... surface, and ground- and drinking-water samples and are recognized as an issue of public health concern.107 The EPA is also conducting research on the presence of illicit drugs in sewage and their ... including the volume of sewage, the pathogenic load (concentration of pathogens and/ or chemicals), the type of exposure (inhalation, ingestion, dermal, etc.), the duration of exposure, and the ability ... percent over land areas of the Northern Hemisphere during the 20th century,155 and global warming is predicted to further increase the intensity of rainfall events for parts of the United States.156...