[Carmine]

Originally Posted by bandersen

Here's a more thorough lead leaching test of monochrome and color CRTs

http://www.pca.state.mn.us/index.php....html?gid=4865

The second table seems to show that it's not the thick, heavy face that's the source of lead leaching out, it's the neck and especially the funnel.

Here's an excerpt from the conclusion:

We'll probably have to agree to disagree but here are a few issues I have with this report...

The report itself admits that the Toxicity Characteristic Leaching Procedure (TCLP) is not without controversy. I do not accept the premise that the process represents conditions found in the typical municipal landfill. The procedure breaks the CRT into a 9.5mm size that I find reasonable... But then these pieces are "rotated at 30 rpm for 18 ( 2 h in a 12 vessel rotary extractor. The extract was filtered through a glass fiber filter of 0.8-ím pore size and the sample preserved using 2 mL of nitric acid per 500 mL of sample."

Now you are breaking the glass nearly into its basic silica components. Remember, the 9.5mm size is just a maximum size... There are already many sand-like bits created by using a hammer to break down the crt, per the study's methodology. That 18 hour "rock tumbling" is not something I would expect to see occur in a landfill... At least not in a time frame where naturally-occurring lead might migrate through the same soil. Then they are using an acid to "digest" this mix into a sample that can be passed through flame spectrophotometer.

The extracts were stored at 4 °C until digestion. EPA method 3010A (Acid Digestion of Aqueous Samples and Extracts for Total Metals for Analysis by FLAA or ICP Spectroscopy) was used to digest the samples

Sorry, but that process sounds more like what is done to determine material compounds (un-alloying, for lack of a better term), not the process I would expect to occur naturally in a landfill in even 1000 years.

I am not alone in finding fault with this methodology. Below I began selecting relevant text from a 1999 letter sent to the EPA critical of the text methodology, and I've left it if anyone wants to read it. But in summary it sounds like whoever conducted the study used a method that would basically separate the silica from the lead and give the expected result. Consider that there is money to be made (and government bureaucracies to be propped-up) in re-classifying CRTs as hazardous waste. Funny how water sits inside lead pipes in municipal water systems, yet there is no "push" to replace these systems. Maybe the lobby group and the money just haven't arrived yet for that cause, but does that make it more or less of a risk to health?

http://www.google.com/url?sa=t&rct=j...84349003,d.aWw

Waste Leachability: The Need for Review of Current
Agency Procedures... First, the TCLP is applied too broadly. Second, leach
tests, including the TCLP when used to characterize toxicity, can be improved by accounting for additional parameters. In 1990, EPA promulgated the TCLP as a method to characterize the toxicity potential of wastes using a particular worst-case scenario. In addition to its use as a waste classification test, the TCLP is being used by regulators and industry more broadly. The TCLP may be inappropriate in some of these broad applications...

...To be most scientifically supportable, a leaching protocol should be both accurate and reasonably related to conditions governing leachability under actual waste disposal conditions.

...Kinetics: The TCLP is based on an extraction time of 18 hours. This time frame was arbitrarily chosen and does not necessarily bear any relation to an equilibrium state.

...Liquid/Solid Ratio: The TCLP uses a 20:1 liquid to solid ratio. [Is this a realistic representation of what you would find in a municipal landfill? ]

...Particle Size Reduction: TCLP particle size reduction requirements may not
represent field conditions. The TCLP requires that solids must be reduced in size to pass a 9.5-mm sieve before the waste is mixed with the extraction fluid. This reduction in size increases the specific surface area of the particles, which increases the leaching potential. Monolithic wastes have a lower leaching potential due to physical stabilization and the resultant increase in the length of the diffusion pathway from waste into the leachate. Additionally, some processes also provide for chemical stabilization by binding heavy metals in insoluble hydroxide and other complexes.18 Consequently, reductions in leachability that derive from solidification/stabilization associated with monolithic wastes are ignored.