Uninsured Missouri residents planning to purchase health insurance as part of the new federal health care law are still waiting for details as the start of enrollment looms. The insurance exchanges, which are essentially online marketplaces to compare and buy health insurance, open on Oct. 1. The federal government plans to publish details online after final certification decisions are made early next month, but some consumer advocates worry that the lack of details so far including coverage levels and premium costs will make it harder for residents to participate, The St. Louis Post-Dispatch reported Wednesday.