The GMB is concerned that Asda wants to raise pick rate levels following the introduction of new voice-picking technology and claims that the retailer has failed to take the weight of items into account.
It said that on Tuesday (11 July) an ergonomics expert from the Robens Centre of Health Ergonomics at the University of Surrey would visit Asda's ambient distribution centre in Wigan to meet its health and safety manager and witness first-hand how staff worked.
The expert would then produce a report for the GMB and its findings would be sent to the new Asda/GMB National Joint Council, the first meeting of which is expected in a few weeks.
Eddie Gaudie, regional organiser for the GMB, said: "Products picked can range from 2kg-20kg in weight, so if items are heavy, pick rates should be reduced to take these into account."
A spokeswoman for Asda said: "We have already had a branch of the HSE visit our Wigan depot to assess the new technology and how our colleagues use it. They've given us a clean bill of health. We're obviously working closely with the GMB to discuss pick rates through the newly established National Joint Council."