On Friday, workers at the Smithfield pork processing plant in Sioux Falls, South Dakota, said they were "fed up" with the company.
The United Food and Commercial Workers local union said Smithfield was no longer working in good faith.
According to the union, workers are upset over increased production line speeds, verbal abuse and the removal of sanitation and other safety measures.
B.J. Motley, the local union president, said the conditions are causing high numbers of injuries, grievances, resignations and "overall unhappiness."
Smithfield was surprised by the claims and disagreed with how working conditions were portrayed in the statement, according to the Argus Leader.
Four months ago, the union signed a new contract increasing wages, adding a bonus and providing more options for breaks and leaves of absence.
The union claims workers have since been forced to work overtime, sometimes in different departments.
The company calls the claims "inaccurate and unfair.”
