Traditional exposure assessments are appropriate in situations where chemical hazards are reliably measurable through validated quantitative methodologies, budgets support a battery of tests, and formal exposure limits exist with which to create the benchmark of acceptable exposures. In non-ideal situations, however, exposure assessments can be costly and require the expertise of an IH professional to interpret data. Utilizing banding logic prior to exposure assessment helps prioritize hazards, ensuring that limited resources are allocated to appropriate areas.

Starting in 2022, AIHA’s Principles of Good Practice (PGP) project has aimed to bridge the gap created by these non-ideal situations. The document “Principles of Good Practice for the Industrial Hygienist/Occupational Hygienist” identifies control banding as an “enhanced practice” that can make the exposure assessment and management process more efficient and effective. We propose an integration of the traditional exposure assessment paradigm with the decision logic of banding strategies; this proposed integration serves two purposes. First, it allows for immediate implementation of appropriate control strategies to protect workers sooner; and second, it provides context to the chemical hazard conversation, allowing for better-informed decision-making related to exposure assessment prioritization.

The context of IH involves the collection of information from various sources, including samples if possible, to quantitatively determine the level of exposure risk and, thus, which controls are most appropriate to reduce risk and protect workers. Application of the decision logic of banding strategies helps prioritize resource allocation and provides the IH professional with additional tools with which to navigate complex situations.

ORDER FROM CHAOS Hazard and control banding strategies are based on the principle of grouping like with like. This strategy is commonplace when dealing with disordered situations. For example, imagine a table filled with puzzle pieces—a mess of random shapes and colors. By grouping the edge pieces together, we allow the image to take shape. Through sorting, order and logic emerge from seemingly chaotic groupings. This simple strategy forms the basis of banding concepts. (For a more thorough summary of banding strategies, read “Battle of the Bands” in the December 2023 Synergist.)

In the case of hazard banding, chemical hazards are grouped together based on their intrinsic hazardous properties, such as toxicity, corrosiveness, flammability, and reactivity. This information is based on the Globally Harmonized System of Classification and Labelling of Chemicals. GHS classifications have become available for tens of thousands substances in recent years through company safety data sheets and public databases, such as the EU ECHA website or the Australian GHS Hazardous Chemical Information System. GHS hazard statements, also known as H-statements, align with the hazardous properties associated with the product. These H-statements act like puzzle pieces, allowing products with similar chemical hazards to be grouped together and categorized into hazard bands.

Control banding relies on groupings of exposure controls according to their effectiveness for specific exposure situations. Most banding schemes link hazard and control banding to identify appropriate controls to mitigate the exposure risk of a substance. One banding scheme that works this way is the Chemical Hazard Assessment and Prioritization tool (CHAP), which allows users to use simplified inputs to generate a hazard band and corresponding control band focused on health-based risk reduction. CHAP offers several free downloads in both paper and electronic versions under a Creative Commons license. For more information, visit the Toronto Metropolitan University website.

Similar tools such as COSHH Essentials, Einfaches Maßnahmenkonzept Gefahrstoffe (EMKG) from Germany’s BAuA agency, CB Nanotool 2.0, and the NIOSH Occupational Exposure Banding Tier 1 tool also help users with the hazard banding and chemical risk assessment process by providing corresponding control bands or appropriate exposure ranges. This article uses CHAP for demonstration because it is freely available from Toronto Metropolitan University.

HOW TO HAZARD BAND USING GHS H-STATEMENTS Hazard bands begin with A (lowest hazard) and progress to E (highest hazard). Table 1 outlines the hazard band and potential health effects for each. If a chemical product has multiple hazardous properties, the product is placed in the highest band for which any component qualifies. For example, a chemical that is both an eye irritant (Band C) and a carcinogen (Band E) will be placed in Band E.

Safety hazards such as flammability are not comprehensibly assessed in CHAP. Only H-statements relevant for health outcomes are utilized for CHAP. These statements are associated with potentially adverse health effects, as shown in Table 2.

The hazard levels used in CHAP come directly from “Hazard Banding in Compliance with the New Globally Harmonized System (GHS) for Use in Control Banding Tools” published in the peer-reviewed journal Regulatory Toxicology and Pharmacology in 2015. 

Once a chemical has a hazard band, a qualitative risk assessment can be conducted by applying the exposure level of the product. The exposure potential is derived using the quantity of the product used and the potential dustiness or volatility of the product (liquid/solid) or task.

CONTROL BANDING After completing the risk assessment in the CHAP spreadsheet (see Table 3), a corresponding control band is recommended based on the risk assessment, as shown in Table 4.

Baseline administrative controls include restricted access to the work area; workplace cleaning, housekeeping, and personal decontamination practices; and worker training and supervision. Personal protective equipment for Control Band 1 would typically consist of coveralls, general purpose gloves, and safety glasses to protect a worker’s skin and eyes. Respiratory protective equipment is not usually needed for normal operations in this band.

Control Band 2 This band applies to Risk Level 2 and calls for a higher level of control as chemical products become dusty, volatile, corrosive, sensitizing to skin, or toxic to organs. Examples of these products include a scale remover like lactic acid or an ethylene glycol antifreeze. For anything more than a consumer product exposure scenario, local exhaust ventilation (LEV) becomes important, which removes contaminated air from the source, before it is allowed to dissipate into the surrounding areas.

Administrative controls also require a higher level of diligence and may involve restricted site access, ventilation equipment maintenance, examination and testing, workplace cleaning, housekeeping and personal decontamination practices, and worker training and supervision. The level of PPE for this control approach becomes chemical- and process-specific: chemical protective coveralls or apron and gloves, goggles, and potentially a respirator if the ventilation is unable to reduce air concentration below an acceptable level, such as the occupational exposure limit.

Control Band 3 This band applies to Risk Level 3. Chemicals in this category, such as liquid mercury or a solvent like dichloromethane (DCM), are toxic and associated with more hazardous health effects. The controls for these hazards engage the higher levels of the hierarchy of controls: elimination, substitution, and engineering controls. From our example, the mercury in older thermometers, fluorescent lamps, dental amalgam, or liquid mirrors is a classic candidate for elimination or substitution: less hazardous products can be used for the same purposes, thus requiring less stringent controls. Where elimination or substitution is not possible—for example, when chemicals are essential to operations, like DCM for paint stripping—engineering controls such as process/product containment are recommended to minimize exposure and reduce risk. Examples of these controls include fume hoods and storage tanks or reaction vessels with dedicated piping and valves.

Administrative controls in this band are the same as for lower bands; however, for Control Band 3, the containment system is included in equipment maintenance, examination, and testing. The level of PPE depends on the extent to which the product is contained. Activities that involve breaking containment or situations where containment is not possible—for example, using DCM to strip surface coatings from alloy wheels—require extensive PPE, such as a chemical protective suit, gloves, goggles, and a respirator with an appropriate cartridge or supplied air, in addition to local exhaust ventilation and automation of the stripping task to further reduce risk and the potential for exposure.

Control Band 4 This band applies to Risk Level 4 and represents the highest level of control. Chemicals in Risk Level 4 are confirmed carcinogens, mutagens, or respiratory sensitizers and are often present in such large quantities that products can easily become airborne and cause serious health effects. At this risk level, expert advice from a qualified industrial hygienist, such as a CIH or ROH, is necessary. The risk assessment required to adequately control chemicals in this band must go beyond the basic; it must be site- and process-specific, with integrated solutions for each task to help reduce exposure to health hazards.

Applicable control measures from all levels of the hierarchy of controls need to be implemented for this band: ventilation, engineering controls, work practices, and PPE. In addition to worker health monitoring, exposure monitoring and equipment assessments to validate the effectiveness of controls are essential at this level. This stringent approach and additional oversight ensure the risk of exposure to highly hazardous chemicals is adequately monitored and controlled.

Managing Chemical Risk Overall, hazard and control banding allow initial assignment of appropriate controls, require minimal input, and can be conducted by those with little expertise in toxicology. The outputs for an airborne chemical hazard range from confirmation that general ventilation and PPE are sufficient to identification of a highly hazardous substance and recommendation to seek a professional. As with any exposure control strategy, control measures will need to be regularly maintained and validated for effectiveness. If exposure measurements indicate residual risk or lower risk, controls will warrant adjustment.

Banding tools can be seen as simplistic and overly conservative in control recommendations; however, they reduce the complexity of chemical risk management and provide a way to quickly manage chemical risk by connecting hazards with appropriate and applicable control measures. Integrating the decision logic of banding strategies with the traditional exposure assessment paradigm helps prioritize controls, ensuring that limited resources are allocated in appropriate areas.

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