The death this week of a veteran farmworker for Delano-based Sunview Vineyards of California Inc. came even as lawmakers in Sacramento were examining legislation that could strengthen protections for people who labor under a hot sun.

Rodolfo Ceballos Carrillo, a 54-year-old father of three adults, collapsed Wednesday afternoon in a vineyard in Arvin while loading crates of grapes.

Temperatures in Arvin peaked at 99 degrees Wednesday, the National Weather Service reported.

State officials are investigating whether Carrillo's death was heat-related. If so, it could be the first such case statewide this year.

A spokeswoman for Cal-OSHA said investigators had little to go on so soon after Carrillo, of Earlimart, collapsed.

"We include everything that could be heat-related as heat-related until we determine that it's not," spokeswoman Erika Monterroza said. She added that such investigations typically take three to four months.

On the day of Carrillo's death, lawmakers, farmworker advocates and industry representatives convened for a hearing on a bill introduced this year by Senate Majority Leader Dean Florez, D-Shafter. It would tighten existing heat safety rules by requiring that farmworkers, oil field workers and others receive mandatory breaks and enough shade for an entire work crew once temperatures reach 75 degrees.

Six California workers died of heat-related illness in 2008, half of them in agriculture, according to Cal-OSHA. Last year, there was only one such death statewide, and it was in the construction field. So far this year, the department has classified five deaths as possibly heat-related, but none have been confirmed as such.

Cal-OSHA has stepped up enforcement of heat illness protections in recent years, increasing workplace inspections and launching multilingual advertising campaigns urging workers to seek shade and cool water when it gets hot.

The department reported that between 2008 and 2009, heat safety inspections increased by 30 percent to 3,371, while heat-related violations by employers declined by 8 percent to 831, and workshops and other educational activities more than doubled to 2,562.

So far this year, Cal-OSHA said it has conducted 1,338 inspections and found 316 heat-related violations; this year's outreach efforts stand at 939.

"I don't think there's one employer who doesn't know what they're supposed to do," said Joan Cuadra, a safety trainer for Visalia-based nonprofit Proteus Inc. "I think that Cal-OSHA has done, you know, a good job educating employers."

But she added: "There always needs to be more enforcement and more education."

The human resources director at Sunview, where Carrillo worked for about 34 years, said the death does not appear to be heat-related, and that the company has an extensive heat illness program.

"Everyone here, we are deeply and sincerely saddened by the death of Mr. Ceballos, and we continue to offer our condolences and support to his family," said the director, Dan Gallegos.

Gallegos added that Carrillo was on medication for high cholesterol, high blood pressure and coronary artery disease.

County sheriff's officials would not confirm whether Carrillo was taking medications.

A national vice president for United Farm Workers of America, Armando Elenes, said Carrillo's position as a "swamper" is a particularly demanding job, and one made harder by the fact that he was paid according to how many crates he loaded in a day.

"Normally the workers try to choose: What should I do? On one hand I need to take a break or drink water or whatnot, but on the other hand ... I'm trying to make ends meet or I'm trying to make a quota," Elenes said.