The Conurbano area is an area of suburbs & also huge
slums.
"According to varying estimates from city agencies, 300,000 to 500,000 in this city of 3 million live in the slums."
http://www.washingtonpost.com/wp-dyn/content/article/2007/04/28/AR2007042801178.html
A recent bbc story:
"The population in the so-called "emergency villages" of the Argentine capital has grown by 25% in the last two years, now housing some 200,000 people.
That is equivalent to almost 7% of the inhabitants of the city, or the arrival of 11 families per day to the 14 slums and at least 40 settlements within Buenos Aires's perimeter.
http://news.bbc.co.uk/2/hi/business/8103595.stm
Lack of running water, no sanitary sewage, poor nutrition, substance abuse, & no preventative health care are all issues in these areas.