Communities in developing countries especially in Asia are facing increasing health and environmental risks linked to exposure to mercury, according to a new study by the United Nations Environment Program (UNEP).
Parts of Africa, Asia and South America could see increasing emissions of mercury into the environment, due mainly to the use of the toxic element in small-scale gold mining, and through the burning of coal for electricity generation.
The Global Mercury Assessment 2013 reports that emissions of the toxic metal from gold mining have doubled since 2005, in part due to new and better information, but also due to rising gold prices that are expected to lead to further increases.
"Due to rapid industrialization, Asia is the largest regional emitter of mercury, and accounts for just under half of all global releases," said a statement issued by the UNEP.
The UNEP study assesses for the first time at a global level releases of mercury into rivers and lakes. Much human exposure to mercury is through the consumption of contaminated fish, making aquatic environments the critical link to human health.
In the past 100 years, man-made emissions have caused the amount of mercury in the top 100 meters of the world's oceans to double. Concentrations in deeper waters have increased by up to 25 percent.
The study, which provides a comprehensive breakdown of mercury emissions by region and economic sectors, also highlights significant releases into the environment linked to contaminated sites and deforestation.
The report says an estimated 260 tonnes of mercury - previously held in soil - are being released into rivers and lakes.
"Mercury, which exists in various forms, remains a major global, regional and national challenge in terms of threats to human health and the environment," said United Nations Under-Secretary-General and UNEP executive director Achim Steiner.
Greater exposure to mercury poses a direct threat to the health of some 10-15 million people who are directly involved in small-scale gold mining, mainly in Africa, Asia and South America. An estimated 3 million women and children work in the industry.