MERRILLVILLE, Ind. (AP) — Consumer and environmental groups are arguing that Indiana utility regulators are unfairly shifting electricity costs from some large industrial customers to homeowners and small businesses.

Their objections come after the Indiana Utility Regulatory Commission approved a proposal from Northern Indiana Public Service Co. allowing six large companies to seek electricity from other sources.

The commission says NIPSCO faces a “unique business risk” because it sells about 40% of its electricity to those companies, including U.S. Steel, ArcelorMittal and BP.

Opponents maintain that decision will shift between $40 million and $60 million in annual costs to other customers.