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Risk and Decision

Evaluating Pesticide Approval in California

​John Froines

Susan Kegley

Sarah Kobylewski


Risk and Decision
Fumigant pesticides are widely used in agriculture in California and other states to control soil pests for high-value crops such as strawberries, peppers, tomatoes, and stone fruits. This report focuses on one fumigant--methyl iodide--and the story of its approval for use in California by the Department of Pesticide Regulation (DPR) in a process known as registration.

Methyl iodide (used in combination with chloropicrin) was introduced as a substitute for methyl bromide, a widely used fumigant slated for phase out by 2015 due to its ozone-depleting nature. While the methyl iodide/chloropicrin mixture was a promising alternative in terms of performance, it raised substantial human health issues, including neurotoxicity, carcinogenicity, and developmental toxicity. As a result, the approval of the methyl iodide/chloropicrin mixture as a fumigant pesticide was the subject of substantial controversy at both the Federal and state levels.

This report uses methyl iodide as a case study to explore the limitations of the risk governance approach reflected in California's registration process. Risk governance refers to the social, legal, and institutional decision-making processes used in identifying and responding to risks facing society. In evaluating the scientific, social, and legal dimensions of registration, the report draws upon reports, letters, hearing transcripts and other documents generated as part of the registration process. From existing literature, it identifies the best practices for the relevant elements of risk governance--Problem Identification/Framing; Risk Assessment; Evaluation/Option Selection and Stakeholder communication--and assesses the methyl iodide registration process against them. The report identifies a variety of deficits in the pesticide registration process, and concludes by presenting recommendations to improve pesticide risk governance in light of these themes, drawing in large part from the new approaches offered by the National Research Council in 2009 as a way forward.