The list, compiled by the New York-based non-profit group the Blacksmith Institute, said the world's pollution is sickening up to one billion people.
Blacksmith Director Richard Fuller said environmental problems cause up to 20 per cent of deaths in developing countries.
He said the environmental toxins in these towns put residents at risk of being poisoned, developing cancers and lung infections and having mentally retarded children.
"The worst problem is the damage it does to children's development ... and that damages the future of the countries," Mr Fuller said.
In Dzerzhinsk, Russia, a former Cold War-era centre for making chemical weapons, including Sarin and mustard gas, the average life expectancy is 42 for men and 47 for women.
Chemicals from the weapons manufacturing were dumped into an aquifer that also provides the local community with drinking water, according to Blacksmith.
"Norilsk in Russia is also just a horror story," Mr Fuller said about an industrial city founded as a slave labour camp in 1935.
"Smelters with no pollution control: nickel, copper, lead, cadmium. No pollution control. Just an awful place," he added.
In Kabwe, Zambia, one of six towns around the country's copper belt, soil contamination levels of heavy metals are higher than those recommended by the World Health Organisation.
There, the average level of lead in a child's blood is five to 10 times the levels allowed in the United States, Blacksmith said.
The group researched 300 sites to come up with its list of ten. The sites were not ranked because health records in some developing countries were not available.
The following countries make up the list: Chernobyl, Ukraine, Dzerzhinsk, Russia, Haina, Dominican Republic, Kabwe, Zambia, La Oroya, Peru, Linfen, China, Mailuu-Suu, Kyrgyzstan, Norilsk, Russia, Ranipet, India and Rudnaya Pristan, Russia.