The state Department of Agriculture has launched an investigation after 10 Syngenta workers on Kauai were taken to the emergency room.

It happened on Wednesday, Jan. 20.

According to Syngenta site manager Joshua Uyehara, the workers walked onto a field that had been sprayed with the pesticide chlorpyrifos. The sprayed field was adjacent to the field they were supposed to be working in.

Of those taken to the hospital, three were held overnight for observation.

Uyehara said there is typically a 24-hour period of restricted entry after a field has been sprayed, “so people were in the field four hours prior to when they should have been.”

Six employees returned to work last Friday, and the remaining four returned on Monday.

Uyehara said Syngenta is still investigating how and why the workers entered the wrong field. He said a sign is usually posted at the front of each field that lists the time it has been sprayed and when it is safe to enter.

“What we’ve done, effectively immediately as of the following morning, was the procedure on how to safely enter the field and check that it’s safe to enter the field is now a permanent agenda item in the morning huddle. So everyone will be reminded on top of the training they all receive,” Uyehara said.

The incident was also reported to Hawaii Occupational Safety and Health.