Paul Kenny, the GMB's acting general secretary said the technology could be useful in improving efficiency, but was currently being misused by the warehouses to create a "dehumanised"workplace. The union threatened work action if the practice does not stop.
"The GMB is no Luddite organisation but we will not stand idly by to see our members reduced to automatons," he said. "The use of this technology needs to be redesigned to be an aide to the worker rather than making the worker its slave. The supermarkets that rely on just in time shelf filling rather than holding buffer stocks are incredibly profitable companies. They can well afford to operate a humanized supply chain. They should do so quickly otherwise the GMB will ensure that the shelves do not get filled."
The warehouses say the wearable devices provide reliable inventory numbers, improve their efficiency in filling orders, reduce in-transit theft and help them to accurately track goods.
A report produced for the union found the warehouses are using a variety of wearable devices. Some consist of computers worn on the arm and finger and are linked to local area radio networks and to GPS systems.
"Orders from shops are beamed to warehouses workers wearing these devices to tell them which goods to pick in different parts of the warehouses, for dispatch to top up the shelves,"the report states. "The only role for the worker is to do as the computer order requires. These devices calculate how long it takes to go from one part of the warehouse to the other and what breaks the workers need and how long they need to go to the toilet. Any deviation from these times is not tolerated. In effect these devices to dispatch goods to supermarkets and shops have made workers the aid to the computer rather than the other way round. The only functions that the human do are the bits that have not yet been automated."
According to the report, the technology is being used in warehouses in Aberdeen, Baskingstoke, Bellshill, Bichester, Birmingham, Bracmills, Bristol, Daventry, Earlestown, Edinburgh, East Kilbride, Glasgow, Hemel Hempstead, Leicester, Leeds, Livingstone, Lutterworth, Maidstone, Milton Keynes, Neasden, North Fleet, Northampton, Radlet, Reading, Runcorn, Salford, Scunthrope, Slough, Stroud, Swindon, Telford, Thurrock and Wellingborough.
The devices being used include the SRS-1 Wearable Ring Scanner, Vocollect's Talkman, the Mobile Assistant V and the WSS 1040 terminal, the report found.
The SRS-1 fits on the index finger and allows users to pick and scan packages in tight spaces. Vocollect's Talkman is marketed as a wearable computer that can operate through voice commands. The Talkmanprovides a means of communications between teams working in the plant floor and the company's inventory management system.
"The current situation could be regarded as a stage along a process towards full automation," the union claims. "If automated picking machines can be produced that have the sophistication and flexibility of human fine motor control, then one human advantage is removed. The use of headsets, voice-recognition, arm-mounted wearable computers in effect make the humans become an extension of the information systems that drive the supply-chain."
The report was produced for the GMB by Michael Blakemore, a professor of geography at Durham University. The GMB has about 600,000 members and represents workers at 34 of the UK's biggest 50 companies.US-based Venture Development forecasts that global shipments of wearable computers will reach about $563m (€459m) in 2006.