Document p68z20w3Y4ZbXQ8ROmm6LnD7

June 24, 1961 Malcolm H. Merrill, M.D., Director State Department of Public Health 2151 Berkeley Way Berkeley 4 California Dear Malcolm: I am directing to your attention a few critical remarks relating to the article on "Lead Poisoning in Industry", which I received a - day or two ago from your Department, under the heading Occupational Health, technical information service. I send these to you for two reasons, one being that I do not know who prepared the article; the other is that I do not wish to take any one of your group "over the coals". What I have to say is meant to be constructive criticism, and it is 30 crucial to the proper application of certain measures of industrial hygiene in the lead trades, that it must, I believe, be said with all the vigor that it deserves. I have not had the time to go over every part of the statement carefully, and I have not considered this necessary. What has been said on a number of matters is not what I would say, nor is it said in the manner in which I would say it. That is of little importance, for no two people see things quite the same or speak of them in the same manner. There are two points, however, that deal with quantitative data and relationships in which one is either right or wrong, and in this instance incorrect statements are made. (1) The first of these occurs under "Coproporphyrinuria", in which the flat statement i3 made that "a high degree of correlation has been - demonstrated between coproporphyrin {concentrations) and urinary or blood levels." This is not as bad as it seems at first, but actually it is not true. The concentration of coproporphyrin in the urine does not vary with the extent of the absorption of lead or with its rate of excretion in the urine or with its concentration in the blood; it tends to increase abruptly when the level of absorption exceeds the critical point of danger, whereas it remains within normal limits at ail safe levels of lead absorption. It is a sign, not of absorption of lead, but of interference with a normal function of the body, and hence it denotes intoxication. It does vary some what in degree with the severity of the intoxication, but not necessarily with the extent of absorption of lead. What is said in the article is not altogether untrue at the higher levels of absorption, but it is misleading, especially because it confuses the issue in industrial hygiene by using a sign of intoxication as a sign of danger after the fact. What one says here has to be 3aid carefully, and from precise knowledge. (2) More serious errors are the statements concerning lead in the Malcolm H. Merrill, M.D 2 June 24, 1961 blood, "it is well established that clinical signs and symptoms of lead intoxication may exist with levels below 0.08 mgm per 100 grams." This is not strictly untrue, but what the author of this statement means is untrue, as is shown by the sentences that precede and follow it. For example "The upper limit of normal for blood lead is 0.08 mgm/100 gm whole blood"-- . This is a flatly incorrect statement. The concentration of lead in the blood of normal persons in the United States rarely exceeds 0.05, and never exceeds 0.06 mg. per 100 grams. The latter level is found so rarely as to- be regarded as the result of a greater than usual analytical deviation. Much, of course, depends upon the analytical procedure, but a properly carried out procedure need not be in error by more than + 0.01 mg. per 100 grams of whole blood, in dealing with quantities of 10 grams of blood. The concentration of 0.08 mgm per 100 grams of whole blood is an absolutely critical one. I have never seen a single case of lead poisoning in a child or an adult at the time of onset of intoxication, whose blood level was below 0.08 mg. per 100 g., and X believe I can say without any possibility of doubt, that we have checked this point by more observations than has anyone else in this country or elsewhere, and by methods of analysis that are of high and known accuracy. Symptoms may persist after the concentration of lead in the blood has diminished, and therefore, if the sick person is not investigated early in the disease, it may happen that the concentration in the blood is as low as 0.06 rag. per ICO grams. The fact as I have stated it, is of the greatest importance, however, in industrial hygiene, for if an individual is removed from work just before the threshold level of 0.08 has been reached, he does not develop lead intoxication. You will recognize, therefore, that I am not dealing with an academic point, but with a highly significant fact which has been put to crucial test in practice for a period of years. On this point the entire medical regimen of industrial hygiene in the lead trades depends for its certainty that it can recognize danger before any illness of any kind develops. In the tetraethyllead industry we have to depend solely upon the urine instead of the blood, (for the metabolism of TEL in the body is such that the concentration in the blood is no index of the concentration in the body). The principle is the same, however although the practice differs somewhat. I would appreciate it if you would call these matters to the attention of your people. I do not expect them to alter or retract these statements, at present, but they should know that they are incorrect. In due course, if the matter comes up, I shall have to take issue with such statements. These are not the only misstatements on the record, however, and they will not be the last. The recent book of Johnstone and Miller contain the astonishing mis statement that the threshold of danger, with respect to the concentration of lead in the blood is 0.10 mg. per 100 grams. Where they got this figure, I have no idea, but I have chided them about it. These things will be straightened out in time, and my only reason for referring this to you is to make such corrections as easy as possible rather than as difficult as it may become if some one's feelings get hurtl With best personal regards. Sincerely yours, RAK:ss Robert A. Kehoe, M. D WE B E L I E V E T H E A T T A C H E D M A T E R I A L W I L L BE OF I N T E R E S T TO Y O U 0O0O0O0O0O0O0O0 B u r e a u of O c c u p a t i o n a l H e a l t h C a l i f o r n i a D e p a r t m e n t of P u b l i c H e a l t h 2151 B e r k e l e y Way B e r k e l e y 1, C a l i f o r n i a N13155.01 ^ 0012451 occupational Health tefitnicl information service CALIFORNIA STATE DEPARTMENT OF PUBLIC HEALTH BUREAU OF OCCUPATIONAL HEALTH 2151 BERKELEY WAY BERKELEY 4, CALIFORNIA LEAD POI SONI NG I N I NDUSTRY Fat al l ead p oi so n i n gs have p r o gr e ssi v e l y de c l i n e d over t he past t h i r t y y e ar s i n many i ndus t r i e s, but cont r ol of t he l ead hazar d i s st i l l u n sa t i sf a c t o r y . Dur i ng t he y e ar 1959, t w ent yni ne cases o f l ead p o i so n i n g were r epor t ed t o t he Bur eau o f Occu p at i onal Heal t h, Ca l i f o r n i a Depar t ment o f Pu b l i c He al t h . It i s p r o b ab l e t hat many more c ase s r emai n unr epor t ed and many wer e not r e c ogn i ze d . Met hods o f compl et e con t r ol of t he l ead hazar d ar e wel l known so t hat , i d e al l y , no case o f l ead p oi so n i n g shoul d occur , y e t n o n f a t a l l e a d p o i so n i n g i s a common sy s t em i c o c c u p a t i o n a l d i se a se . Some o f t h i s i s f rom t he u n w i t t i ng use of l ead compounds i n new p r ocesses, but exposur e i s known t o be p o ssi b l e i n more t han a hundr ed d i f f e r e n t k i n d s of i ndus t r i e s, i n c l u d i n g sm e l t i n g, r e f i n i n g , l ead r e cl ai mi ng, bat t er y manuf act ure, out door pai nt i ng wi t h l ead based p ai n t s, p ot t er y gl azi n g, wel di ng and sol d er i ng, met al i zi n g, and shi p scr appi ng. ROUTES OF ABSORPTION Lead i s t aken i n t o t he body by i n h a l a t i o n , by i n ge st i o n , and, r a r e l y , t h r ou gh t he i n t a c t sk i n . By f a r t he gr e a t e st number o f c a se s i n i n d u st r y ar e f rom i n h a l a t i o n o f l e a d dust and f umes, si nce r e l a t i v e l y i n so l u b l e l ead compounds may be d i sso l v e d i n t he l u n g s and ab so r b e d t h r ough t he r e sp i r a t o r y mucous membr anes. At pr esent , t et r aet hyl l ead as f ound i n gaso l i n e i s t he onl y w i del y d i st r i b u t e d f orm o f l ead capabl e o f b ei ng absor bed t h r ough t h e sk i n . Cases o f p o i so n i n g f rom t e t r ae t h yl l ead have been re por t ed, but f o r t u n a t e l y ar e r ar e because st r i c t i n d u st r i a l hygi ene c o n t r o l s ar e enf or ced by t he t e t r ae t h y l l ead i n d u st r y , and because t he concent r et t i on i n o r d i n a r y ga so l i n e i s so l ow as t o pr esent l i t t l e o r no hazar d t o handl er s, such as t r u c k e r s, se r v i c e st a t i o n a t t e n d a n t s, and ot h e r s. ( Tet r amet hyl l ead has been added re cent l y t o ga so l i n e as a su b st i t u t e f or t e t r a et hyl l ead but t he amount of l ead i s about t he same. ) TYPE OF POISONING 1. Acut e Po i so n i n g: T h i s f orm u su a l l y r e su l t s f rom t he i n ge st i o n of 1a r g e amount s o i l ead sa l t s, commonl y t he ace t at e or sub acet at e. In i nd u st r y, however , t h i s f or m o f acut e l ead p o i soni ng i s r e l a t i v e l y r ar e. It does occur occa si o n a l l y f rom ex p osu r e t o t e t r a e t h y l l e ad o r l ead f umes. The i n g e st i o n o f l e a d sa l t s p r o d u ces si g n s and sympt oms i n c l u d i n g a m e t a l l i c t ast e, vom i t i ng, sever e c o l i c , and c o n st i p a t i o n o r b l o o d y d i a r r h e a . Ce n t r a l n e r v o u s sy st e m sympt oms pr edomi nat e i n t e t r ae t h yl l ead p oi son i ng and i n c l u d e Insom n i a, ment al i r r i t a b i l i t y and i n st a b i l i t y as e a r l y si g n i f i c a n t f i n d i n g s. These may be f ol l ow e d by headache, c o n v u l si v e movement s, f r ank c on v u l si on s, and deat h. 2. Ch r on i c Po i so n i n g : T h i s i s t he most f r e quent t ype o f l ead p o i so n i n g. For d e sc r i p t i v e p ur p oses t he si g n s and sympt oms may be c l a ssi f i ed as e ar l y and l a t e m an i f e st at i on s. Ear l y - The onset o f c h r o n i c l ead i n t o x i c a t i on i s f r e q u e n t l y i n si d i o u s wi t h headache, w eakness, l a ssi t u d e and c o n st i p a t i o n , f o l l owed soon by t he p ai n of i n t e st i n a l c o l i c . A l e a d l i n e al o n g t h e gum m ar gi n may be pr esent ; t h i s i s one i n d i c a t i o n o f l ead ab sor p t i on , but not n e c e ssa r i l y o f i n t o x i c a t i o n . These e a r l y sympt oms ar e by f a r t he most common p r e se n t i n g c o m p l a i n t s o f l e ad poi soni ng. N13155.02 Lat e - I f t he p at i e n t f a i l s t o heed t he e a r l y w ar ni ng sympt oms and e x p osu r e con t i n u e s, n e r vou s m a n i f e st a t i o n s soon er o r l a t e r devel op, These f r e q u e n t l y begi n wi t h ner vousness, t r emor s, weakness of t he ext en so r m u sc l e s -- o ar t i c u l ar l y t h ose o f t he hands and f or ear ms -- and sen sor y d i st u r b ances, i n c l u d i n g p a r e st h e si a and anest he si a. Even t u al l y e x t en sor p a r a l y si s may de vel op, w i t h obvi ous w r i st or f oot drop. Sever e chr oni c p oi soni ng may be f ol l ow ed by sympt omat i c i nvol vement of t he cent r al ner vous syst em, as wi t h acut e p oi son i n g. . For t unat el y, encephal opat hy i s r e l a t i v e l y r ar e, o c c u r r i n g u su a l l y a f t e r exp osur e t o t e t r a et hyl lead, or nonoccupat l onal l y in chi l dr en who i n ge st l eaded p a i n t f r om f u r n i t u r e o r w al l s. In t he acut e st at e, t her e i s e x c i t a t i o n and con f usi on whi ch may be f ol l ow ed by st u p o r w i t h o r w i t hout c o n v u l si o n s, coma, and deat h. In t he c h r o n i c t yp e o f sever e l ead p o i so n i n g, i nvol vement may o c c u r wi t h i nsomni a, v e r t i go , p e r so n a l i t y changes, and v i su al di st ur bances. HI STORY Accur at e d i f f e r e n t i a l d i a gn o si s r e q u i r e s a car e f ul syst ems r evi ew t o r u l e out ap p e n d i c i t i s, acu t e g a st r o e n t e r i t i s, r en al c o l i c and o t h e r causes of abdomi nal pai n whi ch may si m ul at e l ead c o l i c . Numerous d i so r d e r s of t he ner vous syst em may be conf used wi t h t he p e r i p h e r al n e u r i t i s or e n c e p h a l i t i s o f 1ead poi soni ng. Such d i se a se s i ncl ude p o l i o m y e l i t i s and ot h er i n f e c t i o n s, cen t r a l n e r vo u s syst em ne op l asm s, and p o i so n i n g f rom t o x i c subst ances ot her t han l ead. Pa r t i c u l a r l y i mpor t ant i s t he occupat i onal h i st o r y o f t he p at i e nt . Po i n t s t o c o n si d e r ar e p r e v i o u s and p r esent exposur e t o sp e c i f i c j obs, d u r a t i o n o f e x p osu r e, p r e se n c e o r ab sence o f sympt oms i n o t h e r wor ker s, and t i me o f onset of sympt oms i n r e l a t i o n t o occupat i onal exposur es. PHYSI CAL EXAMINATION Al t hough none of t he si gn s ar e pat hognomoni c of l ead p o i so n i n g, t he most commonl y o c c u r r i n g ar e as f ol l ow s: 2 1. pal 1o r : T h i s i s p r ob ab l y a m an i f e st a t i on of inadequat e per ipher al c i r c u l a t i o n and may o r may not be a sso c i a t e d wi t h anemi a. 2. Weak ness and p a r a l y si s: T h i s o c c u r s m ai n l y i n t he e x t e n so r m uscl e s of t he w r i st . Ear l y st age s can be det ect ed by e x c e ssi v e f a t i g a b i l i t y of t hese m uscl es when t hey ar e exer ci sed. Ther e may be no o b j e c t i v e evi dence of gener al m uscul ar weakness, so t hat t he st r i k i n g f eat ure of t he condi t i on i s t he d i sc r e p an cy bet ween t he muscul ar d evel opment of t he p a t i e n t and h i s ap par ent Tack o f st r e n g t h when t e st e d . Tr u e w r i st drop or ot her p a r a l y si s i s a r e l a t i v e l y uncommon occur r ence. 3. Gl n gi v al 1ead 1 i n e : Bel i eve d t o be due t o a d ep osi t of l ead su l f i d e ; t h i s si gn appears as a gr a y i sh bl ack se r i e s of d o t s most e a si l y seen al ong t he gum mar gi n w i t h t h e ai d o f a good m agn i f y i n g gl a ss. A good occup at i onal h i st o r y can d i f f e r e n t i at e a l ead l i n e from l i n e s caused by ot her heavy met al s. LABORATORY DATA A d i a gn o si s o f l ead i n t o x i c a t i o n cannot be made by l ab o r at o r y exami nat i on al one. The l ab or at or y suppl ement s t he h i st o r y and p hysi cal ex ami nat i on. Hemat ol ogy - Anemi a due t o l e ad p o i so n i n g i s nor mocyt i c i n t ype and u su a l l y not sever e. De f e c t i v e e r y t h r o c y t e s ar e common, however , and pol ychromat ophil ia, b asop h i l i c st i p p l i n g, p o i - k i l o c y t o si s, and a n i so c y t o si s may a l l be f ound i n t he pher i pher al c i r c u l a t i o n . Demonst r at i on of a l l t h e se abnor mal c e l l s may r e q u i r e m u l t i p l e smear s. . Baso p h i l i c st i p p l i n g o f t he er yt hr ocyt es i s t he pr i nci pal si gn i f i c a n t f i nd i ng in t he bl ood. When det er m i ned by an e x p e r i e n c e d t e c h n i c i a n f rom a c a r e f u l l y p r ep ar ed smear , t h i s f i n d i n g has d i a gn o st i c si g n i f i c a n c e . Pol ych r om asi a i s of t en c l o se l y assoc i at ed w i t h b aso p h i l i c st i p p l i n g and may be o b se r v e d i n t h e same c e l l . St i p p l e d e r y t h r o c y t e s ar e not pat hognomoni c of l ead p oi son i n g but r epr esent a r eact i on of bone marr ow t o a t o x i c sub st anc e . T h e i r v al u e i s enhanced by p e r i o d i c exami nat i on of t he bl ood t o obser ve changes i n t he p r op or t i on of st i p p l i n g. In c ase s of known l ead exposur e st i p p l e d c e l l s i n e x c e ss o f 12 c e l l s p e r 50 o i l i m m e r si on f i e l d s ar e su g g e st i v e o f e x c e ssi v e l ead ab sor pt i on. Ur i nar y Lead - Al t hough day t o day v a r i a t i o n i n ur i nar y volume i s r e l a t i v e l y l ar ge, val u e s of l ead when cor r ect ed f o r sp e c i f i c gr avi t y , cor r e l a t e f a i r l y wel l w i t h t he q u an t i t y o f l ead ab sorbed. The pr ocedur e f o r c o l l e c t i o n of u r i n ar y sam p l es f rom l e ad w o r k e r s must be m e t i c u l o u s si nce t her e i s al ways t he p o ssi b i l i t y of cont am i n at i o n by l ead f rom c l o t h i n g o r sk i n , o r f rom gl a ssw a r e , o r t he su r r o u n d i n g at m osp h e r e . Twent y-f our hour sampl es ar e p r ef er r ed over spot sampl es f o r a c c u r ac y . Normal l e a d e x c r e t i o n v a r i e s f r om 0.01 mg t o 0.08 m g/ l i t e r i n l a r g e sampl es o f over one l i t e r . Spot sampl es (50 ml o r more) var y f r om 0. 05 t o 0. 12 m g/ l i t e r . In cr e asi n g v al u e s above 0. 15 m g/ l i t e r i nd i c at e ex c e ssi ve l ead ab sor p t i on; however, c on cent r at i ons c o n si d e r ab l y in e x c e ss of 0. 15 m g/ l i t e r have been f ound i n t h e absence o f si g n i f i c a n t e v i dence o f l ead p o i so n i n g. As a r u l e o f t humb, however, one may a n t i c i p a t e si g n s and sympt oms of l ead i nt oxi cat i on as t he ur i nar y l ead concen t r at i on exceeds t h i s val ue, ur inar y lead det er minat ions require exact ing anal yt ical procedures and, t her ef or e, r eq ui r e t he se r v i c e s of a compe t ent chemi cal anal yst . Co p r o p o r p h y r l n u r a - The pr esence of p or p h yr i n s i n t he u r i n e o c c u r s i n a number of d i se ase s, e sp e c i a l l y t hose of t he l i v e r and b l o o d . Al co hol and b ar b i t u r at e s ar e exampl es o f i n t o x i c an t s whi ch may a l so mar kedl y e l e v at e u r i n a r y por phy r i n s. Such t o x i c o r d i se a se d st a t e s must be c on si d e r e d i n t he d i f f e r e n t i a l d i a gn o si s; how ever , i n t he known l e ad w or ker a f r ank i i + t e st f o r c o p r o p o r p h y r i n u r i a i s most l i k e l y t o i n d i cat e appr oaching l ead i n t o x i c at i o n . In l ead i n t o x i c a t i o n p o r p h y r n u r a i s u su a l l y more mar ked t han i n o t h e r d i so r d e r s and i s o f t e n demonst r abl e bef or e b a so p h i l i c st i p p l i n g of red c e l l s i s obser ved. A hi gh degr ee of c o r r e l a t i o n has been s a t i s f a c t o r i l y d em on st r at e d bet ween q u a n t i t a t i v e c o p r o p o r p h y r i n v a l u e s and u r i n a r y or bl ood l ead l e v e l s. 3 Bl ood Lead - The anal yst s o f bl ood f o r 1ead i s sp e c i f i c and i s ge n e r a l l y c on si d er e d t o c o r r e l a t e more c l o se l y w i t h a c l i n i c a l d i a gn o si s of l ead p o i so n i n g t han do u r i n a r y l ead d et er m i na t i o n s. The a n a l y t i c a l pr ocedur es, however, ar e a s e x a c t i n g and t i m e con su m i n g as t h o se f o r u r i n a r y l ead . The upper l i m i t o f nor mal f o r bl ood l e ad i s gi v e n as 0. 08 mgm/100 gm whol e bl ood, and c o n c e n t r at i o n s i n excess of t h i s ar e i n d i c a t i v e o f e x c e ssi v e ab sor p t i on , and t h e r e f or e o b j e c t i o n a b l e exposur e. Val ues f rom 0. 06 t o 0. 08 ar e c o n si d e r e d a t r a n si t i o n zone and amount s bel ow 0. 06 ar e normal f o r p e r so n s w i t h no exposur e t o l ead. It i s well e st ab l i sh e d t hat c l i n i c a l si gn s and sympt oms o f l ead i n t o x i c a t i o n may e x i st wi t h l e v e l s bel ow 0. 08 mgm per 100 gm bl ood, and con v e r se l y , evi dence of i n t o x i c a t i o n may be absent when bl ood l ead c o n c e n t r a t i o n s ar e q u i t e hi gh. For t hese r eason s t he d i a gn o si s of l ead p o i so n i ng r e q u i r e s much more t han a l ab o r a t o r y pr oce dur e. Bl ood l ead c o n c e n t r at i o n s ar e l e ss v a r i a b l e t han u r i n e v a l u e s. The r i sk o f c o n t am i n at i o n of sampl e i s much l e ss t han w i t h u r i n e sampl es si nce t he b l ood must be c o l l e c t e d by a t r a i n e d t e chn i c i an or p h ysi ci an. THERAPY Nat i onal t r eat ment of l ead p oi so n i n g f i r st r e q u i r e s t hat a l l l ead ex p osu r es be t e m p or ar i l y t e r m i n at e d . Case s w i t h m i l d sympt oms and no d i sa b i l i t y may o f t e n r e q u i r e no t r eat ment ot her t han removal f rom exp osur e and medi cal obser va t i o n . In such i n st a n c e s t he sour ce o f t he ex c e ssi v e ex p osu r e shoul d be det er mi ned and c or rect ed immediat ely. Abdomi nal cr amps ar e best r el i eved by i n t r a venous i n j e c t i o n o f 10 cc of 10 per cent so l u t i o n o'f 'caf ci um gl uconat e repeat ed ever y t hr ee t o f o u r h o u r s as n e c e ssa r y f o r p a i n . When t he d i a g n o si s o f acut e su r g i c a l abdomen has been d e f i n i t e l y r u l e d out , c o n st i p a t i o n may be r e l i e v e d by t he a d m i n i st r a t i o n of one ounce of magnesi um su l f a t e d a i l y . Thi s al so hel p s remove w hat ever l ead may be p r e se n t i n t he g a st r o i n t e st i n al t r act . Anemia, i f pr esent , i s not of t he i r on d e f i c i e n c y t ype and t he a d m i n i st r a t i o n of i r o n i s unnecessar y. A hi gh p r ot e i n , hi gh vi t am i n d i e t i s d esi r ab l e , however. i n cases p r e se n t i n g w r i st dr op, a cock-up sp l i n t , t o i n c l u d e t he f i n g e r s, worn day and n i gh t , i s used u n t i l f u n c t i o n r e t u r n s. Gent l e massage ever y day o r t wo and hot wat er bat hs ar e used. St r enuous e x e r c i se s o r massage sh o u l d be avoi ded. In c a se s o f l ead encep hal op at hy, sed at i on may be r eq ui r ed. For c o n v u l si o n s, b ar b i t u r at e s ar e e f f e c t i v e -- sodi um amobar bi t al 0. 25 t o 0. 5 gm may be gi v e n i n t r a v e n o u sl y , f o r exampl e. Lumbar punct ur e may be r e q u i r e d t o r e l i e v e i n cr eased i n t r a c r a n i a l p r e ssu r e . In sever e cases neur osur gi cal decompr essi on may be i ndi cat ed. EDTA Ther apy ( Ed at h am i l ) - Et h y l e n e - d i a m i n e t e t r a - a c e t i c aci d i s a se q u e st e r i n g c h e l at i n g compound capabl e of combi ni ng wi t h l ead, cal ci um and ot h e r m u l t i v a l e n t c a t i o n s t o f orm a noni oni zed ( sequest er ed) , r i n g- t y p e ( chel at ed) com pl ex. The ad m i n i st r at i o n o f EOTA o r i t s sodi um sa l t s t o man o r ani mal s r e su l t s i n t he ch e l at i on and e l i m i n at i o n o f cal ci um w i t h consequent hypo cal cem i a. To avoi d t h i s, t he cal c i u m d i sod i um sa l t o f EOTA i s used. Lead i o n s w i l l r e p l ac e c al c i u m i n t he compl ex because of t he gr e a t e r st a b i l i t y o f t he l ead compl ex. The l ead compl ex i s h i gh l y sol u b l e i n aqueous so l u t i o n s, i s noni o n i z e d and r e a d i l y e x c r e t e d by t he k i d n ey. Th i s bound l ead bei ng n on - i on i ze d does not exer t i t s c h a r a c t e r i st i c t o x i c e f f e c t s. EDTA and i t s sa l t s i n c r e ase u r i n a r y l ead e x c r e t i o n in pl umbi sm by as much as t went y t i mes, and hence, ar e e f f e c t i v e "d e l e ad i n g" agent s. The t o x i c o l o g i c a l p o t e n t i a l o f t h e se com p ounds, how ever , i s not f u l l y u n d e r st o od and sever al p at i e n t s wi t h pl umbi sm t r eat ed wi t h EDTA have di ed of r enal d i se ase , at t r i b u t e d t o t he use of t he dr ug. The use o f EDTA and i t s sa l t s shoul d be r ese r ve d f o r t h o se c ase s o f pl umbi sm t h at f a i l t o r espond s a t i s f a c t o r i l y t o e st ab l i sh e d t h e r ap e u t i c measur es, and t hen on l y when k i dney f u n c t i on st u d i e s i n d i c a t e t he absence o f renal d i sease. Such st u d i e s shoul d be done con c u r r e n t l y wi t h t he ad m i n i st r at i o n of EDTA. Wi t h EDTA i t i s p o ssi b l e t o ap p r e ci ab l y i n cr ease t he e x c r e t i o n o f l ead, but t he r e su l t s of t h i s cannot r e c e ssa r i l y be p r e d i c t e d . i n many li p at i e n t s t her e has been dr amat i c su b j e c t i v e im provement o ccu r r i ng sh o r t l y af t er t r eat ment i s begun. In ot h e r c ase s sympt oms p e r si st e d w i t h out si g n i f i c a n t change. The recommended maximum dose f o r ad m i n i st r at i o n i n t r ave n ou sl y of edat hami l cal ci um di sod i um i s 0. 17 gm per hour , 0.33 gm per day, o r 1. 67 gm per week f o r each 10 l b s. o f body w e i gh t . The a d m i n i st r a t i o n of EDTA by mout h as a su b st i t u t e f o r adequat e i n d u st r i a l hygi ene cont r ol of l ead exposur e i s c e r t a i n l y t o be condemned as bot h i r r a t i o n a l and danger ous. PREVENTION AND CONTROL Ther e ar e t h r e e e sse n t i a l f e a t u r e s o f an adequat e pr ogr am f o r c o n t r o l of an at mospher i c heal t h hazard: 1. Pr o v i si o n of adequat e envi r onment al cont r ol t o pr event exp osu r e o f t he w or ker t o con t ami nat ed a i r and t o p r ovi d e f a c i l i t i e s f o r m a i n t a i n i n g h i gh st a n d a r d s o f p e r son al c l e an l i n e ss. . 2. A p r o gr am o f i n s t r u c t i o n ai med at ( l ) a l e r t i n g t he w or k er s t o t he need f o r mai n t a i n i n g hi gh degr ee o f per sonal c l e a n l i n e ss, and ( 2) i n st r u c t i o n s of t he w or ker i n t he pr oper op er at i onal pr ocedur es which w i l l r e su l t i n minimum envi r onment al exposur es. 3. A medi cal pr ogr am t h at i s adequat e t o de t e ct e a r l y e v i d e n c e o f ove r e x p o su r e so as not o n l y t o pr event p oi son i n g but p r ovi d e a check on t he e f f e c t i v e n e ss of t he pr o t ect i ve devices provided. These t h r e e f e at u r e s may f u n c t i o n i n a num ber of ways. The f o l l o w i n g ar e exampl es: 1. Adequat e envi r onment al cont r ol a. So u r c e s o f l e a d c o n t am i n at i o n can be el i m i nat ed or r educed by "d e si gn i n g i n" cont r ol f e at u r e s i n t he o r i gi n a l st r u c t ure o r machinery. b. Al l o p e r at i on s whi ch mi ght d i sp e r se l ead d ust o r f ume shoul d be encl osed as much as p o ssi b l e . Such o p e r a t i o n s as mat e r i a l con veyi ng, m i x i ng o r gr i n d i n y , can of t en be per f or med w i t h i n compl et e encl osur es. c. Where coni ol et e encl osur e i s not p ossi b l e , l oc al exhaust shoul d be pr ovi ded. Local exhaust syst ems must act l a r ge l y by con t r o l l i n g t he mot ion of t he cont aminat ed a i r . The i m p or t an t c o n si d e r a t i o n s i n t h ! s t ype of v e n t i l a t i o n cont r ol are: { l) c o l l e c t i on of t he cont aminat ed a i r i n as concent r at ed a f orm as p o ssi b l e , and ( 2) p r o v i si o n of su f f i c i e n t t r anspor t ai r ve l oci t y t o convey t he cont aminant t o su i t a b l e d i sp osal equi pment . d. Lead f umes f rom heat ed l ead p ot s, p ar t i c u l a r l y above 700 F. , shoul d be con t r o l l e d by l o c a l e x h au st I n an upw ar d direct ion t o t ake advant age of t he nat ur al convect i on a i r cur r ent s. e. Good housek eep i ng i s e sse n t i a l t o p r e vent t he accumul at i on of l ead dust . The amount o f d u st i n e ss whi ch i s cont r i b ut ed t o t he a i r by t he cont i nual r edi ssem i na t i o n of se t t l e d d u st i s somet i mes more t han 50 p er cen t o f t he t o t al d u st con c e n t r a t i o n . Such d u st can be r emoved f rom f l o o r s and su r f a c e s by i n d u st r i a l vacuum s y s t e m s o r p o r t a b l e vacuum c l e an e r s and/ or w et t i ng down f o r subse: quent wast e d i sp osal . Per sonnel i n st r u c t i o n on p r op e r o p e r a t i n g pr ocedur es and good per sonal hygi ene. a. Wor ker s h a n d l i n g l e a d - c o n t a i n i n g m a t e r i a l s sh o u l d be p r o v i d e d w i t h and r equi r ed t o use adeouat . e washroom f a c i l i t i e s t o pr event i n ge st i o n of lead compounds. Si nce smoki ng can be a sTg-- n i f scan t c au se o f l e ad i n h a l a t i o n , i t shoul d be r e st r i c t e d t o uncont am i nat ed ar eas. b. Re sp i r at o r y p r o t e c t i v e d evi ces, i f pr o v i d ed , shoul d be appr oved by t he Ca l i f o r n i a Di v i si o n of In d u st r i al saf e t y or t he U. S. Bur eau o f Mi nes f o r p r o t e c t i o n a ga i n st l ead d u st o r f umes. Si n c e un cl ean o r f a u l t y r e sp i r a t o r s can cause a f a l se sense of se c u r i t y , r e sp o n si b i l i t y f o r t h e i r m ai n t e n an c e , r e p a i r , and c l e a n l i n e ss shoul d be j o i n t l y shar ed by management and t he empl oyee. Many com p a n i e s f i n d i t f e a si b l e and u se f u l t o have w or k er s t u r n In a used r e sp i r a t o r at t he end o f each sh i f t , so t h at t hey 5 can be r e i ssu e d a cl eaned and r e l i a b l e r e sp i r a t o r at t he b egi nni ng of t he next sh i f t . It sh o u l d he r emembered t hat r e sp i r a t o r s are: ac c e p t ab l e o n l y whor e t he con t r ol o f t he envi r onment i s not p o ssi b l e , o r where t he exp osur e i s f o r shor t p e r i o d s of t i me. T h e e ar e v e r y f ew o p e r a t i o n s t h a t can n ot be s a t i s f a c t o r i l y c o n t r o l l e d by good i n d u st r i a l hygi ene e n g i n e e r i n g d e si g n , so t h a t r e sp i r a t o r s shoul d be used onl y as a t em por ar y and secondar y expedi ent . 3. The e d u c a t i o n o f t he w or ker f o r h i s own p r o t e c t i o n i s f u l l y as i mpor t ant as t he p r e ven t i on o f d i sp e r sa l o f dust ai d f umes. He must be t o l d t he p r op e r way t o per f or m h i s j ob; he must be i nf or m ed o f t he p r o t ect ive devices buil t in or provided for h i s p r o t e c t i o n ; and he must be so l d on t he val ue of avoi di ng hi gh concent r at i ons of l ead dust . 4. A p h y si c i a n shoul d su p e r v i se t he he al t h of t he e m p l o y e e s, i n c l u d i n g t he m ak i n g of p e r i o d i c exami nat i ons and per f onni nc, l ab o r at or y work. Lead- af f ect ad w or ker s f ound at t hese exam i nat i ons shoul d be t r an sf e r r e d t o nonhazardous j obs w i t hi n t he pl ant , t here t o r ecover under p h y si c i a n ` s su p e r v i si o n . They sh o u l d not be al l o w e d t o r e t u r n t o t hei r former occupat i on unt i l t he hazard has been el i mi nat ed. The f o r e go i n g r ecommendat i ons have been d i r e c t e d at r e d u c i n g at m osp her i c cont act nat i on and i n se c u r i n g m edi cal d at a t o be used as a sour ce o f i nf or m at i on t o i n d i c at e where i moroved envi r onment al cont r ol shoul d be ap p l i ed . The p r e se n t l y accept ed maximum con cent r at i on whi ch may be t o l e r at e d by empl oyees f o r an ei ght hour w or ki ng day, i s 0.2 m i l l i gr a m o f l ead, or any o f t h e l e ad compounds, p er c u b i c met er of a i r . Exp er i en ce h as shown t hat exceedi ng t h i s f i gu r e i n most cases w i l l l ead t o e x c e ssi v e ' ead ab sor p t i on, i f not t o l ead p oi soni ng. It i s bel i eved t hat a m aj or i t y of p l an t s in whi ch l ead i s used i n some way w i l l endor se such a c on t r ol pr ogr am. To t he f ew who may d i sse n t , we must poi nt out t hat cont i nued f a i l u r e t o meet t he accept ed st an d ar d s f o r t he p r o t e c t i o n of wor ker s i n t he i nd ust r y can r e su l t onl y i n unde si r a b l e e f f e c t s on t he- w or ker , t he i n d u st r y and t h e communi t y. It can be st a t e d w i t h al m ost c e r t a i n t y t hat a f o r t h r i g h t and c o n st r u c t i v e 6 approach t o t he probl em w i l l r e su l t i n improved mor al e and e f f i c i e n c y o f w or ker s and w i l l act u a l l y r e su l t i n savi n gs t o t he i n d u st r y . REFERENCES BOOKS Hami l t on, , Al i c e and Hardy, Har r i et L. : Industrial Toxicology. Hoeber. New Yor k. 2nd ed. 1949. Johnst one, Rut her f or d T. and Mi l l e r , Seward E.: Occupational Diseases and Industrial Medicine. Saunder s. Phi l adel phi a. 1960. Sol l mann, Toral d: A Manual of Pharmacology, Saunder s. Phi l adel phi a. 8t h ed. 1957. von Oet t i ngen, W. F. : Poisoning - A Guide to Clinical Diagnosis and Treatment. Saunders. Ph i l ad e l p h i a. 2nd ed. 1958. Wi nt r obe, M. M. : Clinical Hematology. Lea 4 Febt ger . Phi l adel phi a. 4t h ed. 1956. PERIODICALS Lead I n d u st r i e s Asso c i a t i o n . The Lead Hygi ene Conf er ence, November 6- 7, 1958, Chi cago. Pap e r s r ead by E. L. Bel k nap, Ru t h e r f o r d T. Jo h n st o n e , Rober t A. Kehoe, and o t h e r s. Industrial Medicine and Surgery, Vol . 28, March 1959, Joh nst one , Ru t h e r f o r d T. : A Re- ex am i nat i on of t he Pi c t u r e o f Pl umbi sm. Industrial Medicine and Surgery, Vol . 26, pp. 323 f f . , Jul y 1957. Wyl l i e, J. : ur i nar y Por phyr i ns in Lead Absor pt i on. A.M.A. Archives of Industrial Health, Vol . 12, pp. 396 f f . , Jul y- Dee. 1955. 19 6 1 001245