Exposure-Based Policy under Section 5 of TSCA

TSCA section 5(e) provides EPA with the authority to regulate new substances pending development of health and environmental effects data based on either the potential risk presented by the substance ("risk-based") or the potential for substantial production volume and substantial or significant human exposure or substantial environmental release ("exposure-based"). Action under section 5(e) for a new chemical substance is taken based under either or both of these authorities.

In 1988, EPA developed internal guidelines to assist in identifying new chemical substances received as Premanufacture Notices (PMNs) which would meet the "exposure-based" finding. These exposure-based guidelines were announced to the chemical industry in a letter to Geraldine V. Cox of the then-Chemical Manufacturers Association (now the American Chemistry Council).

Because only limited test data are submitted or otherwise available on new chemical substances, EPA often relies on Structure Activity Relationship (SAR) predictions to evaluate potential effects associated with these substances.

Data obtained from PMN submitters by EPA using the exposure-based finding can:

• Better characterize the tested chemical
• Confirm or refute a "negative" prediction of no risk or low risk
• Supplement and validate the use of SAR in the review of PMNs.

Expanded use of this finding was warranted for these reasons and because Congress intended that a greater priority for testing exists for high exposure chemicals. Exposure-based testing is usually required via a negotiated section 5(e) consent order.

These exposure-based guidelines in the table below capture all PMN chemicals with estimated production volumes greater than or equal to 100,000 kilograms per year, and include specific exposure/release criteria (such as > 10,000 kg/year total release to environmental media or >0.003 mg/kg/day exposure via air).

The objectives of this approach were to:

• Encourage fair and consistent decisions across numerous chemical categories and uses
• To provide clear guidance to the public and industry about EPA's policy and expectations
• To implement the policy in the simplest, least resource-intensive way.