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Assessing Risk

Risk managers within the Agency assess whether potential risks associated with exposure to a new chemical are reasonable in light of the expected benefits of use of the chemical (unreasonable risk), and whether and how any potential risk can be controlled.Agency risk managers are provided with an estimate of potential risk by EPA toxicologists, chemists, biochemists, engineers, and experts in other disciplines who work together to predict the potential risks to humans or the environment from each new substance. In doing so, they draw on information and data submitted with the PMN form, other information available to the agency, and exposure and release modeling. Risk is predicted as a function of hazardousness of the substance and expected exposure to it:

Hazard x Exposure = Risk

There is no defined base data set required before PMN, and the TSCA does not require prior testing of new chemicals. Consequently, less than half of the PMNs submitted include toxicological data. In these cases, OPPT scientists assess the chemical's structural similarity to chemicals for which data are available - called structure-activity relationship (SAR)- to help predict toxicity. A useful discussion of SAR is found in an OECO monograph, "US EPA/EC Joint Project on the Evaluation of (Quantitative) Structure Activity Relationships" (PDF) (81 pp, 160K, about PDF).

When information available to the New Chemicals Program is not adequate to make predictions of toxicity, data will be required as part of PMN. The New Chemicals Program has issued a document called Chemical Categories which describes information often sought for chemicals of frequently-submitted types, and which can be useful to intending submitters in planning appropriate information to submit.



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