HE 0015672