Posted By Derrick Robinson I wonder if an colleagues out there can help me with a situation I have been asked to advise on which is outside my normal area of work. I have been asked for advice about the risks of HAVs from a vortex mixing machine in a micro biology laboratory. The person in question has a past history of carpal tunnel syndrome with previous surgery on both hands. She is required to use a vortex mixer and the accumulated use can be in excess of 80 minutes per day though it varies markedly between days. The employer appears to have no risk assessment or data about the equipment. I have looked on the Internet and I have only found 1 useful reference from a manufacturer who claims to be the only manufacturer of such equipment who has measured vibration. The figures they quote suggest to me that there is a cause for concern. I have 2 questions. Firstly do any colleagues who work in laboratory environments have any experience with this kind of equipment? are they normally considered a hazard and is there any published guidance? Obviously we will need proper measurements to carry out a risk assessment but a steer in the right direction would be helpful. Secondly can anyone advise me with regard to the operators carpal tunnel syndrome. My instinct is to say she should avoid vibrating equipment totally but is this the normal approach in these circumstances? Thanks in advance for any help that might be available Derrick

Posted By Ian Futcher Many years ago I used to work in a lab where there were things called "Swirli-mixers" which were used for test tubes contents-swirling. Even then, they had a stand so that you didn't have to hold the tube, so I guess there must be set-ups where the item swirled is fixed to that it need not be hand-held. Ian

Posted By Ian Blenkharn Vortex mixing is fast and simple, but yes, it does cause a nuisance due to vibration and in general that is unavoidable - firm pressure is needed if the conact is to be activated and the tube contents mixed properly. But there may be a reason NOT to use a vortex mixer in a microbiology environment where aerosols may be produced and released when the cap is removed from the tube. It is unlilely to be a big propblem, but if you need to persuade someone, that may do the trick And there are many other types of mixer that will do the job. Rotary mixers, ossillating mixers, shakers, and many others. All of these are hands free, though most will require far longer to mix fluids of disperse a suspension (minutes rather than seconds) but will do the job and remove the HAV problem completely. In fact, it would be hard to imagine any competent microbiology lab without a range of mixers available.