Biosafety of sorting revisited

Howard Shapiro hms at shapirolab.com
Mon Apr 19 20:53:35 EST 2004


Alice Givan wrote:

>I am also just now going through these issues about the biosafety with 
>regard to sorting
>-- in preparation for the purchase and siting of a new sorter in our 
>facility.  When I
>suggested to my users that human samples for sorting should all be tested 
>in advance for
>Hep and HIV, they, essentially,  said that this would not be 
>advisable/possible for the
>following reasons.
>1) Timing would be difficult
>2) It would be expensive
>3) It would bring up ethical issues
>4) Negative tests for a few specific pathogens would not rule out recent 
>exposure of the
>donor to those pathogens and/or positivity to all the other untested 
>pathogens.
>
>I have absolutely no sympathy for the first three excuses.  But,  the 
>fourth excuse does
>have some validity.  If we realize that negative results for a few 
>pathogens does not
>really mean that a sample is safe,  then we must treat all samples with 
>high precaution.
>And,  if we need to treat all samples with high precaution,  then it can 
>be argued that
>there is no real point in testing (and it could lead to false security).

Re 1): Timing could be difficult; some experiments require that cells be 
"fresh and frisky", and the turnaround time for testing might preclude this.
Re 2): Yes, it would be expensive, but so are reagents, sorter and tech 
time, etc.
Re 3): You bet. If I am not mistaken, there are many jurisdictions in which 
it is illegal to test specimens for HIV without the donor's consent, and 
there is new legislation about privacy and patients' rights that would 
complicate the issue further.
Re 4): Right on. That is why "universal precautions" are observed in 
handling human clinical specimens. This doesn't mean BSL4 or BSL3, it means 
taking reasonable precautions to avoid infection, in terms of wearing 
gloves, masks, etc. as appropriate, handwashing, disposal of material as 
biohazard waste, and so on. In terms of sorting, having a tested aerosol 
containment mechanism would seem to be satisfactory. Any given sample might 
conceivably contain, say, Mycobacterium tuberculosis, which is highly 
contagious via the airborne route, and could conceivably be transmitted 
that way, but, if we don't have any reason to strongly suspect the organism 
is in the sample, we run it, presumably at BSL2. If we *know* there's M. 
tuberculosis in it, we can't work with it except at BSL3. But we don't test 
every sample for TB, even though it is far more likely to spread in an 
aerosol than, say, hepatitis A, B, or C or HIV.

Now, admittedly, if universal precautions are not taken seriously and 
monitored, people can get sloppy about them. However, if precautions are 
only taken when there is a sample on hand that is known or strongly 
suspected to harbor a serious pathogen, lapses in technique it would seem 
at least as likely as in the former case.

-Howard





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