- Alcohol & substance abuse, from kids in African slums to adults in the US, this is a very common self-destructing habit often taken as a way to cope with huge amounts of stress and... well, despair;
- Crippling accidents due to unsafe working environments (machinery in factories or agriculture) as well as other work hazards such as lead poisoning, pesticide poisoning, bites from wild animals due to lack of proper protection;
- Poor housing & living conditions, a classic cause of diseases;
- Water and food-related diseases, simply because the poor can't always afford "safe" foods.
The feature of a rich or developed country for example is the presence of a middle class, but recently we've seen even Western countries gradually losing their middle class, hence the increasing number of riots and clashes. In a society, poverty is a very dangerous factor that can destabilize and entire country. The Arab Spring is another good example, in all of the countries concerned, the revolts started because of the lack of jobs and high poverty levels. This has led to most governments being overthrown).