(AP) -- A U.N.-sponsored treaty to combat highly dangerous chemicals has been expanded beyond the original "dirty dozen" to include nine more substances that are used in pesticides, flame retardants and other products, U.N. officials said Saturday.
A 160-nation meeting this week added the chemicals - labeled as posing a risk to people's health and the environment - to the list of the Stockholm Convention on Persistent Organic Pollutants, or POPs, which bans or restricts their use, according to a statement by the U.N. Environment Program.
"The tremendous impact of these substances on human health and the environment has been acknowledged today," said Achim Steiner, the U.N. undersecretary-general who heads the program.
The 2004 treaty aims to protect the environment and people's health from very dangerous chemicals that last a long time in the Earth's atmosphere, soil or water and ultimately phase them out.
The treaty has so far included the dirty dozen list of 12 chemicals, such as the widely banned pesticides DDT and chlordane. Countries that have ratified the treaty also enact national legislation to enforce the bans and restrictions it imposes.
The use of DDT in sprays to kill malaria-spreading mosquitoes has been allowed under an exception in the treaty. But the U.N. environmental and health agencies said this week that there are good alternatives to combat malaria. They announced the aim of phasing out DDT completely by the early 2020s.
The so-called POPs pose a risk to humans and the environment because they often damage reproductive health, can lead to mental health problems, cause cancer or impede normal growth, said Donald Cooper, executive secretary to the treaty.
The pollutants have some characteristics that make them exceptionally dangerous, he said.
"These chemicals transit boundaries. They are found everywhere in the world," Cooper said. "They don't go away. They persist in the atmosphere, they persist in the soil, in the water for extremely long periods of time."
The chemicals accumulate in the environment up through the food chain and stay in people's bodies, he said.
"Once you have a small amount in your body," Cooper said, "it doesn't go away and you add another bit, and another bit and another bit, it keeps adding up and getting worse and worse."
In its additions, the meeting decided to ban chlordecone, which was used as an agricultural pesticide; hexabromobiphenyl, an industrial chemical that was used as a flame retardant; and lindane, which has been used in insecticides for soil, wood and animals.
Lindane is only produced by a few countries today and chlordecone and hexabromobiphenyl are actually not used anymore, said David Ogden, coordinator for the treaty.
But their inclusion in the treaty is to make sure that these chemicals remain banned, he said.
The meeting also decided to restrict the use, production and trade of so-called PFOS, a toxic chemical used in many electronic applications, such as semiconductor chips.
PFOS has been the most difficult chemical to list because it is still widely used, Cooper said.
"The trade in PFOS is extensive. It is easily in the billions of dollars on an annual basis and over a very wide area of products," said Cooper.
Associated Press writer Alexander G. Higgins contributed to this report.
©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Explore further: Polar bears hold key to understanding health risk of environmental pollutants