***Special Point: Toxicity vs. Toxicity characteristic.

Toxicity is a general term for poisons - chemicals the harm the body. You learned from Paraclesus that all chemicals are poisons, it is the dose that matters. As a practical matter, we are not talking about drowning in a chemical but an "environmental" or "workplace" exposure. For these types of exposures, some chemicals are very toxic, that is, harmful in small quantities. While others are (relatively) nontoxic. We may describe this using the LD50 or similar description. RCRA is the US hazardous waste law. It has lists of chemicals and wastes. Almost all the chemicals and wastes on those lists are toxic in relatively small quantities. Some have other bad characteristic too, flammable, reactive, or corrosive for example. RCRA also also has "characteristic" of toxicity. There are relatively few chemicals for which this "toxicity characteristic" might apply. This toxicity characteristic is determined by a TCLP test. See the second paragraph on http://www.faculty.uaf.edu/ffrap/EQE_649/Module_03/Submodule3B/Submodule3B_3.htm This distinction would make a good quiz question.

*** Q. It seems to me that the criteria for toxicity according to RCRA is fairly narrow. I was very surprised that there were not concentrations listed for strong acids under this category. Obviously they would still be considered hazardous wastes as they fall under the characteristic of corrosivity. My question is, does this narrow definition of toxicity generally prevail in environment literature?
A. Not at all. But when you say "toxic" in science, you immediately need to bring up the issues we mentioned in Module 1 about dose, route, target organ, LD50, etc. The RCRA characteristic is a very narrow dealing with leachate from landfills.

***Q. 2- Phenylphenol. (also called o-Phenyl Phenol) This is used as a germicide and fungicide…so I would think it's potentially pretty darned hazardous. But, I could not find it on any of the lists (U, P, F, or K). Nor did I find any properties listed on this chemical to suggest it is ignitable, reactive, corrosive or "toxic" (it's not listed on the TCLP website).
A. Remember that RCRA is all about "wastes" that go to a landfill or went to landfills or belong or don't belong in landfills. A pesticide could be very toxic and otherwise hazardous (those are regulated by FIFRA) but if it was applied in beneficial use, it is disposed, all right, but never becomes a "waste."

**Q. RCRA defined liquids in tanks as “solid waste”.  Does this mean that a company could pipe liquid waste directly to a farm and (if the liquid is suitable) apply the liquid for irrigation or other land application without ever considering it a “solid waste”. 
A. Is the product a “waste?”  If the farm were hooked into the plant such that the chemicals do not leave the process stream, it is not a waste.  When you take it out of the stream, especially if you store it for a day or two, then you have a waste for sure.  Recycling can be a complex issue too. 

** Q. Where can I find the wastes with the EPA Hazardous Waste Number of D001, D002 and D003 ?
A. See http://www.geai.com/waste.html for an overview. But those numbers are used for the other characteristics: Ignitability, Corrosivity, and Reactivity.

*Q. The toxicity characteristic threshold for Barium is 100 mg/L. I did not see any reference to drilling muds or barium on the F or K lists. The U list listed barium cyanide as a hazardous waste.
A. The muds and other petroleum processing materials are exempt from RCRA.

*Q. I found it difficult to find what I was looking for in the F list. How did they end up classifying those particular methods/procedures as hazardous? I would think that the list would be a lot longer.
A. Those processes cover most of the general sources of hazardous waste. There are also some catchall categories that get about all of it.

Q. I was confused by the definition of combustibility in the MDSE.. If the MSDS says a product is combustible does it meet the RCRA characteristic of ignitability?
A. We'll cover flammability vs. combustible in a few weeks.