Regression method to estimate provisional TLV/WEEL-equivalents for non-carcinogens

• Published in: The Annals of occupational hygiene 2000-08, Vol.44 (5), p.361-374
• Main Authors: Whaley, David A., Attfield, Michael D., Bedillion, Erik J., Walter, Kenneth M., Yi, Quilong
• Format: Article
• Language: English
• Subjects: exposure criterion; exposure limits; regression; TLV; toxicity estimates; WEEL
• ISSN: 0003-4878; 1475-3162; 1475-3162
• DOI: 10.1093/annhyg/44.5.361

There is a huge and changing number of chemicals in commerce for which workplace exposure criteria have not been assigned. Assigning an exposure criterion by an expert committee is resource-intensive—not soon available for the large majority of chemicals in current use. In the absence of assigned criteria, we have provided a regression method to estimate a first-screen estimate of a ‘TLV/WEEL-equivalent’ inhalation time-weighted average exposure criterion for a pure chemical (or chemical group) from a measure of a non-stochastic toxic exposure to elicit a chronic or sub-chronic health effect, known as a lowest observable adverse effect level (LOAEL) or a (highest) no observable adverse effect level (NOAEL). Results are presented for six data sets for which both a threshold limit value (TLV) or workplace environmental exposure level (WEEL) exposure criterion is presently assigned, and a LOAEL or NOAEL measure of toxic health effect was available from the United States Environmental Protection Agency Integrated Risk Information System data base. The results can be applied as a first estimate of exposure to substances for which no TLV or WEEL (TLV/WEEL) exists, and also serve as a mechanism for identifying substances for potential re-evaluation of their exposure limit, based on their relative position about the prediction models.