I'm not going to try to answer this one for EPA or librarians in general, but, in the off chance that anyone reading this ever has a similar problem, I'll say what my answer would be.
I interned for CCHW, now CHEJ (the Center for Health, Environment, and Justice) quite a few years back -- they were formed from people who lived at Love Canal. They provide help to community groups with these kinds of questions; their Web site is at www.chej.org. They taught me that research is always of secondary importance when facing something like this, community organization is more important. (By research, I mean the kind of library research that you talked about in your example.)
In the example you gave, there was a chemical release near a school. If that happened, it's likely that your child would not be the only one affected; there would probably be many people's children. When this happens, your first response should be to get together as a group. If you can get a group of ten or twenty people, it's likely that one person in the group will have the ability to start doing research for everyone. Meanwhile, the fact that you are now a group, rather than a collection of relatively powerless individuals, means that you'll be more likely to have the power to change things.
None of this excuses any failure to deliver information to the public understandably. But, as a researcher myself, I know that no amount of research will really help you fix this situation. You already know that your child had some kind of serious reaction to this event. Assuming that it's likely that what happened once will happen again, all that research could tell you is that your child would be better off in another school, which you knew already. But, since you probably can't move -- and anyway, not everyone can move -- you need to have things fixed so this kind of release won't happen again. And you could have all the research in the world, proving pretty clearly that there is a serious health hazard, and people will still ignore it unless you show that you have the power to make them pay attention.
Having said that, it's not the librarians' or EPA's job to do your political organizing for you, so they should still respond to the question about how ordinary people can find information. But if something like that does happen, your second call after your call to your pediatrician should not be to EPA or a library, it should be to an environmental group that will help you with organizing as well as research.