Will the US$1.90 allow you to purchase sufficient food to meet the your caloric needs as well as provide a sufficiently diversified diet to avoid malnutrition? In this case I would want caloric needs to also reflect the manual energy work load expected of the individual. This I would place at 4000 kcal/day instead of the 2200 kcal/day used by FAO for a sedimentary life style. I seriously doubt if the US$1.90 will provide this. Thus should the poverty line be defined in terms of providing sufficient buying power for people to survive with a balanced diet and enough energy to undertake the manual labor expected of them. You might want to look at the consumer price comparison page on the www.smallholderagriculture.com website to get an idea of what US$1.90 can purchase and what kind of diet it will allow.