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Occupational exposure banding

The Hierarchy of Occupational Exposure Limits, of which occupational exposure banding is a member

Occupational exposure banding, also known as hazard banding, is a process intended to quickly and accurately assign chemicals into specific categories (bands), each corresponding to a range of exposure concentrations designed to protect worker health. These bands are assigned based on a chemical’s toxicological potency and the adverse health effects associated with exposure to the chemical. The output of this process is an occupational exposure band (OEB). Occupational exposure banding has been used by the pharmaceutical sector and by some major chemical companies over the past several decades to establish exposure control limits or ranges for new or existing chemicals that do not have formal OELs. A similar concept used in the pharmaceutical industry is the Threshold of Toxicological Concern (TTC), which incorporates the consideration of a chemical’s structural features in predicting potency.^[4] Occupational exposure banding has become an important component of the Hierarchy of Occupational Exposure Limits (OELs). Occupational exposure banding is the lowest tier in the Hierarchy of Occupational Exposure Limits (OELs).^[3]

The U.S. National Institute for Occupational Safety and Health (NIOSH) has proposed a process that could be used to apply occupational exposure banding to a broader spectrum of occupational settings. The proposed NIOSH occupational exposure banding process utilizes available, but often limited, toxicological data to determine a potential range of chemical exposure levels that can be used as targets for exposure controls to reduce risk among workers. An OEB is not meant to replace an OEL, rather it serves as a starting point to inform risk management decisions. Therefore, the OEB process should not be applied to a chemical with an existing OEL.

Purpose

Occupational Exposure Limits (OELs) play a critical role in protecting workers from exposure to dangerous concentrations of hazardous material. In the absence of an OEL, determining the controls needed to protect workers from chemical exposures can be challenging. According to the U.S. Environmental Protection Agency, the Toxic Substances Control Act Chemical Substance Inventory currently contains over 85,000 chemicals that are commercially available, but a quantitative health-based OEL has been developed for only about 1,000 of these chemicals. Furthermore, the rate at which new chemicals are being introduced into commerce significantly outpaces OEL development, creating a need for guidance on tens of thousands of chemicals that lack reliable exposure limits.

The NIOSH occupational exposure banding process has been created to provide a reliable approximation of a safe exposure level for potentially hazardous and unregulated chemicals in the workplace. Occupational exposure banding uses limited chemical toxicity data to group chemicals into one of five bands.

Benefits

• Defines a set range of exposures expected to protect worker health
• Identifies potential health effects and target organs with 9 toxicological endpoints
• Provides critical information on chemical potency
• Time and data requirements are much less intensive than developing an OEL^[1]
• Informs decisions on control methods, hazard communications, and medical surveillance
• Draws attention to where data is lacking

Assignment Process

The proposed NIOSH occupational exposure banding process utilizes a three-tiered approach. Each tier of the process has different requirements for data sufficiency, which allows stakeholders to use the occupational exposure banding process in many different situations. Selection of the most appropriate tier for a specific banding situation depends on the quantity and quality of the available data and the training and expertise of the user.

Each of the five occupational exposure bands (OEBs) define a range of exposures expected to protect worker health. Band A has the highest exposure range for the least severe hazards, while band E has the lowest exposure range.

The three tiers of the NIOSH occupational exposure banding process

The process places chemicals into one of five bands, designated A through E. Each band is associated with a specific range of exposure concentrations. Band E represents the lowest range of exposure concentrations, while Band A represents the highest range. Assignment of a chemical to a band is based on both the potency of the chemical and the severity of the health effect. Band A and band B include chemicals with reversible health effects or produce adverse effects at only high concentration levels. Band C, band D, and band E include chemicals with serious or irreversible effects and those that cause problems at low concentration ranges. The draft resulting airborne concentration target ranges are shown in the graphic to the right.

Tier 1: Qualitative

Tier 1 produces an occupational exposure band (OEB) assignment based on qualitative data from the Globally Harmonized System of Classification and Labeling of Chemicals (GHS); it involves assigning the OEB based on criteria aligned with specific GHS hazard codes and categories. These hazard codes are typically pulled from GESTIS, ECHA Annex VI, or safety data sheets (SDS).^[19] The Tier 1 process can be performed by a health & safety generalist and takes only minutes to complete with the NIOSH OEB e-tool. The e-tool is free to use and can be accessed through the NIOSH website.

Tier 2: Semi-quantitative

Tier 2 produces a OEB assignment based on both quantitative and qualitative data from secondary sources; it involves assigning the OEB on the basis of key findings from prescribed literature sources, including use of data from specific types of studies. Tier 2 focuses on 9 toxicological endpoints.^[19] The Tier 2 process can be performed by an occupational hygienist but requires some formal training. Tier 2 banding is also incorporated into the NIOSH OEB e-tool, but can take hours instead of minutes to complete for a given chemical. However, the resulting band is considered more robust than a Tier 1 band due to the in-depth retrieval of published data.^[19]

Tier 3: Expert judgement

Tier 3 relies on expert judgement to produce a band based on primary and secondary data that is available to the user. This level of OEB would require the advanced knowledge and experience held by a toxicologist or veteran occupational hygienist. The Tier 3 process allows the professional to incorporate their own raw data in conjunction with the availability of data drawn from published literature.^[19]

Reliability

Since unveiling the occupational exposure banding technique in 2017, NIOSH has sought out feedback from its users and has self-evaluated the reliability of this tool. Overall, there has been an overwhelming response of positive feedback. Users commonly describe Tier 1 as a helpful screening tool, Tier 2 as a basic assessment for a new chemical on the worksite, and Tier 3 as a personalized in-depth analysis.^[20] During pilot testing, NIOSH performed several self-evaluations of the Tier 1 and Tier 2 protocols with chemicals that had published OELs.^[21][22] For >90% of these chemicals, the resultant Tier 1 and Tier 2 bands were found to be equal or more stringent than the OELs.^[19]This emphasizes the confidence health & safety professionals can have in the OEB process when making risk management decisions for chemicals with little or no published data. Hines et al. performed a case study on bisphenol A using the Tier 1 and Tier 2 process.^[23] The resultant band under Tier 1 and Tier 2 was “E”, however it changed to “D” when one toxicological endpoint was excluded. Therefore, it is important to consider the limitations of the OEB method when data is lacking.

Limitations

Although occupational exposure banding holds a great deal of promise for the occupational hygiene profession, there are potential limitations that should be considered. As with any analysis, the outcome of the NIOSH occupational exposure banding process – the OEB – is dependent upon the quantity and the quality of data used and the expertise of the individual using the process. In order to maximize data quality, NIOSH has compiled a list of NIOSH-recommended sources which can provide data that can be used for banding. Furthermore, for some chemicals the amount of quality data may not be sufficient to derive an OEB. It is important to note that the lack of data does not indicate that the chemical is safe. Other risk management strategies, such as control banding, can then be applied.

Control banding versus exposure banding

The proposed NIOSH occupational exposure banding process guides a user through the evaluation and selection of critical health hazard information to select an OEB from among five categories of severity. For OEBs, the process uses only hazard-based data (e.g., studies on human health effects or toxicology studies) to identify an overall level of hazard potential and associated airborne concentration range for chemicals with similar hazard profiles. While the output of this process can be used by informed occupational safety and health professionals to make risk management and exposure control decisions, the process does not supply such recommendations directly.

In contrast, control banding is a strategy that groups workplace risks into control categories or bands based on combinations of both hazard and exposure information. Control banding combines hazard banding with exposure risk management and exposure management to directly link hazard to specific control measures. Various toolkit models for control banding have been developed in the UK, Germany, and the Netherlands.^[24] Since each model operates using different GHS/CLP groupings, there is some skepticism on their validity. COSHH Essentials was the first widely adopted banding scheme, but assessment has shown that about 50% of chemicals could be over-controlled.^[26] Other models such as Stoffenmanager, EMKG, and International Chemical Control Toolkit of the ILO were found to be less conservative.^[26] While evaluation of control banding models has shown some variation, occupational exposure banding has emerged as a helpful supplementary exposure assessment tool.^[25]

When conducting a workplace hazard assessment, occupational exposure banding is a good starting point before moving into control banding to determine what the most effective control measures may be. The toxicity of a chemical established through the OEB process will aid the health & safety professional in selecting an intervention from the Hierarchy of hazard controls that is expected to adequately reduce exposure.

See also

• Control banding
• Occupational exposure limit
• Recommended exposure limit
• Threshold limit value
• Hierarchy of hazard controls
• Occupational hygiene

References (new ones to add listed under existing)

19. NIOSH [2019]. Technical report: The NIOSH occupational exposure banding process for chemical risk management. By Lentz TJ, Seaton M, Rane P, Gilbert SJ, McKernan LT, Whittaker C. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2019-132, https://doi.org/10.26616/NIOSHPUB2019132external icon

20. “The ‘BANDITS’ Speak: NIOSH Considers Feedback from Users of its Proposed Occupational Exposure Banding Process”. The Synergist. American Industrial Hygiene Association. 2018.

21. McKernan, L. Models vs. measurement. Are we on the right track? The promise and limitations of occupational exposure banding. (2015). Annals of Occupational Hygiene; 59(Suppl 1):25-26. Abstract retrieved from NIOSHTIC-2 Publications Search.

22. Whittaker, C., Gilbert, S., McKernan, L., Seaton, M. Preliminary evaluation of the draft NIOSH occupational exposure banding protocol. (2016). Toxicologist; 150(1):273. Abstract retrieved from NIOSHTIC-2 Publications Search.

23. Hines, C.J., et al. (2019). “Application of the Draft NIOSH Occupational Exposure Banding Process to Bisphenol A: A case study.” Journal of Occupational and Environmental Hygiene 16(2): 120-128.

24. Zalk, D. M., & Heussen, G. H. (2011). Banding the world together; the global growth of control banding and qualitative occupational risk management. Safety and health at work, 2(4), 375–379. https://doi.org/10.5491/SHAW.2011.2.4.375

25. Scheffers, T., et al. (2016). "On the Strength and Validity of Hazard Banding." The Annals of occupational hygiene 60(9): 1049-1061.26. Arnone, M., et al. (2015). "Hazard banding in compliance with the new Globally Harmonised System (GHS) for use in control banding tools." Regul Toxicol Pharmacol 73(1): 287-295.

26. Arnone, M., et al. (2015). "Hazard banding in compliance with the new Globally Harmonised System (GHS) for use in control banding tools." Regul Toxicol Pharmacol 73(1): 287-295.