LANSING (WWJ/AP) – Some American Red Cross workers in Michigan could go on strike Friday in a dispute over contract negotiations.

The American Red Cross Great Lakes Blood Services Region has received notices of intent to strike from staff members represented by the Office and Professional Employees International Union Local 459 and Teamsters Local 580.

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The strike could involve the region’s more than 60 counties and include about 250 workers.

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Red Cross spokeswoman Monica Stoneking said health benefits are a key part of the dispute, while the Teamsters union said collective bargaining rights and safety of the blood supply are key issues.

Stoneking said it would be the third time the unions have gone on strike in the past two years.

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