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

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.

Incorporation of potential for multimedia exposure into chemical hazard scores for pollution prevention.

We are reporting a chemical hazard score for pollution prevention, called the Purdue score. The Purdue score provides a relative quantitative measure combining a variety of chemical hazards into a single quantitative hazard weighting factor for the non-expert to use. The main expected uses are to design safer products, assist in implementing and measuring achievement in pollution prevention, and as an adjunct for reporting Toxic Release Inventory data to the U.S. Government. Scoring results are presented for 200 Superfund chemicals, rank ordered by the worker hazard part of the score, by the environmental hazard part, and by combined worker and environmental hazard scores. We have reviewed the extent to which the Purdue score presently incorporates potential for multimedia pathway and multiroute absorption exposure. Until other possible uses have been carefully tested, peer-reviewed and published, users are advised to limit use of this system to planning, implementing and measuring pollution prevention and to enhancing the interpretation of Toxic Release Inventory data. The objective of this report is to look at how the structure of this score handles exposure to chemicals, both via multi-compartment pathways and multi-routes for contact or absorption health damage, as well as how it handles habitat degradation by chemicals. For all of these, the approach is built on inherent properties of each chemical, which are true for all sites and scenarios. The biggest obstacle to scoring is lack of measured chemical property data needed for scoring. We handle missing data by regression, quantitative structure activity relationship estimations, and a missing data default rule. The limitations of chemical hazard scoring are reviewed. At present, there is no widely accepted single measure of relative chemical hazard, against which to calibrate this hazard score for accuracy, except experience from industrial use. However, despite limitations, we suggest there is a strong value added for industry and society in availability of a concise, simple-to-use measure of relative chemical hazard. The Purdue score enables separate or combined consideration of chemical hazard to workers and to the natural environment. The Purdue score has potential for major cost savings in relative hazard ranking and business decision making regarding little-studied organic chemicals, because of the extensive use of advanced property estimation software. We conclude that there is societal need to warrant advanced development of this risk management tool, which is now ready for pilot use by industry. The Purdue score is mainly intended to assist and encourage businesses to implement and measure pollution prevention-especially small businesses--in a cost-effective way. The Purdue score relies strongly on sublethal toxicity, and there is practical potential for it to be used with thousands of chemicals.