A new independent report says the Army spraying over the Twin Cities in the 1950s and 1960s probably didn't hurt anyone's health. The Army says it was testing how biological warfare substances might disperse in the air, so it sprayed zinc cadmium sulfide over several neighborhoods as well as the Chippewa National Forest. The substance is fluorescent, and can be traced easily. But cadmium's also carcinogenic, although that wasn't known at the time. When details of the spraying were revealed a couple of years ago, many people worried about the health impact, including Representative Martin Sabo, who successfully pushed for a million-dollar study. That study, by the independent National Research Council, is now complete.