Advocates for the uninsured are urging some of Ohio's biggest employers to follow a new state law that allows young adults to stay on their parents' health insurance until they turn 28, even though the companies are exempt. The law, which takes effect July 1, makes Ohio one of the few states to exceed the extension to age 26 mandated by President Barack Obama's healthcare overhaul. About 6.6 million Ohioans get health insurance through employer-based coverage, and about half of those are with employers that self-insure.