Battle of the Bands
Alternative Strategies for Risk Management in the Workplace
BY ALEX MERCER
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As IH professionals, we love the details: data, measurements, numbers. The ability to measure something elusive in a quantitative way feels like taking control; we make sense of the chaos, squeezing logic out of the mess. But what happens when this approach fails due to lack of data or exposure limits? Preserving the safety and well-being of employees in the workplace is paramount for any responsible employer, but without the structure of quantitative data, this task can feel like navigating a minefield while blindfolded.
Formal exposure limits such as the ACGIH threshold limit values (TLVs), OSHA permissible exposure limits (PELs), NIOSH recommended exposure limits (RELs), and Occupational Alliance for Risk Science workplace environmental exposure levels (WEELs) require exhaustive research and extensive data to solidify. For this reason, a vast number of products that present exposure risks lack formal exposure limits, leaving a noticeable gap in the traditional risk management and control process. According to EPA, only 1/85th of products in the United States have formal exposure limits.
Enter “the bands”: hazard banding, control banding, and occupational exposure banding. These practical approaches provide alternative strategies for assessing and managing workplace chemical hazards and risks through qualitative or semi-quantitative assessment frameworks, even in the absence of formal exposure limits.
HAZARD AND CONTROL BANDING
Hazard banding refers to the process of categorizing chemical hazards into groups or bands based on their intrinsic hazardous properties, such as toxicity, corrosiveness, flammability, and reactivity. Similarly, control banding is a grouping of control solutions according to their effectiveness for specific exposure situations. A hazard band can be linked with an appropriate control band based on the risk properties of the substance in question. Tools such as COSHH Essentials, developed by the United Kingdom’s Health and Safety Executive (HSE), provide a user-friendly platform for hazard and control banding.
COSHH Essentials—the acronym stands for Control of Substances Hazardous to Health—assigns one of five hazard bands to a chemical based on the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) hazard statements (also known as H-statements) associated with the substance. The classification ranges from A, signifying low hazard, to E, for high hazard. A risk assessment is then conducted within the tool: as the user inputs the physical properties and usage quantities of the substance, the exposure potential is assessed. The output is a control approach appropriate to the anticipated airborne concentration range of the substance.
Tools like COSHH Essentials were designed to allow small to medium-size enterprises (SMEs) with minimal background in industrial hygiene or toxicology to effectively assess chemical hazards and mitigate risks. For this reason, the control outputs tend toward the simplistic. Recommendations range from specific (for example, local exhaust ventilation to control an airborne chemical hazard at the source) to vague (a suggestion to “consult a professional” for high hazard products where additional expertise beyond the capacity of the tool is required to ensure the well-being of workers). When used in alignment with their intended scope, tools like COSHH Essentials can simplify the risk assessment and control process, link hazards with appropriate control measures, and ensure control efforts are proportionate to the identified risks.
Banding tools allow users from different backgrounds to deal with all chemical substances.
OCCUPATIONAL EXPOSURE BANDING
Like hazard banding, occupational exposure banding is a process of categorizing chemical hazards into groups based on a substance’s hazardous properties. Occupational exposure banding provides a stepwise strategy for categorically assigning chemical substances to an occupational exposure band, or OEB, based on the body of knowledge surrounding health effects or outcomes of specific chemicals. More involved than hazard banding and control banding, occupational exposure banding is best utilized or overseen by an industrial hygienist or toxicologist. Several occupational exposure banding schemes exist; many are company- or industry specific. The NIOSH scheme is, by far, the most widely used and cited.
The occupational exposure banding process starts with a chemical’s state of matter (gas/vapor vs. dust/particulate) and considers nine categories of potential health outcomes: carcinogenicity, reproductive toxicity, specific target organ toxicity, genotoxicity, respiratory sensitization, skin sensitization, acute toxicity, skin corrosion and irritation, and eye damage and irritation. The NIOSH scheme groups substances into one of five OEBs—A through E—based on its health hazard potential. The least harmful chemicals, which require high concentrations to cause health effects, are assigned to Band A, whereas the most harmful, which cause health effects at very low concentrations, are assigned to Band E.
The NIOSH occupational exposure banding process utilizes a tiered approach tailored to the assessor’s skill. A Tier 1 assessment, which is a starting point for the creation of a NIOSH OEB, uses information solely from publicly available data such as GHS H-statements and requires basic understanding of toxicological principles. Because many products are associated with multiple cross-category health effects—for example, a chemical can be both carcinogenic and a skin sensitizer—each health effect category associated with a product must be assessed separately through the Tier 1 criteria. For products with multiple Tier 1 criteria, the most stringent OEB would be selected for risk management.
As an initial qualitative screening based on limited inputs, the Tier 1 process allows chemicals to be assigned only to bands C, D, or E. The endpoint of the Tier 1 approach determines whether the process will progress to Tier 2. If the result of the Tier 1 evaluation is Band C or Band D, the user must conduct a Tier 2 evaluation. An output of Band E—the most hazardous category—stops at Tier 1, as no further stringency can be applied with additional inputs. To assign a substance to either Band A or Band B, the Tier 2 process must be conducted.
Compared to Tier 1, Tier 2 is a semiquantitative process that requires additional data as well as an experienced assessor to complete. The assessor must have a solid working understanding of toxicological principles. Tier 2 uses a NIOSH-approved database search of health effects. Each of the nine categories of potential health outcomes is assigned an endpoint determinant score (EDS). (For a full explanation of EDS values, see “The NIOSH Occupational Exposure Banding Process for Chemical Risk Management.”) Finally, all the EDSs are summed to determine the total determinant score (TDS) and the Tier 2 band. A substance with a TDS below 30 progresses to the Tier 3 process. (NIOSH has developed an e-tool for occupational exposure banding that can assist with either Tier 1 or Tier 2 assessments.)
The Tier 3 process is the final stage, requiring extensive, advanced toxicological expertise from an experienced industrial hygienist or toxicologist. Tier 3 utilizes all available data from peer-reviewed reports and literature. A proper Tier 3 assessment may take months or even years, as new data is continuously being generated. Extensive professional review of all available data is conducted, with the endpoint being assignment of an OEB band with much more confidence than can be assigned through a Tier 1 or Tier 2 approach.
Overall, the outcomes of the NIOSH occupational exposure banding system align well with formal exposure limits—that is, they provide comparable health protection. A NIOSH evaluation of 606 chemical substances with known OELs using the Tier 1 process resulted in banding recommendations that were in alignment with, or more stringent than, the OEL in 91 percent of cases. A similar assessment of the Tier 2 strategy showed 98 percent of the banding recommendations were in alignment with or more stringent than the OEL.
LIMITATIONS OF BANDING
The banding approach, regardless of the system, provides a consistent and documented process of assessment according to the industry-recognized principles of hazard recognition, evaluation, and control. Banding tools allow users from different backgrounds to deal with all chemical substances, regardless of whether they are accompanied by formal exposure limits.
As with all tools, limitations restrict the utility of banding approaches in some circumstances; the outputs of the process are completely dependent on the quality of the input. COSHH Essentials tends to be overprotective but may be suitable for SMEs. The NIOSH occupational exposure banding approach is more nuanced, but professional expertise in toxicology is required for anything past a Tier 1 assessment. Even for professionals, data gaps in the literature, changing information, and personal experiential bias may restrict the utility of a Tier 2 or 3 assessment; databases require regular updates and potential realignment of relevant data sources with health endpoints and outcomes.
Mixed exposures present another challenge. No single process is currently available for assessing mixed exposures, though several methodologies have been proposed:
• the whole mixture process considers the mixture as a single entity, conducting the OEB process for the mixture in the same way as for a single substance
• the similar mixture process uses a toxicologically similar mixture as a proxy
• the group of similar mixtures process uses data from animal studies to extrapolate to humans
• the component-based mixture process assesses the most toxic component of the mixture
When applying these processes to a mixture, each chemical constituent requires individual assessment and assignment of the appropriate band.
Table 1. Banding Tool Comparison
Click or tap on the table to open a larger version in your browser.
In circumstances where short-term exposures are of concern, banding approaches are not appropriate. For example, the occupational exposure banding strategy is based on 8-hour limits only. Moreover, some health endpoints such as genotoxicity are generally less predictive of the overall recommended band than other health endpoints such as carcinogenicity. Additional research may allow for the impact of more highly predictive health endpoints to weigh more heavily on the endpoint band, thus refining the overall process.
Lastly, banding approaches do not consider dermal exposures. As the health effects of substances due to dermal exposures become more widely known and appreciated, tools should be developed that allow for the overall deleterious effect of chemicals on the body to be considered.
ADDING VALUE
Despite their limitations, banding approaches provide a strategy for risk assessment and control and management of workplace chemical hazards in the absence of prescriptive limits. But how does one know which approach is most appropriate? Table 1 answers this question by comparing the two most basic tools—the COSHH Essentials e-tool and the NIOSH Tier 1 occupational exposure banding tool—in terms of inputs required and outputs provided.
Either approach requires little more than the product safety data sheet or access to approved public databases and (for COSHH Essentials) some procedural knowledge. These banding tools and the alternative strategies they provide are bound to add value to the toolbox of every OEHS professional, allowing all to assess and manage workplace chemical hazards.
ALEX MERCER, MSc, CIH, ROH, is an industrial hygienist and current operations manager for JADA Solutions (HSE) Inc., a health, safety, and environmental consulting firm out of Sherwood Park, Alberta, Canada.
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RESOURCES
Health and Safety Executive: “COSHH Essentials.”
NIOSH: “NIOSH Occupational Exposure Banding e-Tool.”
NIOSH: “Occupational Exposure Banding.”
NIOSH: “The NIOSH Occupational Exposure Banding Process for Chemical Risk Management” (July 2019).
NIOSH: “Mixed Exposures Research Agenda: A Report by the NORA Mixed Exposures Team” (PDF, December 2004)
The Synergist: “Banding Together: Making the Case for Occupational Exposure Bands” (May 2022).
The Synergist: “Hyped about Hazard Banding: New Hope for an Established Practice” (October 2009).
The Synergist: “The ‘Bandits’ Speak: NIOSH Considers Feedback from Users of its Proposed Occupational Exposure Banding Process” (May 2018).
The Synergist: “The NIOSH Decision Logic for OEBs: Applying Occupational Exposure Bands” (March 2016).