**Q. Question #6 on the quiz asked where to look up Hexachlorophene in the lists.  The correct answer is d) both the U and P lists however I was only able to locate Hexachlorophene on the U-list.  Am I just misunderstanding the question? A. You would look on both lists, since it could be on one or the other.  If, instead of “look up” it said “find,” then U would be correct.  Didn’t mean to split hairs on that one.

**Q. When it is a known fact that toxicity testing of most chemicals used in commerce is not done so why can't it be done? Why still testing is not done on so many other chemicals which are used commercially?
A. There is a big difference between "commercial use" and "consumer use." Consumers are everyday people who go to the store and buy food, cosmetics, etc. Almost all consumer products are tested, most fairly well tested. Commercial products might be any of the thousands of chemicals that stay inside processing plants or move around in tank cars and pipeline. These chemicals are not intended for human use or even human exposure, except perhaps in the workplace, presumably by trained and equipped workers. Many of these chemicals will never be tested, unless some special law or disaster requires it.

**Q. We have talked about many hazardous materials, how can we say that a particular chemical is hazardous as we use some chemicals in our diet (directly or indirectly) and when taken excess lead to poisoning, so how can we know or organizations decide which is hazardous and when taken in what amounts they are harmful and how do we know that?
A. A lot of good questions. How do we "know" anything? I know some things with "reasonable certainty" and make personal choices based on the knowledge. That is not the same as knowing something as "scientific fact." In the U.S. all new food additives are tested and the old additives have been around for a long time and not led to epidemics. I am reasonably certain that all foods available in the U.S., when taken in moderation, are not poisonous. There are many substances, alcohol and saturated fat, for example, that are certainly very bad, if taken in excess.

Q. I have a question regarding the enforcement of the lists. Are industries required to follow the rules on their own or are there enforcement officers who check in - such as OSHA does with workplace regulations?
A. We'll spend some more time on this. EPA enforces RCRA, where you find the lists.

Q. Also, are compounds labeled hazardous only after a certain number of deaths or injuries? I guess I am thinking about synthetic compounds and new combinations of chemicals that most likely aren't being tested before being used.
A. Yes, until something happens they are not likely to be tested. However, manufacturers are usually "deep pockets" who are targets of lawsuits, and they are careful. Several of the items on the K and F lists are catchall that the new product might fit. See Wastes, next submodule.