Document pm9NkYrmOVRMEd2Jx0yQOzjo6

AMA Arch, of Industrial Health 21:536-48, 1960 Plastics The Toxicology of Synthetic Resins REX H. WILSON, M.D., and WILLIAM E. McCORMICK, M.S., Akron, Ohio This presentation is the third revision of a paper originally written1 in 1954. It represents a compilation of the literature concerning the toxicological properties of synthetic resins. While not all-inclusive, the bibliography can be used as a reference for the investigator of the toxicology of plastics. The second revision * was presented in November, 1955. I'laslics is a familiar word to everyone. \\ lio among ns does not possess or use some thing made from a plastic? The manufacture of plastic .articles and materials is both big and little industry. A small shop with few employees can make profitably a plastic water pistol. A large company makes nylon stock ings or plastic garden hose. Automobile bodies .and telephones .are molded from plastics. These plastic articles are important to our social progress, and the jobs resulting from their manufacture are important to our national economy. Plastic compounds arc ever changing. 1 he public demand for articles made from plastics is so great that the growth possibili ties are seemingly endless. Vast sums of money arc spent each year on plastic re search, resulting in new materials. The industrial physician and hygienist must know the toxic properties of these items. The working environment is only as safe as the industrial hygicni-l makes it. Any material can be handled safely if one knows what it is and then handles it properly. Overex posure to a toxic material represents care lessness or ignorance. Received for publication Nov. 18, 1959. I lie B. R Goodrich Co. Presented at the Industrial Health Conference, Chicago, April 30, 1959. Numerous papers have been written by authors from many different parts of the world concerning the general hazards of the plastic industry.'1'* Obviously, occupational hazards may exist in the production and processing of some plastic material." Toxic hazards can arise from the use oi plastics which contain toxic substances, particularly in food-packaging applications where extrac tion into the food may occur. Polymerized synthetic resins, which form the base for many plastics, in themselves are usually not a hazard because of their insolubility and unreactivily. The risk arises from plas ticizers, lubricants, stabilizers, colors, and fillers used with them to form the finished plastic.10 There may also be significant hazards existing in the use or manufacture of the monomers of these resins, prior to polymerization. In this discussion we have separated the resins into general classifications. In so doing we appreciate that there is considerable overlapping in many instances. I. Acrylic Resins The acrylic resins are used in many differ ent ways including the making of aircraft turrets; automobile tail lights, brushbacks, signs, and various types of textiles. Non irritating contact lenses for the 'eye can he made from methyl methacrylate.11 These resins are extensively used in maxillofacial surgery. Prosthetic appliances for various parts of the human body can be fashioned from acrylic plastic material. An acrylic plastic material is used as a replacement12 for blood vessels and heart valves because it docs not promote the clotting of blood. Aubrey,13 Endler,14 Scholler,11 and other medicaj reporters18 have stated that the 56/536 SPI -12699 ri.Asncs acrylic resins have the best properties of all of the synthetic resins for use in facial surgery and produce minimum tissue reac tions. They feel that the acrylics arc belter than any other previous material for tissue compatibility 17 and that they can be used in cosmetic surgery without causing skin irrita tion. Human implants have been made.1'* Intraocular acrylic lenses have been used as a substitute for the lenses of the eye for three and one-half years and over 150 successful eye operations have been reported without evidence of excessive foreign-body reac tion.18 The use of an acrylic plastic replacement for the femoral lxme head has shown a high percentage of failure due to sepsis.18 How ever, the septic process is not from direct irritation by the acrylic material. The pro duction of malignant tumors in rats by the implanting of plasties of various types has been reported,10 '" but there arc no reported cases of malignant growths developing in human beings from their use. Baskin21 referred to an experiment in which subcutaneous implantation of acrylic film in mice results in a 25% incidence of fibrosarcomas. These tumors developed be tween 257 and 469 days after implantation. Because of these findings lie cautioned further use of acrylic in humans for pur poses of femoral beads, intraocular prostheses, and jaw reconstruction. MacKay 21 referred to the use of methyl methacrylate implants for the repair of cranial defects. In over 100 cases he cited no significant reaction to the substance even when it was placed in infected wounds. He considered the plastic "biologically entirely inert and innocuous." Morgenstern and associate2'' described a case of sensitization to nielli,acrylic acid and its polymerization products resulting from their use in dental prosthesis. Patty "* stated that polymerized methyl methacrylate is inert; only its stabilizers and antioxidants have adverse physiological effects, particularly dermatitis. Because of its inert properties, it was chosen to make an artificial kidney. Karpov212,1 rc|K)rtcd on the effects of monomeric methyl methacrylate vapors. Symptoms of irritability, tiredness, somno lence, headache, loss of appetite, and a drop in blood pressure--attributed to a disturb ance of the dynamic equilihruin in the cortex of tlie brain caused by inhalation of these vapors--were observed. In human beings it lowers the blood pressure. Deichman 27 and Spealman 28 have studied the effects of monomeric methyl methacry late vapors on laboratory animals. Deichman found that a concentration of 19 mg. per liter of air killed all exposed animals in 2.5 to 5 hours, fiross pathological changes were confined to the respiratory system. Spealman observed that the vapors were more acutely toxic than acetone for mice and less than those of ethyl acetate. An I.t .-.i, for mice for three hours' exposure was found to lie 55 mg. per liter. Karpov 2r' gave a suggested tolerance for monomeric methyl methacrylate vapors in industrial establishments of 0.05 mg. per liter. lie also observed that the'respiratory mucosa may be irritated when vapor con centration reaches 0.25 mg. per liter. Baines20 called attention to the high toxicity of methyl methacrylate, widely used as a monomer in the polymerization of plastics and dentures. Upper limits of its vapor concentration in air which arc per missible are stated as 0.05 mg. per liter. Summary.--Methyl methacrylate vapors have some systemic effects on the brain cortex and on the blood pressure, resulting in lowering. The acrylic resins themselves appear to be substances which can be used successfully ns bone replacements, artificial eyes, and other prosthetic appliances. When placed in certain regions of the human body, however, they should he kept under observa tion because tumor formation, tissue reac tion, and sepsis have been reported. II. Alkyd Resins The alkyd resins are being used in the manufacture of linoleum surfacings, paints Wilson--McCormick 57/537 SPI-12700 A. M. A. ARCHIVES OR INDUSTRIAL HEALTH for refrigerators and autos, ignition parts, magnetorotors, and food wrappings. Morris,30 on reviewing the reactions in volved in the production of aminoplasts, phcnoplasts, and alkyd resins, stated that the finished products arc dermatologically inert. Schwartz, Tulipan, and 1'irminghatn31 found that the alkyd resins may produce dermatitis. Schwartz32 reported that alkyd resins when used as finishes for textiles have caused some cases of dermatitis. Summary.--The alkyd resins arc capable of causing occasional mild cases of dematitis. III. Amino (Urea and Melamine) Resins This group of plastics is used for many articles including buttons, dishes, laminated table tops, and housings for kitchen appli ances. They arc used as soap fillers and finishes for textiles. They can he used to treat paper for food-wrapping purposes. Likins 3,1 stated, "nitrogen bearing plastics, such as melamine, have been said to give off hydrogen cyanide when heated, but the quantities arc apparently not sufficient to jiroduce real danger." Hudgins'14 stated that heat-converted films of urca-formaldchydc-cthylcne glycol resins used as food-wrapping material showed no toxic effect when fed to guinea pigs in single (loses of 100 mg. Repeat doses to rats of 10 mg. per day for 30 days produced mild ellects on the liver, kidney, and gastroin testinal tract. Moss,'11 in studying the pyro lysis of melamine formaldehyde compounds, found that mixtures of 200 ppm carbon monoxide and 10 ppm hydrogen cyanide were produced which killed rats within 30 minutes. He noted that hydrogen cyanide increases the rate of respiration and, hence, intake of carbon monoxide. Schneider18 studied the effects on human skin of soaps containing urea-formaldehyde resin filler. -\Tn significant diflcrcncc was observed be tween soaps filled with urca-formaldchvdc and other soaps. Cases of dermatitis were found due to the fatly acids used. Segal'17,38 found little indication of toxici ty in rats fed Amberlite resin, a polyamine formaldehyde resin, when diets containing 0.5% to 2% of the crude resin were used. There was no histological evidence of dam age resulting from ingestion of the resins noted. 1 le stated that the over-all toxicity of Amberlite, even at 20%, is negligible. Markuson30 reported on the prevention and control of dermatitis due to formalde hyde resins. Vil'kovich40 noted that the introduction of powdered aminoplastic. resin, used in kitch enware, into the regular diet of white mice led to 70% to 80% fatalities. lie also found both hot and cold aqueous extracts, obtained by placing water into aminoplastic dishes, led to considerable intoxication. Schwartz 31,32 felt that urea-formaldehyde resins, when used as finishes for textiles, caused occasional cases of dermatitis. Lehman 41 stated that a polymer of ureaformaldehyde is acceptable as a treatment of paper for food-wrapping puqxjscs. He also stated that melamine formaldehyde polymer is satis factory for the same purpose. Lieber,3 in discussing industrial derma titis, stated that the amino resins can affect many people who have hereditary hypersen sitivities. Summary.--The amino resins (urea and melamine) can in certain combinations, particularly melamine formaldehyde com pounds, pyrolyze into hydrogen cyanide and carbon monoxide. Urca-formaldehyde-ethylene glycol resins can safely be used as food wrapping material. The aminoplasts may Ire very toxic. Dermatitis has resulted in work ers handling these resins. IV. Cellulose Plastic Materials Cellulose plastic materials are used ex tensively in display packaging, irrigation pipe, frames for eyeglasses, cigarette filters, tire cord, and in rayon acetate textiles. Some of the cellulose plastics are suitable for food packaging.42 Maramorosch 43 stated that sheets of cel lulose acetate were found to be toxic to plants and fish. This toxicity is due to diethyl phthalate. 58/538 SPI - 12701 Vol 21, June, I960 rr.isTics Opponheimer 10-" noted that malignant tumors including sarcomas were produced in groups of rats and mice by subcutaneouslv imbedding cellophane tilms. lie stated that additives, plasticizers, etc., apparently do not account for the production of these malignant tumors. Schwartz, Tulipan, and Birmingham31 found only rare cases of dermatitis due to cellulose resins. l'armeggiani and associates,11 in discussing the occupational risks and pathology in the production and manipulation of some plastic materials, stated that in the manufacture of cellulose acetate, the acetic acid content in the air caused mucosal irritation, blackening of the skin, and erosion of the teeth. Summary.--Cellulose plastics can be used safely externally. They only rarely produce dermatitis. Internal use may be hazardous. There is some occupational risks in the manufacture of cellulose acetate. V. Coumarone-Indene Resins Coumarone-indene resins are used in the manufacture of asphalt floor tiles, aluminum paints, waterproof coatings, printing inks, and chewing gum. Geiger44 stated that coumarone-indene resins present little if any industrial hazard from the point of view of toxicity, as wit nessed by their long-continued use in chew ing gum. The main hazards are involved in the use of the monomers, to which some individuals exhibit allergic tendencies. Cases of dermatitis among workers han dling coumarone-indene resins31 have been reported. Summary.--A relatively nontoxic variety of resins. The hypersensitive person can acquire a dermatitis from handling these materials. VI. Epoxies During the past few years there have been marked advances made in the chemical technology of the epoxy resins. Currently these resins are widely manufactured and are available under a variety of trade names. Wilson--McCormick They arc used in corrosion-resistant sur face coatings, molding compounds, castings, laminating or reinforcing plastics, encap sulating electronic circuits, printed circuit hacking, and adhesives. Metal-lo-metal bonding can be accomplished with an epoxy adhesive. Lea and associates45 have attempted to assess in a general manner the irritating and sensitizing capacity of the c.omi>onent ma terials in the epoxy resin formulations. The resins were found to be irritating to the skin by means of human patch-testing. Mine and associates 46 discussed the tox icity of six epoxy resins. Morris47 stated that exposure to epoxy resins in industry has resulted in dermato ses. He said that the epoxies, the curing agents, and some of the additives are severe skin irritants. Bourne 48 stated that contact with triethylcnetetramine used as a polymerizing agent will give rise to an erythema of the face and arms. Dorman40 stated that uncured liquid epoxy resins and amine type curing agents are capable of causing allergic epidermal eczema. He outlined preventive measures that can be undertaken. Grandjean60 stated that dermatoses oc curred in half the workers using an epoxy resin in 11 factories making electrical equipment. Pitt and Paul51 stated that a series of A7-hydroxy alkyl-polyamines were evaluated as cross linking agents for polyepoxy resins. The availability of these cross linking agents with lower toxicity offers a means of overcoming one of the major deterrents in the widespread utilization of epoxy resins. Summary.---The epoxy resins are rela tively inert chemically' and are resistant to heat. Severe skin irritation can occur in their manufacture and use. They must be handled with care. The curing agents used with these resins appear to be the primary cause of the skin irritant effects. 59/539 SPI -12702 A. k A. ARCHIVES OF INDUSTRIAL HEALTH VII. Fluorocarbons 1-1Veen,Br` in reporting on the tissue re The fluorocarbons are used in the manu facture of such articles as pump diaphragms, chemical tubing, high temperature insula tion, coating of molds and bread pans, and gasket material in jet engines. Teflon is being used extensively in surgery for su tures and tubing. Recent work by Zapp and associates52 indicates various fluorine compounds to be present in the decomposition products, the specific ones, as well as the amounts of each, depending on the temperature of de composition. In the range of 300 to 360 C, hexafluorcthane was observed; above 380 C, an extremely toxic compound, octafluoroisobutylene, was detected; from 500 to 550 C, the chief pyrolysis products were tetrafluorocthylene, hexafluoropropylene, octafluorocyclobutane, octafluoroisobutylene, a Cs olefin, and a complex mixture of perfluoroolefins. Fairhall 03 stated that'polytctrafluoroethylcne (Teflon) is physiologically inert and has been rated as nontoxic. However, when heated above 400 C, unidentified volatile gases are evolved which may be toxic. In halation of Teflon dust appears to produce a condition resembling metal-fume fever. Pulmonary edema may result. action to plastics used in surgery, made special reference to Teflon. He felt that it could be safely used. However, Oppenheimer 1B noted that malignant tumors have been induced by Teflon when it was im bedded in rodents. Treon and associates 114 reported animal fatalities resulting from exposure to the decomposition products of Teflon and Kel-F when heated to 752 F. T-ehman42 found that polytetrafiuoroethylene, when used as a coating for bread pans, created no significant increase in the fluoride level of the bread. Sendroy,* in studying the effects of pyrolyzed products of PTFE (a fluorocarbon polymer) when used on electric motor wind ings, under conditions simulating those on , submarine operations, concluded that no carbon monoxide hazard would exist with operating conditions in excess of 250 C but that excessive concentrations of fluorine compounds might arise. Summary.--The fluorocarbons are ex tremely resistant to corrosive agents and solvents. The end-products are inert and nontoxic, but toxic decomposition products may be produced. Inhalation of Teflon dust may cause an effect resembling "metal-fume fever." Irritation of the mucous membranes Stokinger4 stated that industrial hazards arid pulmonary edema can occur from inhal from Teflon are due to exposure to its dust ing the decomposition products. and to its decomposition products derived from heating. In the first instance, a con dition resembling metal-fume fever, "the shakes," is observed. The effect usually dis appears within 24 hours with no after-effect. There is pain and aching in muscles and joints, accompanied by chills and profuse perspiration alternating with fever. When heated above 360 F, the Teflon sublimate is believed to contain absorbed hydrogen' fluoride. This can produce irritation of nasal membranes and may ultimately result in pulmonary edema. VIII. Nylon Nylon is used extensively in the manu facture of gears, slide fasteners, combs, tumblers, tire cord, tennis racket strings, and textiles. It is used as surgical suture material, catheters, and toothbrush bristles. Experiments7 have proved that the type of nylon polymer used in yams is not toxic and does not cause any skin reaction. Nylon has met the rigid suture requirements of the medical profession. Gipstein 68 reported that a papulovesicular dermatitis was observed on a 20-year-old Wilson and McCormick1 stressed the woman and found that patch tests revealed need - for .adequate-,ventilation--when-using --that-the-nylon-fabrigy-dyed-or undyed, was Teflon to avoid ill effects. / the agent. . 60/540 Vol. 21, June, I960 SPI -12703 I'l.tSTICS Tnderfurth r'n stak'd that undyed and un finished nylon possessed no toxicological property and caused no skin reaction. Its use as suture material and toothbrush bris tles confirms this report. l-ast,ln noted no intra-arterial toxicity from nylon catheters, and Sehweisheimer flt stated that nylon was well tolerated and applicable for hone sutures. Nylon button type closures 12 arc safely used for openings between the two auricles of the heart. Also surgical tubing has been made of nylon and has been used perfectly safely. I'.lunt 17 noted that nylon, when studied for tissue inertness in dogs for periods up to six months, showed less reaction than silk or cotton. There was a small foreignprotein reaction about the implant after six months. Oppenhcimer noted that some malig nant tumors have been induced from im bedding nylon in rodents. Summary.--Nylon is a perfectly safe material. The fashionable women of the world have proved this by' wearing nylon hose. In spite of its widespread use, only occasional cases of proved contact derma titis have been reported. Nylon can be im planted in the human body with little or no tissue reaction. IX. Phenolic Resins The phenolic resins are used in the manu facture of telephone handsets, electrical in sulation, radio-TV cabinets, varnish, shell molding, dials, grinding wheels, plywood, Mirgieal braces, and other external surgical prosthetic devices. Demole02 studied the effect of phenolformaldehyde resins on gastric juice. The action on gastric acidity was variable and of short duration, and there was no influence en the proteolytic enzymes. Klkins,n reported that phenol-formalde hyde varnishes have been particularly bad producers of dermatitis. VedorovM made a clinical study of the sensitization and development of allergy in H-'il.um--McCormick chemical workers exposed to various sub stances including phenol-aldehyde resins. 1 .ttvoni n:' reported that several foundry workers handling phcnolic-crcsolic resins developed an eczematous dermatitis. Re moval of the affected persons from exposure resulted in the disappearance of the skin affections. He felt that a form of allergy was responsible. Scndroy slated that electric motors in sulated with CNSV. a phenolic resin, when operated continuously for 96 hours under conditions, simulating submarine operation, gave off carbon monoxide in concentrations up to 1,620 ppm. Phenolic laminates12 have been safely used for braces and other external prosthetic devices. Fairhall m stated that dermatitis may re sult from repeated or prolonged contact with low concentrations of phenol in any form. It causes about 2Qr/o of the derma titis cases of the phenol-formaldehyde in dustry'. 1 .ieber 7 believed that phenolic resins may affect many people who have hereditary hypersensitivity. Summary.--The phenolics as finished lam inates are inert and nontoxic. They can be used safely as external prosthetic appliances. Many workers exposed to these resins dur ing manufacturing processes have developed severe dermatoses. X. Polyethylene Polyethylene plastic is used in the manu facture of squeezable bottles, semirigid kitchenware, packaging materials, coaxial cables, surgical tubing, cartilage and bone substitutes, and surgical repair materials. Polyethylene 12 is used safely in surgical repair, suture tubing, skull covering, plastic lung prosthesis, arterial reinforcement, and hernial repair. Polyethylene has been used extensively as surgical repair materials, both in and out of the body, with no apparent adverse effects. Occasional skin reactions have been reported. In general, it appears to be a perfectly safe, nontoxic, inert mate- 61/541 SPI -12704 A. M. A. ARCHIVES OE INDUSTRIAL HEALTH rial. It dots not change composition when it is autoclaved. Patty7 stated that polyethylene is inert and that only its antioxidants and stabilizers have adverse effects. Lehman 42 found polyethylene to he satis factory as a food-packaging material. Bing08 stated that physical rather than chemical characteristics influence the body reaction to polyethylene. Implantation of irregular pieces causes more reaction. Poly ethylene mesh and nylon suture materials produce similar reactions. Macrophages are found to absorb a plastic sponge of formal ized polyvinyl alcohol formerly thought use ful as a permanent prosthesis. Tusitig0 found no skin reactions and no evidence of systemic toxicity in rabbits after prolonged dermal contact with polyglycols. Because it has no adverse effect on body tissue70 and is not affected by normal tem perature ranges, polyethylene is a satisfac tory' substitute for human cartilage and bone. Tucll71 stated that prolonged intravenous use of polyethylene tubing sometimes causes thrombophlebitis in the vein containing the tube. Tissue reactions are stated to arise from dicetyl phosphate in the mix or from the breakdown products of polyethylene which have been extruded at 250_. Oppenheimer10'20 found that malignant tumors including sarcomas were produced in groups of rats and mice by subcutaneous imbedding of polyethylene. Summary.--Polyethylene is a perfectly safe, nontoxic, inert material. It can be used as a surgical repair material both in and out of the body. Occasional tissue re action can occur, probably only in the sensitive person. XI. Polyester Resins 1 lie polyester resins are used in the man ufacture of reinforced plastics for automo bile bodies, boats, and translucent panels, and in Dacron textiles. They' arc excellent for the formation of artificial limbs. They are weather-resistant, can be formed with low pressure, are strong and colorful, and arc compatible with many fillers. Very little lias been rejiortcd concerning their relative toxicity'. The end-products contain ing polyester resins arc considered to l>e inert and nontoxic. Some of the organic peroxides used in their manufacture pre sent safety and dermatology problems. Polyester resins and glass doth are used to form artificial limbs of light weight and great strength. Virtually no one seems to be allergic to this material.72 Lieberr' said polyester resins may have a dermatitis effect in people who have hered itary hypersensitivity. Nummary.--The polyester resins are rela tively inert, nontoxic materials. Virtually no one appears to be allergic to them. XII. Silicones The silicones are used for insulation for generator coils, auto polishes, waterproof coatings, silicone rubber, and circuit break ers. They are used in the medical field 73 in needles, syringes, tubing, and in ointment bases. It is reported that silicones 74 in protective creams, suntan lotions, and other pharma ceutical preparations are nonsensitizing and .nonirritating,.. Schoog73 found no evidence of silicone causing skin irritation and felt that it was safe to use it as an ointment base. Lesser73 stated that silicone fluids are practically inert physiologically and appear to be nontoxic. They have little or no effect when administered up to 2% of body weight. Certain silicotic fluids cause a transitory conjunctival irritation in the eye but no corneal damage. Silicone-containing foods fed to rats showed a low order of toxicity. In skin tests silicone showed no irritation. Silicones used in the medical field in needles, syringes, taping, etc., are chemically inert and have no effect on blood samples taken for hematologic, bacteriologic, or biochemi cal study. Taylor70 reviewed the properties and their effects of the silicates and silicones. 62/542 Vol. 21, June, 1960 SPI -12705 ri..iSTics Walker77 studied the toxicity of silicone insulation in submarines. Clilting noted that DC 200 silicone pro duced renal tubular damage when fed as 1% of the diet of rabbits for three to four months. IOC Anti foam A caused widespread cellular infiltration in the kidneys and the liver when fed as 0.25'% to 1% of the diet for the same period. MacDougall 7* reported that silicone rublicrs appeared to be nontoxic when used in tissue culture techniques. This was in contrast to results with vulcanized rubber. Poleman 80 noted no acute or chronic toxic effects of methyl polysiloxane, anti foam sili cone emulsion, and the resin used for coat ing capsules. Rowe 8182 studied methyl silicones, methyl phcnylsilicones, and methyl polysiloxane and found them to be relatively nontoxic. He reported that DC Anti foam A is very low in chronic oral toxicity but did cause transitory conjunctival irritation but no cor neal damage. Lehman 11,72 found methyl polysiloxane satisfactory for treating paper for food packaging applications. Coppack8,1 reviewed the toxicological problems of silicones and plastics associated with organic chemicals in food processing. Oppenheimer10 noted malignant tumors were induced from imbedding silastic (sili cone) in rodents. Summary.--The silicones are practically physiologically inert and nontoxic. They may cause a transitory conjunctival irrita tion when introduced into the eye but no corneal damage. Silicones are nonsensitizing and nonirritating. XIII. Polystyrene Polystyrene resins .are used in the manu facture of kitchen housewares, refrigerator parts, food packaging, toys and novelties, wall tiles, and light fixtures. Goggin 81 stated that polystyrene is non toxic and in molded form has no taste or odor. Lehman42 approved of the use of poly styrene as a food-packaging material. Patty85 stated that polystyrene is inert; however, the antioxidants and stabilizers may' cause dermatitis. Struthers 8,1 reported that polystyrene may be used in contact with the skin and food without danger. Polystyrene, free from low molecular weight polymer or addition agents, presents no health hazard from oral inges tion. Oppenheimer10 reported that malignant tumors have resulted from imbedding poly styrene in rats. Lieber5 stated that polystyrene resins may have a dermatitis effect in many people who have hereditary hypersensitivity. Parmeggiani and associates* stated that nervous excitation, leukopenia, and occa sional dermatitis followed exposure to ethyl benzene among polystyrene workers. S'Mmniory.--Polystyrene presents no health hazard from oral ingestion or skin contact, being inert and npntoxic. In its manufacture some hazards are encountered, especially from ethylbenzene. Dermatitis can occur. XIV. Vinyl Resins The vinyl resins are used in the manufac ture of floor tiling, packaging film, rainwear, toys, upholstery material, pipe and pipe fit ting, valves, electrical insulation, sponge, machine and structural parts, and metal and fabric coatings. They are used for plastic blood-transfusion equipment and an atomical repair film. Plastic blood-transfusion equipment87 made of vinyl with nylon and phenolic molded parts has no toxic properties. According to Lehman,12 several of the vinyl resins have been found to be satisfac tory for food-packaging materials. Morris 88 studied the dermatological and chemical aspects of the vinyl plastics. Patty 80 stated that vinyl chloride and vinyl acetate plastics have proved to be inert; only their antioxidants and stabilizers have ad verse physiological effects. Wilson--McCormick 63/543 SPI -12706 A. M. A. ARUliri'.S or INDUSTRIAL HEALTH Pulaski 80 noted no signs of toxicity when large amounts, even up to 20 liters, of p<i!yvinyl pyrrolidone ltatl been given to human subjects. There is some storage of polyvinyl pyrrolidone in the tissues, lie also staled that a decision as to the presence of chronic toxicity has not been determined ns yet. Armstrong01 stated that dextran and polyvinyl pyrrolidone are much superior to saline in the maintenance of blood volume after venisection. Systemic allergic reac tions occurred in some subjects who re ceived dextran blit in none who received polyvinyl pyrrolidone. Bernhard * slated that polyvinyl pyrroli done is not toxic, antigenic, pyrogenic, or infectious. Lesser0'1 stated that polyvinyl pyrrolidone is nontoxic by' oral administration, skin ab sorption, inhalation, or injection. Studies made on its storage in the body do not show any toxic effects. However, Hueper01 has reported poly vinyl pyrrolidone to be carcinogenic to rats, and Lusky and Nelson05 produced fibrosar coma in rats with multiple subcutaneous injections. Wilson and McCormick 1 reported no signs of toxicity in a chronic study of a vinyl-vinylidene chloride copolymer W'ith which rats were fed for two years and dogs for one year at a 5% dietary level. Geon polyvinyl chloride08 was found least toxic in a series of experiments on resins for use in the chest cavity. Vinyl copolymers and polyvinyl alcohols are reported under study for anatomical repair purposes. Oppenheimer 10,00 did note that some ma lignant tumors resulted from imbedding polyvinyl chloride film in rodents. Hcdri and associates07 stated that poly vinyl chloride V-10 is considered unsuitable, for use in surgery due to toxic effects in the liver, kidney, and spleen of dogs and mice. These effects appear to be related to high monomer content and lead contamina tion of the V-10. Roubal and Pokorny08 stated that acne on the face and forearms of workers han- dliug polyvinyl chloride sheets or products is caused by chlorinated naphthalene. Addi tion of paraffin to prevent adhesion facili tates the rise of this chemical to the surface and should he avoided. Tucll71 stated that polyvinyl chloride does not change chemical composition upon auto claving. Farmeggiani 0 stated that in the manufac ture of polyvinyl chloride only slight sips of irritation existed. Summary.--The vinyl resins are used for a variety of purposes. Polyvinyl pyrroli done (PVP) is nontoxic and can be used in the human body. Folyvinyl chloride fTVC) has been stored with little reaction in the chest cavity. Some slight skin irrita tions have been observed in workers manu facturing PVC. XV. Polyurethanes This class of polymers is relatively new. having been commercialized in the United States primarily during the past decade. They are high molecular weight polymers and may be used in the manufacture of ad hesives, plastics, rigid or elastic foams, or synthetic rubber. Finished polymers are rather inert chemi cally and no more hazardous than more common plastics or rubbers. The polymers are manufactured from a class of materials called diisocyanatcs. These materials present serious inhalation hazards. Common raw materials are toluene diisocyanate (TDI), methylene bis (4-phenyl isocyanate) (MDI), and para phenylene diisocyanate (PPDI). In general, all the diisocyanatcs so far investigated show similar toxicological prop erties. Animal experimentation and limited human experience indicate that this type of chemical is extremely hazardous via inhala tion. In acute inhalation studies on TDI, Zapp00 found that 600 ppm for six hours was lethal to rats, while 60 ppm was not. Animals which died showed acute pulmo nary congestion and edema. Six exposures, averaging 9 ppm, killed three of six rats. 64/544 Vol 21, June. I960 SPI -12707 i. PLASTICS Thirty six-hour exposures of 1 to 2 ppm caused microscopic evidence of tracheobron chitis. Zapp concluded that TDI is a rather jxtwerful irritant to the eyes, skin, and riastics, Trudy Leningrad. Sanit.-Gigien. Med. Inst. 14:5, 1953; CA. 49:8629c, 1955. 4. Fitzhtigh, A. F., et al.: Malignant Tumors and High Tolymers, Science 118:783, 1953. 5. Licber, E. E.: Dermatitis: An Industrial respiratory tract. Chronic exposures to 1 . Problem, Brit. Plastics 28:428, 1955; CA 51:638, to 2 ppm of TDI resulted in bronchitis in experimental animals with the attendant hazard of bronchial pneumonia. 1, 1957. 6. Rogers, J. C.: Industrial Hygiene Problems in the Field of Plastics, A.M.A. Arch. Indust. Health 12:470, 1955; Indust. Arts Index 44:1507, 1956. Zapp100 stated that, although polyisocya- . 7. Koulial, J.; Scdivcc, V., and Vasak, V.: Hy nate polymers are physiologically inert, the monomers may cause irritation to the skin, eyes, and respiratory tract and allergic re actions. Polyurethane foam plastics caused virtually no skin irritation or sensitization. gienic Rc|K>rt of Polymerization and Weaving of Caprolactom, Ceskoslav. Hyg. Epidemiol., Micro biol., Imunol. 4:66, 1955; CA 49:8605c, 1955. 8. Schcpcrs, G. W. H.; Durkan, T. M.; Delehant, A. B.; Redlin, A. J.; Schmidt, J. G.; Grecdon, F. T.; Jacobsen, J. W., and Bailey, D. A.: Pyrolysis products show some toxicity but are not more hazardous than those of other elastomers tested. Biological Action of Fiberglas-Plastic Dust., A.M.A. Arch. Indust. Health 18:34, 1958; CA 52: 15754o, 1958. 9. Parmeggiani, L., and Sassi, C.: Occupational Industrial use of TDI has caused many Risk and Pathology in the Production and Manipu cases of asthmatic type reactions, some very serious. ^ The high inhalation toxicity is reflected in lation of Some Plastic Material, Med. Iavoro 46: 14, 1955; CA 49:9317A, 1955. 10. Toxicity of Plastics, Brit. Plastics 31:115, 1958; Indust. Arts Index 46:266, 1958. the fact that the threshold limit value for 11. Fairhall, L. T.: Industrial Toxicology, Ed. TDI is 0.1 ppm.101 It is interesting to note that the odor threshold of TDI is about 0.4 ppm, and this 2, Baltimore, The Williams & Wilkins Co., 1957, pp. 291-292. 12. Why Doctors Are Using More Plastics, Mod. Plastics 29:87, 1951. means that odor cannot serve as a warning 13. Aubrey, M.: Synthetic Resins in the Tissues of hazardous concentrations. Summary.--The polyurethanes are a rela tively new class of polymers. The finished polymers are inert chemically and present in Facial Surgery, Ann. oto-laryng. 13:10, 1946. 14. Endler, F.: The General Material Properties of Methyl Methacrylate Endoprosthesis for the Hip Joint, and Their Significance for the LongTerm Prognosis of an Artificial Hip Arthroplasty, no toxic hazards. During manufacture severe industrial health hazards occur because of the use of isocyanates. These compounds can be lethal and in small amounts are very irritating to Arch. Orthopad. u. Unfall-Chir. 46:35, 1953. li. Scholler, C.: Solvents, Emulsifiers and the Like in Cosmetics, Seifen-Ole-Fettc-Wachsc 76: 52, 1950. 16. Five Reasons Surgeons Use Plastics, Mod. Plastics 24:102, 1946. mucous membranes, producing an asthmatic 17. Blunt, J. W., et al.: Metals and Plastics in type of effect. Great care must be taken in their use. 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