Document 6b9nGm139EY3LwOMXbRqek9ym

N40684 i* &L_ DUP050056006 DRAFT CHAPTER 7o NONBIODOGIC EFFECTS OF IFAD The Panel has asked its consultants for information on the effect of airborne lead on only two classes of material, glass and textile fabrics, as being representative of the examples that could be cited* This does not mean that other effects do not exist, but only that these were examined. If the reviewers are aware of other effects, the Panel would appreciate having its attention called to them. DUP050056007 NONBIOLOGIC EFFECTS Chapter 7 Page 1 Draft - Rizzo & The presence of lead in textile materials in any of its numerous possible chemical forms derives from the following avenues: a. By assimulation or contamination during fiber growth or formation. b. By contamination during the processing of the fabrics - washing, . dyeing and finishing, *c, By deliberately-applied additives to achieve specific functional 'V ** attributes not inherent in the basic .fibrous materials. d* From atmospheric and other forms of contamination of end products. Because lead- compounds generally tend to have rather poor solubility in aqueous media, the amounts of lead introduced into textile fibers via 11 the first two of these four basic mechanisms are generally low and the further potential transfer from the textile material to humans and to animal pets is similarly inhibited, ' Lead Compounds Acquisition During Fiber Growth or Formation ^Pf)rganic fibrous materials utilized in clothing and*in the large number of household and utilitarian end items made from them fall into two basic categories; the natural'fibers among which wool and cottdn are the economically most significant members, and the man-made or synthetic fibers among which there is an ever growing and important number of in dividual types. '. In the two basic natural fibers, the lead content derives either from the soil in consequence of the natural occurrence of lead compounds or of DUP050056008 Chapter 7 Page 2 chemical additives to the soil for any one of several possible reasons, or from, pest control measures and atmospheric contamination of the living plant. O) The natural lead content of soils varies widely. Huff of the U. S, Geological Survey reports that the concentration of lead in normal soils varies from 20 to 200 p.p.ra. and other investigators of this same group have reported values for lead in the ash of plants ranging from .008 to 0.18#. Thus, the contents of lead compounds.in plants grown in normal soils are consistent with the values found in average soils. The literature discloses that plants grown in areas near metalliferous vein's containing high lead concentrations display substantial levels of lead compounds far in excess of those in normal soils, thus suggesting that the capacity of plants to assimulate lead compounds from the soil and from deposits impinging upon plant surfaces is such as to overcome the solubility factor. In the apparent absence of recorded data, one may assume that normal values for lead content will apply to both the cotton plant and to the cotton fiber grown in normal lead content soils. The lead, content of wool has been reported to be 1 to 3 mgm per 100 (2) (3) ^ grams . Data reported by Kraut and Weber - for human hair from . normal individuals working in activities not involving lead products average 1.7 mgm per 100 grams. These two sets of values for wool and human hair are thus in consonance with each other. Work accomplished by thf^oi "iwsig-jOfctrer . some years past during assessment of damage to the wool fiber induced by chemical treatments and photochemical degradation DUP050056009 Chapter 7 Page 3 using plumbite solutions showed that the uptake of lead by wool is raonotonically related to the formation of lead sulfur linkages with sulfbydryl groups generated by the splitting of the disulfide linkage (?) in the wool structure, Thorsen has more recently shown that plumbite staining of wool occurs strongly in the paracortex of the fiber and pro gressive levels of staining in this component may be taken as an indicator of increased damage to the fiber. By extrapolation from these facts, one may thus assume that the lead content of wool fibers is associated with free-SH groups in the fiber. The distribution of lead in the tissues of animals deliberately injected with lead sailts favors (6) the bone structure , which suggests that the concentration in the wool fiber will be limited by this factor even when higher lead containing feeds are ingested by the sheep. The lew content of lead reported for the natural fibers is thus related to the relatively low solubility of most lead compounds found in the soil, the low natural concentration of-lead in normal soils, and in the case of wool, by the metabolic balance 'in the tissues. This latter situation may also exist in the case of plants. -One is encouraged by virtue of the low concentration of lead thus found in the natural fibers to the conclusion that such concentrations may be within the tolerance limits of humans for lead compounds even if the lead contents are labile to the point of complete transfer from- the textile, material to the human skin. '' ' Lead contents of the man-made synthetic fibers as initially produced may DUP050056010 Chapter 7 Page 4 be derived from the process water, the reacting intermediates and chemicals used to produce the fiber, from the equipment in which the synthesis and subsequent spinning (extrusion) takes place and from the subsequent yarn handling systems. More often, this occurs, from deliberately added compounds, a subject that will be discussed later, in-thla-gaper under 'thethi-gd.-basic-area "fluflue<l above in \iovi'na"U:chi'e'V'Biimt^f'^upp^emefttaa^^. fl+.taaa3audP<.. ? In the modern fiber producing facilities of the industry, lead as a structural element has been supplanted by alloy metals and by glass, plastic X and alloy clad materials which drasticallysreduce not only the lead content but more generally the.s non-fibrous components since these tend to affect the color of the produced fiber and oftentimes its processing and chemical .Vreactivity characteristics. .In the case of viscose rayon manufacture, * lead sulfide contamination is particularly detrimental as it causes both color and spinning problems and measures are taken to remove such con- (7) / tamination from the dope prior to spinning the yarns , lead contents of the man-made fibers to which deliberate additions of lead compounds' have not been made are generally below the levels found in the natural fibers. Lead Compound Acquisition by Contamination During the Processing of Fabrics Acquisition of lead contaminants by textile fibers during the essential V steps of washing, dyeing and finishing of the fabrics to provide the aesthetic, tactile and added functional attributes is achieved through the medium of the process water, the dyes and chemicals utilized ip the processing, from the equipment on which the processing takes place, , .r *4 DUP050056011 s> i *' ' Chapter 7 . ' Page 5 . and from deliberately-applied additives. These several factors are less significant in modern facilities for wet finishing than ,they^|fere a half century ago. Hie underlying reasons are: a. Processing.water is now largely deionized, since trace elements in the water tend to contribute stains, discoloration, and interference with dye " it" , and finish applications. In many cases also, trace elements act catalytically with many of the functional additives thus contributing to a downgrading of product quality and performance. '-v. b. The use of metal alloys and plastics as^ structural and motive elements . of equipment has significanttly reduced these as sources of lead contamination, ~ (8,9) c. Hie dyes used in the coloring of the textiles yand the chemicals i;V applied both in the dyeing and in the general preparation and treatment ^ ' of fabrics are being produced in modern facilities in equipment and under conditions where contamination is reduced to levels approaching those of analytical laboratory reagents. (10) d. Hie widespread use of sequestering agents in the dyeing and wet processing of textile materials further insures that metallic contaminant content in textile materials is minimal and certainly not above the level in the fiber initially. v (H) While lead containers or equipment have been reported to be satisfactory for peroxide bleaching baths, the tendency of the industry has been towards stainless steel and other metal alloy equipment for this purpose. However, the strong oxidative conditions existing in such baths reduce the potential 1 r DUP050056012 ~. ...... . Chapter 7 Page 6 1 of contamination. A similar use of lead vessels was common in past years for the so-called carbonizing process for wool fabrics wherein vegetable matter contamination of the fabric originating with the wool itself was burned out with 5$ solutions of sulfuric acid dried into the fabric and baked. Today, lead containers are not likely to be found in the industry and the use of alloy metal equipment devoid of lead is general in the industry. Metallic contaminants, including lead, are sources of difficulty for the textile vret processing industry and H . * . ' thus all possible measures are taken to avoid them. Such contaminants are the sources of the dulling of colors, of deposits on fabric surfaces, A of stains and often instabilities of chemical baths which result in unmerchantable goods. The industry thus makes substantial use of se ques*t*e*ri*n*g agents to limit the metallic .contaminants and the problems that these generate in processing and in marketing. j A significant advance within the past quarter century in reducing metallic contamination in textile materials has come from two sources: one, the widespread use of deionized water in the wet processing and dyeing and two, the replacement of soap with'synthetic detergents. While.soap forms a precipitate with all heavy metal elements, including lead, which deposits either in or on the surface of the fabric, the synthetic detergents, particularly those of the non-ionic type, act as sequestrants and generally produce soluble forms of these contaminants that are thus not permitted to enter the fabrics. In today's textile wet processing operations the introduction of lead contaminants is not likely to increase the level above that of the fiber initially used and, in general, will tend to DUP050056013 Chapter 7 Page 7 reduce it substantially. . Lead Compound Acquisition by Deliberate Additives for Functional Purposes. By far the most significant source of lead content in textiles is by deliberate action to achieve specific functional properties not inherent in the basic fiber of the fabric. In some instances, it is accidental as for instance in yarns which have been, delustered by the use of titanium dioxide pigments. This is a widely practiced procedure in the man-made or synthetic fiber industry to achieve a matte appearance in the final *v, fabric product, There are two accepted levels of dulling or delustering generally characterized as semi-dull and dull, the former containing about 0,3$ of fiC>2, the latter about 1$ on the weight of the fiber. Lead is a natural impurity or contaminant of the' TiC^ pigment. It is present in a highly insoluble form and is well embedded in the fiber _ H- polymer substance. :v / Qrgano-lead compounds and lead compounds formed in situ with many organic high molecular weight acidic compounds have been applied to textile materials to impart waterproofing or repellency, fungus proofing and (12,13) occasionally delustering characteristics to textile materials By nature of the properties involved and achieved by these treatments, .. they are applied largely for end uses other than for clothing, primarily for outdoor items that are exposed extensively to the sun and the elements of weather. Other compositions involving compounds with more favorable toxicological and dermatological characteristics are available today and are therefore more generally used both for clothing materials and also ' s; for textiles that go into industrial and non-clothing items. Aluminum DUP050056014 Chapter 7 Page 8 ' /; j ' . > ' ealts and soaps, organic quarternary compounds, silicone polymers, fluoroehemicals and resins are used for water repellency; copper salts and organo-copper compounds, as well as some zinc compounds, are widely used for mildew and fungus proofing; mothproofing of wool is generally / . achieved with chlorine containing organics or with quarternaries; latices of elastomeric compounds and polymeric films are used for coating compositions. Thus the use of lead compounds for water and fungus proofing and for other protective properties is minimal. *. V ; Lead pigments are not generally used on textile materials. These go V primarily into paints and other uses. For most practical purposes, ' where surface pigmentation is to be applied, as well as for mass pig- mentation, the textile industry resorts to the use of organic pigments of which there is a full spectrum of colors of good colorfastness properties, When inorganic pigments are used in those applications where outdoor use is paramount, iron and chromium oxid.es, carbon black and the more lightfast organic pigments such as copper-phthalocyanines are selected. The presence of trace amounts of lead compounds primarily in the inorganic pigments must he recognized as inevitable,' the amountdepending upon the quality of the pigment being us'ed. There are two main applications of lead compounds in textile materials. The synthetic fib er-producing industry introduces small amounts of metal compounds into the polymer prior to its extrusion in fiber form to provide (14) &nti-oxidative properties > heat and photochemical stability, and to depress certain degradative tendencies * Lead compounds are particularly DUP050056015 Chapter 7 Page 9 applied to polyvinyl chloride resins and thus to the fibers derived 4 therefrom to depress the photochemically and thermally induced de(15,16,17,18) halogenation that would otherwise occur with this polymer Lead compounds are introduced into other polymer types to impart the (19,20,21,22) i. same type of properties , The degree and nature of chemical bonding of these additives is not always clear, but they obviously are sufficiently bound to the polymer substrate by either physical or Chemical processes to remain essentially undiminished during '* the active life of the textile materials. The protective qualities of lead towards gamma and X-rays is well known, (23,24) Textile fabrics impregnated with lead salts and fabric composites with lead sheets are items of commerce for both laboratory and medical shielding-purposes. Lead Compound Acquisition from the Atmosphere i With the use of lead tetraethyl as a general additive to motor fuels for octane enhancement, the incidence of lead compounds in the atmosphere is unavoidable. Some lead products have entered the atmosphere ftom 'S. % industrial operations. Exposed textile materials must acquire a deposit of whatever is in the atmosphere* The extent of this deposit will vary considerably depending upon location and circumstances. There is little doubt that city atmospheres vail achieve higher deposits than those in urban or in still more open areas. These deposits of contaminants are known to have deteriorative properties on textile materials, the greatest DUP050056016 Chapter 7 Page 10 effect being on those items that are left out of doors either full 1 time or for substantial periods. There is one significant factor that limits the impact of these contaminants at least on clothing materials, ~ namely, the fact of laundering or drycleaning, both of which reduce surface soils on such materials. The modern household and industrial detergents that are high in synthetic compounds and contain builders including sequestering agents will achieve significant reductions of all such deposit syt6 levels that should not be at variance with the contents of the fiber when first produced. Summary In reviewing the role of lead in textile materials one is impressed `with the fact that this material is not a significant factor in clothjjig textile materials, although it may play a greater role in industrial and in non-clothing type fabrics. Given the knowledge that fiber producers for self-protective reasons subject their products to toxicological and dermatological testing, the role of lead in those cases where it is deliberately added for specific protective qualities would not seem to achieve significance in terms of potential hazard to humans. The secondary factor in this respect is the low level of addition that is effective in achieving the desired results. . Future Research The status of lead in the textile industry does not suggest any major research effort. There are two specific areas in which studies may be appropriate. One is the area of the influence of lead contamination DUP050056017 Chapter 7 Page 11 from the atmosphere in degrading textile materials. The other is to verify the le^el of transfer of lead contaminants from textile materials to human skin particularly under conditions where high levels of perspiration occur. The sensitivity of analytical methods available for the detection and quantitative estimation of lead makes this latter effort rather a simple one. Skin simulants saturated with collected human perspiration could be used to achieve this measure without dtirectly involving human subjects wearing the leaded fabrics. DUP050056018 REFERENCES RIZZO Chapter 7 Page 12 1. Huff, L. C. 2. Danck Worth, P. W. 3. Kraut, H. and Weber, M. 4. Rizzo, F. J. ' . 5 Thorsen, W. J. 6* Scino, S 7. Walker, I. F. 8. Harrow, L. S. 9. Etelstein, N. 10* Summersgill, J. V. 11. Mills, R*. ' 12. Coes, L. 13. Esteve, R. M. Jr., Weight, G.' C. and Mack, P. 5. _ ibid 14. Merrifield, D. B. 15. Mack, G. P. 16. Elliott, S. B. 17. Kuebne, W., Dohleinanra, H. and Krzkalla, H. Bcon. Geol. 47, 517-1*2 (1952) Deut. Tierarztl, Woehschr, 50, 28 (1942) Via CA 53~311o4 Biochero. Z. 317, 133-1(0 (1944) Private F.es. Report to Wm. Whitman Co. (1937) Tex. Res* J. 28, 185-9 (1958) Japan J. Nation's Health, 23, 59-72 (1954) Via CA 49-1208b US Patent.2,364,407 (1944) J. Assoc. Off. Ag. Cheia. 31, " 677-83 (1948) J. Assoc. Off. Ag. Chem. 32, 622-3 (1949) J. Soc. Dyers and Col. 70, 278-83 (1954) Am. Dyest. Reptr. 35, 388-9 (1946) US Patent 2,456,919 (1947) Tex. Res. J. 29, 760 (1959) Am. Dyest. Reptr. 48, #19, 139-42 (1959) US Patent 2,954,356 (1955) Modern Plastics 31, #3, 150-4 218-26 (1953) US Patent 2,918,451 (1959) US Patent 2,954,363 (I960) DUP050056019 RIZZO - Chapter 7 Page 13 38. Myers, 0. S., Wilson, J. E. Bostwiek 1?. Norland, S, C. and Tamblyn, J.W, 20. Safford, M. M. and Corrin,H.L* 21. Windeiauth, E. 22. Young, D. M.', and Horn, Oy Hostettler, 23. Selker, A. H. 2U. Morrison, P. US Patent 2,820,77b (1958) US Patent 2,96b,b9S (i960) US Patent 2,928,801 (I960) US Patent 2,897,181 (1959) US Patent 2,890,218 (io<<5) Modern Plastics Uo, #1, 172, 2iilt-5 (1962) US Patent 2,580,360 (15^) DUP050056020