Monoethyl Phthalate (MEP) is a metabolite of plasticizer diethyl phthalate (DEP). Monoethyl Phthalate is a one of the most abundant phthalate metabolites present in human urine. It is also present in other body fluids including breast milk, serum, semen, saliva and amniotic. Monoethyl Phthalate (MEP), together with mono-benzyl phthalate and mono-isobutyl phthalate has been associated with obesity in children, anomalities in pubertal development in girls, and increased risk of endometriosis in women. MEP and MiBP (mono-isobutyl phthalate) representing low molecular weight phthalates, and MECPP (Mono-(2-ethyl-5-carboxypentyl) phthalate) and MCiOP (Mono-(carboxyisooctyl) phthalate) representing high molecular weight phthalates have been used as indicators of phthalate exposure. Application Metabolomics, Microbiome