Occupational Exposure Banding: An OEL Placeholder
EH&S News – May 11, 2017
Written by: Joe Mangiardi, NES, Inc.
Occupational exposure banding is a process spanning various levels of scientific knowledge
Occupational Exposure Banding and NIOSH
The National Institute for Occupational Safety and Health (NIOSH) has recently made available for comments a draft document entitled The NIOSH Occupational Exposure Banding Process: Guidance for the Evaluation of Chemical Hazards (Draft Document), which describes occupational exposure banding (OEB), a proposed process to aid in determining exposure limits for chemicals that do not have an official occupational exposure limit (OEL). The lack of an OEL can constrain an employer’s ability to arrive at well-informed occupational risk management decisions, which is a crucial component of occupational safety and health. Affected employers that wish to do right by their employees and comply with the law must perform a risk assessment based on any chemicals to which workers can be exposed and must subsequently implement safety measures to protect those workers. NIOSH recognizes the need for an expedited process with which employers can make such assessments and so has offered OEB for public consideration, with a public meeting to be held Tuesday, May 23, 2017. Comments can be submitted until 11:59 p.m. ET on June 13, 2017 (for more information on how to respond to the Draft Document, click here).
What is an Occupational Exposure Limit?
According to the American Industrial Hygiene Association (AIHA), an occupational exposure limit is “an upper limit on the acceptable concentration of a hazardous substance in workplace air for a particular material or class of materials.” This threshold is usually determined by national authorities as the result of a vast amount of time spent and data collected on, in particular, the toxicological and epidemiological effects of a given chemical. A chemical’s OEL is critical in determining the proper measures that should be taken to ensure worker/workplace safety.
Pharmaceutical industry worker exposed to chemicals
The Problem that Led to Occupational Exposure Banding
An occupational exposure limit is a firmly robust scientific metric and is the gold standard for chemical exposure risk assessments; however, the vast majority of chemicals used in manufacturing today do not have an OEL. The time, money, and qualified personnel resources required to arrive at an authoritative OEL—that is, a governmental, consensus, or peer-reviewed OEL—simply cannot keep pace with the introduction of more and more new chemicals brought on by flourishing industrial innovation. To put the issue in numerical terms, the NIOSH Draft Document states that of the estimated 80,000 hazardous chemicals in use in the United States today, only 1,000 of them have published OELs guiding their workplace handling and exposure. With a gap of such significance it is no wonder that NIOSH has moved to advance a passable stand-in solution to the OEL void.
Miscellaneous chemical substances
What is Occupational Exposure Banding and How Does it Work?
Occupational exposure banding, also known as hazard banding or health hazard banding, is defined in the Draft Document as “a systematic process using qualitative or quantitative hazard information on selected health effect endpoints to identify potential inhalation-based exposure ranges or categories for guiding occupational risk assessment and risk management.” The Draft Document describes OEB as a further tool for use by employers and occupational hygienists to evaluate workplace hazards.
OEB was developed so that it aligns with the anticipated OEL for a chemical with similar hazard-related characteristics. The band assigned is meant to be at least as protective, or stringent, as an OEL would be, were the chemical to have one. This approach is cautious by design so as to avoid overexposure.
The “health effect endpoints” referred to above are toxicological or human health markers of response from exposure to a hazard. These include the following nine categories:
- Reproductive toxicity
- Specific target organ toxicity
- Respiratory sensitization
- Skin sensitization
- Acute toxicity
- Skin corrosion and irritation
- Eye damage/irritation
Each health effect endpoint is evaluated and an overall score is given. Based on the severity of the most severe health outcome, a band designation of A, B, C, D, or E is applied to the substance being investigated, with ‘A’ being the least hazardous indicator and ‘E’ being the most hazardous. Each OEB designation has an associated airborne target range for particulate concentration and for gas/vapor concentration.
Pharmaceutical factory worker handling chemicals
NIOSH fully understands the varying sizes and capabilities of businesses and has designed the proposed OEB process accordingly. OEB incorporates levels of risk assessment at three tiers of confidence:
Tier 1 is a qualitative assessment informed by a chemical’s globally harmonized system (GHS) hazard codes and is intended for users with a limited understanding of toxicology (for the United Nations GHS reference document, click here). As of June 1, 2015, safety data sheets (SDSs) are required by OSHA to contain GHS information for all chemicals; consequently, a current and OSHA-compliant SDS can be used for Tier 1 evaluations. Chemicals that have the potential to cause irreversible health effects at low doses are to be interpreted as falling into band D or band E. If a chemical is likely to cause reversible health effects, it is to be interpreted assigned to band C. Due to the low data sufficiency requirements at this level, bands A and B do not apply at Tier 1.
Tier 2 is phrased in the Draft Document as “semi-quantitative” and is geared toward those with intermediate toxicology backgrounds. Band assignment at Tier 2 is informed by prescribed literature sources. Bands A-E all apply at this level and are assigned by interpreting relevant endpoints based on provided instructions. After all endpoints are considered and scored, a total determinant score (TDS) is calculated for use in the OEB algorithm. NIOSH recommends that users at this level be trained to perform such an evaluation.
While Tier 2 utilizes secondary sources to inform band assignment judgments, the conclusions at Tier 3 incorporate primary sources as well and involve a significantly more quantitative and detailed assessment. As can be expected, Tier 3 requires individuals with advanced toxicology knowledge, such as professional toxicologists or occupational/industrial hygienists.
It is important to remember that better (i.e., more scientifically robust) results can be derived from a higher tier; if the resources are available, NIOSH suggests always opting for the highest achievable tier.
Occupational exposure banding tiers: Tier 1 (left) requires only basic toxicology knowledge; Tier 2 (center) requires intermediate toxicology knowledge and some resources; Tier 3 (right) requires substantial personnel, equipment, and research and produces the most reliable OEB results.
Occupational Exposure Banding – A conversation with Lauralynn Taylor McKernan, ScD, CIH
In this video, Lauralynn Taylor McKernan, ScD, CIH provides an overview of occupational exposure banding. She explains why OEBs are important, the hierarchy of occupational exposure limits, common misconceptions about OEBs, the value of OEBs, and the next steps NIOSH plans to take with regard to OEBs. The video utilizes helpful infographics and makes the OEB concept as clear as is possible in under eight minutes.
Testing the Process
To test the accuracy and reliability of the OEB process, NIOSH compared the OELs of 600 chemicals to the results of Tier 1 determinations and found that the band assigned was at least as stringent as the OEL in 91.5% of cases. For Tier 2 determinations, 130 chemicals were evaluated; these results showed OEBs at least as protective as the established OEL for 98% of the chemicals tested. The Draft Document considers this to support the assertion that the OEB process provides an adequate placeholder when an OEL is not available. The document does advise to use caution when assessing substances made up of two or more chemicals and in other special cases.
Occupational Exposure Banding vs. Control Banding
The idea behind occupational exposure banding is not new. Various processes to aid in coping with the lack of OELs have been around for years, including control banding. Control banding focuses on applying standard control measures used to protect workers as if there were an established OEL for the workplace chemicals in question. These measures include ventilation, personal protective equipment (PPE), engineering controls, containment, and proven safe work practices. Substitution is another highly recommended control measure, as it encourages the replacement of a hazardous substance with a less hazardous and more thoroughly studied chemical. Control banding cannot replace in-depth scientific studies nor does it preclude the need for recommended testing, such as exposure monitoring, which can also serve as a quality check on the implemented control measures to ensure they are contributing to a safe and healthful work environment.
Similarly, occupational exposure banding is also not intended to replace more rigorous processes. A key difference, however, is that OEB does not explicitly point to necessary control measures, though the process does indirectly suggest appropriate such measures. Results from OEB can be correlated with established OELs, and the control measures associated with the chemicals bearing those OELs can then be interpreted to apply. OEB information can also be effectively utilized following initial control banding efforts. OEBs and exposure assessments can be considered jointly to more confidently assess implemented control measures. Overall, OEB introduces a process whereby more informed control banding decisions could be made, but the process itself is distinct from the concept of control banding.
Benefits of Occupational Exposure Banding
While only an interim solution to the overall issue, occupational exposure banding presents several benefits. OEB prompts the organization of available data on chemical hazards and facilitates the identification of gaps in those data. Further, chemicals whose OEB results are D or E can be prioritized as more in need of eventual OEL-caliber attention. Another benefit is that OEB data can serve as corroborative review for existing or future OEL determinations, either bolstering or calling needed attention to those results. Perhaps the most obvious benefit of all is that the OEB technique allows for testing where there otherwise may have been none, which should lead to better health and safety protective measures for workers—if this comes to be, then the development of occupational exposure banding by NIOSH will have been well justified.
Chemical manufacturing processes
Where does NES Come in?
NES has a team of certified industrial hygienists (CIHs) and experienced industrial hygienists ready to assist businesses with their risk assessment and general health and safety needs. To learn more, visit our Industrial Hygiene Services page or contact our office at 1.800.NES.ADVISE (1.800.637.2384) or firstname.lastname@example.org.
AIHA Publication: Occupational Exposure Limits
NIOSH Article: Control Banding