The United Nations International Children's Emergency Fund estimates one billion children, almost half the children in the world, live in urban areas. According to UNICEF Cities, a report by the children's agency, as cities grow larger, so do the problems children living there have to endure.
The UNICEF report says more than 80 percent of the one billion children who live in cities live in mega-cities in Africa, Asia and Latin America.
UNICEF spokesman Patrick McCormick said the children in these large cities are the most vulnerable to various forms of exploitation, from child labor to prostitution. They are so poor, Mr. McCormick said, they are often willing to do anything to survive.
"It is a pretty ferocious environment, when you are down on the bottom, to fight for the scraps that come your way," said Mr. McCormick. "There is a huge temptation to go into the criminal world. You can see that all over the world. Especially in developing countries, children who are reduced to begging or stealing, or reduced to doing jobs like washing wind screens or handing out newspapers, or whatever it is. These are not sustainable occupations."
The UNICEF report notes that during the last century the world's urban population grew more than tenfold. As the cities have grown bigger, health conditions have often become worse. In some cities in developing countries, the report says, child mortality rates are as high as 100-200 per 1,000 live births, and many children suffer from anemia and malnutrition.
However, UNICEF says there is some room for optimism. The report says that some cities around the world are taking steps to make their environments safer and healthier for children.
It says, in Calcutta, India's second largest city, as many as 42 police stations are involved in activities to protect children at risk, especially street children.
Another child friendly project is under way in the Dominican Republic. The study says 14 cities in that Caribbean country are working with UNICEF to create parks where children can play safely.