Document 4v6k19rBMp4YX93BJBvXxknK1

LEAD TETRAETHYL ) ')P' /iw, * .5 /> / KE 001055 C 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. ---- rvio-- -- I) M/U<LTaCTURING, BLENDING WITH OT?!ER INGREDIENTS Wifi PACKAGING; a) Manufacturing Plant end Equipment: - Hygienic Ann?ct,- - The deir;n :+nz CQli** truction of buildings and equipment for manufacturing op?ration IS ' j fur the most important factor in determining the degree of safety associated with the manufactu re of lead tetraethyl. Other measures of control have bo-on found nec'/rcary in order tc obtain satisfactory results,but it must be recognized os r. first principle that no amount of caution and no amount of nodical and hygienic supervision con possibly modify significantly the basic conditions of lead exposure which arise from the cha racter and quality of the equipment. The oily liquid ,ljad tetrrafhj 1, is sufficiontly volatile at ordinary temperatures to give rise to acute danger of death from, its inha lation. Fatal poisoning can result from exposure for half an hour or less under suita ble conditions. The compound is also capable of fairly rapid absorption threap': the he&lthv and unbroken skin,so that all contact with tbo skin rust be avoided. Therefore this material must be kept and handled in closed pipes and containers. This is difficult to accomplish since ths liquid tends to creep along a surface v/ith which it is in contact,and if there is the slightest opportunity,it 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 lead tsttaothyl occurs in the vapor state,,.nd at times under pressure. In such a stats it is even lore difficult '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 typ8 most commonly used in tne chemical industry are quite unsatisfactory for handling lead tetraethyl,for leakage is absolutely ine vitable. A vertical,cylindrical typo of pump,in v/nicn there is e revolving shaft with a pecking gland at the top only (which must always 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 no agitators vhioh penetrate their shell. All such 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. r -2- Accordinglyevery 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 levelo 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 load concentration in the air 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 linesi- (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 within 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 3hould be cared 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 v/ith 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 equipmentrequires 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 necessarytherefore, 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 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 air-line hose masks must be provided and must be 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 outsider, 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 m 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 a s to ascertain the extent of the lead contamination and to keep it under control The disposal of Plant wastes:- All sra&'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 -way 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 volaiile 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 packaging. 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 00105S; . -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 v/ith 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 b3 moved by gravity flow so far as possible,but mixture must be 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 which can be taken towards this end is to send the product out of a plant only in such packages as can be used safely at their destination. The distribution of small cans of such' a product is an inevitably hazardous procedure because of tho 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 Ine -./eight of the liquid hie likelihood of breakage of the oon- tainer. The distribution of any quantity of lead tetraethyl or its concentrated mixtures to irresponsible or uninstructed persons would be an act of carelessness and negligence. Not only is the uso of numerous types of containers (especially small ones) dan;erous beyond the limits of the manufacturing plant,but it liso unnecessarily hazardous within the plant, 3*fety 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 bo kept at a minimum. Moreover,the 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 laud 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,the 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 musj? be handled wit'n highly specialized and thoroughly ventilated equipment if they are to be done satisfactorily and safely. Before a/iy drum-is to ( -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 made 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. C7-.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 f illness among workmen be recognized and identified,if there is to be effective medical control based upon a proper degree of mutual confidence between the 'workmen and tne medical staff. It is not enough to bo 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 go the and attention slip-shod of the workmen. examinations or bTyhesceerttahiinngsparcatninaoltlybespaeccicfoimcplilsahboexd'atboyrycuriast-oo,4rt-yP-j cut only by careful and regular study of each workman. In these occupations each workman who is potentially oxposod 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 men 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 3 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 basopnilic granulation, ("stippling" ), The teeth and gums should bo examined for sponginess or congestion and for the presence of a lead lineespecially on the inner aspect of the rums opposite the molar teeth The strength of the grip of eacn hand should be deter mined anc recorded. At least once a year each man must have a complete and detailed physical examination,including a general neurological examination. c -d- 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 bo 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 sigr.3 of arteriosclerosis; 4) Yfhcn they have organic disease of tha nervous system,a history of epilepsy, or of functional disturbances associated with mental instablity; 5) y/hon they have active organic disease of the kidneys,liver or lungs; 6) When they have other wall-dafinad 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) When they urn excessively addicted uo the use of alcof.ol,or- when because of ignorance,stupidity,undue approhsnsivenesa or other evidences of unreliability, they are unsuited to onoloyraent in a potentially hazardous occupation; 3) When they are less then 21 years of age or more than 45 to 10 years of 'Jen who have been sccaptod for employment should be remover therefrom; 1) hen they develop symptoms suggestive of lead tetraethyl intoxication; 2) Vhen they develop physical signs and laboratory evidence*:? of significant lead absorption; 3) When they develop organic disease, which, in the mind of the examiner invol ves undue risk to their safety find that of others; 4) When they show a cars less or .irresponsible attitude toward the hazards of the occupation, or sitornately,.? ,en they enow undue anxiety respect co such hazards. Excretory Analyses - Determination of the rate of the load 'sxcrotion of represen tative workers portrays an highly accurate picture of the conditions of load expo sure to vrhicr. they are subjected. The interpretation of such resulss cannot ta discussed in r.r.y detail hare but published information on this subjosi is available* Under hazardous conditions of excloyment such as those dealt .-ith herein,in u.doh brief exposure to high concentrations of load vapor can give Vise to prompt and serious effects,adequate hygienic contrcl cannot certainly bo maintained ritheut such deterntinatiens. ihs methods employed ir; the collection of saaiples anu in their analysis must fcsva tlx; utrcct precision to be of value, f'vl tnoroiVr* :ruzt be vorksi out and applied with great cars. This work can rarely if over bo dona wit via the K 0010558 c manufacturing plant*but should be carrioddout elsawhere in order to avoid tha contanination of samples from the plant environment. In addition to the control analyses referred to aboveaccess to analytical data on the blood and urine,in nuspected or doubtful cases of intoxication,i3 of the greatest practical usefulness. Facilities for obtaining such data arc absolu tely essential to sound clinical work in this oecupo.iiontin viaw of the necessity for the prompt interpretation of sympkowB, Critoriu based on broad s;cpaxianco in the application of analytical findings of t(9 type referred to nbevt* *vav been set up es practical rules for the guidance of plant physicians in evaluating the significance of the occupational load exposure and also for the handling of individual workman under & variety of conc;itions, lb nuut bo rrmu-.boron in relation to those criteria,that thy analytical data on which they ars based wf.u of s very high order of accuracy. The case critoria cannot be applied at ail to analytical ate that are appreciably less accurate. Moreover,it should be stressed tnat it is a useless waste of money and effort- to perform any of the&e uiuiiycea unless the methods of campling and analycis era such as to yield dependable and highly accurate results, Safe versus d ;arout! :o.tcj-i-ivr.a o i o c oupt-ti o n a l l ead sxr-osu re i n term s o f J.VviCi^A i.<Lt c-ii_Lhw _wC6o end urine of regularly employed vertw.er.- - "1t<r in halation of air containing lead fumes and dusts results in the entrapment of a considerable proportion of iaeee lead compounds in tne upper respiratory tract, from which tfcsy gain ontranee to the gustro-enteric tract by being swallowed uitii tr.a nasopharyngeal soc/etions, for this reason the collection and analysis ci representative ample of the regular {daily approximately) fecal evacuations of iX *x*5 ci vuen engaged m vie several occupations of ;rads will give highly valuable inforration no to thy magnitude of the exposure to load dusts. that is associated eiin these occupations. In this connection each sample vill rovsal tna amount of lead (leas 10 per cent .more ox- lima j that vac cwulicked by the individual in iyusation during the period of tine represented by the oamol. nov;over,the status of the individual eith respect to Rfoeorbed lead ill not bo shown by this means. On the other hand the analysis of a representative cample of urina aspoolally when coupled ith that of a sample of bloodwill give a very clear idea of the magnitude and hygienic significance of the lead that has been absorbed by tha individual. The combination of the information obtained by ths analysis of boin faces and urine,-si11 shorn ths severity of ths exposure to dust on a particular occasion and the general significance of the exposure up to the time of the analyses, when this ia dona on a sorioa of individuals representing nil of ;ho occupations of a lead industry,the location end overity of the dusty exposures ua well as the overall oagaitude o: vne ana uoeorpticn *ro~ t!laU and other types of exposurecan be seen clearly. It cats be said ir relation to analytical data of this typo that: 1) Whan the noun focal JLesd excretion of the group exposed to lead dusts end furr.os is .consistently oi the order of magnitude of O.DG mg,per sample {upproxiratel/ 11 hours) or leas ,f..a cupouure t<> dust and .funeo (hut not to vs:pnru) is wit.'i.-.v. at'ia lonctoj Z) Then tha naan focal lead -excretion of 3uch groups ia above 1.00 fag.per 24 hours,ho exposure io dusts and fumes is definitely hazardous; KE 0010559 c "> -- 3) 7/hon the mean. urinary lead concentration of an occupational group in a plant is not in excess of 0.10 mg,per liter the lead exposure (all types) of the entire plant is within safe limits* 4) When the mean urinary ler.d concentration in any occupational group is in excess of 0,15 ng.per .litrecases 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-5, 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 workman whose symptomatology or whoso hygienic status is in doubt for any reason. For this purpose analysis of Efemple3 of urine and blood,taken at the same tire,ere invaluable. Analytical results on such samples should be obtainable 'itliin a few days. Criteria for 'he interpretation of such data and for determining .feet should be done are recommended, Their correct application is dependent to some decree on experience end expertnsss iu tne recognition of the subjective s^tuptonia and objective signs -of lead tetraethyl intoxication. To core extent however*?X3 ?aay be apparent,they ray b? accepted iu lieu of such clinical Vnowledga end judgment. (lid a1`allC3 UEC jHjH rii1 to. microscopic blood exa,-ainations,huitt it must bo SiUpha- sized that such Qz&xd. exposure to load totr in oonneat ion rith the case of the56 men wiicsa work brings then into exposure with mstellic lead and inorrunic lead compounds, Actually the rise to E bOoally different set of symptoms,physics! signs,and laboratory findings from those associated with the Wbtorpt!on of inorganic lead compounds, Therefore,no stippling is seenand insofar so absorption of lead tetraethyl is concerned there will be no chronic lead poisoning as we know it clinically. Therefore,the doctors will have to be prepared for the recognition of a. totally different, syndrome of intoxi cation, For this reason the regulations should not put tress upon blodfi exami nations as a means of recognising lead exposure. On the other hand,it is certain that no cne will be able to operate n lead tetraethyl manufacturing plant without careful measurements of the Magnitude of the lesd exposure either by noons of comprehensive and frequently repeated air analyses or by a.wall rsgulated system of following the axpesed personnal by uear.s of analyses of their urine cr.d blood, the urine and feeas,or all of these materials, There is no question about the roluliva importance of follovdng ths lead absorption r.nu excretion of the workmen as a control raeasuro. From the medical point of view it is the most important single feature.) '/hen analytlcrl data are available on persons with symptoms 1) The symptomatology shonl-d be interpreted in complete independence of the ns Xytical results in cn effort to arrive lie*1.]. one uc-.cn. nuking '.,,so of any ar.c. every avr.ilu.blo diagnostic procedure for that purpose, Z) then ths clinical symptomatology is non-specific in character,in the case of non -ho have been working steadily up to tho tine the sampler: v/or9 obtained for analysis,o cause snd effect relationship between lead absorption and the present illness can bo excluded,when a) the results on a sample of blood and a representative sample of \ -9- of urine ore within safe limits as herein defined,(i.s.,less than 0,06 rtg.Pfc par ICO grams of whole blood,end not more than 0,10 rig. IJb per liter of urino);or when b) the average results on a series of spot sample's (approximately 100 ill,) of urine or on at least two largo samples (several liters) of urine are within safe limits aa defined above, ` 3) A cause acd relationship between non-specific symptoiBaiology and lead absorption my be eseumea to exist 7.nsn u) other cause; for the syaptoiaaiology have been excluded beyond reasonable dcubt ,rmd the enalytical resuita are above the s&fo iitdts dofined above:or when b) the cause of* symptomatology is quite uncertain and the <%alytical resails arc `ithip a dangerous range,i,e. - G,07 to 3,10 ag,Pb (or core) per 100 grairs of whole blood,Glo to 0.40 we.I'b (or more) par liter of arin.o, 4.1 y cciuse : rpls.tiar.abip hettrear strongly cuy^cstire or ihcraci^ria- tie symptors vac lend absorption may bo assumed to exist,nor, u) the xruiiyM cnl results are within the dsr.gerouB rangejor hen u) che av:1yticel results are known to have boon within the n^erc-.u; ra.ngh at the onset of syjnptorsaiology and at lha tins -;n occupation-.? ?.e.sd exposure v*ss occurring. (Thin refers to a sai -.?Sio hua beer. repived from bh w/poaure from owe vrooks -shea* crater/ r?jt *if.3 nbtts'l ,but whoa symptoms pains1st. 1 '`-"ren analytical air. .ro eyoi labia on snployod ~-rrorr yithoufc syeipfeoaa or abjective gjma' of illresg. ~ X) Asymptomatic p*rcns should he roraovod iYc.n; lend expor-ure or tranrf--.rred to work involving gr*-fctlr reduced exposure ,-rhi.n o.) thy analytical result a on bioor* tnrl urine are vd-thin dangerous liiviisji,,rK>re than 0.07 rag.Fo per 100 grama of whole blood,and more ikar. 0,18 ssg.Pb per liter cf urine;or v>hgn t) the analytical results on v. series cf spot samples of urine or on two largo snmplos of urine are viti.in dangerous limits as defined &'*.>vu. "beP remonn previously- removed fror -xt o cure or tre-r.gf>rrac* -,,o oth ir vorV have recover,<1 from a31 ryno toes and ai-rna oi illnasa.x/ 'ay ho returned to thoir lbrnar work -whenx -} l'.\s conditions originally responsible for their hazardous exposure have been recognised and substanttally corrected ;an>! hen b) the analytical results have fallen to levels that aro consistently safe,i.Q.,the lead concentration in the blood ia dovm to 0.05 itupar 100 grams cf whole blood or .lower,and the average urinary lead eoncen- V - 10 tration of a series of spot samples or of two large samples at least* ig not in excess of 0.10 mg.pet' liter. Plant supervision - The plant physician should mite a critical inspection of the plant under operating conditions at intervals of approxirsataly one monthtat which time he should criticize all the procedures and recommend such changes as ere ad visable for the ?aaintn;iRco of safeiy. Air analyses - Kquipcsent should ha available and operated regulf rly to last the air of all vorkin~ spaces for its lead content.. A high decree of accuracy i3 necessary both in the collection of samples and in the analytic procedures, and the net hods must, he such as to dotermine both organic and inorganic lead compounds and to distir.fuish between them -*hn this is rocsscary. All the data referred to above should be reported to the physici an-in-onnrge and should be used by hin to keep himself p.rd the management fully informed as to the higienic r.tutue of the plant as r whole Clothing.Protective fHHinv^nl .end X'ashrcom Feci 13ties - .d^ovefe fiei titios for the protection r-i cicanlinoss of th? vorkreen mv.rt fa -at?: r.vr-i 3able. 'loch -r-r rurt be provided with complete clf:-tfcinr*eo that he su-y nottur>dar cry circurri:?'$ear,neke use of hits regular cJoining in th** pivot. "here roust bo a sysTem of .loubLs lockers, and comfortable and adsquat washrooms shower huiho and toilets. 1 the beginning of the day's v/ork the -,.orkv.n r.ust chnnye int^ r <>i;;JLng, II l-vnc/.-rir:> t h / must wash cnrsfuJly v.nd n-t their lunch in n cl;;,,n lurch rrem* _\t ire i%r\ i of the day they n;;r;i rsr:nvs all fheir c thf.nr,bat he m l c;-.F.rr~o ii.zo :hc:ir c. r. e3o(i:A,:y. The proper arrnnrernnt of thoee fuel] .ties oill rot only ...11 *.r. tl.~- ..illir.gn-ee of workmen c.o comply with the r;?ultt3ons,but also ill provide for ouen r.i.pervi- sion as will not permit CHroleasnofcs on the part of the workman. Imparvioun rloversduot rv sks rhero required ,r.nd air-lino xankn e.e m--ided b-*-t supplied end rsr.ifrr.ni.nod in atisfuetory sondii.ion by ihc ._.>v--.-;*:i of the plant. Their use rust alro be supervised. II ) The spiiiagfi in transit of load t&ir-icihyl or of " : xtjir*~c containin\ high *orr.*mtra tions of lead tetraethyl may ecu- serious difficulties,in that ranr/sron- xpooura may involve crrriors as ,,rll oli-er pr.r-uons ,.lr* -K-y havo no xn-tcr.lrdy-e of the fin gers and no rooena of protecting t:solves. >r-*ver,nt:;vr co-modit i-n **vy bo .m coniordnoicd as ro o_use .be '"de-o\ir'-idon n/ r-.?):"=r 1 ; *-. rrr:ot- ryT)ors. The utmost enro rust bo rxorcirod ',r, oonfirn the hosarda to points nt which tuny can ba controlled. Containers fiiiod '.vitb 3 t`-trv*thyl >ith oorc-rntr-oted :aistur3 of loiul tairaothyl,',vhen shipped by rail should bs s?:ured by su.itr,,hja Penns c*c as not to .'.eve about in trannit. They should not be mixed with other cargo but should be sent direct from manufacturer to destination su$d r*iiould ho handled at b<ith ends of the trip only { ** 11 - by trained and experienced parsons, when transported by water,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 placsd that further leakage will not occur, vary practicable safeguard should fee thrown around this phase of tha 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) BISSDIHg 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 tha 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 plantdescribed below,and the drop in pressure accross this eductor creates a vacuum which draws lead tetraethyl through a stand pips in the drum,into the gasoline stream returning to the risixing 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,where 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 the 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 plant* 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,mouth,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 )( 0 0 1 0 5 6 3 - 12 - present on the platform while & drum of load v*trstbyl in open. Th 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 mixing ia a general factox* in determining i'm extent of exposure of workmen,the nvusber of saxes is usually limited to six g-sr month. After each operation,the sen 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 iamsdi&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. edioel control - 11 men engaged in blending operations should be examined by a physician at least every f> isonths. The type of examination should he as described in chapter (l) - iaiJUFACTURlNO,BLSKDII '3I7H OTHER IJ50RSDISTS Ub I*ACKAGISG - Clinical Work - but there is no need for examinations of feces and urine. The analyses of air ia the plant is also unnecessary. IV) DISTRIBUTION OF GASOLINE OOKTAlNIHG AD TFTRRRTHYL Gasoline containing lead tetraethyl in the concentrations permitted,aa detailed below,has been distributed practically all over the world for between 15 and 20 years. From time to time over this period of year,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 among persons whose work involves skin contact with such gasoline,or exposure to it 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 studios have been published in oedicel literature,and are 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 Denmark) have been in agreement. The status of the problem is outlined in tbs following paragraphs for 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 l*sad tetraethyl. Soiaa few cases of poisoning from decomposition products of lead tetraethyl have been seen among men employed ia cleaning gasoline storage tanks that had been in prolonged service. This type of exposure is wholly different from that arising from handling gasoline, and is dealt with separately). 2) Ho evidence has ever been obtained that contact with commercial leaded gasoline tffe 0010564 \ - 13 or exposure to its vapors,results i/i actual lead absorption,even among severely exposed persons In fact,nil the evidence demonstrates that laud tetraethyl in high dilution in grsolino (one part of lead tetraethyl to arout 1,000 parts or mono of gasoline) is not absorbed through the shir, in measurable amounts,even though large shin areas be in contact with gasoline repsate?.-!.y and for long periods of time Moreover,chc boiling point of load tetraethyl is so much Higher than that of gasolinethat cere than ten per cent.of the gasoline can eo tveporat?d before measurable ;usncities of lend tetraethyl cone cif in the vapor of leaded gon olinc. 3) from Time to time certain suss3 of carbon monoxide poisoning and scute gasoline intoxication (from the inhalation of vapors) have been raistankonly attributed to the effects of lead sbsorptio.u by laymen,only to be recognised subsequently by physicians in their true light* This has occurred bcaauss persons who have heard of tho early cases of poisoning from exposure to the concentrated lead tetra ethyl",lave continued to confuse the real clangors of exposure to the concentra ted product,with the purely hypothetical possibilities of exposure to co-veroial loaded nsolinc? 4) "ises o:''skin irritation of a variety of i, pus have also benn i-aatakenl;/ attributed to the xdnubo load content of gusoline. Invnnilgai.ion das shown tnat gasoline itself is much tor? irritating to ;.hs shin than sro the ingredients of leaf t?t r:ethyl ,s;m it h~r. further ba~n lex-ore:rated Vv.d curtain products of vapor rhaso -rid cThrr tyre of tmcoilnr'' ..r--. upcoiuI.W ii -.1....Lay .c she dim of susceptiol-s parsons, Iii view of these faces,the precautions required for hand ling and dio ve.iaiu-r, cu;.r- m*rci?.i loo.'isd gasoline,diffsr from cno.ee necessary in cue oaso of ^r-iin-.ry -asc iino or.l; in the folio-in-/ ".p^cts s (1) v-uo cncr.'.traii:no oi' i-jed ".' ...> line mi; not exceed chr-.e imifcc .-nice, s.-:nor.arcs coo o m :o L-- a. ; h.^.o -a;, of load tetraethyl psr iitor in automobile fuel,ani i,~f co.1 .-- d i ~;r liter in certain seromiuticil fuels>; (;) tar .gasoline i t h coloured .c fiffemntiate it from ordinary gasoil.e and containers uro oiripu.o.jiijg .,,a .dt .vat must bs labelled to sho-v toat it contains lead nrxl taut it is deaiy.ru- fur :nv r:s <i motor fuel only. The reasons for chose oi-cviviona arc 1 irl; obviou;., iv;' concentration of load in gasoline is u-vfl.nitviy vi.:> .act A i.t f.-.ct..r of " safety against load r-bsorr.ion. t-d-a ooncentraoion, tx...refo!o,;rusi. bo within propsr limits The differattiiation of leaded gasoline from other gasolines is advisable in order to insure lie use for the purgea3 for which it is intended, one for which it is known to be noth safe and useful namely,us a motor ihicl. Its use for other Purposes such as for cleaning tools and clothing and as s. fuel in stoves and lamps,is unnecessary,inadvisable,and perhaps unsafe,alt hough no cases of lead poisoning have been found a the result, of ouch misuse of the product. Any other rrticnpta to regulate tho manner of handling leaded runolino wust no-,? be regarded as '."holly unnecessary Ir. fnct the irvss iigo.tions r.vA the. experience of the past 13 years have given no evidence of tl.o exi stereo of danger fro.- the nor mal handling and use of leaded yasolire greater thru that associated ith the corresponding practices in the case of oleins ry nor.-lended uasoline. V) 0u:AMI i-G OF T t i l t s U f Ji: p e r; l l f l l l l CJh SlLI Fh -*5.TK T-gAl! ,, y k T ih JiT lf : L .1:1- STCICM.Cj .GCLI f ?; " r O W M l-V k l U i:AD TTITK.Uf'I.yb.- One of the greatest hazards connected with the handling o.f gasoline containing 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 operational 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 lias 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 raaterials 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* B) 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 the clothing gets soaked with sludge,the workman must bathe at once and put on clean clothes* At the end of each day and after the job has been completed,respira tors,boots,gloves,and tools mu3t be thoroughly cleaned. Before taking any meals, the face and hands must alwa^y be washed and clothing must b3 changed if inspection show3 that it is badly contaminated, E) Sludge or scale is dangerous to handle,even after it has been taken out of the tank. It should be kept wet and buried at once,in a place where it will not be uncovered later, PIPE LINE OPERATIONSt-- Storage tanks employed in connection with the pumpimg of leaded gasoline through trunk pipe lines,such as Surge,Belancing,or Settling Tanks, etc,are subject to the above regulations* Deposits which may periodically be removed frcm separators should be burisd promptly whilst in the wet state Similarlywhen renewing the charges of filtering medium in separators,the old charges should be disposed of promptly by burying, PRECAUTIONS FOR RBPAIR1SSN:- 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 (r remain or 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 tanks 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 these tanks,or on any component thereofmust 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 W A G G O N S The 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 lead fames in hot work,by the wearing of suitable masks. Goggles should also be worn during the performance of such work.