(AP) — More than 1 million low-income residents in 21 states could soon lose their government food stamps if they fail to meet work requirements that began kicking in this month. The rule change in the federal Supplemental Nutrition Assistance Program was triggered by the improving economy — specifically, falling unemployment. But it is raising concerns among the poor, social service providers and food pantry workers, who fear an influx of hungry people. Recent experience in other states indicates that most of those affected will probably not meet the work requirements and will be cut off from food stamps. For many people, "it means less food, less adequate nutrition. And over the span of time, that can certainly have an impact on health — and the health care system," said Dave Krepcho, president and chief executive of the Second Harvest Food Bank of Central Florida. Advocates say some adults trying to find work face a host of obstacles, including criminal records, disabilities or lack of a driver's license.