More than 100 million people worldwide are exposed to dangerous levels of toxic chemicals. These pollutants include radionuclides, industrial chemicals, pesticides and heavy metals, which may come from activities such as mining, industry, agriculture and weapons manufacture.
1. Air pollution: Linfen, China
According to one World Bank report, 16 out of 20 of the world's worst cities for air pollution are found in China and Linfen has the highest levels of pollution.This city, in China's Shanxi Province, is at the centre of the nation's coal industry. Here, emissions from vehicles and industry have created an atmosphere where people literally choke on coal dust. High levels of pollutants such as fly ash, carbon monoxide, sulphur dioxide and arsenic are taking their toll on the greater city's three million residents: clinics here see high levels of bronchitis, pneumonia and lung cancer and lead poisoning in children is alarmingly common.
2. Industrial chemicals: Bhopal, India
A woman looks at photographic exhibit on the Bhopal disaster. (Source: Reuters)
In terms of number of deaths, Bhopal remains the worst industrial accident yet. In December 1984, 40 tonnes of isocyanate gas escaped from a pesticide plant in this central Indian city of 1.8 million people. The accident killed nearly 4,000 people outright and the number of fatalities rose to 15,000 in following weeks.
"More than 26 years have passed since the disaster, yet thousands in Bhopal continue to suffer and die from chronic illnesses, with as many as 500,000 people suffering ill health as a result," says Dr Mariann Lloyd-Smith a senior advisor to the National Toxics Network, an Australian NGO based in Bangalow NSW.
3. Mercury: Central Kalimantan province, Indonesia
The largest concentration of people at risk from mercury pollution is in Indonesia. Here, in Borneo's Central Kalimantan province, mercury is commonly used to extract gold from ore by small-scale processing operations. According to the WWF, so-called artisanal gold mining (ASGM) here results in the emission of 45 tonnes of mercury into the environment annually. "There's also lots of environmental damage, because the mercury finds its way into the environment, where it can be converted to methyl-mercury, which is even more hazardous to human health when ingested," says Professor Ian Rae, an expert on environmental pollution at the University of Melbourne.
4. Pesticide: Kasargod, India
Endosulfan, an organic pesticide now banned in many countries, has been responsible for poisonings in Africa, India and Latin America, says Dr Lloyd-Smith from the National Toxics Network. "In Kasargod, in southern India, 20 years of aerial spraying of cashew nut plantations has left a legacy of disease, death and deformity.
Numerous congenital, reproductive and long term neurological and other effects have been experienced, including congenital deformities, cerebral palsy, epilepsy, lowered IQ, delayed development [and] cancer."
5. Chemical weapons manufacture waste: Dzerhinsk, Russia
Dzerzhinsk has the unenviable status as one of the former Soviet Union's major sites for chemical weapons production - and remains a significant chemical manufacturing site. But little of the chemical weapons industry was properly regulated, and according to the city's own figures, more than 270,000 tonnes of chemical waste were poorly disposed of between 1930 and 1998.
As of 2007, the average life expectancy in the city of 250,000 people was reported to be 42 for men and 47 for women.
6. Organic chemicals: Sumgayit, Azerbaijan
Sumgayit Factory workers and residents of the city have been exposed to a
combination of high-level occupational and environmental pollution
problems for several decades.
Sumgayit was another centre for Soviet industry with more than 40 factories producing industrial and agricultural chemicals. In their heyday these factories - which manufactured products ranging from detergents and pesticides to chlorine and aluminium - chugged out 64,000 to 109,000 tonnes of harmful emissions into the air each year, which has left a heavy legacy of pollution. During that time the city had one of the highest morbidity rates in Azerbaijan.
Today incidence rates of cancer are 22 to 51 per cent higher than the national average, while mortality rates from cancer are eight per cent higher.
7. Lead: Tianying, China
Smoggy day in Tianying
Around the world, an estimated 19 million people are at risk from lead smelting operations while either using ore or recycling scrap metal. Tianying in China's Anhui province is one of the centres of the nation's lead mining and processing industry, and accounts for approximately half of Chinese production.
Small-scale operations there have been notorious for disobeying regulations, which has resulted in lead concentrations in the air and soil to being 8.5 and 10 times higher than the national health standard.
8. Hexavalent chromium: Sukinda, India
Women working in a chromium mine, Sukinda, India
Hexavalent chromium (chromium VI), one of two forms of the metal, is a carcinogen which can cause or increase the chance of developing some kinds of cancer. Sukinda, in India's state of Orissa, has 97 per cent of India's reserves of chromite ore, one of the only sources of chromium. It also has one of the world's largest open-cast chromite mines.
According to the Blacksmith Institute, as of 2007, 12 mines continued to operate with no environmental management plans, spreading waste rock over the surrounding area and discharging untreated water into the rivers.
9. Radiation: Chernobyl, Ukraine
The abandoned city of Pripyat with Chernobyl plant in the distance
A 30-kilometre exclusion zone around the city remains dangerously radioactive and uninhabitable today.
10. Persistent organic pollutants (POPs): Arctic Canada
"The contamination of the Arctic with POPs seriously threatens the very existence of indigenous communities," says Lloyd-Smith. "Some of these poisons have been banned…but many go unregulated and travel the world on water and air currents."
POPs are organic chemicals which break down very slowly in the environment, such as hexachlorobenzene or DDT. They are often industrial products, byproducts or pesticides. These accumulate in Arctic environments and in the animals that inhabit them and get concentrated in whale and seal blubber and other traditional foods that Inuit people eat.