The wide use of pharmaceuticals in human and veterinary medicines has increased their concentrations in the environment in the past 20 years. Pharmaceuticals reach the environment through the discharge of effluent from urban wastewater treatment plants, the spreading of animal manure and aquaculture, discharge of effluent from plants, the spreading of sewage sludge, grazing livestock, the treatment of pets, improper disposal into landfill of unused pharmaceuticals and contaminated waste.