The workers, who are not represented by a union, didn't report to work Wednesday, according to a spokeswoman for Warehouse Workers United, an advocacy group.
In recent months, they have complained about poor working conditions at a Mira Loma warehouse operated by Olivet International Inc., which sells luggage to various retailers, including Wal-Mart, Target and Sears, according to its website.
The employees said they had told management that there was inadequate access to drinking water, lack of ventilation and blocked fire exits, among other conditions, said Elizabeth Brennan, a spokeswoman for Warehouse Workers United.
Brennan said workers submitted a formal complaint to the state's Division of Occupational Safety and Health, or Cal/OSHA, in May.
A Wal-Mart spokeswoman said Wednesday that the company holds suppliers who run warehouses to high standards to ensure workers throughout the supply chain are in safe working conditions.
"Even though the workers in this specific warehouse aren't employed by Wal-Mart, we take these allegations very seriously," said Brooke Buchanan, a Wal-Mart spokeswoman.
According to workers, management began cracking down on workers after they reported the poor working conditions, installing more than two dozen cameras around the property to monitor employees. Managers have also issued new rules aimed at keeping workers from discussing health and safety problems, Brennan said.
The most egregious problems, Brennan said, have been fixed. Fire exits are no longer blocked, she said.
Warehouse workers are also demanding better pay, health benefits and more consistent work schedules.
Organizers are planning a rally at the Mira Loma warehouse at 11 a.m. Wednesday.
The strike comes about a year after workers at another Wal-Mart-contracted warehouse in nearby Eastvale complained about poor working conditions there.