SafeWork South Australia has warned businesses using forklifts after "half-hearted" efforts to manage risks have resulted in three safety convictions.

In the last three weeks, three workplace injury convictions in South Australia involved forklifts.

SafeWork SA executive director Michele Patterson said the cases had resulted from apathy.

"Workers have been injured because of poor assessments of safety risks and half-hearted efforts to manage them," she said.

In the most recent case, Corporate Flooring Pty Ltd was convicted and fined AUD35,000 after pleading guilty to two breaches of the South Australian Occupational Health Safety & Welfare Act 1986, a SafeWork SA statement said.

It said the South Australian Industrial Relations Court heard that, in April 2004, a German backpacker, then 24, suffered a broken lower leg when she was run over by a forklift. She had fallen from the tynes after being invited to ride on the forklift. She had been in Australia just four days.

Industrial Magistrate Richard Hardy found the company had offered no adequate information or instruction on forklift safety, no supervision, no written procedures on health and safety practices and no communication to employees.

Last week, Herbalife Australasia Pty Ltd was convicted and fined AUD18,750 after an employee fell about six metres to the ground and suffered wrist and elbow injuries. The employee was being lifted in a metal cage on the tynes of a forklift to remove louvres from an overhead air conditioning duct.

The cage was "not designed as a personnel box" and not secured.

Also this month, De Ville Australia Pty Ltd and Vermont Holdings Pty Ltd were fined AUD72,000 after a roller door installer standing on a forklift fell three metres and then had a heavy metal cage fall on him.

In his judgement, Industrial Magistrate Stephen Lieschke said the two companies had shown "a high degree of complacency" and such incidents resulted when forklifts were "informally adapted for non-standard uses".