Numerous products made from these materials are included in other major groups, such as boats in Major Group 37, and toys, buckles, and buttons. in Major Group 39. This group includes establishments primarily manufacturing tires, but establishments primarily recapping and retreading automobile tires are classified in services, Industry 7534. Establishments primarily engaged in manufacturing synthetic rubber and synthetic plastics resins are classified in Industry Group 282. Rubberized products can be used in automotive, mechanical engineering, building construction, footwear, furniture, textiles, electrical equipment, sporting, and leisure goods.
Many of these establishments are primarily engaged in manufacturing pneumatic casings, inner tubes, and solid and cushion tires for all types of vehicles, airplanes, farm equipment, and children's vehicles; tiring; camelback; and tire repair and retreading materials. Other establishments are engaged in manufacturing fabric upper footwear having rubber or plastics soles vulcanized, injection-molded, or cemented to the uppers, and rubber and plastics protective footwear. Establishments primarily engaged in manufacturing rubber, composition, and fiber heels, soles, soling strips, and related shoe making and repairing materials are classified in Industry 3069; those manufacturing plastics soles and soling strips are classified in Industry 3089, and those manufacturing other footwear of rubber or plastics are classified in Industry Group 314.
This section includes establishments primarily engaged in manufacturing rubber and plastics hose and belting, including garden hose along with the manufacture of gaskets, gasketing materials, compression packings, mold packings, oil seals, and mechanical seals. Included are gaskets, packing, and sealing devices made of leather, rubber, metal, asbestos, and plastics.
Some establishments are engaged in manufacturing molded, extruded, and lathe-cut mechanical rubber goods. The products are generally parts for machinery and equipment. While this market segment is diverse, other establishments are engaged in manufacturing industrial rubber goods, rubberized fabrics, and vulcanized rubber clothing, and miscellaneous rubber specialties and sundries. This group also includes a wide range of miscellaneous plastic products. These industries include plastic film and sheet, profile shapes, pipes, bottles, foam products, resins, and plumbing fixtures.
OSHA inspection reports were reviewed to identify occupational exposures that were most frequently found in the tire and non-tire plants and to determine whether any of these exposures exceeded OSHA standards. Data were reviewed from OSHA inspections conducted during the period 1982–90 in tire and inner tube facilities (SIC 3011), rubber and plastics footwear facilities (SIC 3021), rubber and plastics hose facilities (SIC 3052), and fabricated rubber products facilities (SIC 3069) [OSHA 1990].
Citations can be issued by OSHA for chemical exposures that exceed the PEL, failure to abate a hazard, lack of adequate engineering controls and personal protective equipment, lack of adequate training, lack of medical surveillance, or failure to meet other occupational safety and health standards. Of the hazards cited, only continuous or intermittent noise was noted in all four of these SIC codes. However, because not all facilities were inspected and only a small proportion of the workers were observed, these data do not provide adequate information about the health and safety risks for this industry.
For example, although most inspections were conducted in the fabricated rubber products industry (SIC 3069), only about one-third of the total plants in this industry were inspected. In addition, the substances monitored during these OSHA inspections were usually those that had OSHA PELs and sampling methods [29 CFR 1910]. Thus, the substances monitored may not have been the substances that represented the greatest hazards. Stewart and Rice  have suggested that research be conducted to determine whether the OSHA database of monitoring results is representative of national exposure situations.
In the early 1980s, NIOSH conducted industrial hygiene surveys of the tire and rubber industry and recommended that engineering controls be implemented and that substitute chemical formulations be introduced to reduce worker exposure to toxic agents [NIOSH 1983a, 1984]. However, few studies have been conducted since then to determine whether these recommendations have been instituted.
Researchers in Italy sampled volatile emissions in three locations: the vulcanization area of a shoe sole factory, the vulcanization and extrusion areas of a tire retreading factory, and the extrusion area of an electrical cable insulation plant [Cocheo et al. 1983]. Approximately 100 different chemicals were identified, but the health effects associated with exposure to these chemicals have not been studied. In addition, it is not known whether the chemicals identified are representative of the emissions in other plants.
Many epidemiologic studies have reported excess deaths from bladder, stomach, lung, hematopoietic, and other cancers among tire and non-tire rubber products workers. Most of these excess deaths cannot be attributed to a specific chemical because (1) workplace exposures involve many individual chemicals and combinations, and (2) changes occur in chemical formulations. Most of the chemicals found in these industries have not been tested for carcinogenicity or toxicity, nor do they have Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs) or National Institute for Occupational Safety and Health (NIOSH) recommended exposure limits (RELs). This Special NIOSH Hazard Review summarizes the adverse health effects of worker exposures in the rubber products industry; it also examines research needed to assess and prevent these effects.
Historically, cancer has been the chronic disease most frequently reported in cohort studies of rubber products workers. In the late 1940s, British rubber workers were reported to be at increased risk of bladder cancer from exposure to an antioxidant that contained 1-naphthylamine(alpha-naphthylamine) and 2-naphthylamine (beta-naphthylamine) [Case and Hosker 1954].
In the United States, early investigations by Mancuso et al.  revealed excess cancer deaths among a cohort of Ohio rubber products workers employed in 1938 and 1939; these investigators recommended additional studies of U.S. rubber workers. In 1970, the United Rubber, Cork, Linoleum, and Plastic Workers of America (URW) joined with six major American rubber companies to establish a joint occupational health program. A contract was negotiated with the Schools of Public Health at Harvard University and the University of North Carolina to conduct epidemiologic studies of rubber workers that emphasized cancer incidence and mortality [IARC 1982]. A large number of published and unpublished reports were produced as a result of these studies until the program was discontinued in 1980. The principal adverse health effects reported were cancer and respiratory effects (e.g., reductions in pulmonary function, chest tightness, shortness of breath, and other respiratory symptoms).
Currently, the risks for cancer and other chronic diseases in rubber products workers are unknown because of the lack of substantial epidemiologic and industrial hygiene research in the past decade. Toxicity data are also lacking for many chemical formulations found in tire and non-tire manufacturing. Categories of rubber compounding additives may include the following [IARC 1982]:
- Oils (process and extender)
- Organic vulcanizers
- Pigment blends
- Antitack agents
- Chemical byproducts
- Reinforcing agents
- Curing fumes
Most studies of cancer among rubber products workers have been conducted as retrospective cohort or case control mortality studies of workers employed in the tire and non-tire industries between 1940 and 1975. Many of these studies have reported statistically significant numbers of excess deaths from bladder cancer (P<0.05) [Checkoway et al. 1981; Bovet and Lob 1980; Monson and Nakano 1976; Negri et al. 1989; Fox and Collier 1976], lymphatic and hematopoietic cancers [Checkoway et al. 1984; Arp et al. 1983; Wilcosky et al. 1984; McMichael et al. 1975; Wolf et al. 1981; McGlothlin and Wilcox 1984], lung cancer [Fox et al. 1974; Zhang et al. 1989; Andjelkovich et al. 1988; Delzell et al. 1982; Delzell and Monson 1985; Monson and Fine 1978; Parkes et al. 1982], and stomach cancer [Blum et al. 1979; McMichael et al. 1974; Parkes et al. 1982; Andjelkovich et al. 1977; Sorahan et al. 1989; Sorahan et al. 1986]. Excess deaths from colon cancer [Delzell and Monson 1982], prostate cancer [Goldsmith et al. 1980], liver and biliary cancer [Delzell and Monson 1982], and esophageal cancer [Parkes et al. 1982] have been noted in individual studies. Occupational exposure data do not exist for most of these studies and have been estimated historically. The uncertainty of these exposure estimates is exacerbated by chemical formulations that differ with each plant or process.
In 1980, OSHA (1980) published a report informing tire and non-tire workers of their risk for cancer as reported in several studies by Harvard University and the University of North Carolina [Monson and Fine 1978; Monson and Nakano 1976; McMichael et al. 1974, 1975, 1976a,b,c; Andjelkovic et al. 1976; Tyroler et al. 1976; Andjelkovich et al. 1977; Blum et al. 1979].
Disorders associated with repeated trauma” is a broad BLS category that includes noise-induced hearing loss, synovitis, tenosynovitis, carpal tunnel syndrome, and other conditions resulting from repeated motion, vibration, or pressure. No data show the number of rubber and plastics workers affected by each of these disorders, but the overall incidence in 1991 was 80.5 cases/10,000 full-time workers [DOL 1993]. Data also indicate that this incidence rate has increased yearly since 1988, when the incidence rate was 56.5 per 10,000 [DOL 1990, 1991, 1992, 1993]. Only 9 of 31 additional 2digit SIC industries have higher incidence rates, and rubber and plastics footwear manufacturing have the 18th highest rate (160.3 cases/10,000) [DOL 1993].
Rubber manufacturing generally comprises the following operations: raw materials handling, weighing and mixing; milling; extruding and calendering; component assembly and building; ‘curing’ or vulcanizing; inspection and finishing; storage and dispatch. Here is a description of some of the processes used in rubber manufacturing.
Raw Materials Handling, Weighing, and Mixing All the materials required for the manufacture of the finished product are assembled. The raw polymer, either natural or synthetic is brought together at this stage with a variety of compounding chemical additives before being introduced into a mixer. The extensive range of chemicals required, and the volume of raw material handled can give rise to substantial quantities of airborne dust.
Bale Cutting Before being added to the mixer, the rubber may need to be cut into small pieces on a bale cutter or guillotine. Most of the rubber industry uses mechanical handling such as the vacuum bale lifter. These are reliable and low-cost options for handling standard 33.3kg bales.
Milling From the mixer, the uncured rubber compound usually passes to one or more milling machines, where it is thoroughly blended to ensure even dispersion of chemical constituents. At this stage, considerable heat is generated, and, although many technical improvements have been introduced in recent years, the job of mill operator still involves a considerable degree of physical exertion and exposure to fumes arising from the heated compound.
Extruding and Calendering The extruders force the rubber compound through a die into various forms, which are then cut to appropriate lengths. Strips of softened rubber compound are fed into multiple-roll milling machines (calenders) to form rubber sheeting, or to apply the rubber directly onto the woven textile fabric, which can then be wound off onto a roll. During such manufacturing operations, fumes are often generated.
Component Assembly and Building At this stage, solvents are frequently used, with the possibility of inhalation of solvent vapors or of direct effects of the solvent on the skin of the operator.
Curing or Vulcanizing Heat is applied to the product, usually by use of steam, in a curing mould, press, or autoclave. Operators working in the area are exposed both to heat from the presses and to fumes from the heated rubber products. Chemical reactions take place throughout the manufacturing process and may give rise to new, more volatile chemicals.
Inspection and Finishing This process involves the handling of cured rubber products, often while still hot. It usually involves direct and extensive skin contact with the surface of the finished article (during inspection) and may also involve exposure to vulcanizing fumes. Grinding, trimming, repair, painting, and cleaning may and exposure to rubber dust, fumes, and solvents.
Storage and Dispatch Large quantities of stored rubber goods may release considerable amounts of toxic substances, either as vapors or as constituents of the ‘bloom’ on the surface of finished goods.
Chemicals Used in Rubber Production Process A wide variety of natural or synthetic elastomers, fillers (e.g. carbon black, precipitated silica, or silicates), and additives are used in compounding to create the necessary properties of the final rubber product. The actual chemicals used in this process have changed over time and vary extensively depending on the manufacture (e.g. tires, general rubber goods, re-treading), and on the specific plant. More information on the rubber sheet making process can be found at: https://youtu.be/dLwsoM3WnuQ
Compounding ingredients are classified as vulcanizing agents (e.g. elemental sulfur, sulfur donors such as organic disulphides and higher sulphides, peroxides, urethane crosslinking agents); vulcanization accelerators (e.g. sulphenamides, thiazoles, guanidines, thiurams, dithiocarbamates, dithiophosphates, and miscellaneous accelerators such as zinc isopropyl xanthate and ethylene thiourea); vulcanization activators (e.g. zinc oxide, magnesium oxide, lead oxide); retarders and inhibitors of vulcanization (e.g. benzoic acid, salicylic acid, phthalic anhydride, N-nitrosodiphenylamine (NDPA), N-(cyclohexylthio)phthalimide); antidegradants; antioxidants (e.g. phenolics, phosphites, thioesters, amines, bound antioxidants such as quinone-diimines, miscellaneous antioxidants such as zinc and nickel salts of dithiocarbamates); antiozonants (e.g. para-phenylenediamines, triazine derivatives, waxes); anti-reversion agents (e.g. zinc carboxylates, thiophosphoryl derivatives, silane coupling agents, sulphenimide accelerator, hexamethylene-1,6-bis thiosulphate disodium dehydrate, and 1,3-bis(citranimidomethyl) benzene); plasticizers and softeners (e.g. petroleum products such as petroleum waxes and mineral oils, coal-tar products such as coumarone resin, pine products, synthetic softeners, and other products such as vegetable oils and fats); and miscellaneous ingredients (such as peptizing agents, blowing agents, bonding agents, and pigments) (Datta and Ingham, 2001).
An industry-wide survey in the Netherlands in 1998 showed geometric mean concentrations of inhalable dust that varied from 0.8 to 1.9 mg/m3 and from 0.2 to 2.0 mg/m3 when analyzed by plant and by department, respectively. Actual inhalable dust concentrations depended to a large extent on specific conditions within the departments of the 10 plants involved in the study (Kromhout et al., 1994). Comparison of the exposure levels nine years later revealed a reduction rate of 5.7% per annum for exposure to inhalable particulate matter. On average, median inhalable dust concentrations went down from 1.00 mg/m3 to 0.59 mg/m3 between 1988 and 1997. The steepest decline was observed in companies and departments with the highest exposure levels in 1988 and in workers with long employment. However, the highest concentrations were still seen in the compounding and mixing departments (Vermeulen et al., 2000).
Dost et al. (2000) reported on exposure data collected in an industry-wide inventory in the United Kingdom during 1995–97 from 29 re-treading plants, 52 producers of general rubber goods, and seven producers of new tires. The results show similar patterns at somewhat elevated levels.
These findings were confirmed in an analysis of dust-exposure data (13380 inhalable and 816 respirable dust measurements collected between 1969 and 2003) in the EXASRUB database. Geometric mean inhalable dust concentrations changed by −4% (range −5.8 to +2.9%) per year.
Significant reductions were found in all five participating countries for ‘handling of crude materials and mixing and milling’ (−7% to −4% per year) and for ‘miscellaneous workers’ (−11% to −5% per year). Average geometric mean personal exposure levels ranged from 0.72 mg/m3 in the Netherlands to 1.97 mg/m3 in Germany. Up to 4–5-fold differences were observed between the countries in the early eighties, but these differences diminished considerably in the two decades afterward. In most countries, personal measurements appeared to be on average 2–4 times higher than stationary measurements (de Vocht et al., 2008).
Natural Rubber Latex Allergy from Manufacture and Use of Products
A wide variety of products contain latex: medical supplies, personal protective equipment, and numerous household objects. Most people who encounter latex products only through their general use in society have no health problems from the use of these products. Workers who repeatedly use latex products are the focus of this notification of hazard. Three types of reactions can occur in persons manufacturing or using latex products. These include (a) irritant contact dermatitis – the development of dry, itchy, and irritated areas on the skin. (b) allergic contact dermatitis (delayed hypersensitivity using resulting from the chemicals added to the latex during harvesting, processing, or manufacture, and (c) latex allergy (immediate hypersensitivity) causing an allergic contact dermatitis reaction. Although the amount of exposure to cause sensitization is unknown, exposures at low levels can trigger a reaction in some sensitive individuals. Latex is used in many products for office supplies, household objects, personal protective equipment, emergency equipment, and hospital supplies.
Plastic products are part of our daily lives, and they can be seen everywhere from our homes, offices, parks, malls, etc. Even though plastic objects are everywhere in our environment, a lot of people do not really know how these products get manufactured. The plastic industry is a complex one, but it is much better to add up to our stock knowledge. Let’s look at the 7 different methods for manufacturing plastic products.
1. Plastic Injection Molding
Plastic injection molding is accountable for more than 75% of plastic products we see out there today and is the most popular way of manufacturing plastic products. It is the process of using molds or die made out of aluminum or stainless steel to create plastic. The mold consists of a cavity side and core side and is placed into the injection molding machine. Plastic material is molten and injected into the empty cavity of the mold. Under great hydraulic pressure, the plastic part is ejected out of the mold once it cooled and hardened. The plastic injection molding method is hugely popular among manufacturing companies because of its capability to produce thousands of plastic parts at once.
2. Rotational Molding (Roto)
Rotational molding or commonly known as roto-molding is a plastic manufacturing method that also uses mold with a core and cavity side but follows a different process compared to injection molding. Plastic material is poured into the empty cavity and heated inside an oven. The mold is constantly rotated by two axes while gravity makes sure the plastic remains on the tool walls to build up the right amount of thickness. The part is allowed to cool before the tool gets opened and have the part removed
3. Injection Blow Molding
Plastic manufacturers use gas pressure to force molten plastic into the mold with injection blow molding. This method is commonly used to create plastic bottles. Plastic material used for this method are usually PET (polyethylene terephthalate) or PEEK (polyether-ether-ketone) due to their clarity and is known to be safe to use for consumables. Both types of plastic are also easy to recycle which is a plus for the companies who intend to use plastic bottles.
4. Extrusion Blow Molding
Extrusion blow molding uses parison which is molten plastic in the form of a balloon and is placed into a dual-piece clam-type mold. Once the mold is sealed, the parison is inflated until it fills the empty cavity of the mold. The sides are water-cooled so the plastic quickly hardens and can easily be ejected. Extrusion blow molding is best used to create plastic cups, small or regular-sized plastic containers, and plastic bottles.
5. Reaction Injection Molding (RMI)
This type of plastic manufacturing method is best used to produce rigid plastic parts. The automotive industry is the biggest gainer of the RMI method since it is commonly used to create plastic vehicle parts such as dashboards, bumpers, stepping boards, etc. It uses thermosetting plastic which undergoes a chemical reaction inside the mold causing them to expand and fill the cavity of the mold. Once the chemical reaction is complete, the plastic part takes its final form. RMI is relatively considered to be an expensive plastic manufacturing option due to the material and intensive labor involved.
6. Vacuum Casting
Vacuum casting is ideal to create numerous plastic parts without a big capital for tools and plastic material. A 3D prototype of the product is enough to jumpstart this plastic manufacturing process which is then placed into a sealed box filled with silicone or urethane. Once the 3D image model is removed, a cavity is formed and that can be filled with plastic resin to resemble the original model. Vacuum pressure is applied to take out the air of the mold. However, plastic parts made out of this aren’t durable and can degrade after a few production processes.
This process is much like vacuum casting except plastic is placed over a die which is heated until it becomes pliable. The plastic material is stretched on the surface while vacuum pressure is constantly applied to pull the sheet down until it takes its final shape. This method can be done with a rudimentary approach and different products can be expected off of it but you cannot expect top-quality results compared to the other methods mentioned beforehand.
Robert E. Eckardt (1976) described plastic as a material that contains as an essential ingredient an organic substance of large molecular weight, is solid in its finished state, and, at some stage in its manufacture or in its processing into finished articles, can be shaped into a useable product. In many cases, the terms plastic and resin are used in an overlapping sense. However, a resin is a homogeneous polymer used as the building material in the production of a molded article, while the plastic finished product may contain fillers, plasticizers, stabilizers, and pigments.
In general, the principal hazards of plastics are associated with their monomers and with the plasticizers, stabilizers, "activators," fillers, and pigments that are used. The oldest synthetic plastic is celluloid, a cellulose nitrate. Its principal occupational hazard arose from the nitric acid used in its manufacture, a well-recognized industrial hazard. Bakelite, a condensation product of phenol and formaldehyde, was one of the next commercial plastics. Its components, phenol, and formaldehyde, are both well-recognized industrial toxic materials that have to be handled with caution. Cellulose acetate replaced cellulose nitrate for use in photographic film and considerably reduced the flammability hazard and the hazard of nitrogen oxides evolution in a fire.
Urea-formaldehyde resins came into use in 1929, and again the toxic properties of the ingredients were pretty well understood. Urea has been shown to be an irritant to the lung but is otherwise considered nontoxic because it is a natural metabolite of protein. Formaldehyde is a well-known mucous membrane irritant and a cause of dermatitis in those who become sensitized to it by direct contact or vapor in the air.
Polyvinyl esters, which include poly (vinyl acetate), poly (vinyl chloride), copolymers of vinyl chloride and vinyl acetate, and poly (vinyl acetals), came into use about the same time as urea-formaldehyde resins. Vinyl acetate does not have the same carcinogenic properties as vinyl chloride.
When high purity styrene could be produced in 1937, this led to the introduction of polystyrene. Styrene is not at the present time believed to be a particularly toxic material, but it is undergoing intensive toxicological testing at present time by the Manufacturing Chemists Association.
Nylons are polyamides, with different grades being made by different processes. Nylon 66 is a condensation product of both adipic acid and hexamethylenediamine. Hexamethylenediamine is a skin and eye irritant and skin sensitizer, and therefore, should be handled with adequate precautions in the occupational setting. When nylon stockings were first introduced, there were many reported cases of skin reactions, at first believed due to the nylon itself. Extensive studies by the DuPont Company established that most, if not all of these, were due to the sizing and dyes rather than to the nylon itself. Nylon 6 is a polymerization product of caprolactam. Caprolactam is an irritant to skin and mucous membranes and has to be used in the occupational setting with adequate protection.
Melamine-formaldehyde resins came into use in the late 1930s and are extensively used in tableware. The problems of formaldehyde are well known as a potential human carcinogen, and melamine has been shown to have a low order of toxicity. Also, formaldehyde-containing plastics could produce dermatitis if some unreacted formaldehyde is present. Skin and eye irritation could result from unreacted resin.
Cellophane, interestingly enough, is reconstituted cellulose that could be described as a form of rayon. Its principal occupational hazard is carbon disulfide used as a solvent in the manufacturing process. The toxic properties of carbon disulfide have been under study for a number of years. It is an acutely toxic material with reactions similar to those produced by hydrogen sulfide. Chronically, it can produce a whole host of symptoms, terminating in chronic dementia if exposure is long enough to a sufficiently high level. Although the presently accepted American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) for carbon disulfide is 1 ppm for an 8-hour time-weighted average exposure.
Silicones are organo-siloxane polymers which are organo-siloxane polymers that can be made in a variety of forms from liquids to solids, depending on the molecular weight. They have found a large variety of industrial and consumer uses, even including breast enlargement. They are very nontoxic materials and should present no occupational or environmental problems. Since a great variety of fillers, pigments, stabilizers, inhibitors, etc. are used in the finished products. Glass, wood dust, asbestos, and cadmium or chromium salts, may be used in such applications. Besides these chemical hazards, OSHA also identifies musculoskeletal disorders from manual material handling and noise as other potential exposures to workers.
Polyethylene and polypropylene and ethylene-propylene copolymers are made from the indicated hydrocarbons ethylene and propylene. These hydrocarbons, particularly ethylene, are said to be simple asphyxiants and, therefore, to constitute no hazard to humans. In this process, the ethylene is subject to very high pressure (5000 psi), from which it is suddenly released in the presence of a peroxide catalyst.
A variety of dermatoses and acute and chronic pulmonary problems have been associated with the use of two plastics, namely epoxides and polyurethanes, especially polyurethane foams. In the case of epoxy resins, these effects have been associated with the curing agents, namely ethylenediamine, diethylenetriamine, and triethylenetetramine. These chemical substances are highly alkaline compounds capable of causing extensive corrosive skin reactions. The area also are known skin sensitizers, and hence may cause allergic skin reactions. Because the reaction is exothermal, fumes may be produced which in sensitized individuals can lead to bronchial asthma. Since the curing agents may be used in excess, in order to drive the polymerization to completion, subsequent grinding, sanding, or polishing of epoxy resins may produce dusts and fumes. It is essential, therefore, that epoxy resins, ether being cured or finished should be performed with proper local exhaust ventilation and/or use of respirators and other personal protective equipment.
In the case of polyurethanes, toluene diisocyanate (TDI) or p,p-diphenylmethane diisocyanate (MDI) are used as catalysts and these can cause both acute and chronic pulmonary reactions. Bronchial asthma often develops in these workers. Peters and other principle investigators have shown that chronic impairment of pulmonary function in industrial workers may well result. If unreacted TDI or MDI remains in the product, this hazard can present itself to subsequent users of the polyurethane foam.
Polytetrafluorethylene (Teflon) has come into extensive use because of its extreme reactivity. However, if it is ground or sanded, a fine dust can be produced which produces a polymer fume fever quite similar to metal fume fever. On the other hand, acrylic resins are polymers of acrylic acid, methacrylic acid, esters of these acids, or acrylonitrile, of which Lucite is a good example, and are widely used, especially in the preparation of dentures. These monomers may be severe skin and eye irritants, and acrylonitrile. They must be used with adequate precautions in the industry.
Note: The following table represents only the potential occupational health concerns for both the refining of petroleum products and the related industry based on a job task or work activity and any related OSHA standards for regulatory compliance. The information presented does not indicate or suggest a relative risk of exposure based on the location within the table nor provides any exposure information. Health risks associated with fatigue, working long hours, stress living away from home, and other psychosocial disorders are not addressed.
The data from the OSHA IMIS does not specify the job title or position description of the worker who was sampled. Therefore, the identification of the Exposed Personnel reflects the best judgment of the author of the profile.
The focus of this information is to provide guidance to understand the occupational health hazards from chemical substances, physical and biological agents, radiological, ergonomic, and environmental hazards from exposure to plants and animals. Potential occupational health exposures in this industry were derived from the OSHA Integrated Management Information System database between 1984 to 2020. Additional information was obtained from the National Institute for Occupational Safety and Health (NIOSH) Health Hazard Evaluations performed by
request of employee representatives and organizations from 1978 to 2020. Also consulted was the NIOSH Report on Air Contaminants in Tire Manufacture (https://www.cdc.gov/niosh/docs/84-111/pdf/84-111.pdf?id=10.26616/NIOSHPUB84111 and the NIOSH Current Intelligence Bulletins https://www.cdc.gov/niosh/pubs/cib_date_desc_nopubnumbers.html
This document discusses occupational health exposures in curing rubber and the selection and use of solvents, which may be responsible for cancer in humans. In particular, there is evidence to show an increased incidence of the bladder. Larynx, stomach, esophagus, prostate, and lung cancer; leukemia; and malignant lymphoma including multiple myeloma and other lymphopoietic cancers. More information is discussed in the various International Agency for Research on Cancer (IARC) Monographs on the Occupational Exposures in the Rubber Manufacturing Industry. (https://monographs.iarc.fr/wp-content/uploads/2018/06/mono100F-36.pdf and IARC Monograph on Select Monomers, Plastics, Synthetic Elastomers and Resins (https://publications.iarc.fr/37)
Debono et. al. reported that occupational exposure to agents in plastics and rubber manufacturing has been associated with an elevated risk of certain cancers. As compared to the cohort of women in materials processing occupations, they had an elevated rate of lung cancer (HR 1.38, 95% CI 1.20 to 1.58) that was not observed among men. An elevated rate of breast cancer was observed among female laborers (HR 1.36, 95% CI 1.01 to 1.82) and molders (HR 1.47, 95% CI 0.91 to 2.37) in plastics and rubber product fabricating occupations. Overall, elevated rates were observed for esophageal, liver, stomach, prostate, and kidney cancer in job-specific subgroups, including mixing and blending, bonding and cementing, and laboring. There was little evidence of association for lymphatic or hematopoietic cancers. Ref: https://oem.bmj.com/content/77/12/847
The following table represents only the potential occupational health concerns related to the entire rubber and plastics industry based on a job task or work activity, and any related OSHA standards for regulatory compliance. The information presented does not indicate or suggest a relative risk of exposure based on the location within the table nor provides any exposure information. Health risks associated with fatigue, working long hours, and other psychosocial disorders.
Acrylate resins are a class of thermoplastic resins produced by polymerization of acrylic acids derivatives.
Banbury Mixing involves combining raw ingredients of plastic and rubber fillers, extender oils, accelerators, antioxidants together into a mixer called a Banbury. This process breaks down rubber materials for thorough and uniform dispersion of the ingredients
Bead Building in the tire industry provides parallel steel wire with vulcanized rubber into a semi-hard material and covered with a rubberized fabric. The beads maintain the shape of the tire on a rim.
Blow Molding is a process for the production of hollow thermoplastic shapes. This method of fabricating involves a plastic parison (hollow tube) placed between two halves of a mold (cavity) and by using air pressure the parison is forced to take the shape of the cavity. Air pressure is introduced through the inside to force the plastic against the mold surface that defines the shape.
Cement is the dispersion of "solution" of unvulcanized rubber or plastic in a volatile solvent and may or may not be an adhesive composition.
Calendering is a process to roll the softened rubber plastic mixture from the feed mill and then applying fabric to form into continuous sheets of plystock with an exact thickness.
Catalysis is the acceleration (or retardation) of a chemical reaction in the presence of a comparatively small amount of a chemical substance called a catalyst.
Compounding are batch lots of rubber stock ingredients that are weighed and prepared for subsequent mixing in Banbury; solvents and cements are prepared for process use.
Curing is the process to assemble green or uncured tires with chemical substances to keep them from sticking to the mold during vulcanization. It is also the technique of cross-linking a plastic material.
Elastomer is a material exhibiting complete recovery to its original size after undergoing strain.
Extrusion of the softened rubber mixture is forced under pressure through a die forming a long continuous strip in the shape of tread or tube stock. The strip is cut into specific lengths and cut ends are cemented.
Final Inspection and Repair is a process to examine a cured tire prior to passing final inspection
Heat Sealing is a method of joining plastic films by simultaneous application of heat and pressure to areas in contact. Heat may be supplied conductively or dielectrically/\.
Injection Molding is a method of forming a plastic to the desired shape by forcing heat softening plastic into a relatively cool cavity where it rapidly solidifies.
Milling is another process beyond batching on a mill. Material is cooled and sheets or slabs are coated with industrial talc, which may contain asbestos in the mix. The stock is returned for mixing additional ingredients or it goes to a breakdown or feed mills before extrusion or calendering.
Mold is a cavity into which the plastic composition is placed and from which it takes it form.
Plasticizer is a liquid or solid incorporated in natural and synthetic resins and related substances to develop such properties as resiliency, elasticity, and flexibility.
Plystock Preparation occurs when the calendering material is cut and applied to the size of tire building or rubberized product so strains of fiberglass or other material have the proper orientation.
Polymerization is a chemical change resulting in the formation of a new compound whose molecular weight is usually a multiple of that of the original substance.
Resin is any base material used to make thermoplastic materials (polyvinyl, polystyrene, polyethylene) or thermosetting polyesters, epoxies, and silicones.
Thermoplastic is any material, such as polyethylene, PVC, and ABS, which can be re-melted and reprocessed without considerable loss of properties or scrap loss.
Thermoset is a term that refers to the family of materials that can be melted only once during the original processing and cannot be reprocessed after the original part is made.
Welding is the joining of two or more pieces of plastic by fusion of the material in the pieces at adjoining or nearby areas either with or without the addition of plastic from another source.
Photos courtesy of Getty Images.
Worker Exposure Profiles in Rubber and Plastic Products
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