Re: Biodegradeable Liquid Scintillation Cocktails

[Wes Van Pelt <VanPeltW@IDT.NET>]

Ron Amoling wrote:
> 
> True, diluting with 42 x the volume with water would take care of the
> problem, but our local wastewater regulatory agency would much rather
> see source reduction/waste generation reduction than dilution to beat
> the concentration limits.
> 
> Regards,
> Ron Amoling
> Joslin Diabetes Center
> amolingr@joslab.harvard.edu

Ron, and all,

There may be reasons (expediency, political, etc.) to accede to the
"wishes" of a local wastewater regulatory agency, but one must only obey
the written published regulations of government. 

Of course we must all obey the regulations. I do not dispute this.

But let's look at the quantitative toxiclogy of this.

Sewerage containing the limit level of 0.1 ppb of mercury is a very very
very low concentration indeed.  50 gallons of this wastewater contains
only 20 micrograms of Hg. (I calculate that this would be a 70
micrometer radius ball of Hg if completely extracted as the metal).

The lowest level of observed adverse effect from mercury in adults is
300 micrograms/day (see Casarett and Doull's Toxicology, p 712).
Therefore, even drinking 50 gallons per day of this sewerage gives a
safety factor of more than 10 for any observed adverse effects.

Of course there is bioconcentration of Hg by aquatic organisms to take
into consideration, but that is another story.

My main point is that we should be prepared to do quantitative risk
assessment on these things, if only to satisfy ourselves of the real
safety of our recommendations.

Cheers, Wes

-- 
Wesley R. Van Pelt, Ph.D., CIH, CHP                KF2LG
President, Van Pelt Associates, Inc.     
Consulting in radiological health and safety.
mailto:VanPeltW@IDT.net        
http://shell.idt.net/~vanpeltw/index.html