In a state where employers offer health insurance to only about half their workers, California's restaurants and hotels rank worst in providing coverage, according to a study released Wednesday.

The analysis by the Center on Policy Initiatives found about 20 percent of the state's food and accommodation employees get health insurance through their job. Employers in agriculture, construction and retail all covered less than 40 percent of their employees.

Only one sector covered more than 70 percent of its employees: public administration, which includes government employees.

The study by the San Diego research and advocacy organization is based on UCLA data from a 2005 survey of 45,000 households. It looked at 17 of the state's major industries and showed some of the fastest-growing sectors — food and lodging, retail, and arts and entertainment — offered relatively low amounts of health insurance.

That means the ranks of the working uninsured is only going to grow, said Murtaza Baxamusa, research and policy director for the Center on Policy Initiatives.

"Some industries are doing their fair share," he said. "Others are pulling down the healthcare system."

The study concluded that about 49 percent of working adults, including seniors, are not covered by their employers. Industries that pay the lowest wages are the least likely to offer insurance.

"It's a double whammy," Baxamusa said. "You don't only get a low wage. You also don't get health insurance."

In restaurants and hotels, the average annual wage was $16,848, according to the 2005 statistics. About 43 percent of the workers in the industry buy their own insurance or receive it through a family member or the government. About 35.6 percent of the workers don't have any insurance.

The problem is profit, said Kearsten Shepherd of the California Restaurant Association. Restaurateurs don't make enough of it to survive and offer health insurance at rates employees can pay.

"It's not that they don't want to; it's that generally they can't afford to," she said, emphasizing the insurance crisis is a societal problem. "Throwing it on employers is misplaced. If you're basically stating that employers should carry the brunt, there's no way most employers, especially small businesses like restaurants, can afford it."

Scott Deardorff, an Oxnard farmer, offers insurance to all his workers, even those hired temporarily. But many farmers, he said, don't do that.

"It gets pretty hard to justify paying insurance when you have temporary workers coming in at a month at a time to harvest your crop," he said.

Temporary agencies also rank near the bottom of the list, providing insurance to about 28 percent of their workers. Only about 31 percent of the people working in real estate are covered by their employers, but many of those are independent contractors who have insurance through another source.

The inability of employers to cover workers can't be explained quite so easily, said Maricela Morales of the Central Coast Alliance United for a Sustainable Economy. She points blame not at small businesses but at profit-heavy corporations that pay low wages and still don't offer benefits. Their workers aren't unionized and don't have any bargaining power.

Their health needs fall into the government's safety net. That means taxpayers pay, said Morales, who advocates government reform.

She said the county's reliance on industries that struggle with insurance also doesn't bode well. "It means we can only foresee it getting worse."