CHICAGO (CBS) — Nurse practitioners working at Walgreens drugstore clinics have voted to unionize.

The Illinois Nurses Association announced Thursday that it will represent about 180 nurse practitioners who work in Take Care Clinics in the Chicago area, Rockford and Peoria.

The association filed a petition with the National Labor Relations Board to organize the Walgreens nurse practitioners. A hearing Monday will deal with which classifications of employees constitute an appropriate bargaining unit.

The nurses are concerned about a pay reduction, an increase in the cost of health benefits and other issues.

Sandra Ryan of Walgreen Co. subsidiary Take Care Health Systems says clinic employees receive compensation and benefits that align with health care industry standards.

Deerfield-based Walgreen Co. operates 45 Take Care Clinics in Illinois.

Walgreens and its unionized employees have run into conflict in past years.

In 2005, 1,200 Walgreens pharmacists represented by the National Pharmacists Association went on strike for 20 days in July, over low staffing levels and growing workloads that they claimed increased the risk of mistakes that could harm patients. While the union insisted the strike had nothing to do with compensation, Walgreen officials said the union was using the issue as a bargaining chip for better pay.

Pharmacists also went on strike for six days in 1990.

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