Air Pollution:

EPA's Strategy To Control Emissions of Benzene and Gasoline Vapor

RCED-86-6: Published: Dec 18, 1985. Publicly Released: Feb 5, 1986.

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Pursuant to a congressional request, GAO reviewed the Environmental Protection Agency's (EPA) decision to regulate benzene emissions through controls on automobile refuelling.

GAO noted that: (1) EPA based its decision to control benzene emissions on risk assessments that evaluated the relationship between benzene exposure and the potential occurrence of leukemia; (2) the health, emission, population, and modeling data EPA used were based on assumptions; (3) EPA did not consider three relevant health studies completed between 1981 and 1983 because it believed that the studies would not significantly change its benzene health assessment; (4) EPA emission data showed that three plants were using benzene to manufacture a product used in making plastics and chemicals, but only one plant was actually using benzene at the time EPA issued its final decision; and (5) EPA updated some information that changed its estimate of risk to the public, but was not significant enough to change its 1983 decision. GAO found that: (1) as of October 1985, EPA did not have written guidance detailing how quantitative risk assessment values are developed for hazardous air pollutants; (2) EPA plans to control automobile refuelling emissions will be based on a decision as to whether nationwide or local controls should be implemented; (3) California and the District of Columbia have implemented controls on gasoline pumps in the absence of EPA regulations for controlling refuelling vapor; (4) if the risk from gasoline vapor and/or benzene is not significant, EPA could require controls only in those areas not in compliance with EPA ozone standards; and (5) more than 2 years will be required for implementing the automobile refuelling control options.

Recommendations for Executive Action

  1. Status: Closed - Implemented

    Comments: EPA agreed with this recommendation and implemented it to some extent, but with a clarification. EPA will include a discussion of uncertainty in risk assessment numbers only for regulatory decisions, not pollutant screening or other analyses.

    Recommendation: To improve the risk assessments for hazardous air pollutants, such as benzene, the Administrator, EPA, should direct that the proposed Operating Manual for the EPA Pollutant Assessment Branch include a requirement that, to the extent possible, current and verified data be used in developing quantitative risk assessments or that an explanation be included in the assessment as to why those data are not being used.

    Agency Affected: Environmental Protection Agency

  2. Status: Closed - Implemented

    Comments: EPA issued a Regulatory Import Analysis (RIA) of refueling emission regulations for gasoline-field motor vehicles in July 1978. EPA used RIA to support its decision to propose on-board emission controls for motor vehicles. RIA included range values which reflected the various uncertainties in its cost-effectiveness analysis for the on-board controls.

    Recommendation: To improve EPA cost-effectiveness analysis used to help determine the best alternative for controlling automobile refueling vapor emissions, the Administrator, EPA, should direct that range values be provided to reflect the various uncertainties inherent in its cost-effectiveness analysis.

    Agency Affected: Environmental Protection Agency


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