Analyzing Occupational Injury And Illnesses By Categories

 

To devise methods of reducing the burden of illness and injury arising from employment and the work environment, it is essential to analyze patterns of disease outcomes in ways that reflect the mechanisms by which the injury or illness may have occurred. The three most useful broad categories are industry classification, occupational group, and health outcomes.

For industry classification, the BLS employs 20 major categories of activity and many subcategories in the official U.S. system for categorizing employment (the North American Industrial Classification System, or NAICS). A useful grouping for analysis by process type is:

 	
mining and extractive;
 	
construction;
 	
transportation;
 	
manufacturing;
 	
retail and wholesale trade;
 	
service (including health care and education);
 	
finance;
 	


For occupational groups, the BLS employs 36 major categories. Job assignment groups have different spectra of risks. For manufacturing industry, some useful groupings of jobs categories are:

 	
skilled trades (maintenance, repair, installation, service);
 	
mechanical material handling (powered industrial trucks, cranes);
 	
other support (cleaners, production service);
 	
fixed production (machine operators and assemblers);
 	
clerical and technical;
 	
executive and professional.

For health outcomes, the BLS categories that are used to describe the nature of the condition are not as useful. A more useful cause-oriented grouping combining both nature of injury and gravity is:

 	
fatal or severe acute injuries;
 	
injuries and illnesses of lesser gravity;
 	
musculoskeletal disorders;
 	
short-onset chemical effects;
 	
chronic disease related to long-term chemical exposure;
 	
outcomes from psychosocial stressors.

It is important to realize that there is a great deal of overlap between categories in actual practice. First, with regard to health effects, it is very likely that a worker who develops one kind of impairment may be simultaneously exposed to several hazards and would, in any case, be more susceptible to additional problems once any aspect of his or her health has been compromised on the job.

Also, many types of jobs cross industry category lines. For example, truck drivers are employed in the service sector, in construction, in manufacturing, and in agriculture, not just in transportation. Thus they face the same risks as those of a transportation employer and in addition are exposed to the particular hazards that are found in their industrial sector.

Some of these employment categories are very broad. For example, service sector job environments are quite diverse and include two major and very different employment groups: health care and education services. Health care itself is a very broad category that clearly encompasses many more opportunities for intense exposure to injury and chemical and physical hazards, as well as unique hazards in patient handling and infectious disease. Educational services’ physical hazards are less intense, but they are not benign. Hazards in educational services can include exposure to infectious agents; physical attack, even murder; very poor indoor air quality; and extreme stress.

It is also important to recognize that the diversity of the employed population may lead to differing levels of risk in the various worker demographic groups present. The differing risk may be a reflection of different susceptibilities and physical characteristics, different types and levels of exposure, or both. One typical breakdown of worker demographics focused on vulnerability is:

 	
women;
 	
young workers;
 	
older workers;
 	
minority status;
 	
immigrant status;
 	
poverty status.

These demographic categories may not be particularly useful for prevention or intervention. It is, in general, very difficult to change the workers (and probably illegal to try), and in any case, making the workplace safe for all demographic groups qualified to work in it is the preferable approach. Often if different risks are observed between workers in these categories, the differences arise from substantially different employment patterns and exposures on the job rather than from true inherent differences among categories of workers. Indeed, studies that have controlled for job characteristics and industrial sector have generally found fewer differences based on worker demographics. In addition, another practical problem is that vulnerable workers may be exposed to worse working conditions and at the same time may have less ability to ensure that their employment rights are intact. Thus, ensuring that workplace rights and guarantees are available to all workers, rather than creating separate employment classes, is the means by which the workplace can be made safer for all workers.
Contrasting Approaches To Prevention
In 1931, H.W. Heinrich published Industrial Accident Prevention, and his approach became the dominant paradigm for prevention of occupational injury (Heinrich, 1931). Underlying his model was the assertion that 90% of workplace injuries are caused by ‘unsafe acts’ – in other words, the antithesis of a systems approach to accident prevention. The concept and the canonically repeated 90% incidence became a mainstay of occupational safety practice and theory. This proportion has never been verified in the published literature. The idea that unsafe acts cause most accidents and injuries remains the conceptual framework underlying the historical approach to health and safety. Specifically, the unsafe acts theory posits that:

 	
accidents are caused by unsafe acts and operator error;
 	
accidents can be averted if employees are trained to follow safety rules;
 	
employees should be motivated to follow safety rules.

In the 1970s, the quality movement, a new and contrasting approach to that of Heinrich and the ‘unsafe worker’ conceptualization, was developing. In the quality movement approach, occupational injury is viewed as follows:

 	
Adverse effects are caused by the physical environment and production system.
 	
Processes can be modified to avoid injuries and illnesses.
 	
Workers can be trained to recognize hazards and system failures.
 	
Workers can be motivated to participate in hazard identification and abatement.

The quality movement is reflected in competing approaches to injury prevention; the best known is the Hierarchy of Controls (Rosenstock, 1996; Plog et al., 2002). The hierarchy is an approach to modifying the environment in various categories in order to prevent injury and illness, rather than prescribing worker-behavioral modification within an unchanging environment. The ‘hierarchy of controls’ is:

 	
elimination;
 	
substitution;
 	
engineering;
 	
warnings;
 	
training and procedures;
 	
personal protective equipment.

The hierarchy of controls has been more readily recognized in practice for chemical and physical health hazards than it has for safety hazards. For example, most modern safety practitioners will prefer higher-level environmental controls for noise and chemical exposures, like vibration damping, noise enclosure or fume capture technologies, to earplugs and respirators. The approach is far less commonly applied to injury controls, where, in the United States, safety rhetoric favors ‘working safely’ rather than extending the reach of safety devices and guards. The hierarchy of controls, however, is much more commonly practiced for injury control in the European Union, where most experts agree that ‘unsafe behaviors’ are best reduced by modifying the social environment or work organization that causes and reinforces such behaviors.