Inherent Safety

An iterative risk assessment will enable researchers to integrate safety and health throughout the life cycle of products or processes. Inherently safer technologies are intended to significantly reduce or eliminate biological, chemical, and physical hazards simultaneously, so that issues such as chemical toxicity are evaluated concurrently with explosion potential, flammability, ergonomic or injury hazards, radiation, and noise [Zwetsloot and Ashford 2003]. Inherent safety is an intrinsic feature of the design. It is best implemented early in the design process prior to huge capital expenditure and can even lead to cost savings [Mannan 2002; Christensen and Manuele 1999].

The simplification of the production process for the chemical synthesis of DNA is an example of an inherently safer design. Two principles of inherent safety—simplification and substitution—were applied to reduce the hazard and cost of bringing this technology to market. The production process underwent redesign to use fewer solvents and reagents by halving the number of steps from four to two. The use of the most highly toxic reagents and solvents was eliminated and chemical waste was reduced by 75%. Not only was safety improved, but the expense of hazardous solvent and reagent waste disposal was reduced—a cost that was equivalent to the purchase of the chemicals [Sprackland 2002].

The occupational safety and health community can play an important role in improving the evaluation of emerging technologies for inherently safer design opportunities by nurturing partnerships to pilot these approaches. It can assist firms in these tasks as well as to provide businesses, government and academia with the tools they need to partner in these efforts. For example, occupational safety and health professionals should be involved in the prospective analysis steps and iterate within the process to distinguish potential benign technologies for hazardous technologies.

How to Achieve Inherently Safer Designs

Inherently safer technologies emerge from designs that focus on the elimination of hazards from the production process rather than the management and control of those hazards. In theory the inherently safer design process is less vulnerable to failure since the hazards have been significantly reduced or eliminated [Ashford 2000]. Nonetheless, a broad array of inherently safer design methods must be considered so a technology will not create a new problem while solving another. Inherently safer design, simply defined, is one that “avoids hazards instead of controlling them” [Hendershot 1999] and involves several methods, also called principles [Hazell 2000; Hendershot 1999; Bollinger et al. 1996]. The following list describes several inherently safer design methods:

• Intensification (also referred to as minimization) involves using minimal amounts of hazardous materials so that releases are not catastrophic. While this method may lead to storing smaller quantities of a chemical, it may also result in more frequent deliveries of the chemical, and thus, increase the potential for transport spills [Mannan 2002]. This example illustrates that an array of methods must be considered, because focusing on only one method may create new hazards.
• Substitution occurs when safer materials are used. For example, the Phosphorous Match Act of 1912 led to the elimination—through substitution—of the use of white phosphorous in manufacturing matches, and thus, the elimination of the devastating disease, phosphorous necrosis of the jaw [Myers and McGlothlin 1996].
• Alternative reaction routes is a method exemplified by a change in the process used to produce the insecticide, Carbaryl, for which methyl isocyanate was an intermediate product. Methyl isocyanate was the chemical released at Bhopal, India, where approximately 3,800 people died. By using the same raw materials but changing the process by sequencing the chemical reactions in a different order, methyl isocyanate was eliminated as an intermediate product [Bollinger et al. 1996].
• Modified storage requirements keep chemicals such as ammonia or chlorine at a pressure below their boiling point where, in case of a leak, the evaporation rate would be relatively low.
• Energy limitation reduces the amount of energy available in the production process. A historical example serves to illustrate this method in preventing hazardous exposures. Gustave Eiffel, in constructing his tower in 1889—an emerging technology of his day—assembled parts of the tower on the ground to avoid exposure to falls from a high elevation on the tower. No employee lost his life while working on this project [Barry 1972].
• Simplification uses processes and facilities that are designed to eliminate unnecessary complexity and be tolerant of operators’ errors. The nuclear power plant incident at Three-Mile Island in 1979 is an example of a complex process that encouraged errors [Perrow 1999].
• Optimal plant layout is an additional method which is an inherently safer design for logistical activities [Zwetsloot and Ashford 2003].

Inherently safer and cleaner technologies may result from technology-forcing performance regulations [Strasser 1997]. More than a century ago, the Safe Appliances Act of 1893 required that railroad companies use the latest safety innovations to protect their workforce, and as a result air brakes and automatic couplers were adopted nationwide followed by many other technologies that steadily reduced the rates of fatal and serious injuries to workers [MacLaury 1981; Holbrook 1939]. The resulting design principles need to incorporate intervention and prevention strategies based on safety and health research findings.

The long-range implications of the technology need to be understood to ensure that technology forcing does not shift one kind of risk into another type of risk. Moreover, all of these principles need to be considered together so as to avoid the creation of unanticipated hazards [Mannan 2002].

The investigation of candidate principles can include the results of other investigations. One of these is the Theory of Inventive Problem Solving [Rantanen and Domb 2002], which is an engineering design approach that uses 40 principles to resolve contradictions between risks and benefits. It is a tool for engineers to view problems outside of their experience and avoid tradeoffs by eliminating risks and exploiting benefits at the design stage (Altshuller et al. 1997).

Cleaner Production Technologies and the Work Environment

The relationship between environmental innovations and worker health is an important example of unintended hazards. The substitution of hydrochlorofluorocarbons for chlorofluorocarbons reduced damage to the ozone layer, but it created both a carcinogenic and flammability risk to workers. In another example, water-based paints eliminated volatile organic solvents but created a biocide hazard for workers [Ashford 1997].

Ensuring worker safety and health and environmental improvement must be seen as interrelated rather than as separate activities. Environmental concerns now are increasingly factored into design and operational decisions, but in order to further integrate the work environment, managers need to encourage scientists, engineers, and technology developers to include safety and health concerns in both their design and operational criteria. The recent occupational health literature contains a growing number of studies addressing the theory and practice of the integration of industrial hygiene and environmental preventive procedures [Armenti 2002; Roelofs 2001; Bartlett et al. 1999; Quinn et al. 1998; Enander et al. 1998; Ellenbecker 1996; Goldschmidt 1993]. Finally, a recent study of the benefits and barriers of next generation environmental technologies in a number of U.S. industries concluded that, although in its infancy, green chemistry technologies provide significant benefits for occupational health, environmental health, and economic security [Lempert et al. 2003].

The diversity of work environments, however, makes implementing such strategies challenging. It is difficult to know every organization’s facility layout, degree of automation, equipment status, engineering controls, and administrative practices such as shift work [Ashford 1997].

Chemical manufacturing processes in the United States, Italy, and China, for example, range from manual reactor vessel charging, mixing, packaging, and maintenance to processes that are enclosed and automatic. The same process under these different conditions has different implications for worker safety and health. If a worker was exposed, the physiologic route of entry cannot always be anticipated, because knowledge of the physical state of the substances at different stages in the process is lacking.

Figure 5. Robotic welders in a modern automotive assembly. Note the absence of sparks and intense UV radiation. Manufacturing engineers responsible for the robotic system operate in front of a control panel that is not in view.

In order to facilitate exposure reduction and injury prevention, researchers must articulate and evaluate technical options using multivariate criteria, which include safety and health, economic, and environmental factors. These criteria can also be used to compare improvements that each option might offer over existing technological solutions [Zwetsloot and Ashford 2003]. One approach is Technology Options Analysis (TOA), which entails the identification of inherently cleaner and safer options for the technology being considered. TOAs can identify designs that might be expanded into widespread use, technologies that might be transferred from one industrial sector to another, or benign technologies that still need to be developed. TOAs expand risk assessments to include alternative production technologies, e.g., input substitution and process redesigns [Ashford 1997].

TOAs need to be augmented by analyses that identify where in the production process changes to inherently safer inputs, processes, and products could be made. Such analyses have addressed environmental impacts, but they need to be expanded to include the occupational environment. The Toxics Use Reduction (TUR) Institute of Massachusetts evaluated the application of TUR in OSHA programs [Penney and Moure-Eraso 1995; Roelofs et al. 2000]. It evaluated the impact on occupational health practices in 35 Massachusetts firms where the State promoted cleaner production alternatives. The study concluded that TUR activities improved the work environment, but that such improvements were neither systematically planned nor incorporated into their activities. Information about superior technologies regarding existing options to protect both workers and the environment were also missing.

An opportunity for improved occupational safety and health exists with firms that develop emerging technologies, because they are more likely to adopt more benign technologies in new facilities or operations [Zwetsloot and Ashford 2003].

New operations, which may be driven by emerging technologies, are most receptive to modifying their processes and final products. Firms in transition may delay implementing safety improvements even though they require new investments in an existing facility. Nonetheless, these firms may adopt emerging technologies with inherently safer designs if they are searching for ways to improve safety, protect the environment, or reduce high costs related to energy, water, or materials.

The receptivity to inherently safer designs differs for primary, secondary, and ancillary production processes as well as final products. These processes are exemplified in Table 2. The most resistance to innovation might be expected from existing firms whenever demands are placed on changing their primary process. When a new process is adopted, usually by the diffusion of an alternative technology, the firm may be hesitant to change a proven method and take a chance on altering the appearance of its product. It may be relatively easy for the firm to find an alternative, safer process if it focuses on the ancillary process. Inherently safer designs are better received with emerging technologies in the later stages of production, although in the designto- technology adoption process, a design freeze will need to be anticipated.

Advancing Inherently Safer Designs

Expanding Inherently Safer Designs

Most attention to inherent safety principles for workers has occurred in the chemical manufacturing sector [Hunter 1999], but these approaches need to be explored in other sectors such as agriculture, construction, transportation, healthcare, and services. Scientific research is needed to advance the foundations for inherently safer and cleaner industrial processes and to translate that knowledge into practice. Systematic analytic methodologies are needed to measure the degree of inherent safety to allow for the comparison of alternative designs. Research is needed so emerging technologies that are designed to improve the environment also improve occupational safety and health [Ashford et al. 1996]. A systems approach is needed for integrating occupational and environmental assessments into operations at the firm and corporate levels. This includes the development, validation, and dissemination of data elements and models that can be used by safety and health professionals throughout industry to support early and effective technology evaluation. Researchers also need methods to identify benign emerging technologies during the prospective analysis that can substitute for traditionally risky technologies.

Table 2. The stage of production explained by an example of casting and electroplating in metal screw manufacturing.

Stage of production	Example	Potential occupational hazards
Primary	Casting	Toxic fumes and molten metal contact
Secondary	Electroplating	Toxic and corrosive hazards
Ancillary	Cleaning or degreasing	Toxic and flammable solvents
Product	Metal screws	Injury

Integrating Inherently Safer Design into Business Practice

Experts in occupational safety and health need to attend conferences or other forums to identify workplace applications for new technologies. Such forums will also allow these experts to share their expertise with technology developers so that new applications will either enhance occupational safety and health or at least be introduced safely in the workplace. Research is needed to overcome barriers in improving workplace conditions and economics, while maintaining high-quality and innovative products or services. Firms that have succeeded in these improvements have developed strategies that enable them to thrive in the midst of change. Their example suggests a need for research strategies that identify information needs and technology gaps in order to encourage widespread development and implementation of inherently safer technologies. These include a need to:

• Access knowledge about inherently safer technologies;
• Apply or adapt emerging technology to specific workplaces or facilities;
• Overcome resistance to change;
• Ensure that inherent safety is implanted early in the design of emerging technologies.

Applying Science to Engineering

Green chemistry [Anastas and Williamson 1998], green engineering [Allen and Shonnard 2002], and inherently safer chemical processes [Bollinger et al. 1996] represent current attempts at filling some of the gaps for new synthetic pathways, production processes, and design as a comprehensive system, but attempts are also needed in areas beyond chemical production. In addition, progress needs to be made in methods to interpret data and information by broadening the criteria upon which technologies are evaluated.