CHICAGO (AP) _ A circuit judge Friday approved a proposal by attorneys to consolidate evidence-gathering efforts in lawsuits growing out of the nation's worst episode of salmonella food poisoning.

''Right now, we know of just over 100 lawsuits, but that's not a true reading,'' said Nicholas J. Motherway, one of five lawyers handling the suits. ''There are certain to be many, many more.''

The proposed joint effort was approved by Cook County Judge Lester Forman.

Jewel Companies Inc. is named as the defendant in all suits filed thus far.

The epidemic began in late March and was traced to milk produced by the company's dairy and sold in more than 200 Jewel grocery stores in four states - Illinois, Indiana, Michigan and Iowa.

By Friday, 15,232 cases of salmonella food poisoning had been reported in those four states, Wisconsin and Minnesota. Of those reported, 13,691 had been confirmed.

Motherway said that while attorneys are seeking to have the evidence- gatherin g portions of the case consolidated, they will not ask that the cases themselves be consolidated.

He said the attorneys proposed that the state court employ provisions like those used at the federal level to allow some co-ordination of efforts.

''Key people at Jewel, for example technicians and people responsible for running the Hillfarm dairy, should obviously be required to give depositions and answer questions,'' said Motherway.

''But it's obviously unfair to have them give depositions and answer questions hundreds of times.''

Motherway said the proposal also asks the court that all exchanges, oral or written, between plaintiffs' attorneys be privileged.

He noted several of the attorneys had been involved in similarly complicated litigation involving numerous plaintiffs. Formation of the lawyers' group was approved April 24 to help reduce the time and cost of the litigation.

A task force made up of state, federal and dairy health officials was still trying Friday to find the source of the bacteria that tainted milk processed at the now-closed Hillfarm Dairy in suburban Melrose Park.

Dr. Bernard Turnock, acting public health director, has said a leading theory is that an improper valve alignment may have led to the inadvertent mixture of raw and pasteurized milk.