If drinking water supplies are low in fluoride, many communities add fluorides to help prevent cavities. Some skin medicines and cancer treatment drugs also contain fluorides. Fluorine forms salts with minerals in soil, and doesn't evaporate back into air as a gas. Fluorides in released to the air from volcanoes and industry are carried by wind and rain to nearby water, soil, and food sources. They erode from rocks into soil and water, and leach from phosphorus fertilizers into food and water supplies.
Some plants take up and store fluorides in their leaves and stems.
Breathing workplace air where fluorides are used or released Eating food from soil with high natural levels or high levels from fertilizers or nearby waste sites Eating toothpaste that contains fluorides Drinking contaminated water Ingesting contaminated soil particles. Fluorides are everywhere throughout the environment, but at very low levels that are not believed to be harmful. At high levels , fluorine gas and hydrogen fluoride gas can harm the lungs and heart and can cause death. Even at low levels, these gases can irritate your eyes, skin, and lungs. Contact with hydrofluoric acid can burn the eyes and skin.