Synergist - October 2009

Control of Substances Hazardous to Health regulations (COSHH)—health hazard bands are determined using regulatory risk phrases, or R-phrases. These R-phrases are assigned to a particular hazard or toxicity profile for each tested toxicity endpoint. For countries that do not utilize R-phrases, the EU toolkit offers little assistance. For example, in the U.S., workers, employers, and even hygienists must use the confusing toxicity phrases found in Section 11 of most material safety data sheets (MSDSs). Translating those phrases into R-phrases in order to determine hazard bands has been virtually impossible; experts must first translate the toxicity endpoints. As a result, various groups are working together to establish guidance for employers and workers on the relative (albeit qualitative) health hazard groups.

The United Kingdom Health and Safety
Executive developed an electronic tool,
referred to as the eCOSHH toolkit, to aid
employers in performing the control band-
ing risk assessments, with the ability to
archive the assessment and return for fu-
ture reference3. The simple matrix provided
by the eCOSHH toolkit allows hygienists to
derive a health hazard group—and thus an
acceptable range of exposures for further
controls. Figure 1 shows the evaluation of
Dichloroacetic Acid (DCA) using the
eCOSHH methodology.

Hazard Banding’s Role in
WEEL Development

Advantages and Disadvantages

Hazard bands are screening-level hazard groups, often based on limited data. Critical limitations of hazard banding include the lack of standardized hazard phrases in MSDSs and the lack of expertise to translate those phrases into hazard

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The mission of the AIHA® Workplace Environmental Exposure Levels (WEEL) Committee is to develop health-based airborne chemical occupational exposure limits (WEELs) where adequate guidance for use by health professionals is not available. WEELs are developed using science-based risk assessment methods by a multidisciplinary volunteer team of industrial hygienists, epidemiologists, occupational medicine professionals and toxicologists. The committee uses a tiered review process that includes a scientific review of all the health effects, exposure, and toxicity information for the chemical. The product of this effort is the WEEL documentation that summarizes the data and provides the rationale for the WEEL and any notations that are assigned. The full WEEL documentation is published, and the WEEL value and notations are also published in the WEEL Handbook. Currently, over 100 WEEL values are available.

A cornerstone of developing a WEEL is the critical examination of the available data. Hazard banding has provided an important tool to organize the available data, identify key data gaps that affect the overall weight of evidence for the WEEL, and help set priorities for WEEL development. If the evaluation indicates that data are too limited for a WEEL, then the data matrix may be used by other groups for hazard banding to provide interim guidance. The WEEL committee continues to evaluate and validate hazard banding methods and is studying best practices for making use of this tool.

AIHA members interested in lending their expertise to developing additional occupational exposure limit resources for the profession or who want to learn more about WEEL development are encouraged to visit the WEEL web page at www.aiha.org or contact Andrew Maier, WEEL Committee chair, at maier@tera.org.