Canadian Occupational Safety

18 Canadian Occupational Safety www.cos-mag.com environment co-ordinator at Dura- built Windows & Doors in Edmonton. This program, called Durabod- ies, is very important in preventing musculoskeletal injuries (MSIs) and repetitive strain injuries (RSIs) caused by manual material handling at the company. At Durabuilt, 70 per cent of the work is done manually. Manual material handling — which includes lifting, lowering, pushing, pulling, holding and carrying — is a top concern in manufacturing. It is one of the main contributors to work- place injuries in the industry. "They're handling everything from large pieces of equipment to boxes and every manufacturing environment tends to have some shipping, receiv- ing, packaging type department where (manual material handling) tends to be an employee's main role," says "Since we are starting at 6 a.m., defi nitely people will be half awake. They will be in sleeping mode. Who knows whether they have gone to bed at the right time or they are get- ting suffi cient seven hours sleep or not; it's just a wake-up call for them. They are tuning the body to work," says Zybin Christy, health, safety and Marnie Downey, president of ERGO Consulting in Barrie, Ont. "That is probably their number 1 risk." Back injury is a top concern for these workers. Three in four Canadians whose job includes manual material handling suffer pain due to back injury at some time. These back injuries account for about one-third of all lost work and more than one-third of all com- pensation costs, according to the Canadian Centre for Occupational Health and Safety. Manufacturing workers can also experience shoulder injuries and aggravation to the upper limbs and spine, especially if heavy objects are being lifted. The risk factors of manual material handling can be divided into three categories: Forceful exertion, awkward posture and repetitive motion. FoRCeFUl exeRTion Force is the amount of muscular effort expended to perform work. Overexer- tion — which occurs when a worker is pushing, pulling, lifting or carrying loads that are beyond his capabili- ties — has been found to be the main cause of MSIs from manual material handling, says Downey. The ISO Standard 11228 Part 1: Lifting is commonly used to deter- mine safe lifting limits. For example, when two-handed lifting, it says men should lift a maximum of 25 kg and women should lift a maximum of 15 kg, under ideal conditions. A variety of criteria make up "ideal conditions," including: • standing symmetrically • trunk is upright • horizontal distance to object is less than 25 cm • lifting duration of less than one hour per day. The limit for safe lifting decreases under non-ideal conditions. More detailed information for lift- ing, lowering, pushing, pulling and carrying are provided in the widely cited Liberty Mutual Manual Mate- rial Handling Tables. The tables provide both the male and female population percentages capable of performing manual material handling tasks without overexertion, rather 0than maximum acceptable weights and forces. To address forceful exertion, manu- facturing employers should consider the weight, shape and orientation of the object being handled. "Can they make it in a smaller pack- age? Does the box have to be long in the front and short on the side? Can they re-orient it?" asks Downey. Employers also need to consider if there are any mechanical aids they can put in place. Durabuilt uses a number of mechanical aids including forklifts, overhead cranes, jip cranes, shelf trol- leys, pallet jacks, engine hoists and ball tables with rollers. SPOT THE HAZARDS sTRengTH/FoRce • two-handed lift with weight greater than 25 lb (11 kg) • one-handed lift with weight greater than 15 lb (7 kg) • Lifting above shoulder height or below knee level • Carrying weight greater than 25 lb AwkwARD posTuRes • Neck bent more than 20 degrees • Shoulder postures greater than 45 degrees • Forearm rotation greater than 45 degrees • Wrist postures greater than 20 degrees (up, down, sideways) • Back bending forward greater than 20 degrees • Back bending backwards RepeTiTion • Neck movements greater than two times per minute • Shoulder movement greater than 1.5 times per minute • Wrist movement greater than 15 times per minute • gripping more than 15 times per minute oTHeR FaCToRs • task performed longer than four hours • task performed in cold conditions • Exposure to vibration • Impact loading on body Source: ERGO Consulting

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