Document kDYV0abmJDyZYzakr52R0YKdB

! /" HE 001055 V \ 5) .:.-; ,;Vvv ;-r?^ I ' -* LEAD TETRAETHYL Thi3 memorandum deals with the hygienic require ments for the handling of lead tetraethyl in con nection with the following operations: I) MANUFACTURING,BLENDING WITH OTHER INGREDIENTS AND PACKAGING. II) TRANSPORTATION. III) BLENDING WITH GASOLINE. IV) DISTRIBUTION OF GASOLINE CONTAINING LEAD TETRAETHYL. V) CLEANING OF TANKS USED FOR MIXING GASOLINE WITH LEAD TETRAETHYL AND FOR STORING GASOLINE CONTAINING LEAD TETRAETHYL. --.-.-.<->00--*-- I) ma n u f a c t u r in g ,b l e n d in g w it h o t h e r in g r e d ie n t s -t ip p a c k a g in g ? a) Manufacturing Plant end Equipment: - Hygienic Anpacts - The d'-nigrt and cons truction of buildings and equipment for mcnufi-.ntuHng op?rations is by fur the most important factor in determining the degree of safety associated v/ith the juamsf&ctu- re of lead tetraethyl. Other nr-asuros of control hove hoe found cur}'- m ore si tc obtain satisfactory results,but it must be recognized as r. first principle that no amount of caution and no amount of nodical snd hygienic puporvim3 on can possibly modify significantly the basic conditions of lead exposure which arise from tha cha racter and quality of the equipment. The oily liquid ,l.iad tetrrath>l,is sufficiently volatile at ordinary temperatures to give rise to acute danger of tooth from, its inha lation. Fatal poisoning can result from exposure for half an hour or loss under suita ble conditions. The compound is also capable of fairly rapid absorption through the healthy ar.d unbroken skin,so that all contact with the skin must be avoid ed# Therefore this material must be kept and handled in closed pipes and containers. This is difficult to accomplish since tho liquid tends to creep along a surface v/ith which it is in contact,and if there ia the slightest opportunity,!! escapes from the joints of the pipes,pumps and storage tanks. The methods of manufacture also involve chemical reactions and separatory processes (distillation,etc.) in which load tstimathyl occurs in tho vapor state,,.nd at times under pressure. In such a state it is even more difficult J o prevent leakage. All the equipment employed,such as reaction vessels,distilling apparatus,pipe lines,pumps,separa tory tanks and storage tanks must be constructed on precise specifications and with the highest quality of workmanship. Pipe-joints should, be eliminated by employing welded construction wherever feasible. Sight-glasses,which are required in certain pipe-lines in connection with several operations,are a potential sowree of significant leakage and must be specially constructed so as not to leak or be subject to breakage. (The customary type of sight--glass leaks regularly and continuously.) Pumps of the type most commonly used in the chemical industry are quite unsatisfactory for handling lead tetraethyl,for leakage is absolutely ine vitable. A vertical,cylindrical type of pump,in v/nich there is a revolving shaft with a packing gland at the top only (which must el^ays be above the liquid level of the material being ramped),is satisfactory. Because of tne slight leakage of vapor at the top of this pump local ventilation must be employed so as to carry away all vapors. Reaction vessels or other apparatus may need to be equipped with certain moving parts such as agitators vhich ps-oIrate their shell. All ouch vessels,regardless of the excellence of their construction and maintenance,will inevitably leak at stuffing-boxes or packing glands unless they are carefully inspected and maintained. If badly designed and constructed,they will leak profusely. 001055 r --2** Accordingly*every effort must be made to obtain the best of workmanship in the construction of such vessels, Even so,it is advisable to apply unit ventilation to these pieces of apparatus,to such an extent as to maintain a safe atmosphere around them. Avoidance of Exposure to Vapors and Liquid Lead Compounds -- All parts of the manufacturing plant in which liquid lead compounds are produced and handled must be carefully ventilated to such degree as is necessary to maintain the atmospheric lead concentration below a toxic level. The lead concentration in any part of the plant should not be permitted to exceed 2 milligrams of lead per 10 cubic meters of air for more than very brief periods,and the basic concentration of any point should not exceed 1,5 milligrams per 10 cubic meters. The lead concentration in the a;`r should be determined regularly by precise methods of air-sampling and analysis,so that there may be no conjecture as to the actual conditions prevailing in the plant. It has been found that the ventilation to be efficient and uniformly adequate must be operated along the following liness- (a) Points at which small quantities of vapor may escape regularly or frequently from equipment must be locally ventilated by suction to avoid significant contamination of adjacent areas, (b) Fresh,clean air must be introduced into individual rooms and working spaces in all parts of the plant so as to produce complete changes with sufficient frequency to overcome the lead contamination from apparatus v/ithin such spaces-, and to maintain safe conditions as specified, (c) The air introduced into rooms or buildings must bo balanced by the withdrawal of air by suction fans, (d) Concentrated vapors of lead tetraethyl which regularly escape from the vents or stacks of operating equipment in the course of normal operations must be removed by accessory exhaust ventilation but should not be carried by general ventilating ducts,ie.they should be eared for by a separate system of ventilation, (e) The most rigorous care must be taken in locating the air intake and exhaust openings so as not to reintroduce exhausted air into the building through the intake ducts and so as not to pick up other objectionable or toxic fumes or vapors, (f) Residue or "sludge" removed from reaction vessels must be carried in a tightly closed line to a pit or receptacle which is.; completely enclosed and kept under slightly negative pressure by exhaust ventilation in such manner that the overlying vapors do not escape into the adjacent atmosphere. Reaction vessels,in which high pressure may develop,must be equipped with vents and also with pressure disks so as to prevent explosions within the building,if and when the reaction proceeds at an uncontrollable speed. Every operation in the manufacture and handling of lead tetraethyl and in the maintenance and repair of equipment,requires skill and training and also expert supervision. The repair operations,the removal of old equipment,and the replace ment of new apparatus are especially hazardous. It i3 highly necessary,therefore, that care be exercised in the selection and training of the plant personnel. Complete details of every operation should oe worked out and recorded as operating and safety instructions. Careful discipline must be maintained in carrying out He 0010554 c -3 such instructions. The men should be fully informed and instructed as to the dangers of their occupation and the means of protecting themselves against lead absorption at all steps. Emergency showers,with water*should be available in all parts of the plant where contact with lead tetraethyl may accidentally occur,and a convenient supply of kerosene must always be available at all such points,so that any lead tetraethyl which may come in contact with the skin can promptly be washed off with this material. Ordinary wash stands with soap,and toilet facilities, must be conveniently situated. Positive pressure sir-line hose masks must be provided and must b conveniently available for use in the several operations and emergencies which otherwise involve unavoidable exposure of lead tetraethyl vapors. Other masks,equipped with full face pieces,and with canisters containing not less than 500 c.c.of high-grade activated charcoal,must be available in sufficient number and at proper locations to be available for use in any emergency in which air-line respirators cannot be used,(as for example,in power failures,or in accidents resulting in extensive contamination of outsidi&air.) Control of exposure to inorganic lead fumes and lead-bearing dusts:- The handling of inorganic lead compounds in various stages of the manufacturing operations involves opportunities for exposure to fumes of molten metal,and to dusts of lead compounds and lead-bearing wastes and slag0 (Certain of these materials, such as sludge from reaction vessels,may also contain lead tetraethyl. Such materials,as indicated previously,must be handled with great care in closed equipment so as to prevent exposure to the vapors of lead tetraethyl and so as to avoid contact with the skin of 'workmen.) Exposure to the inorganic lead compounds must be controlled effectively at all times,and by means comparable to those used successfully in certain of the more commom dusty lead trades. Contamination of the atmosphere in work areas must be limited by suitable opera ting devices and by local exhaust ventilation so es to comply with the standards referred to above in the case of vapors of lead tetraethyl. Systematic analyses of the air of work rooms should be made at suitable intervals so as to ascertain the extent of the lead contamination and to keep it under control. The disposal of Plant wastes:- All ws&te materials from the plant,including exhausted air,fumes from stacks,waste water from plant operations and that used to wash down floors,together with all lead-bearing materials from reaction ves sels,pipe lines and other containers,must be dealt with or diluted in such a -,vay as to prevent hazardous exposure of plant personnel and all others,and so as to avoid the pollution of adjacent soil and streams. Materials and equipment which: are to be discarded should be destroyed,if possible by burning,and should,in any case,be freed of volatile lead compounds by being burned to a dull red heat in a bonfire under conditions which will not give rise to exposure to fumes and smoke on the part of the plant personnel or others. Discarded slag or equipment contaminated with lead compounds must be buried or so disposed of as to prevent harm to uninformed parsons* b) Blending with other ingredients and packageing. Hygienic aspects - The exposure to lead tetraethyl is of the same type in all other operations in which it is handled after its manufacture. If the finished KE 0010555 -4- lead compound is to be mixed with other ingredients,the 3ame precautions,in principle,as those described previously,must be taken to prevent hazardous exposure on the part of workmen* It is necessary that such precautions be taken with great care and under expert supervision. Since containers must be filled,the piping system must be open at the point where such filling operations are carried out. A filling booth or hood must be constructed in such a way that all vapors are carried away complete ly and all control apparatus is operated entirely from the outside* The ingredients which are to be mixed should bs moved by gravity flow so far as possible,but mixture must bs accomplished by agitation. Accordingly,the top of mixing tanks must be so ventilated as to prevent leakage of vapors into the rooms from the stuffing box around the agitator shaft. The containers for the finished product must b3 limited as to type and capacity to those which are capable of safe transportation and safe handling at the point at which the product is to be used. It is of the most hygienic importance that irregular and improvised procedures for handling lead tetraethyl and concentrated mixtures of it should be avoided. The most important means ,/hich cun be taken towards this end is to send the product out of a plant only in such packages as carx be used safely at their destination. The distribution of small cans of sach- a product is an inevitably hazardous procedure because of the difficulty of con trolling their destination or use. fragile tin cans containing sovoral liters of lead tetraethyl are dangerous to transport and even more dangerous -so handle, because of the -./eight of the liquid and likelihood of breakage of the con tainer. The distribution of any quantity of lead tetraethyl or its concentrated mixtures to irresponsible or uniustmcied persons would be an act of carslsssness and negligence. Not only is the use of numerous types of containers (especially small ones) dan gerous beyond the limits of the manufacturing plant,but it is also unnecessarily hazardous within the plant * Safety in the packaging operations depends fundamen tally upon the simplicity and uniformity of daily procedures. Irregular practices are likely to create new and difficultly controlled hazards and should be kept at a minimum. Moreover>th hazard of filling n snail package is as great as that of filling a large one,therefore the packages should be as large and as few as possi ble with due regard to the limitation of hazard in transportation and in other types of handling beyond the limit of the manufacturing plant. Drums employed for the shipment of lead tetraethyl or concentrated mixtures containing lead tetraethyl,should be of exceedingly strong and durable construction, with I-beams on which they can be rolled,and-with double bungs for the avoidance of leakage. Safety in the continued use of these drums will depend on the care -taken in inspecting and repairing them when possible end replacing them when necessary. After every trip to a consignee each drum must be cleaned thoroughly,inspected critically for corrosion,injury or weakness .and should be repainted. After being filled each drum should be tested for at least twenty--four hours by standing with the bung downward,and by carefully inspecting the seams for leaks. Such leaks will show up clearly on the freshly painted outer 3urfc-.ce of the drum,if the pro duct is highly coloured and if the drums are painted white or light gray. For this and other reasons,th3 product should be brightly coloured for purposes of commer cial handling. Obviously,the opening,cleaning and testing of returned drums are dangerous opera tions. They musjr be handled witVi highly specialized and thoroughly ventilated equipment if they are to be done satisfactorily and safely. Before any drum is to K 00:lQ'55o ( -5- be repaired it must be thoroughly cleaned so as to eliminate all volatile lead compounds and all but traces of inorganic lead compounds which may be suspended in the air by mechanical means or by local heating, General Hygienic Measures - The potential hazards associated with the manufac ture of lead tetraethyl are the most serious that can be found in any of the lead trades* They are capable of complete control if proper provisions are mode to maintain an adequate degree of precision and caution in carrying out plant ope rations, However,it is exceedingly doubtful if this can be done unless the most rigid and critical medical supervision is established and maintained. The ccntiol measures consist of the following co-ordinated types of hygienic supervision,namely,(1) careful and complete clinical study of all workmen,(2) regular study of the magnitude of the lead exposure and lead absorption of representative groups of workmen by means of periodic determination of the rate of lead excretion in the urine and fecsc,(3) regular periodic critical survey of plant activities and operations by the phy3ician-in-charse,and (4) regular determination of the lead content of the air of all rooms and working spaces in th? plant. C'.ir.ical work Hot only is it necessary to maintain a sharp search for clini cal evidence of lead absorption,but it is also imperative that all types of illness among workmen be recognized and identified,if there is to be effective medical control bao .pen a nrooer decree of mutual confidence b*1 worxmen ana medical staff. It is not enough to be cr. the lookout for sub jective symptoms of incipient intoxication,or to watch for changes in the blood of workmen,or to see the cruder evidences of lead absorption, It is also necessary to recognize the occurrence and character of non-occupations! disease see that it is adequately cared for or at losst it brought to the attention of the workmen. These things cannot be accomplished by cursory end slip-shod examinations or by curtain partially specific laboratory tints, but only by careful unci regular study of each workman. In these occupations each workman who is potentially exposed to lead tetraethyl should be examined at least once per month,while men whoso work involves exposure only to dust and fume of inorganic lead compounds should bo examined at intervals of not more than three months, (It is advisable to examine the mon more frequently unless and until it has been clearly established that the dangers of normal plant operations have been brought under adequate control,) At aach examination each workman is questioned carefully in search of subjective symptoms and other evidences of incipient illness, Ihi3 must be done without leading questions and without establishing a pattern of inisrrogation. The temperature,pulse,blood press ure,and weight should be noted and recorded,and the urine should be exami ned a3 to its reaction,and the presence or absence in it of sugar,albumin and microscopic abnormalities. Such other clinical study as is required to determine his physical status should be carried out,together v,ith an examination of his blood,including,at least,the determination of the hemoglobin and a quantitative determination of the number of erythrocytes which show basophilic granulation, ("stippling'*), The teeth and gums should bo examined for sponginess or congestion and for the presence of a lead line,especially on the inner aspect of the rums opposite the molar teetho The strength of the grip of eacn hand should be deter mined and recorded. At least once a year each man must have a complete and detailed physical examination,including a general neurological examination. # 0010557 c v An initial examination of a complete and thorough type should be employed aa the basis for the selection of an essentially sound and healthy operating crew. The results of this examination should be carefully recorded in the case of all men accepted for employment and should be used as a basis for future compa risons. \7orkaen should be rejected: 1) when they have had significant exposure to lead compounds in other occupa tions within the period of five years immediately preceding; 2) .Yhem they have had an illness associated with a previous occupation which is indicative or strongly suggestive of lead intoxication; 3) '.?hsn they have a significant degree of organic disease of the circulatory system,especially symptoms and signs of arteriosclerosis; 4) Yfhcn they have organic disease of ins nervous system,a history of epilepsy, or of functional disturbances associated with mental inotablliy; 5) Y/hon they have active organic disease of the kidneys,liver or lungs; 6) when they have other well-defined chronic diseases,such us oral or upper respiratory infections of a savors and potentially disabling type which,in the opinion of the examiner,are 'unlikely to respond to corrective Treasures; 7) then they aro excessively addicted uo the use of alcohol,or when bocuuae of ignorance,stupidity,undue approhensivenens or other evidences of unx*e.]lability, they are unsuited to onuloyraorrt in a potentially hazardous occupation; 3) 7/hen tht*y are less than 21 years of age or r.Tors than 45 io 50 years of ago. Man who have been escorted for assloynent should be i ?r o yea thorn arc: 1) yhen they develop symptoms suggestive of lead tetraethyl intoxication; 2) '.'Oner, they develop physics 1 signs and laboratory evidences of significant lead absorption; 3) *hen they develop organic disease,which,in the mind of the examiner,invol ves undue risk to their s&fsiy find that of others; 4) When they show a careless or i responsible attitude toward the hazards of the occupation,or alternately,whan they show undue anxiety with respect co such hazards. Excretory Analyses - Determination of the rate ci iha lead excretion of represen tative workers portrays an highly accurate picture of the conditions of load =xposurs to which they are subjected. The interprets, tic n of such results cannot ta discussed in r.r.y detail hers it Tp: ublished information on this subjoct is available. Under hazardous conditions cf employment such as tbsae dealt .-il !rua,i x.aca brief -exposure to high concentrations of load vapor can give Vise to prompt and serious effects,adequate hygienic control cannot certainly be ear intuited sitheut such determinations, ihs methods employed in the collection ci samples and in their analysis must have the utrcct precision to be of value,rud t norof or* :ruut be sorks-i out and applied v;ith great cers* This cork can rarely if over be done wit .tin the KE 0010558 manufacturing plant,but should ba carrioddout elsewhere in order to avoid the contanination of samples from the plant environment. In addition to the control analyses referred to asove,access to analytical data on the blood and urine,in suspected or doubtful cases of intoxication,i3 of the greatest practical usefulness. Facilities for obtaining such data are absolu tely essential to sound clinical work in this occupation,!^ view of the necessity for the prompt intr3>ret*.fc ion of syraptows. Criteria baaed on broad eccperianco in the application of analytical findings of the type referred to above :v;ve been set up cs practical rules for the guidance of plant physicians in evaluating the significance of the occupational lend exposure and also for the handling of individual workman under & variety of con ditions. It nuut bo rrraeiibered in relation to those criteria,that thy analytical data on which they ars based uf.u of a very high order of accuracy. The c&no cri teria cannot be applied at all "to analytical data that are appreciably less accurate. Moreover,it should ba stressed tnat it is a useless mate of money and effort- to perform any of thocs noblyvoa unless the methods of campling and analy sis era such ta to yield dependable and highly accurate results. Safe versus dangsrout; oonditieps oi occupational lead sxe-osur? .interms cf xiaUyUca^uat*, on .the _fyQoo ^d. urine_.of_.regularly,etjplpyed vpi^rcn. - The in halation of air containing lead fumes and dusts results in the entrapment of a considerable proportion of these lead compounds in tm> upper respiratory tract, from which they gain eutranee to ilia gustro-enterio tract by being swallowed uicji in* nasopharyngeal nocraiiona, for this reason the collection snd onelysis of representative sample* of the regular {daily approximately) fecal evacuations of a ceri.-,s cf van engaged in the several occupations of a trace will give highly valuable inforration na to thy magnitude of the exposure zo load dusts, that is associated wiin these occupations. In this connection each sample will rovsal tna amount of lead (leas 10 per cent .more ox- loan} that was svatllowed by the individual in question during the period of tine represented by the canal. Ho;;over,tJio status of the individual eifch respect to absorbed lead %?ili not bo shorn by this mean. On the other hand the analysis of a representative cample of urina especially vuian coupled ith that of a sample of blood,will give a veryclear idea of the taagnituda uad hygienic significance of the lead that huz been absorbed by the individual. The combination of the information obtained by the analysis of bain faces and urine,will shoe the severity of tha exposure to dust c-sx a particular occasion and the general significance of the exposure up to the time of the uxiulyaus. whoa this i3 dona on a morion ox" individuals representing nil of cho occupations of a lead industry,the locution and severity of the dusty sxpouuroa ua toll as the overall oagniiude of trie land absorption froci this and other types of exposure,can be seen clearly. It oats be said in relation to analytical data of this typo xhnt! 1) Whan iho noun fecal lead excretion of the group exposed to loed dusts end furr.es is .consistently of the order of magnitude of O.hO tngper sample {approxi mately 11 hours) or leaaft.*o .tapoaura to dust and funou (hut not to v:pnrs) is y. i t i iv. a a ff> li ::.L1 a 5 Z) then ih-3 naan focal lead excretion of 3uch groups ia above 1.00 mg.per 24 hour-J,the exposure io dusts and fumes is definitely hazardous; KE 0010553 c 3) 7/hen the man urinary lead concentration of an occupational group in a plant is not in excess of 0.10 ffig.per liter the lead exposure (all types) of the entire plant is within safe limits; 4) Y.hen the mean urinary lend concentration in ?my occupational group is in excess of 0.15 ng.per litre ..cases of lead poisoning can be expected to occur in that group,and their frequency and severity will be the greater,the higher the mean urinary l3*.d concentration goes above this level. In addition to the application of criteria given above for the interpretation no-s. of the status of individual workmen but rather of the conditions of lead exposure in the plant,it is important to have prompt means of determining the lavsl of lead absorption of any workmen whose symptomatology or whose hygienic status is in doubt for any reason. For this purpose analysis of samples of urine and blood,taken at the same tire,ere invaluable. Analytical results on such samples should ba obtainable within a few days. Criteria for the interpretation of such data and for determining whet should be done are recommended. Their correct application is dependent to s o t re decree on experience end expertness iu uiiS roc cgniii.cn of the subjective symptoms and objective signs of lead tetraethyl intoxication. To cons extent,however,ns may be apparent,they say be accepted iu lieu of such oliniual Vnowledga end judgment. (Reference bus be an made to. microscopic blood examinations,but it 'must be empha sized that such cxs.iiir.stior.s will be of no value whataoevei' in connection with exposure to lead totruothyl. They will be useful,however,in the case of these men whoso work brings then into exposure with metallic lead and inorganic lead compounds. Actually the absorption of lead tetraethyl gives rise to a totally different sat of symptoms,physical signs,and laboratory findings from those associated with the abtorption of inorganic lead compounda* Therafore,no stippling is seen,and insofar as absorption of lead tetraethyl is concerned there will be no chronic lend prisoning as re know i.t clinically. Therefore.,OiU. doctors will have to be prepared for the recognition of a. totally different, syndrome of intoxi cation. Tor this reason the regulations should not put stress upon blodd exami nations S3 a means of recognising lead exposure. On the other hand,it is certain that no cm will be able to operate n lead tetraethyl manufacturing plant without careful measurements of the magnitude of the lead exposure either by noons of comprehensive and frequently repeated air analyses or by a well regulated system of following the exposed persomsl by user.* of analyses of their urine r.r.d blood, the urine and faces,or sll of these materials. There is no question about the relative importance of following the lead absorption and excretion of the workmen as a control measure. From the medical point of view it is the most important single feature.) '/hen analytj.crl fata are available on pornons with symptoms 1) The symptomatology should be interpreted in complete independence of the analytical results in cn effort to arrive at a definite clinical conclusion, making uso of any ar.d every available diagnostic procedure for that purpose. Z} V-her. the clinical symptomatology is non-specific in character,in the case for analysis,n cause snd effect relationship between loud absorption and the present illness can be excludedywhon a) the results on a sample of blood and a representative sample of  9' of urine ore within safe limits as herein claflned,(i3,less than 0.06 ffig.Pb par ICO grains of whole blood,and not more than 0.10 r.~. Pb per liter of i*rino);or when b) th& average results on a series o.f spot sample-s (a?proxiasar,oi.y 100 i'll.) of urine or on at least two large samples (several liters) of urine ar-3 within safe liridta aa defined above. 3) A cause ai-d relationship between non-specific syaaptoisaiology and lead absorption my he ?*sund to exist vnsn u) other causes for the sytaptotaaiology have been excluded beyond reasonable dcuht ,rmd the enalytica.1 results **r above the safo litdts dofined above:or when b) the cruse of symptomatology ia quite uncertain and the analytical res alls ar? withip a dangerous range,i.e. - G.07 to 3.10 ag.Pb (or core) per 130 grvirs of whole blood,O.lo to 0.40 me.Pb (or more) per liter of arino. 4j jt csi'jB-i viid . ,,: r: 1. rbls.tSor.ehir between .strongly r.ug-s; stive or thereetcriafic symptoms t-nc lend sbucrpt.ion may bo nasuiaed to axiai,:*nen u) tbs ruilylionl results are within the dangerous range?or whan u) the crvrlytisel results ore kiiown to have boon vil r.:i the dai^orcra.ngo at the onset of oympboicaialogy and at lha time cr. occupation:--? le.sd exposure *C3 occurring. (This refers to a mu who bus boon j-erovad from b h exposure frorj *o>e v>c>ak$ ,'shes* ekcrotcry rr-te *if.3 abated "r~.?r-hrt ,but whoa aywptojss persist.) `-hen analytical dati. --re *vui ItCclo on onployod rrmore without, syapSoaa or objective glims' oiTineas. X) Asymptomatic p^rnens should he roraoved fre.n; lend exposure or transferred to work involving gr-fitly rv-dueod exposure ,wh&n a.) %hu analytical results on blood and urine are -rithin dangerous liiviisji.-?.,now than 0,07 rag.b psr 100 gram of whole blood,and nors than 0.17 ssg.Pb per liter cf urirssjor y>"km 1) the analytical results on v. series cf a pat samples of urine or on toe largo samples of urine are viti.in darg.crmro limite as defined a.hnvu. "he P rwrsono previously- rants vert fron Bxr-osura or tre-r.gf>rrAd ~.o clfnur vorV b?ivo recovered frcci a31 rv/notom and signs ox ilLnssnythe/ >vty he returned to their fernsr v?ork,v7henx the conditions originally responsible for their hazardous exposure have been recognized and substanttally corrected;an*! when b) the analytical results have fallen to levels that are consistently safe,i.e.,the lead concentration in the blood is down to 0.05 / ` g.psr 100 grams cf whole blood or .lower,and the average urinary lead eoncen- K 0010561 V - 10 tration of a series of spot samples or of two large samples at least, ia not in excess of 0.10 ng.psr liter. Plant supervision - The plant physician should ri# a critical inspection of the plant under operating conditions at intervale of approxiravtaly one month,at which time he should criticize all the procedures and recommend such changes as ere ad visable for the maintenance of safety. Air analyses - Kquipaent should be available and operated ragulrrly to last the air of all working spaces for its lead content.. A high He gras of accuracy i3 necessary both in the collection of samples and in the analytic procedures, and the net hods must, he such as to determine both organic and inorganic lead compounds and to distir.guish hstmeen then -*hers this is rececrary. All the data referred tc above should b* reported to the physic!an-in-?nnrge and should be used by hia to keep himself ard the maneverwwst fully informed as to the higienie r.t-vt-ue of the plant as r whole. Clothing, ifroteative LpnipvianiXashrcom ib.-ai 1 itig-r - ,d equate ficilitios for the protection ri cleanliness of the <": rkusn mv.s.'t ha r.vai 1 solo. 1'cch vertron muet be provided vd.th complete clotfcinr,eo that he m-y not,under sny aircurri :-7`-ce3,ncke use of his regular cJotiiiiw? in th*=* pleat. '.'here mur.t ho a sysrem of double lockers, and comfortable and adequate washrooms,shower butho and toilets, <-l {,!>.*> beginning of the day's v/ork the -,.orkvs. n ?\uat chunge :.nt a y x s r k -c 1 <>i;; .ing * 11 l,: no--t In; 1 he/ must wash cnrsfully ur.-d `-i:t the! r lunch in n cl nan lunch rrem, _\t t.-nv `--ni of the day thoy must rs;:RV2 all s-heir cnt hf.nr, bat he uni ejif.nyo iren :>cir o. r. c-,:y. The proper arrangement of thet-e fuel; infos oiil rot r.iu, ...11 *.r. t<. .- ..*il3i.r.:'n*3 3 of workmen c.o comply wit is the ra^ulat J ons , out also ill provide for sues ?up?r/.i- sion as will not permit caroleosnosa on the part of the rorkmsn. Imporvicun ylovn; ^c'nor. rv sks rhero required ,r,no' air-lino xuskn as n *!?;> .vust b*- supplied snd mr.irrr.-'tinod is: sat.Inflatory oonuivi'm by fha y* ;* :t of the plane. Their use rust also ba supervised. II ) The spillage in transit of lead tetraethyl or of "dxkurr.c? conini-.ini hip's '-no.nnr.ra tions of lead tetraethyl may eeuw* serious difficultleu,in thwt ranr/sreus exposure may involve carriers as ,,u 1 i olicr p-.r^ojts ,hr h-nm no kn-wr.lrdy^ of i.ho dan gers nnJ no :-:CER3 of protectins tne-vsolvoa, `or-wr/er, other cormodit v*n **oy bo so coutordnotcd as \o cause t'.s r'ie renin'it i or of s-'-'o j.r--r? :K?uvr r^rrot- r/y;i ons. The utmost care* rrusi to rxorcisod te oonfim the hazards in points at .vH'.on tivey can ba controlled. Containers filled rith ];-t-d i *-trvetbvl :-r -ith oor.o'Vro.fod rdxturcs of loiul totraothyl,,vhen shipped by rail should bs sacurod by su.Ur.hJa a'snns r*o as not co I'.ovu about in trannit. They should not be mixed with ether cargo but should be aant direct from manufacturer to destination itd onoul.d ho handled at b<ith ends of the trip only HE 001056? { ** 11 - by trained and experienced persons* .Then transported by -star,they 3hould bo loaded on deck under the supervision of fully informed and experienced persona, and should be secured firmly in place so as not to be damaged and so as not to be a source of danger in transit. Any of the material which Kay leak or spill on the deck of u ship or barge should be washed overboard promptly and any leaking or broken drums should be disposed of by being cast overboard if possible or necessary,or by being so placad that further leakage will not occur. Every practicable safeguard should fee thrown around this phase of the industry end to the extent that this coromodity ranuirea unusual care in transport,it should be incumbent upon the manufacturer and shipper to provide conditions compatible with reasonable safety* III) 3LENDING WITH GASOLINE Hygienic aspects - As in the case of Manufacturing,the design and construction of the blending plant,as well as the type of protective equipment usedjare by far the most important factors in determining the degree of safety of the operations. Lead tetraethyl should be extracted by vacuum from the container (drum) and carried by gasoline through a closed system into the mixing tank previously filled with the gasoline to be treated. In no case should lead tetraethyl,or any concentrated mix ture with gasoline,pass through any mechanical part,such as a pump,etc. Tha system which has been safely used for many years is to pump gasoline from the mixing tank and discharge back into the same tank. A venturi type eductor is installed in a by-pass located in the plant,described below,and the drop in pressure accross this eductor creates a vacuum which draws lead tetraethyl through a stand pipe in the drum,into the gasoline stream returning to the ssixing tank* The plant in which the by-pass is installed consists of a concrete platform,covered by a roof,open on three sides and completely surrounded by a kerb, - with a view to lo calising any leakage. The platform should be suitably graded to drains which should discharge into an interceptor,or trap,before passing into the main drainage system (or sea). The fourth aids of the platform - which should be large enough to provi de a mixing area,whsre the by-paao is installed,and enough storage capacity - nay be of solid construction to form one of the walls of a dressing room^to be provided for the operators. The dressing room should be equipped with a shower and wash basin, and a small kerosene tank should be installed connected to a tap over the wash basin (kerosene is used to wash off any fluid which may accidentally bo 3pillsd on the skin of any of the operators.) Water end kerosene points should be installed on the platform for the purpose of washing down tho platform after the raixing operation. Complete specifications of the minimus requirements of such a plant can be provided. The operators should change into special clothing while working in tha plants The clothing recommended,apart from underwear,consists of a white overall,acid-proof rubber boots,apron and gloves - preferably white - (Heavy clothing to be worn under the overall must be provided as needed.) The operators should also be supplied with a gas mask equipped with a rubber pace piece (preferably white) covering the entire face,eyes,nose,nouth,with eye pieces of splinterless glass,a rubber breathing tube, end a canister separated from the face piece,containing not lass than 500 cc's of high quality activated charcoal. This gas mask must be worn by tha operators whenever they are ^ 0010563 \ - 12 - present on the platfora while a drum of load tetrsaifayl if? open, Too canisters have a limited life and should be changed after 100 hours use or after being in service for six months. Since the frequency of fixing is a general factor in determining the extent of exposure of work&en,th6 number of saxes is usually limited to six per month. After each operation,the men should bathe before dressing in their own clothing. Should any lead tetraethyl have been accidentally spilled on the skin,it should be first washed off with kerosene,then with soap and water. Lead tetraethyl should be coloured so that any stain will be visible lamsdl&taly. It is emphasized that operations in the type of plant and with the type of equip ment described above have been carried out safely for about 20 years. Pedicel control - All non engaged in blending operations should be sxarainod by a physician at least ovary f> rsonths. The type of examination should he as described in chapter (l) - !&?&TAC?URIKG,BI3Ki)IKS '$1?H OTH&R ISORSmSTS AlsU ?.ACKAGlfJG - Clinical Work - but there i3 no need for examinations of feces and urine. The analyses of air i the plant is also unnecessary. IV) DISTRIBUTION OF GASOUNS G0NTAIKXM3 Gasoline containing lead tetraethyl in the concentrations permitted,as detailed below,has been distributed practically all over the world for between 15 and 20 years, From time to time over this period of years,detailed investigations have been carried out in the United States,and in certain other countries,,in search of evidence of lead absorption or load poisoning aaong persons whose work involves skin contact with such gasoline,or exposure to its vapors, Moreover,critical laboratory studies have sought to determine the magnitude and importance of the hypothetical dangers of lead absorption from this source. The results of both the practical field investigations and the laboratory studies have been published in oedicel liierature,and ora now generally accepted as feet,since the conclusions of various investigators,including official public health agencies of four different countries (United States of America - Great Britain - France and Usnaark) have been in agreement. The status of the problem is outlined in tbs following paragraphs fox* the infor mation of those who have not had access to the reports of the investigations, 1) Ko cases of lead poisoning have ever been found by investigators,or reported in medical literature,among refinery workers,garage mechanics,or other persona engaged in handling and dispensing leaded gasoline for automobiles or aeroplanes, (The only cases of lead tetraethyl poisoning that have ever been seen or reported have resulted from exposure to concentrated lead tetraethyl, Some few cases of poisoning from decomposition products of lead tetraethyl have been seen among men employed in cleaning gasoline storage tanks that had been in prolonged service. This type of exposure is wholly different from that arising from handling gasoline, and ia dealt with separately), 2) Ho evidence has ever been obtained that contact with commercial loaded gasoline 0 010 o 6 4 \ 13 or exposure to its vapors^results i/i actual lead absorption,even among ssveroly exposed persons, In fact,all the evidence demonstrates that lead tetra3thyl in high dilution in geaolino (one part of lead tetrr.othyl to about 1,000 parts or more of gasoline) is not absorbed through the shin in measurable amounts,even though large shin areas be in contact with gasoline, repsutec'.J:y and for long periods of time.. Moreover, the boiling point of tone tetraethyl is so mu^h nigner than that of gasoline,that more than ton per cent.of ins gasoline can oo tvaporst?d before measurable yuancities of lend tetraethyl cone exf in the vapor of is ad 3d g.-v a olino,, 3) from viraa to time certain c&sss of carbon monoxide poisoning and scute gasoline intoxication (from the inhalation of vapors) have been raistanknnly attributed to the effects of lead absorption by laymen,only to be recognised subsequently by physicians in their true light* This has occurred because persons wno have hoard of the nnrly cases of poisoning from exposure to the concentrated lead tetra ethyl", have continued t-i confuse the real clangors of exposure to the concentra ted product ,with the purely hypothetical possibility o o*. exposure to oo-mercial leaded rrasolind", 4) Csses of skin irritation of a variety of t. cos Iiuvo also bean Mistakenly attributed to the isinuts load content of gasoline. Invo-itigaiion has shown that gasoline itself is much tor? :i rri. bating o the skin than sro tho ingrodionts of lent lei r :ethvl ,trd it k~.-. further been dntor" : r.v.had Vr.-i carl.-in products of v'.:or rhtsc arid cl bar tyr-e of "ewe!: i.ra"' ..re trtv t'Uh-' i, lap .c the h in of suscsptiols pxrsons* Jr, view of these facts,the precautions required for hand ling and diu ve.iniii-, c*r* n-ercial loaded gasoline,di'Ter from tnoee neceoeary In tno ansa oi or-iir.-xy gaso line or.i,' in the follow in-/ "-- o-^ecs : (1) a-h :: cnc r at ru 11: as of 1-jo.d line T'Vi',* not exceed fhc-.s 'irate roico. s.-:oerivreo ore :. :Lu a...'; p.,^.0 to, of load tetraethyl par liter in automobile fuel,uni i,~0 oo.l-..-.G ...fa.;.. :. r :r liter in certain aeronautic*! fuels;:, (.;) the ptieolluc iruet hi coloured ;o (fifferantiste it from ordinary gusoii-e and containers arm uiripnroloo (if -vat must bs labelled to sho-.v tart it contains lead and that it is 103ig.ru- for : ns a motor fuel only, The reasons for these oroviuloita are il inly ehvJ -ue, lv..- concentration of load in gasoline it definitely eat ruct l. ..ua taut fadh.r e.f safety against load jvhsorntion, ,' Aa concentre-clou, thorefore,mus t bo m^iniaiau-i within prooar limits. The differentiation of leaded gasoline from other gasolines is advisable in order lo insure ite use for the purgoes for vhich it is intended, end for which it is known to be noth safe and useful,namely,as a motor fuel, Its use for other purposes such as for cleaning tools and clothing ar.d us s. fuel in stoves and lamps,is unnecessary,inadvisable,and perhaps unsafe,alt hough no cases of lead poisoning have been found the result - of such .misuse of tha product. Any other at tempt a to regulate the runner of handlin'-* leaded re-soli no must now be regarded an 'shelly unnecessary* In feet the invtcii.gat ions r.ntl the experience of the past 13 years have given no evidence of the existence of danger from the nor mal handling and use of leaded yaeolire greater thru that associated with the corresponding practices in the ce*e of o''cinf. ry nor.-1 ".edad gasoline. V) 1 U-'AMI-hG OF Tfl-TTi TklTT POTi MlllhC MOPTAIM'A? UiAD TkTi-.U/l'I.Yb.- One of the greatest hazards connected with the handling of gasoline containing 0010565 V - 14 - lead tetraethyl arises in connection with the cleaning of tanks used for mixing this compound with gasoline and for storing gasoline containing lead tetraethyl* Th9 following precautions have been recommended for the safe handling of these opsrationsi 1) STORAGE AND BLENDING TANKS - The tanks considered under this section include all storage and blending tanks which have at any time contained leaded gasoline* Tha regulations a3 set down are to be regarded as the minimum requirements for the avoidance of lead exposure* A) A blower-type or positive-pressure full face-piece airline hose mask must be worn by any person who enters a tank which has at any time contained leaded gasolino,and which has not been thoroughly cleaned* This applies not only to tank cleaners but to all others who go into the tank for any.purpose* NOTE; - Experience has indicated that in general the quantities of residual materials to be removed and the time of exposure are much smaller in the case of tanks of under 50 tons capacity. Preferably a full face-piece blower-type airline hose mask is to be worn by any person who enters such a tank,which has at any time contained leaded gaso line and which has not been thoroughly cleaned* When such a mask is not available a free airline mask with a breathing tube extending well to the outside of the tank may be worn* E) Hoselines for air maks have a limited life and must be kept clean* If a workman notices any odour such as gasoline while wearing his mask,he must leave th8 tank at once and find and remedy the cause* C) All workmen must change into special clothing,consisting of clean overalls, shirts,underwear (in cold weather) and socksjalso heavy rubber or acid proof gloves and rubber boots of good quality and in sound condition* D) Clothing must be changed (and laundered) and a bath must be taken every day, either at the end of each day's work or when the job has been finished* If at any time tha clothing gets soaked with sludge,the workman must baths at once and put on cloan clothes* At the end of each day and after tha job has been completed,respira tors,boots,gloves,and tools must be thoroughly cleaned. Before taking any meals, tha face and hands must alwa^y be washed and clothing must be changed if inspection show3 that it is badly contaminated, 3) Sludge or scale is dangerous to handle,even after it has been taken out of the tank. It should be kepi wet and buried at once,in a place vsrhere it will not be uncovered later, PIPE LINE OPERATIONSStorage tanks employed in connection with the pumpimg of leaded gasoline through trunk pipe lines,such as Surge,Balancing,or Settling Tanks, etc*,are subject to the above regulations* Deposits which may periodically be removed frcm separators should bs burisd promptly whilst in the wet state* Similarly,when renewing the charges of filtering medium in separators,the old charges should be disposed of promptly by burying* PRECAUTIONS FOR RSPAIRlSENt- Repairmen engaged in any type of work in tanks which have not been thoroughly cleaned must follow the instructions given above. If possible,all cold work should be done only after the tanks have been thoroughly cleaned* Attention is drawn to the possibility that dust or scale or sludge may 0010560 (r 15 - remain o r ledgos or projections in the tank,or may settle there during; the course of the cleaning oporations. It shall be the duty of the responsible person in charge of cleaning to seo that these sources of dust er vapor are removed so as to prevent exposure during any subsequent operations in the tank. Welding and other hot work should never be done until the tanka have been cleaned and all areas that may get hot are scraped down to clean metal* Work conducted on the outside of tanks or on any component thereof must be under taken under conditions of adequate natural or artificial ventilation,and in such a Conner as to avoid prolonged exposure to dusts,sludge,vapors,or fumes. This regula tion also applies to pipe-line filters and separators,eto. ) GARASS AMD FILLING STATION TANKS - Work conducted on the outside of theae tanks,or on any component thereof,sust be undertaken under conditions of adequate natural or artificial vantilation,and in such a manner as to avoid prolonged exposure to dusts,sludge,vapors,or fumes* If for any reason the tanks have to be entered,then the full regulations set down in SECTION (I) cust be followed. 3} BAIL AKD TtOAD TANK WAGGONSThe only special precautions required under this heading are associated with scaling or repair operations. Steps should be taken to prevent the undue exposure of workmen to lead-bearing dust in cold work ar.d to lsad fames in hot work,by the wearing of suitable masks. Goggles should also be worn during the performance of such work. 0010567