*** Toxicty Characteristic. there were several questions regarding the toxicty characteristic. There is an importnat distinction between a substance being toxic and its place on the list for the toxicty characteristic.

*** Q. Hydrogen cyanide is a P waste (hazardous waste no. P 063), but is not considered a F or K waste. Even though it is not on the characteristic waste list for its toxicity, I would think that would be a good fit for hydrogen cyanide due to its low exposure limits and asphyxiant characteristics.
A. Indeed, but remember that RCRA deals what can go to the landfill and what must be treated as a hazardous waste. The toxicity characteristic refers to its likelihood to leach from a landfill.  HCN is quite reactive and unlikely to leach.  Also, although quite poisonous it is quickly biodegraded. 

**Q. If any chemical is present in U list but don’t have any characteristic attributes to be in a characteristic waste list. Will we call this chemical as hazardous waste or not?
A. The criteria are “or” criteria.  So if it is either on one of the four lists or have one of the four characterises, it is a hazardous waste under RCRA.  

** Q. What does it mean when 2 substances share exactly the same hazardous waste number [these are relatively few in numbers and issued as part of the EPA regulations. ] and abstract number [the CAS number is issued by the private society and there are millions of them.  They are usually quite specific, or as specific as possible.] ? I would think it tells both chemicals have very similar hazard properties.  [If it has the same CAS number, it is the same chemical. But, you always need to read the label.  Many chemicals are sold in special solutions or mixtures and the chemical of interest may be only a fraction of the whole.]  Could this also create a ‘soft’ categorization of some of the millions of uncategorized substances whose effects can only be suspected based on atomic properties they share with other tested substances? Is the thought of adding these millions in some pseudo-category with other substances be a way to ‘categorize’ them though they are yet untested? 
A. It is expensive for the government or industry to do all the testing to categorize a chemical. Therefore only the most “important” chemicals get categorized.  The importance may derive from its known ill effects, or the prevalence of human exposure.  Without the thorough testing, the risk of mis-categorizing the substance might out-weight any benefit from the categorization. 

**Q. I always wondered how one could categorize the toxicity/hazard level of crude oil spills. Would a search for key crude oil components (or direct refined products) under the RCRA listed waste and characteristic waste be a good way to start? 
A. RCRA and CERCLA do not apply to petroleum products.  However if there is a spill, the

**Q. I don’t know if this squarely fits the course interest but this module made me think of it: calculation of fines for spills. Besides the actual environmental restoration cost, and probably punitive component of fines, what informs the charge/payment that go for every barrel spilled? Is there any toxicological reason for this? For example discharge by a petroleum company as opposed to, for example, a barrel of waste from a cement manufacturing company? 
A. An excellent question.  Oil Spills do not come under RCRA or CERCLA, the hazardous waste laws, but rather under the OPA, Oil Pollution Act, of 1990.  Yes, the “Natural Resource Damage Assessment” will determine the fine – or rather, will be used by lawyers on both sides to argue before a court what the fine should be.