Methyl iodide, chemically known as Iodomethane (CAS 74-88-4), once held a significant, albeit controversial, position in agricultural practices as a soil fumigant. Its registration by the U.S. EPA in 2007 marked an attempt to provide a chemical solution for controlling a range of soil-borne pests, including insects, nematodes, and pathogens, as well as weed seeds. This application was particularly relevant in high-value crop production, such as strawberries, tomatoes, and peppers, where soil health is paramount for yield and quality.

The efficacy of Methyl iodide as a pesticide stemmed from its potent biocidal properties. As a volatile liquid, it could penetrate soil and eliminate target organisms. Its development was partly spurred by the need to replace methyl bromide, an ozone-depleting substance regulated under the Montreal Protocol. In this context, Methyl iodide was seen as a potentially viable, ozone-friendly alternative for soil sterilization.

However, the agricultural use of Methyl iodide quickly became a focal point of intense debate and public health advocacy. Environmental groups and scientific bodies raised serious concerns about its toxicity. Investigations and reports highlighted its potential for acute poisoning, neurotoxicity, and, notably, its classification as a suspected human carcinogen. The chemical's volatility also posed risks of off-site drift, leading to potential exposure for farmworkers and nearby communities. Lawsuits were filed, and regulatory bodies faced pressure to re-evaluate its safety profile and the adequacy of the risk assessments conducted prior to its approval.

These mounting concerns eventually led to its withdrawal from the U.S. agricultural market. The manufacturer, Arysta LifeScience, announced its decision to suspend sales, and the EPA formally agreed to terminate all agricultural use registrations by the end of 2012. This marked the end of Methyl iodide's tenure as a registered pesticide in the United States. The story of Methyl iodide in agriculture underscores the critical importance of thorough toxicological evaluation, transparent regulatory processes, and the continuous search for safer, sustainable alternatives in pest management. While its agricultural chapter has closed, its legacy serves as a reminder of the complex interplay between chemical innovation, agricultural needs, and the imperative to protect human health and the environment.