Document xj3JxeXvn3vYZGEB07QY9o8Jy

For Safe Use of BENZENE, TOLUENE, XYLENE THEcoss*r.\s-rLyCRO\\'ISC, STliE.\\I of m,\v product5 that flo\vs from research, and is t h r result of our rapidly changing tcclinology, is introducing potential hazards to those engaged in manufacturing and to the ultimate USCT of the product. As a result, possible benefits from our tcchnologic aclvnnces depend on development and application of control mcasiircs. In the case of tmic chemicals, for example, controls are needed to pre\ ent injurious or objcctionable exposure to the chemical, not only of the workman, but also of the user in industry, on the fann, and in tlie home. Toxicity is a pliysiological property of a substance, a measure of its ability to produce adverse effects when it reaches a susceptible site in the body. The amount of substance required to produce an effect varies widely with individual compounds, but in eiwy instance a specific amount is necessary before an injurious effect is produced. ConverseIy, there is a limit below \vhich no injurious effect is produced, regardless of toxicity. A hazardous exposure exists if the amount of toxic matcxrial is excessive, but a hazard can be prevented b y keeping the amount below injurious levels. It is on this basic principle that hygienic standards can be established to provide safe environmental conditions in industry. h safet). factor is an essential consideration in cstablisliing a standard. The magnitiide of the safeh factor may vary greatly depending on our knowledge of the biological action of the substance in question. If the potential hazard is great, if die margin bet\veen minor injun and scrious injury is narrow, if the injury produced is irreversible, then a greater margin of safetj- is required. On the othcr hand, if the margin between the incipient effects and serious injur). is large, if effects are readily reversible and good diagnostic procedures available to detect early changes. then die margin of safety can be small. The American Standards Association, as a result of Dr Sclirenk, Managing Director, lndristrial Hy,'aiene Forrndafion, Pittsburgh, Pa., is chairman of Sectional Cornniittrc 237, Alloirabk Concentrations of Toxic Dusts and Gase`s. 128 kvork by it5 Sc.ctiona1 Committee Z:37, has reissued revised r\mc,rican Stantlard maximal ncceptali, concentrations of benzene, toluene, and .\)-lent.' +I& standards \ v e x biised on a tliorougli cv;iluntion all available information from laborator)- t o x i c o l o ~ studicbs and field investigations of industrial a p p b tions. Consideration \vas given to such factors as & irritation, potential functional or organic changes, & metabolic pathways in the body. It \vas p r o m that "themaximal acceptable concentration of b e e (benzol) shall be 25 parts per 1,OOO,OOO parts of y by volume, corresponding to 0.0s mg ( m i l l i 6 per liter at 23 C Y U I7~60 mm (millimeter) pres& sfor esposures not exceeding a total of hours per & \vith tlie understanding that variations in con& tions should fluctuate below this level." Similarly,% &-standard for toluene is 200 parts per ~.OOO,OOO of air by volume corresponding to 0.752 mg per @ at 25 C and 760 mni pressure; and for .u).lene,* parts per 1,O00,000 parts of air by volume corres ing to 0.S6S mg per liter at 2.3 C and 760 mm. The standard of 23 parts per million (ppm) benzene \vas changed from the previous value of I@ ppm established in 1911 bj- the American Stnndtr'; This decrease in the standard \vas based primarily> the results of field studies in plants \\-here b e was being used. Improved diagnostic procedure better medical suneillance of the workers were influencing factors. SO new evidence \vas made a+ h,e6able to indicate that a change was needed standards for toliiene and sylene approved by .-\merican Standards .-\ssociation in 1943 and 19 potential hazard from exposure t zene, toluene, or xylene is through inhalation vapor. In acute poisoning resulting from esp high concentrations of vapor, the main eff narcotic action causing depression of the cen vous system, fatigue, headache, confusion, a 1.imerican standard .\la.xhal .icceptable Concentra Benzene, 237.4-1960, S1.00; American Standard h f a x i d ? ceptable Concentration of Sylene, 237.10-1960, $1.00; a n St.tnd,trd . \ h i m a 1 -4cceptable Concentration of T e 237.1~1960, $1.00. The Magazine of Stan 8\ depending upon tlw niagnitude of the esposttre. ost significant Iiazard associated wit11 esposure nzene is chronic poisoning resulting from reesposures over an extended period of time. mary action is on the bone marro\\', resulting rease in tlie \vhite blood cells. platelets, and lood cells. Esposure to toluene and sylene does roduce tlie chronic blood clianges characteristic nzene poisoning, and the hazard of chronic efis not as great as for benzene. This is evident the significant difference in the standards. tation of the eyes, niiicoiis membrane, and up.iton tract may occur on esposure to e\.en ntrations of tolricne and x?lene. Commers of these materials vary in irritant propert h e is also a considerable range of \ w iat`ions response of individuals. nzene, toluene, and xylene are fat solvents and e tlie protective fat of the skin. This may be ed by secondan infection; hence. contact \\ it11 in slioiild be avoidcd. Industrial Applications TOLVESE, ASD SYLESE are used widely in inchemical raw materials, solvents, and motor ley are used as a starting point in preparing esplosives, and many intermediate substances are also used in the synthesis of a multitude anic compounds. They are escellent solvents for ns, and gums. They are used extensively in ufucture of lacqiiers, cnamels, rubber prorotectiiyc clothing, artificial leather, and in d vamisli removers. Owing to their many and pplications, it is obvious that tlie opportunity sure to these compounds is widely spread u t industry, and there is a definite nccd for nic standards. Use of Standard em E~-FL:C~TIVEa, hygienic standard must be iised 3.r rly. Therefore, the .4mcrican Standards definccc.pt;il)le concentrations contain supplemental &ation rcgarding the ptirpose, limit;itions, and ~ r c ~ t a t i oonf the standards, as well as pertinent ;h!.sicii~-c~icmic`it~lata, so tliat tlic maximum benefits a+be deri\.cd from their use. A forc\vortl in each standard explains tlie meaning a4 *rna\imiil nccepta1>leconcentration." nie t>-pe of (laboratory tests on animals or liuman subjccts e)lad. environmental and medical investigations in and tlie criteria follo\ved in establis~iing~ i y stantlards are discussed. The importance of a r interpretation of the standard as it relates to +tin1 pli!~siological effects ancl en\.ironmrntal data 9essed. For example, it is important to know -er the priniar). action of a compound results in %,a t i o n , narcosis, or functional or organic changes; \\hcther brief peaks above the standard are of -r or niajor significance. -4 consideration of these factors is essential in determining &e need, extent, and urgency of control measures. Other significant aspects also are emphasized. Included in the ~hysical-clic.micaldata in the stand- ards are the flash point and flammable limits of tlie respective compounds. These direct attention to tlie potential fire and elplosion hazards. r\lso included is a description of the basic procediires \vliicli should be foll?\vrd in wllecting air samples. CominonIy used analytical procc*durrs ;ire briefly described. Selected rcfcrcnces ;ire given to tllc more important piiblications \vliicli \vcw rc*\kv.cd and ~\hicIipro\.ided the hisic information in c~stablishingthe ni;i\hii:iI accepta1)le concc~ntration. In tlie prcpiration of tlie standards, a preliminary dr.ift \vas prep;ired by a subcommittee clioscn l x - caiise of specific kno\vlcdge of the compoiind in qiiestion. This draft \vas then thoroughly reviewed by the entire 237 committee, and any corrections or changes deemed necessary were made. Hence, the final draft \\as the consensiis of the b e s t collective j u d p e n f of the entire committee lmsed on available facts and espc.rience. Since the standards are the prodiict of judgment and current facts, they are subject to revision as new infomiation becomes available. The .hm-ican Standard blasimal .Allo\vable Concentration is mucli more than the sinq~leespression of a figure. Otlicr mraningful information is given on limitations. interpretations, and applicability \\hich are necessaF for proper utilization of tlie standard. I t has been demonstrated that the most tosic substance can be used safely if stanclards are used, and uscd properly. " T H E T E R l I `HycIESIC ST,iSD.iRD' is creepins into the Iangiiagc of occiipational l~ealth,"points out tlie magazine Smfrty Stntidnrrls, Sovenilwr-Deccmbcr 1960. "The 'hygienic standard` for an air contaminant may be d c f i n c d as tlie liighcst concrntration of the sii1,stnnce u.liicli. if 1)rcxtlicd coiitinuoiisly tlirorigliout ;I -IO-liour \\ork\vc.c.k, is iinlikcly to rc.siilt in noticcable liarmfril cffccts cithrr ;it thc time of esposure or later," tlic magazine c*splains. "Tliis definition is qiialifietl by the tcmis `nnlikc~ly'and `noticeal~lc.'.iltliough sricIi stantlards are basic to industrial hj.gicne, diey can nc'vc`r he precisc \.alric.s marking \\hat is safe and xvliat is hiinnful." "Tliroiigli proccdiircs of tlir .American Standards .issociation, specific siihstanccs such as cliromates. cyanides, and otlicrs, have becm made tlic subject of individual .imcbrican Standards,'' the articlc continues. "These are tcrined masirnum allo\\able conccntrations, commonly kno\vn as JI.iCs. Ho\ve\.cr, the term Iiygicwic standard is used in a sense similar to SLIC or threshold limit in a recently proposed -4merican Standard." 139