After months of negotiations, Bayer Healthcare Pharmaceuticals has reached a proposed contract this week with International Longshore and Warehouse Union Local 6, for its hundreds of workers at Bayer’s plant in South Berkeley.

The proposed contract, which was announced this week by the union and affects approximately 420 workers at the Berkeley plant, includes better job security measures, controls on health care insurance costs – employees’ share of premiums will be frozen at 18 percent — and annual raises of more than 3 percent during the four-year contract, according to a statement released by the union Wednesday.

The proposed agreement comes after a prolonged struggle between Bayer and the union as they sought to produce a new contract for the next four years after the previous one expired on Aug. 24.

Wages for workers in Berkeley will increase 3.1 percent during each of the first three years and 3.2 percent in the fourth year, according to the statement.

“Better job security was a key concern for both workers and the community, and this agreement meets that goal,” said Fred Pecker, the union’s secretary-treasurer, in the statement.

Bayer officials were pleased with the proposed contract as well.

“This is what we feel is a fair and generous contract for our employees and gives us the flexibility we need to navigate these turbulent economic times,” said Sreejit Mohan, Bayer’s director of public policy and communications. “The contract includes above average wage increases and capped health care contributions.”

Negotiations began July 25 and have endured several stops and starts. On Aug. 31, union workers rejected a proposed contract for various reasons including concerns over recent employee layoffs and, in September, the union threatened to end its labor agreement with Bayer “for refusing to provide employees with job security,” according to an earlier statement released by the union.

“For major decisions such as outsourcing or workforce reductions, we agreed to provide contract language that provides for reasonable notice to the union and to listen to alternatives before the company takes action,” Mohan said. “It’s something we practice already — the language (in the proposed contract) just formalizes something we already do.”

The proposed contract will be voted on by union members Oct. 12.

“Bayer workers won real improvements despite the recession because they organized and were willing to take action,” the union said in the statement.

Union officials could not be reached for further comment.

Mohan said that Bayer supports the new contract.

“We are pleased with the terms and conditions that have been defined in the proposed contract,” Mohan said. “The company and the union have a mutual interest in ensuring a strong future for the Berkeley site.”