Sioux City, Iowa, USA 04 March 2016 -- (From ABC9 News) -- Workers at Sioux City's WestRock facility went on strike Thursday afternoon. The company employees 78 people at the site.

Union representatives say WestRock recently tried to implement a new contract with employees, but workers didn't approve the updated terms after concerns over changes to a pension plan and health insurance.

"It's the health insurance that they're trying to push on us, forcing people into positions and on the machine. There are some guys that just can't operate certain machines. I don't like that. I feel like it's going to lead to people losing their jobs," says 15-year employee Jarmin Turner.

West Rock workers are represented by the International Assoc. of Machinists and Aerospace Workers. Striking employees says they plan to stay off the job until an agreement is reached.

"We've got some language that the company was wanting to put in the contract that states that they would have sole right to change things at their own [leisure] Without negotiating," says union rep. Douglas Day.

Those on strike say that they plan a peaceful strike with chants and marching. Workers told ABC9 that they feel a strike is the only way their voices could be heard. ABC9 tried reaching out to company representatives but did not hear back.