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health assessment based). Both risk assessors and public health assessors are often 

 confronted with making significant risk management decisions based on inadequate 

 toxicologic knowledge about substances demonstrably present in environmental 

 media that in turn come into contact with people and ecologic systems. 



The prospect of dealing rationally with the entirety of the TSCA inventory — some 

 60,000 chemicals — is certainly daunting but it should not be paralyzing. Several ap- 

 proaches have been developedr-by other countries and institutions for devising a ra- 

 tional process for identifying^ and prioritizing issues of concern in this large uni- 

 verse. Our inability to do this in the U.S. so far has resulted in very little change 

 from the National Academy of Sciences's 1984 conclusion (in Toxicity Testing) that 

 over 80 percent of existing chemicals have little or no information available upon 

 which to base even the most rudimentary, qualitative assessment of risk. 



Some countries — notably Japan and the Netherlands — have evaluated the uni- 

 verse of existing chemicals in terms of such pragmatic principles as chemical per- 

 sistence, in order to select out those for further analysis and possible prioritization 

 for testing. Other countries — such as Germany and Canada — have developed prior- 

 ity lists of chemicals of concern, based upon incomplete information, but information 

 sufficient to warrant further investigation. 



The OECD has adopted a more innovative approach, and one that we recommend 

 for your consideration in TSCA reauthorization. The OECD approach neatly over- 

 comes the paradox of the unknown: that is, in toxicology and regulatory policy based 

 upon toxicology, we are often guilty of "looking under the lamp post" — focussing our 

 investments upon refining our knowledge about those chemicals about which we al- 

 ready have sufficient information to consider them 'suspect". Thus, we have the 

 spectacle of a nation whose public and private resources over the past decade have 

 continued to be predominantly invested in researching chemicals like lead and 

 dioxin, chemicals about which we know more than almost any other chemical in the 

 environment. The OECD approach radically challenges this paradigm. The OECD 

 program deliberately sought to identify those chemicals about which we do not know 

 enough to be suspicious, but about which we should not be complacent. The need 

 to avoid complacency was based upon production volume. 



Using production volume as the criterion neatly steps over one of the persistent 

 barriers of TSCA's existing chemicals program: how to balance or integrate data on 

 toxicity and data on exposure. In the U.S. experience, too often data on toxicity is 

 discounted by data on exposure — that is, opportunities to gather information on 

 chemicals that may be highly toxic are foregone because of assertions (often based 

 on data that is very limited and/or not publicly available) that exposures are mini- 

 mal. 



The OECD approach resolves this conundrum by using production volume as the 

 primary criterion for selecting chemicals for further evaluation. An international 

 group, composed of industry, academic, government and NGO experts (including my- 

 self and representatives from Monsanto, Dupont, Dow, Eastman Kodsik, and the 

 Chemical Manufacturers Association), agreed that if a more than one million tons 

 of a chemical was produced in at least two OECD countries annually, then it was 

 appropriate to presume that exposures were likely to occur (through production, 

 storage, use, transport, inadvertent releases, accidents, and disposal). 



Upon that basis, a list of priority chemicals was developed through national in- 

 ventories, like the EPA's TSCA inventory. The chemicals on this list was then scru- 

 tinized for the data available on toxicity. The focus of the OECD program was to 

 identify those high production volume chemicals for which inadequate data were 

 available to assess risk; this intent allowed us to go beyond the preoccupation with 

 known risks, and to avoid the continued diversion of all available resources towards 

 refining the risk assessments of chemicals already known to be risky, such as lead 

 and dioxin, the "looking under the lamp post" phenomenon. 



The OECD project succeeded in winnowing out from the national lists of existing 

 chemicals a subset of high production volume chemicals for which inadequate data 

 are available — some 1,800 such chemicals on the first analysis. But we did more. 

 We then confronted the issue of what constitutes an adequate database, and how 

 can it be acquired for a reasonable investment of time and resources by either gov- 

 ernment or the private sector. The jewel in the crown of the OECD chemicals pro- 



