Properties of water equal to that of the hydrogen ion (), which gives a pH of 7 at 25 °C. Action of water on rock over long periods of time typically leads to weathering and water erosion, physical processes that convert solid rocks and minerals into soil and sediment, but under some conditions chemical reactions with water occur as well, resulting in metasomatism or mineral hydration, a type of chemical alteration of a rock which produces clay minerals. It also occurs when Portland cement hardens. Water ice can form clathrate compounds, known as clathrate hydrates, with a variety of small molecules that can
Drinking water quality in the United States in the manufacture of such prominent consumer goods as polytetrafluoroethylene (PTFE; Teflon and similar products). PFOA has been manufactured since the 1940s in industrial quantities. PFOA persists indefinitely in the environment. It is a toxicant and carcinogen in animals. PFOA has been detected in the blood of more than 98% of the general US population in the low and sub-parts per billion (ppb) range, and levels are higher in chemical plant employees and surrounding subpopulations. In the United States there are no federal drinking water standards for PFOA, PFOS or PFNA (collectively referred to as perfluorinated alkylated substances or PFAS)