The death of a pregnant teenager pruning grape vines in scorching heat has outraged California's farmworking community and sparked calls for safety reforms as laborers prepare for the long summer harvest.

Authorities in California — the only state with a heat-illness standard — suspect Maria Isabel Vasquez Jimenez, a 17-year-old undocumented Mexican immigrant, collapsed last month because her farm labor contractor denied employees proper access to shade and water.

On Wednesday, 500 farmworkers and their advocates capped a poignant, four-day march to the statehouse demanding safer conditions on thousands of vineyards and orchards.

Governor Arnold Schwarzenegger and the Mexican government have called the girl's death preventable. State officials say they have revoked the company's license.

Advocates for farm workers, many of whom are immigrants from Mexico and other parts of Latin America, say California's safety rules are routinely violated. Authorities have investigated nearly two dozen suspected heat-related deaths since 2005.

Regulations require farms and contractors to give workers water and breaks, have shade available and have an emergency plan in place to help those suffering from heat exhaustion. The rules are intended to protect 450,000 seasonal workers who pick and sort much of the nation's plums, peaches and other crops during summer's peak.

As the throngs of protesters reached the end of their 50-mile march at the Capitol steps on Wednesday, a Roman Catholic bishop said a prayer.

"Farmworkers like Maria Isabel are not agricultural implements to be used and discarded," said Arturo Rodriguez, president of the United Farm Workers, which organized the trek. "They are important human beings. Important to their loved ones, important because of the work they perform in feeding all of us."

Those at the head of the mass threading its way through backroads toward Sacramento this week held up three caskets: one symbolizing the death of Vasquez Jimenez, one for the fetus she carried and the third for other victims of heat-related illness.

San Joaquin County authorities are considering whether to pursue criminal charges against Vasquez Jimenez's employer, Merced Farm Labor, which was issued three citations in 2006 for exposing workers to heat stroke, failing to train workers on heat stress prevention and not installing toilets at the work site.

The company has yet to pay the $2,250 it owes in fines.

The firm's attorney said in a statement he expected Merced Farm Labor would "be completely exonerated of any fault or wrongdoing," but did not address the proceedings revoking its license.

Health and safety inspectors have investigated 23 suspected heat-related fatalities since 2005, said Dean Fryer, a spokesman for the California Division of Occupational Safety and Health.

Carl Borden, an attorney with the California Farm Bureau Federation, says most farmers strictly adhere to the rules and make a conscious effort to inform workers about how to stay healthy on the job in both Spanish and English.

"California farmers are already subject to the most stringent requirements in the nation," he said. "If they were not being followed, there would be many, many more tragic incidents than what's been reported."

On the day Vasquez Jimenez died, relatives say she was making $8 per hour on a 9.5-hour shift — more than four hours over the state limit for minors working during business days.

After she collapsed, her fiance, Florentino Bautista, 19, said the foreman recommended she rest in a hot van and be revived with rubbing alcohol before he could take her to a Lodi medical clinic, almost two hours later. Doctors later realized she was two months pregnant.

The labor contractor's safety coordinator Elias Armenta says Bautista refused to call medical personnel and said he would take care of Vasquez Jimenez. Only at staff's urging did Bautista consent to take her to the local hospital where she died, the company said.

A funeral ceremony for Vasquez Jimenez was held over the weekend in her Mixtec indigenous village of San Sebastian Nopalera, relatives said.

Since the death, foremen at the vineyard have placed water jugs throughout the grape vines, said the victim's elder brother, who still works for the same contractor.

"They're taking care of everything now, and are putting water all over the place due to what happened," said Jose Luis Vasquez Jimenez, 20. "But there's still no shade."