Reuters: The number of days U.S. beaches were declared unsafe for swimming due to pollution declined by 12 percent in 2007 from the previous year but was still the second highest in 18 years, an environmental group said on Tuesday. The National Resources Defense Council said it recorded 22,571 closures or advisory days at the nation’s 3,516 most popular beaches last year, down from the record 25,643 in 2006. A decline in rainfall in areas of Hawaii and California appeared to be behind …