Coprostan-3-ol is a sterol produced by the bacterial reduction of cholesterol in the intestines of mammals. Used as a biomarker for fecal contamination in environmental samples, including water, soil, and sediment. Helps assess water quality by indicating the presence of human or animal waste and tracing pollution sources. Also applied in forensic, ecological, and geochemical studies to differentiate contamination origins and study ancient ecosystems or past environmental changes. Stable under various conditions, making it reliable for long-term environmental monitoring.