Green | pollution Pollution Decreasing Off US Shores: Study Past 20 years have seen general contaminant decline By Nick McMaster Posted May 12, 2008 6:35 PM CDT Copied A cargo ship passes under the Bay Bridge in the San Francisco bay as seen from the Yerba Buena, Calif, Wednesday, Feb. 13, 2008. (AP Photo/Jeff Chiu) Levels of pesticides and other toxic chemicals in US coastal waters are generally decreasing, McClatchy reports. A 20-year study by the National Oceanographic and Atmospheric Administration's Mussel Watch looked at levels of 140 chemicals and found decreasing trends. Laws banning many of the chemicals were passed in the 1970s, but the long process of their disappearance from the environment continues. "Different regions have different stories," says Gunnar Lauenstein, the program's lead scientist. "But when you look at all the numbers and evaluate them statistically, it shows that on a national basis, concentrations are going down." Read These Next Beyonce leaves national anthem unfinished. Musk says his new party is in business. A Texas man's disappearance is fodder for true-crime mania. Kerr County considered a flood warning system years ago. Report an error