Natural radioactive particles.[4] Perfluorinated alkyl acids, such as perfluorooctanoic acid, which are group of pollutants that have been found in wastewater throughout Europe.[5] There are concerns these chemicals could contaminate raw water sources that are commonly used for drinking water. Endocrine disruptor compounds; chemicals that can interfere with the endocrine system causing cancerous tumors, birth defects, and other developmental disorders.[6]