Manufacturing

Burden

Respiratory diseases caused by mineral dusts and related exposures are a substantial problem in the manufacturing sector. For example, during 1990-–1999, manufacturing accounted for 43.8% of all deaths due to silicosis, which was the largest percentage for any one industrial sector, and nearly twice as much as the next highest sector [NIOSH 2008a]. Silica is a recognized hazard in many manufacturing processes, but new sources of exposure continue to emerge. For example, production of engineered stone countertops was recently recognized as a cause of silicosis [CDC 2015a]. Abrasive blasting with copper or coal slag, such as in the shipbuilding industry, is currently controversial because of disagreement about whether the Occupational Safety and Health (OSHA) Beryllium Rule should address beryllium exposures associated with such blasting activities [OSHA 2017, Pearson 2017]. Mesothelioma deaths are an important marker of previous exposure to asbestos and elongate mineral particles (EMP) with asbestos-like health effects [NIOSH 2011]. The manufacturing sector accounted for a high proportion (24.8%) of mesothelioma deaths in 1999, the last year in which usual industry and occupation was coded from death certificates of a large proportion of states [NIOSH 2008b]. An important emerging source of elongate mineral exposure is manufacturing manmade elongate particles (such as engineered elongate nanomaterials) and using those materials in downstream manufacturing processes [NIOSH 2013]. Another potential source of EMP exposure in manufacturing are crushed stone operations when source materials contain EMP [Kullman et al. 1995, Ryan et al. 2011]. Hypersensitivity pneumonitis caused by used metalworking fluids, which contain metals and other contaminants such as microorganisms, remains an important problem. Approximately 1.2 million workers in the U.S. are exposed to metalworking fluids. Outbreaks of hypersensitivity pneumonitis, a potentially severe disease, continue to occur in these workers yet the specific etiologic agent(s) in used metalworking fluids remain unknown, complicating preventive efforts [Rosenman 2009].

Need

There is a need for basic/etiologic research to characterize the hazards associated with emerging advanced materials such as nanoparticles, EMPs other than asbestos, metalworking fluids, and to assess the risk for beryllium sensitization and chronic beryllium disease posed by abrasive blasting with coal and copper slags containing small amounts of beryllium. If hazards are documented, clarification of exposure-response relationships will also be important. There is a need for surveillance research to develop novel approaches for health and hazard surveillance that will improve the ability to track the burden of hazardous exposures and work-related illnesses associated in particular with respirable crystalline silica, but also with other exposures. Intervention research is needed to improve certain types of exposure assessment, such as developing real-time or near real-time assessment of respirable crystalline silica exposure and developing methods to better assess exposures associated with abrasive blasting. Work could also seek to develop improved, better-performing control technologies (engineering controls, personal protective equipment, etc.) for a variety of manufacturing settings. There is a need to evaluate the effectiveness of primary and secondary preventive interventions, especially for novel exposures and in novel manufacturing settings. Additional research could also help to improve the evidence base for preventive recommendations related to beryllium exposure from materials containing small amounts of beryllium, such as abrasive blasting media made from coal or copper slag and ash generated in coal-fired power plants. Special efforts must be made to address the unique needs of vulnerable workers and small businesses.

Burden

Using data from 2004–-2011, an estimated 3.2% of the average annual number of workers in the manufacturing sector (14.7 million) have chronic obstructive pulmonary disease (COPD), totaling about 470,000 people [NIOSH 2014a]. Evidence documents that workers in certain manufacturing subsectors are at increased risk for COPD. Based on objective spirometry data, odds ratio (OR) for COPD was significantly increased for rubber, plastics, and leather manufacturing (OR 2.5); textile mill products manufacturing (OR 2.2), and food products manufacturing (OR 2.1) [Hnizdo et al. 2002]. A systematic review identified various occupational agents reported to cause COPD. Those exposures relevant to manufacturing, identified with varying degrees of evidence, include silica, asbestos, refractory ceramic fibers, flour, endotoxin, cadmium, carbon black, agricultural dusts (animal and plant), dusts from rubber, cotton, wood, iron/steel and smelting, welding fumes, isocyanates and other chemicals [Fishwick et al. 2015]. Another emerging type of fixed airways disease, obliterative bronchiolitis, can cause very severe disease and is often misdiagnosed as COPD [Cullinan et al. 2017]. Exposure to the food flavoring chemical diacetyl continues to be an important emerging cause of obliterative bronchiolitis in food products manufacturing settings, such as popcorn, flavorings and coffee manufacturing [Kreiss 2013; Duling et al. 2016].

Need

Although much progress has been made in preventing flavorings-related lung disease, much remains to be done. Basic/etiologic research is needed to better define the mechanisms by which diacetyl and related flavoring chemicals damage the airway, since this information can help to better predict what other chemicals could cause similar toxicity and help to better refine our approaches to prevention. There is great need for prevention research to evaluate exposures in a broader range of food products manufacturing settings where diacetyl and related chemicals are present and, for purposes of primary prevention, to develop practical, cost-effective approaches to controlling exposures. Because usual medical testing is insufficiently sensitive to detect many cases of obliterative bronchiolitis, there is need to develop better approaches to early detection for use in secondary prevention efforts. Also, there is need for research to assess the effectiveness of primary and secondary preventive interventions. In addition, basic/etiologic research is needed to improve the strength of evidence for causation of COPD by various occupational exposures and to assess exposure-response relationships. In particular, more information is needed about the impact of organic dust exposures (rubber, cotton, wood, food & seafood-related, endotoxin, etc.) and the ability of various chemical exposures to cause COPD (examples include welding fumes and styrene).

Burden

Work-related asthma (WRA) encompasses occupational asthma (caused by work) and work-exacerbated asthma (existing asthma is made worse by work exposures). The manufacturing workforce in the U.S. is large with 12.3 million workers. While the 6.1% prevalence of asthma for manufacturing workers is not excessive [CDC 2016], this represents a very large number of workers with asthma. Conservatively, about 15% of the 750,000 manufacturing workers have asthma caused by work [Torén and Blanc 2009], totaling about 113,000 workers. In addition, about 21.5% have work-exacerbated asthma (Henneberger, Redlich et al. 2011), totaling about 163,000 workers.

Manufacturing workers are exposed to numerous irritant and sensitizing agents that are risk factors for asthma. In NIOSH state-based surveillance, “miscellaneous chemicals and materials” were the most frequently identified cause of WRA [NIOSH 2015]. Chemicals can frequently be irritants (e.g., chlorine gas, peracetic acid, cleaning agents, etc.) and can also be immune sensitizers, such as widely-used reactive low molecular weight chemicals like isocyanates that are used in paints, plastics, and other materials [NIOSH 2014b]. High molecular weight agents such as proteins encountered in processing foods, whether of plant or animal origin, are also important sensitizers. New asthmagens and settings for WRA continue to be identified by the NIOSH Health Hazard Evaluation Program [NIOSH 2009, CDC 2015b].

Need

Basic/etiologic research is needed to better understand relationships between exposures to irritants and low molecular weight agents and WRA among manufacturing workers and to develop better biomarkers for immune sensitization to low-molecular weight agents. Better understanding of mechanisms of irritant-induced WRA is needed to provide a conceptual basis for better preventive interventions. There are needs to clarify the potential health hazards of new and emerging asthmagens in manufacturing such as chemicals released during additive manufacturing (three dimensional printing). Intervention research is also needed. For example, studies are needed to assess effectiveness of primary and secondary preventive interventions to prevent or mitigate work-related asthma among manufacturing workers. Improving the existence and validated performance of control technologies (engineering controls and PPE) related to WRA is needed in a variety of settings. Better approaches to secondary prevention through identifying workers with WRA and preventing their progression to irreversible disease is needed. Further research is needed to determine how much of a reduction in exposure is needed to prevent WRA for a range of asthmagenic agents. For all types of research special efforts should be made to address the unique needs of vulnerable workers and small businesses.