Geographic distribution of two most studied antibiotics and their relation with natural and socioeconomic variables. Geographic distribution of SMX (A) and TMP (B) concentrations in river waters from different countries. Gross national income (GNI) per capita (C) and population densities (D) of different countries. Comparison of SMX (E) and TMP (I) concentrations in countries of different classification based on human development index (HDI). Linear relationships between the characteristic concentrations (75th, 50th, and 25th percentiles) of SMX (F−H) and TMP (J−L) in river water and HDI.