text: Under the NEPA statute, every agency may establish a set of "Categorical Exclusions" that exempt whole classes or types of activities from the EIS obligation. These may include routine or repetitive actions that, based on past experience, do not have significant impacts on natural, cultural, recreational, historic, or other resources; and also those that do not otherwise, either individually or cumulatively, have any significant environmental impacts. Because they fall into those categories, most small-scale field trials of genetically engineered plants have been categorically excluded by the USDA.