I tend to look at the risk as being relative. For me, downtown Rio around 'Central do Brasil' bus and train station were far higher risk than many slums. Vari

I tend to look at the risk as being relative. For me, downtown Rio around 'Central do Brasil' bus and train station were far higher risk than many slums. Various areas around Rio (and SP) have 'Cracklands' (Cracolândia) with many crack cocaine users who are frighteningly unstable. Reports describing hold-ups, with victims cooperating and getting shot - usually in a better parts of town put things in perspective for me. Some slums are trying to open to tourism, as a starting point you could look up well-reviewed bars\restaurants in slums to get an introduction. As the article suggests, there are many legit businesses in slums, so going to the ones with a lot of business activity is usually a good bet. The economy of a slum can only develop if there is a reasonable level of security. I can only trust my judgement. I have not encountered any problems so far. YMMV.