The food preservative sodium benzoate sickened almost three dozen employees of a Jurupa Valley trucking business.
Firefighters were called to Swift Transportation in the 11800 block of Mission Boulevard about 7:45 p.m. Friday, to respond to a report of employees being ``overcome by an odor of unknown substance in a trailer,'' county fire department spokeswoman Melody Hendrickson said.
Initially, there were 29 employees taken to hospitals, Hendrickson said.
By 10:35 p.m. Friday night, another six employees reported feeling sick, bringing the total taken to hospitals to 35.
Forty firefighters from 10 engine companies, along with a hazardous materials team, responded to the scene, Hendrickson said.