Positive characteristics of knapsack sprayers are described as: no holes under the waterline, no holes, welds screws or rivets through which contents can leak while in an upright position. Knapsack sprayers should stay upright when being filled and they should repel liquid off the external surfaces. It should be possible to pump out all of the liquid in the tank to avoid the risk of cross contamination between plant chemicals and therefore potential damage to the plants. Finally, the straps should be made of non-absorbent materials. The Health and Safety Executive (HSE) in Great Britain is concerned about the potential risks to operators using knapsack sprayers because of the close proximity of chemicals to their bodies and the potential for contamination through leakage or when filling the tanks. As a consequence the HSE is developing a series of ISO/CD Standards for the manufacturers of knapsack sprayers (and has already released a report entitled 'The Performance of UK purchased side-lever knapsack sprayers when subjected to the test methods proposed by ISO/CD 19932-1). Of the 7 models tested, all but one failed an internal reside test and only 2 had satisfactory straps. Four failed the impact test and two failed on leakage. Horticulture Week www.hortweek.com