All of the workers were released from the hospital Thursday afternoon, Lopez said.
Juan Hidalgo, the Santa Cruz County agricultural commissioner, has launched an investigation.
"This is top priority," Hidalgo said. "We want to know what happened."
He said investigators believe the workers may have come in contact with four chemicals: Pristine Fungicide, Rally 40WSP, DiPel-DF and Widespread Max. Leaf samples from the field have been collected for testing.
Hidalgo refused to disclose the names of the companies that employed the workers.
"I want to make sure that the growers we need to talk to, that they can feel free to talk to us about what happened," he said. "I don't want to jeopardize my investigation."
The fields where the incident took place are used by several growers and it's unclear which ones were responsible for the chemical releases and which ones had hired the workers, Hidalgo said.
The case comes a week after 18 celery workers were rushed to the Salinas Valley Memorial Healthcare System emergency room, complaining of dizziness, nausea and stomach pain.
On June 22, a crew of workers employed by the produce company Tanimura & Antle got sick about an hour into their shift with one of them vomiting, according to Bob Roach, an assistant agricultural commissioner in Monterey County.
"The Emergency Department immediately called a code triage, activated a command center and deployed a mobile decontamination trailer," according to a statement from the hospital.
The chemical that sickened the workers may have been the insecticide Methomyl, according to the hospital, who attributed that to a supervisor for the company that hired the workers.
Two nearby fields were sprayed with a set of chemicals the night before the employees got sick, Roach said.
Monterey County inspectors have interviewed the workers, all but one of whom returned to work the next day, according to Roach, who said the county is investigating the incident to determine whether Tanimura & Antle violated any safety laws. Samples from the workers' clothing have been collected for testing.
The company did not respond to a request for comment.
Officials with California's Division of Occupational Safety and Health (Cal/OSHA) and Department of Pesticide Regulation (CDPR) are aware of the two cases but are not leading investigations into them, representatives for both agencies said.
A Cal/OSHA spokesman said in an email that California pesticide regulators had state oversight over the two cases.