I forgot to rinse lentils before adding them to soup. Is the meal still safe to eat?
I can only speak for UK supermarkets and you haven't said where you're from, but our lentils are clean as bought.  A typical packet doesn't say to rinse them. With red lentils the only reaosn I can see for rinsing is to (slightly) reduce foaming; with Puy lentils and some others even that's not an issue and you may lose flavour.

Some Indian recipes (actually from India rather than westernised) say that when you rinse you need to pick over for stones, but I've never had that with dried lentils or beans.