The California Multimedia Risk Assessment Protocol for Alternative Fuels

Any new fuel in California requires approval by the state agencies overseeing human and environmental health. In order to provide a systematic evaluation of new fuel impacts, California now requires a multimedia risk assessment (MMRA) for fuel approval. The fuel MMRA involves all relevant state agencies including: the California Air Resources Board (CARB), the State Water Resources Control Board (SWRCB), the Office of Environmental Health Hazards Assessment (OEHHA), and the Department of Toxic Substances Control (DTSC) overseen by the California Environmental Protection Agency (CalEPA). The lead agency for MMRAs is the CARB. The original law requiring a multimedia assessment is California Health and Safety Code 43830.8. In addition, the low carbon fuel standard (LCFS), the Global Warming Solutions Act (AB32), and the Verified Diesel Emission Control Strategy (VDECS) have provisions that can require a multimedia assessment. In this presentation, I give an overview of the California multimedia risk assessment (MMRA) for new fuels that has been recently developed and applied to several alternative fuels. The objective of the California MMRA is to assess risk of potential impacts of new fuels to multiple environmental media including: air, water, and soil. Attainment of this objective involves many challenges, including varying levels of uncertainty, relative comparison of incommensurate risk factors, and differing levels of priority assigned to risk factors. The MMRA is based on a strategy of relative risk assessment and flexible accommodation of distinct and diverse fuel formulations. The approach is tiered by design, in order to allow for sequentially more sophisticated investigations as knowledge gaps are identified and re-prioritized by the ongoing research. The assessment also involves peer review in order to provide coupling between risk assessment and stakeholder investment, as well as constructive or confrontational feedback. The multimedia assessment framework has been implemented for a number of alternative fuels to date. MMRAs for Biodiesel, Ethanol blended Gasoline, Renewable Diesel, and Biobutanol have been submitted to California for regulatory approval. Currently, assessments are being conducted for natural gasoline (alkanes blended with natural gas) and DiMethyl Ether. With each new fuel MMRA, lessons are learned on how to perform a MMRA better. As a result, the multimedia assessment guidelines are being slightly revised based on lessons learned from the MMRAs completed to date.