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What Do We Mean by Human Studies?
The definitions of "research" and of "human subjects " in the Common Rule are very broad and embrace many different types of studies among them epidemiology studies, observational studies, and studies involving intentional exposure of human subjects. Research involving intentional exposure of a human subject means a study of a substance in which the exposure to the substance experienced by a human subject participating in the study would not have occurred but for the human subject’s participation in the study. Such research may be for many purposes, including testing the effectiveness of insect repellants, measuring the rates and pathways of human processing of environmental chemicals, measuring occupational exposure of workers to chemicals, or measuring the effects of a substance on exposed human subjects. Most human studies submitted to EPA are designed to measure exposure, and many of these exposure studies do not meet the definition of “intentional exposure” because they involve as subjects people who, in the course of their daily activities, would be exposed anyway. More information about the Common Rule.
Examples of human research which does not involve intentional exposure:
- Epidemiological studies
- Investigations of accidents or incidents
- Surveys of use of registered pesticides
- Observational studies involving no direct intervention with subjects
- Studies of exposure of populations who would be exposed whether or not they participated in the research (e.g., pesticide applicators)
Examples of human research involving intentional exposure:
- Studies to identify or measure toxic effects
- Studies to measure skin irritation or sensitization
- Studies of absorption, distribution, metabolism, or excretion in humans (ADME studies)
- Studies of exposure of populations who would not be exposed except as test subjects
- Studies of sensory thresholds (odor, eye irritation, taste)
- Studies of the efficacy of insect repellents
EPA is authorized under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) to require pesticide companies to conduct studies to demonstrate safety following EPA protocols and requirements. Most studies submitted to the Agency are animal studies; however, some human studies have also been submitted. While the focus of recent Congressional and public concern has been on a very small number of human studies that involve intentional dosing of pesticides to determine toxicity, the Agency has never required these types of studies.