Posted By Paul Leadbetter Helen What sort of powders are your employees handling? Paul

Posted By Paul Leadbetter Helen You could rate the substances by acute toxicity, carcinogenicity, mutagenicity, etc. Those high on the scale would require RPE and skin protection, those lower on the scale probably skin protection only. It is difficult to be prescriptive and you may need to use your scientific intuition up to a point. Of course, if any of the substances are reproductive toxins, you should also take into account the gender of the person cleaning up the spillage. Even if the risk of harm is low, women may be reluctant to do the cleaning if there is a risk to their reproductive health. Of course, some substances affect males and the same issue may apply to them. Paul

Posted By Adam Worth hmm this post has got me thinking :) I'm not going to provide a useful answer I'm affraid but some thoughts that might help... I would say you are probably doing much more than other labs by the sound of it already :) What level of toxicity do these powders present and how much is likely to be spilt? I would say working out exposure limits post spillage is going to be really difficult. I would work on worst case for my calcs - i.e. all powder in the air? Then again if you have emergency response teams to clean this type of spillage do they have BA / chem suits etc? if so as spillage of this magnitude is rare (i assume?) then overkill PPE may be the best option. I guess you are looking for away to decide when it should be left to teh fire brigade? As well as exposure don't forget if these dusts are oxidisable they may present an explosion risk too! What happens if you spill one two of these dusts together? or any other mixture... I dropped a bottle of Nitric acid - luckily the HCL I dropped too was in a safe-break bottle!! Again this all depends on quantities. Are you looking for COMAH level repsonse, or are we talknig a man with vaccumn cleaner? Use the manufactures!! They will have spillage procedures of their own and can probable provide more information. if you let us know a bit more about the situaton you might get more relevant information.

Posted By Adam Worth Good to see you;ve thought about it tho! What is the make up of the lab? could a sprinkler type system be used to wash away / suppress powders? (A chemical plant i worked on used to do this for some gases) Can the high risk ones be limited to a confined area? Can quanties be limited to smaller containers? i.e. 250g max. I would try asking a PPE supplier such as 3M for help on RPE options. Hopefully Paul can help further :)

Posted By D. Hilton Helen There was a suggestion in an earlier reply that you may have to consider explosion risk.Based on your conservative estimate of 20g airborne particles and taking into account the typical LEL for particulates are in the order of 100-500g/m3, an explosion risk is not presented in this scenario. As for settling velocities, for 100 micron particles and having a density similar to carbon black i.e 2.25g/cm3, the approximate settling velocity is 0.63 cm/sec. Given the above,I would expect the particles in a typical spill/release to settle in approx 30-60 seconds. I would not agree that the release would result in the dispersion and homogeneous mixing throughout the entire 10 m3 volume of the enclosure and would be surprised if the release were to have a volume of upto 1 m3. Provided the containers are kept sealed during transfer to and from storage and point of dispensary I would find it unlikely that these PE containers would fail on impact from a normal carrying height above the floor or above a bench. Again, I would reasonably expect a release to occur from the spatula during dispensing or toppling/dropping open container from a modest height above a bench/fume cupboard. I would also take a look at the spillage history within the department and frequency of handling of these particulates. It also may be worth considering the provision of LEV or other containment at the dispensary/point of use. Regards D