In April, 2009, an esteemed group of industrial hygienists produced the final draft of a paper that posed the question: “Have traditional OELs run their course of usefulness? Or d we still need traditional Occupational Exposure Limits (OELs) to compare with exposures, perform risk assessments and identify control approaches?”

Here are excerpts from the paper:

Occupational Exposure Limits (OELs) have been established for airborne workplace chemicals by various regulatory and authoritative organizations now for well over 60 years now. With the changing regulatory arena, shifting centers of manufacturing growth, and move towards a more global view on issues, the time to pause and re-examine their continued value is now.

The authors of this Paper, who represent decades of experience in occupational health in all sectors of the profession, believe that OELs continue to be critical to protecting workers from chemical exposures. We believe that most industrial hygienists and other allied professionals strongly support the concept that OELs should be updated, consistent with current scientific knowledge. We also believe that the infrastructure to generate and utilize OELs desperately needs shoring up.

By way of clarification, if we do decide that there is a need to intensify our efforts on OELs relative to current and future global harmonization, it is important for us to recognize that the term “OEL” refers to two quite distinct exposure limits. The first is widely recognized as a “health-based” OEL (or hOEL) and the second a “regulatory-adjusted” OEL (or rOEL).

For health-based OELs, only health-driven risks are considered. The harmonizing global process for health-based OELs will have to define clearly what is to be considered detrimental or adverse, what physiological capacity is to be protected, e.g. functional reserve (transient? or permanent?), and what subpopulations are to be included. The process will have to define the degree of uncertainty permitted in the extrapolation of data from experimental biological systems or from medical surveillance. For the “regulatory adjusted” OELs (or rOEL), consensus from a tri-partite process will have to modify health based OEL values so that they can include non health based considerations such as economics and technical feasibility in order to serve a regulatory function in the jurisdiction that uses them.

Future Direction?

We believe that Industrial Hygienists and allied professionals consider Occupational Exposure Limits (OELs) to be one of the most effective tools for performing risk assessments upon which risk management strategies for worker protection can be based .

We may never have OELs for all chemical hazards; however, it is critical that we accelerate the establishment of credible and respected OELs to provide a basis for protecting workers. It could be argued that the first step in approaching this large task is to come to some agreement on a unitary scientific approach in assessing “hazard” and applying hazard assessments to OEL setting. This would allow more groups to become involved in a credible way. There are many roadblocks to this seemingly obvious solution. These include legal and regulatory issues, economic issues, political and cultural issues and other factors outside of the usual scientific arguments on health effects. These difficulties have resulted in an absence of any significant development of OELs in the United States and, seemingly, the rest of the world.

Those that have been developed outside of the regulatory system as guidance have been subject to significant litigation. At our present rate of progress, it is extremely unlikely that significant numbers of new OELs will to be developed. Litigation could further reduce, restrict or eliminate the efforts of organizations like ACGIH to generate new OELs. There are many in our profession who consider this an unacceptable future. There are other potential approaches to this problem. So, how can we revive the OEL-setting process in a way that provides benefits to all parties involved?

Europe has launched REACh, which requires the development of DNELs. The Derived No-Effect Level (DNEL) is defined in Annex 1 of REACh as the level of exposure above which humans should not be exposed. Manufacturers and importers are required to calculate DNELs as part of their Chemical Safety Assessment (CSA) for any chemicals used in quantities of 10 tons or more per year. The DNEL is to be published in the manufacturer’s Chemical Safety Report and, for hazard communication, in an extended Safety Data Sheet.

However, these will not be consensus recommendations, but rather values determined by the manufacturer or supplier of the material. These manufacturers and suppliers have a very broad range of technical resources and knowledge. As one might guess, small manufacturers will not have the resources to do exhaustive studies. The level of scientific review of the DNELs once submitted is unclear at this time. Additionally, it remains to be seen how effective this system will be in protecting workers.

Control Banding is another approach some would suggest might take the place of OELs. Some would argue that Control Banding does incorporate the concept of OELs since they are defined in hazard bands or ranges of target exposure rather than single values. They certainly move the user towards a decision of “how much is too much”. The big advantage is that, if well executed and guided by professionals who appreciate the science of toxicology, hazard bands can be set for materials that may not have enough toxicity and hazard data available to set a formal single point OEL. Nevertheless, Control Banding still ultimately requires some form of OEL to be adequately applied. Furthermore, the specificity and sensitivity of Control Banding has only been minimally validated, and the preliminary results have not been impressive.

There are governments around the world that are still establishing OELs. These values are not generally applied outside of the host country and may include many more considerations than just health effects in their derivation. Additionally, actual measurements for ambient air levels of the OEL substances are rarely performed except in a few countries. This suggests that the traditional use of OELs is not widely practiced worldwide.

In closing, we believe that Occupational Exposure Limits (OELs) are absolutely critical. We hope that this Paper will encourage our broad audience of stakeholders to discuss the critical issues, continue the dialogue and, as a call to action, help determine what the future for OELs should be. In working together, our profession can lead a way forward.

The authors and contributors welcome your thoughts and input. The challenges and opportunities described impact us all. We believe they are significant enough that action needs to be taken sooner rather than later.

Author: Chuck Adkins, CIH, Lindsay Booher, CIH, Dwight Culver, MD, MS, Tom Grumbles, CIH, Michel Guillemin, Ph.D, Frank Hearl, MS, PE, John Henshaw, CIH, Michael A. Jayjock, Ph.D, CIH, Chris Laszcz-Davis, MS, CIH, REA, Zack Mansdorf, Ph.D, CIH, CSP, QEP, Franklin E. Mirer, Ph.D, CIH, John Mulhausen, Ph.D, CIH, CSP Frank M. Parker, III,CIH,CSP,PE,DEE, Jimmy L. Perkins, Ph.D, CIH, Susan Ripple, MS, CIH, Paul Schulte, Ph.D., Robert D. Soule, Ed.D, CIH, CSP, PE,