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PLASTICS AND THEIR OCCUPATIONAL HEALTH IMPORTANCE 0. Guenther Zentralblatt fur Arbeitsmedizin u. Arbeitsschutz. 61I56-I6O One cannot imagine any more daily life without plastics. While prev ously men had to be satisfied with substances of natural origin, in the last decades the chemical industry created an abundance of plastics on sy thetic base, which are far superior to the natural substances with regard to their applicability. If one follows the economic journals and the pro fessional publications of the pertinent industries and if one takes into consideration the industrial expositions, one can see, that also we here Germany have found since 19^5* with tenaceous work, connection to the manufacturing of the new plastics. Thereby it is interesting to know, th West Germany became since 1953 the second greatest plastic producer,after the USA,of plastic products. The field of plastics has been widened especially in the last years such an extent, that it would go too far to deal within the framework of a short treatise with these substances and their occupational medical im portances. Therefore, a limitation to certain chemically used groups is indispensibly necessary. Also the chemical bases of the plastics can onl be touched here, the intermediary products at the preparation can be men tioned only if they are important and the chemical formulae can be pointe out in simplified form only then when it is absolutely important for the comprehension. It proves to be necessary to maintain a certain scheme, when discus sing plastic materials, which returns always in the pertinent chemical an technical professional books. The producing companies designate the plas tics with trade marks, which shall be also here, mentioned shortly. UCC 065421 I # -2- For the following statements, let us point out again# that the plastics of today, as already mentioned, can he considered in no case mor than substitute materials. The plastics, produced in planned research ar products, which have, mainly, properties, which cannot be found in natura products, especially not without technical finishing. Let us deal first with the modified natural substances, whereby natu al rubber, cellulose, animal and vegetable proteins, as well as resins, colophonium and dry oil are improved with chemical conversions into so called plastics. From natural rubber, which has as base the isoprene molecule ( - CH2 - CH * C - CH2 - ) ch2 one can prepare plastics by isomerization, oxidation, chlorination and ad ding acids, as well as by introducing fillers. The chemical conversions i dicate already here the acting possibilities ctf acid and acid vapors, as well as of chlorine. These actions on the human body are so generally known, that we must not go into this in more details here. The ready ma plastic products of this kind do not have any health hazards in their further finishing. From the abundance of trade marks, let us single out here i - cyclo rubber by isomerization - thermoprene, oxidized rubber - Rubbon chlorinated rubber - Pergut, Alloprene and rubber hydrochloride - Pliofil Cellulose - (C^H^qO^)x - is converted into plastics by dissolution, esterification and etherification, as well as by introducing metal salts. Known arei regenerated cellulose as artificial silk, cellulose acetate an cellulosenitrate as Cellon or Celluloid, the ethers of cellulose as methy UCC 065422 -3- celluloses for lacquer raw materials and vulcanized fiber, prepared by ad dine fillers. The danger in these fabrications is the corrosion possibi lity by the lyes, influences by carbon disulfide, hydrogen sulfide, aceti' acid, acetic acid anhydride and similars. The methods of preparation are already since years known, so that the influence of chemical substances c be extensively eliminated by appropriate measures at the manufacturing, s as casing of the apparatus, sucking off, etc. In the manufacturing of ar tificial silk sometimes also the known eye pftfnomena appear. The easily combustible celluloid is replaced today manifold by Cello which is prepared from acetate cellulose,by adding the gelatinizing agent tricresylphosphate (CH^CgH^J^PO^. Later we shall deal again with the lat mentioned chemical compound, because from the point of view of occupation health, its orthocompounds are of importance. Very well known are the plastics, prepared by Formalin hardening of animal and vegetable albumins, such as casein plastics. Galalith. or Lani al. The skin irritations of the uncovered parts of the body, the irrita tions of the ocular conjunctive and the influence on the upper respirator; tracks by formaldehyde are known. Finally, colophonium resins and dry oils are converted into plastics by salt formation, esterification, oxidation and building in phenols, Th find many applications under the names of "Albertal" and "Beckacite", as lacquering raw materials. From industrialVpoint of view they are not of special importance. Let us discuss now the true plastic materials, which are prepared syi thetically by polymerization, or condensation. Starting materials for thi plastics arei chalk, coal, oxygen and nitrogen, furthermore in cracking UCC 065423 -4- processes treated petroleum, alcohol and watergas. There is here an abun dance of plastics, and it is amazing in what extent the organic synthesis developed in this field. The intermediary products, at the preparation o: plastics are so numerous, that it would need a separate discussion to enu merate all from industrial hygiene point of view. In first place, let us elucidate the end products, which find as plastics comprehensive use in a' branches of technology and economy. Starting from chalk and coal, over carbide and acetylene at the synthesis through different chemical conversions,one obtains the polyvinyl products, such as polyvinylalcohol-, ether-, chloride-, carbazole-, acetate, polymethylacrylicacidraethylesters, polychloroprene and polybutadiene. With regard to indications to possible action, let us enumerate at random some of them. Polyvinyl alcohol from vinyl alcohol CHZ = CH OH known under the trade mark Polyviol, is used as thermoplast. From this material e.g. aprons, gloves and similar are prepared. During the manufac turing several times irritation of the skin occurred. Polyvinyl ether from vinyl ether CH2 CH och2ch3 under the trade mark Igevin, is used as thermoplast and adhesive, no heal hazard properties are known. Polyvinylchloride and mix-polymerizate from vinylchloride CH2 = CH Cl known under the trade marks Igelit -- Mipolam, has multiple use to prepar ucc 065424 -5- commodities, aprons, raincoats. Depending on the addition of plasticizer; also soft-Igelite can be prepared. Let us point out here the earlier men tioned harmful action of soft gelites, where tricresylphosphate is used a; plasticizer, which is very poisonous in its ortho compound. The action o* tricresylphosphate shall be discussed in more details with the plastici; ers. The mentioned harms do not occur any more when phthalate plasticize: are used. Polvvinylcarbazole from vinyl carbazole, known under the trade mark Luvikan, is used manifold as thermoplastic* it is remarkable, that exzema phenomena can be triggered, Polvvinylacetate from vinylacetate CH2 * CH OOCH^ trade mark, Mowilith, or Vinnapas, is also a thermoplast, can c.a.use skin i: ritation, when irritating plasticizers, or hardeners are used and the com pound not reacted chemically completely. Polymethylacrvlicacidmethyl ester from acetone over methylacrylicacit ester finds manifold use under the trade mark Plexiglas. In this respect the acrylonitrile, as intermediary product is very important from occupa tional hygiene point of view. The preparation of acrylonitrile widens al ways more and more because it can be used also for the preparation of othc plastics, such as e.g. the synthetic Buna rubbers. Acrylonitrile (CH2=CHC;N) can be perceived only at dangerous concentration with odor sense. The poisonous effect is probably a direct action of the acrylonitrile molt cule, possible also by cleaving cyanogenJLn the organism. The symptoms of poisoning are similar to the cyanide poisoning,By inhaling small, with ode sense no more percievable amounts, do most poisoning occur. When acrylo nitrile is used,under the name Ventox, as insecticide, a strong smelling warning substance must be added to it. ucc 065425 -6- In animal research by acrylonitrile,irritation of the mucous membran anoxemia, increased secretion of thiocyanate in the urinland death by res piratory paralysis, were observed. Polychloroorene is a synthetic rubber, known under the trade marks Neoprene, Buna, etc. For clarity's sake, let us mention, that from chlor butadiene polychloroprene and from butadiene polvbutadiene is preparedi from the latter by converting with styrene (vinylbenzene) Buna S and with acrylonitrile Perbunan were prepared. Chloroprene (chlorobutadiene, CH = C - CH - CHg) Cl caused poisoning. When inhaled in larger amounts, narcotic phenomane occ with respiratory paralysis. Those workers, employed at the chloroprene distillation are often remarkably tired, have a distinct pressure sensa tion in the chest, before all below the sternum in the area of the trach connected with dyspnea and palpitation of the heart} typical is also a re markable irritability. Among the workers in the polymerization unit, lo of hair on the head can occur, already one month after the starting of th contact with chloroprene. When taken out from this unit, the hair on the head starts growing again. Now, let us mention shortly a group of plastics, which are prepared from coal, by coking. To these belong the aniline resin from aniline (CgH^NKg), named Iga; which is used for compressed masses and hard paper. When one operates wi aniline, the general safety measures must be observed} the influences of aniline on the human body are presumably known. UCC 065426 -7- Folystvrene (CH2 = CH) c6H5 named also Trolitul, is not specially toxic, as this could be ascertained in animal research. At the preparation of styrene (vinylbenzene) special care must be taken, since the aluminumchloride, resp. - hydroxyde, used a catalyst can have a very corrosive influence. Polvethvlenenolvsulfide (CH2 - CHg - S - S -) S-S with the trade mark Thiokol, Perduren, is an oil resistant synthetic rubb< which is used to impregnate synthetic leather. At the influence of skin perspiration, skin irritations can occur. Phenol-, and cresol resins, named Bakelite, Albertite, Resinole, are used as settable synthetic resins and compressed masses. Skin irritations by synthetic resin solutions on basis of formaldehyde, phenol-, and creso: condensation products were reported, important is here the over sensi tivity towards formaldehyde. The dermatitis takes place with strong itch: lasts often for a long time and has' the tendency to recidivation. Also irritations of the mucous membrane of the nose, the upper and deeper resp: tory tracks occur. Most irritations can be avoided, when at the introduc tion of the often fine article, no dust formation takes place. But some kind of sucking measures are not appropriate on account of the light weig> of the dry goods. Therefore one must see to it, that before all at the ms nufacturing of plastics of the phenol form -aldehyde series the apparatus should be jacketed and at times, the workers should wear face shields. Be fore all care must be taken, that well hardened, i.e. chemically well bour plastic masses are finished, which do not evolve excess formaldehyde. UCC 065427 -8- Phthalate resins, or maleic resins are used as lacquering raw materi Intermediary products are phthalicacid-anhydride over ethanol, pentaeryth rite. Here practically no toxic effects are known, merely irritations of Hie mucous membranes, when working for a longer time with these substances Furthermore, let us mention urea and thiourea resins (carbamide resi These substances are, beside their known fields of application, accelerat ors at the vulcanization. They irritate the respiratory tracks and the skin. The chlorinated naphthalene and diphenyls gained importance in recer years under the name Ferna, as synthetic resin in the electro-industr The more chlorine atoms are introduced in these compounds, the more toxi they become. The most dangerous are the penta-, and hexachloro-compounds The vapors, liberated at the heating of e.g. soldering of therewith insu] ated electric wires, are extremely toxic. The endangered units must have very good ventilation. The toxic effect attacks, according to American sources, before all the liver cells, serious jaundice and acute yellow li atrophy are described. Plastic fabrics from polyamide have found application especially in the textile industry, and here again, before all in the clothing and ho siery industry. To the polyamides belong the, for the first time in Ger many manufactured Perlon and the, in the USA developed Nylon. While Perlc is used mainly in hosiery, Nylon is used more in the clothing industry as substitute for silk. From the two polyamides, Perlon and Nylon,today,fir fabrics are prepared with better qualities .than previously. The textiles, made from these chemical substances loose only seldom their shape, do not crease, are easily washable and dry faet. UCC 065428 -9- From occupational hygienic point of view, one oust mention here, tha at the finishing of extremely stable and solid fibers in the hosiery in dustry, mechanical damages of the finger-tips and the surface of the palms can take place at stenter workers and warp-knitters, whereby, seldom also secondary infections can occur. So, in case of a female warp knit worker an occupational disease,liable to indemnity^had to be recogni because according to the course and repeated recidivation as well as the result of the skin tests, Perlon was detected as occupational toxic sub stance, In this connection, let us mention also, that this warp-knit worker was over-sensitive to pure silk. Since skin tests with synthetic silk did not show any over sensitivity, this highly qualified worker coul continue to work in her profession at the finishing of synthetic silk (vi cose synthetic silk - acetate synthetic silk). In the field of the state industrial physician in Bavaria, a case of oversensitivity towards Nylon could be ascertained. Redness of the skin as far As covered with the ho siery was observed. But the skin phenomena caused by Perlon and Nylon di appeared, when the harmful noxious substance was removed. The skin irri tations, designated as Nylon dermatitis, were observed after wearing Nylo. stockings, first in the USA. Thereby it turned out, that undyed Nylon fiber is only seldom the cause of dermatitis. Therefore also the dye of the Nylon tissue was tested, whether it might be cause of the dermatitis. Thereby, actually some dyes were found as atoxic, e.g. black Nylon stockin, which were, evidently, not rinsed sufficiently after dyeing, caused derma titis. After the examinations, one can state, that the polyamides, Nyloi and Perlon,must be considered as good skinfriendly, on the other hand, no doubt, chemicals, which serve as finishings for these plastics, or are brought otherwise in contact with them, can trigger skin reactions. UCC 065429 5 -10- So, e.g. one should avoid to wear Perlon hair nets, when resorcinol containing hair lotions are used. Also not sufficiently chemically react Nylon-, or Perlon-products can cause dermatitis. Nylon-, and Perlon fila ments are used also in e.g. surgery Perlon nets heal well in case of ah inSl ruptures. Examinations hitherto have shown, that men and animal re pond in the same way to bodyforeign substances, and an even, cell-poor co necting tissue surroundsthe polyamide implantation and according to the results of the experiments, there is no increased cancer danger when poly amide, especially the type Supramide is used. But recent experiments hav demonstrated, that polyamide dusts (caprolactam) when introduced into the cavity of the abdomen bring about there a foreign body-granulate tissue, which transforms after months into a caseous necrosis, supplied with cal cium sediments, is surrounded with a lumpy capsule and reminds to the hap pening at tuberculosis. The purpose of further examinations will be to ascertain, how the lung tissues react to the effect of polyamide dusts. But these most recent examinations show, when handling plastics of the po amide series, and especially in form of dust, care must be taken. A group of plastics, which found especially wide acceptance in recen times is the polyurethane. The basic substances of this plastic are the resp. polyisocyanates, which yield in the presence of catalysts polyure thanes. The di-, or polyisocyanates are designated as Desmodur- and th polyesters as Desmophen., While the end products, that is the polyurethan and the Deemophen-types are harmless, the Desmodurs, insofar as they are volatile, are toxic in the sense as irritating substances to the respirat and stomach mucuous membranes. After an interval period, very severe bro. chitis and bronchopneumonia, as well as subsequently very asthmatic state: are observed. Since the isocyanates are used increasingly also for the p: UCC 065430 -11 paration of polyurethane lacquers, at the spray-painting, and brush painti with such lacquers great care must be taken. Similar phenomena can de velop at the preparation of foams,Moltopren, whereby when Desmodur and De mophene are joined by reaction heat,an evaporation of Pesmodure can take place. From the series of thes plastics let us mention also Vulkollan, a substance similar to hard rubbe as well as the adhesive, Polystal, Silicones are a completely new group of plastic, which were develope first in the USA. Also in Germany the preparation of silicones was accep ed and they gained in the practice always more importance on account of their multiple useability in the industry, pharmacy, and medicine. The silicones, scientifically the organopolysiloxanes are highmolecular syn thetic substances, which are built up from silicon and oxygen, and the fr valencies of which are saturated by organic radicals, such as methyl-, an methylphenyl groups, as well as chlorine. From the original oily silicon, by adding fillers, fatty, resinous and rubberlike products form and also plastic masses, which distinguish themselves by biological compatibility. It would be too much to report here about the chemical syntheses of these plastics in more details, but let us point out, that by methylation with chloromethyl such liquids, silanes, result, which separate chlorine and act irritatingly on the mucous membranes of the upper and deeper res piratory air passages. The influence of methylenechloride, which is also used in the cryogenic industry in many ways, is noticeable in local irri tations and narcotic phenomena. We can see, thus, that in the course of manufacturing health damaging influences can occur. To meet these, the aj paratus must be kept tightj against suddenly occurring leakiness of the aj paratus gas masks must be in preparedness. ucc 065431 -12- The silicones themselves are a class of plaBtics without special tox city. With this substance in the USA and also in Germany experiments wer carried on on rats, rabbits and guinea pigs. In incorporating silicon by feeding, or injecting subcutaneously and in the peritoneum, as well as by dropwise introducing in the ocular conjunctive sack, no specific foreign body reactions and no toxic side reactions were observed. As already men tioned a certain danger exists only at the manufacturing. It is not essential to treat comprehensively the different applicate possibilities of silicone in such a short report. The silicones are indi ferent within a certain temperature range (lubricant), they can be used a: base for ointments, without causing dermatitis, they are used as anti-foai agents and can be applied as resin in fireproof forms. So, e.g. silicon resin is calcinated in baking bread mouldsj these mouldings can be then used very often. The silicones serve also as lacquer substances and as se< ing material. In connection to the silicones, let us mention another plastic mater which contains in a chain arranged carbon and fluorine: it has been devel< in the USA under the designation Teflon, and has the trade mark Fluon. Th< properties of this plastic are very remarkable. It distinguishes itself, similar to the silicones, by high thermal stability and on account of its stability at low temperatures. Furthermore, it is very chemicalsresistanespecially to hydrofluoric acid, nitric acid and hydrochloric acidj the electric properties are described as outstanding. The plastic, Teflon is chemically a polytetrafluoroethylene. In the course of further finishing e.g. when heated above 110C, harr ful gaseous products can form. Analogously to metal vapor-, or foundryfever, here a polymer vapor fever is described. After a symptomfree intei UCC 065432 -13- val, symptoms of chest anxiety and throat irritation occur, and the tempe ature can rise suddenly. Observations show, that the occupation with thi plastic at high temperatures causes severe irritation of the respiratory passages, and can occur even in form of lung edema. Finally let us mention shortly the so-called plasticizers, or gelati ating agents. The plasticizers unite with organic film formers, dissolve and not dissolved, into homogeneous products they influence the filmform ing agents in a certain way with respect to the hardness, the flexibility and the gloss of the film (organic filmforming agents, nitrate cellulose acetyl celluloses, rubber, resin and similars.). In a larger sense, one understands under plasticizers also substances, which make a fabric of go feel and supple. Such kinds are used, e.g. in the leather-, and syntheti leather industry. The plasticizers and solvents are marketed under trade names. Let us choose some at random. Tricresylphosphate. In the tricresylphosphate the ortho-bonding isi toxic. Tricresylphosphate caused during the war and in the post ware per sometimes serious poisonings, especially when confused with edible oil.Tht poisonings cause first acute stomach-intestine-irritations, then preponde rantly motoric paralyses in form of polyneuritis and also damages in the spinal cord. As already indicated, the plasticizer tricresylphosphate was used fo the modification of Igelit , and e.g. by wearing aprons from Igelit, or sandals from Igelit the above mentioned disease symptoms can appear in mo or less gross form. This was explained so, that the absorption of the or tho-tricresylphosphate, contained in the Igelit, through the moist skin, occurred under the influence of steam and heat. Today such poisonings, which happened also when Igelit hoses were used for the spirits distillat and at the transportation of butter in Igelit-foils, belongs to the past, because today for such purposes levelling plasticizers on phthalicacid ba are used. UCC 065433 -14- Diethvlphthalate. named also Palatinol has low toxicity and does not trigger any erythema and other skin reactions, hut it can act slightly irritating to the mucous membranes. Among the chlorinated hydrocarbons worth mentioning is the symmetric dlchloroethane - CHgCl - CHgCl of which, from the textbooks and refe rence works, one has the impression, that it is from industrial hygiene point of view not especially remarkable. Recently, however, it was notic that special care must be taken at the place, where it is used. We must count here, before all, with a hepatorenal symptom complex in case of se vere acute intoxications, while the intoxicating danger in chronic poison ing by acutisubtoxic concentrations is relatively small. The toxicology dlchloroethane corresponds farereachingly to that -of carbon tetrachloride The unobjectionable limit concentration is for dlchloroethane, however, lower than for carbon tetrachloride, according to American sources. Benzylacetate. named Plastolin, has a narcotic effect. But this reg resses, in general, as at the esters, behind irritating effects. Industr al poisonings are hitherto almost unknown. Cyclohexanol. named Anol, or Hexaline, is known in industrial useage by its light prenarcotic and cathartic symptoms, but it has not the specific action of benzene. Decahvdronaphthalene. named Dekalin, has a slight irritating effect, which is expressed in catarrh, coughing and reddening of the eyesi also exzema were observed. The narcotic effect is very small. Other specific effects are not known. C/.hea,l With this short report, we wanted to give a survey about the industri hazards of plastics. The survey shows, that the plastics, in their pr UOC 065434 -15perties as end products are, in general, extremely indifferent from health hazards point of view. The health hazards lie, first of all, in the in termediary products and in some admixtures. The recent research on the influence of polyamide dusts, show, however, that under certain circumstar es, disease phenomena can appear. Therefore the further task of the in dustrial hygienic and'toxicologic research is to explain in more details 1 question of the influence of plastics on the human body. UCC 065435