3M Co. announced yesterday that it will stop producing many of its well-known Scotchgard oil- and water-repellant products after finding that one of the chemical compounds they contain lingers in the environment for years and is found widely in the bloodstreams of people around the world. 3M says that the substance, perfluorooctanyl, has not been shown to cause health problems in humans, but the company says the chemical does not easily decompose and therefore is not environmentally friendly. 3M’s Scotchgard line represents about $320 million a year in sales, about 2 percent of the company’s annual sales. Some enviros praised 3M’s proactive move. The decision to drop Scotchgard products could affect many other commercial products that use the compound, including Teflon, which is made by DuPont.