Slacks implies pants of certain materials which are not part of a suit (jeans are not slacks, and you would not refer to the pair of trousers that came with a suit as slacks.) It is also more common to use slacks to refer to pants worn by women, while men would wear trousers.
Health care safety net providers are those that have a legal mandate or mission to offer medical care to all patients, regardless of their ability to pay, and have a substantial number of patients who are uninsured or on Medicaid.
There are currently 12 million undocumented immigrants in the United States - the majority of whom are uninsured. Among all immigrants, both documented and undocumented, less than 40 percent receive employer-sponsored coverage. The only federal health care program that covers undocumented and newly arrived legal immigrants is known as emergency Medicaid.