No, it is not illegal to send a worker to an area of a city that the worker thinks is dangerous, just like it's not illegal for a store or business in that area to have workers in it, or for a cab driver to drive to that area, etc. The law does not recognize different neighborhoods as inherently unsafe for a variety of reasons, not least of which is, to do so would undoubtedly be legally racist in many situations. All municipal areas are treated the same for this purpose, so there was, legally, no inherent danger.