Endrin-ketone is primarily used in environmental studies and research as a marker or indicator for the presence of endrin, a now-banned organochlorine pesticide. It helps in monitoring soil and water contamination to assess the extent of environmental pollution caused by historical pesticide use. Additionally, it is utilized in analytical chemistry for developing and validating detection methods to ensure accurate measurement of pesticide residues in various samples. Its role is crucial in understanding the long-term impact of persistent organic pollutants on ecosystems and in guiding remediation efforts.