GENEVA (AP) — A U.N.-sponsored treaty to combat highly dangerous chemicals has been expanded to include nine more substances that are used in pesticides, electronics and other products, U.N. officials said Saturday.

The additions include one called PFOS worth billions of dollars in a wide range of uses from making semiconductor chips to fighting fires. Another is lindane, a pesticide widely used in combatting head lice.

The chemicals accumulate in the environment up through the food chain and stay in people’s bodies, said Donald Cooper, executive secretary to the Stockholm Convention on Persistent Organic Pollutants, or POPs.

He said they travel long distances in the air.

The alarm over the original chemicals was sounded because they were being found in high concentrations in the fatty tissues and blood of the Inuit Indians in Canada even though they were thousands of miles away from the production or use of any of the chemicals, Cooper said.

Participating countries have one year to say whether they will ban or restrict the chemicals or whether they will need more time or an exemption, Cooper said.

The additions to the list make it possible for developing countries to receive international help in containing and destroying stockpiles of the chemicals which might otherwise seep into the soil and water supply, Cooper said.

The 2004 treaty aims to protect the environment and people’s health from very dangerous chemicals that last a long time in the atmosphere, soil or water, and ultimately phase them out.

The treaty had included 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 Cooper.

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.”

Some of the additions to the list are chemicals that are used less than they once were, but there may be large stockpiles of them around the world in leaky containers.

Among them are 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.

Now the pressure will be on to switch to safer alternatives, he said.

The meeting also decided to restrict the use, production and trade of PFOS, a toxic chemical used in many electronic applications, such as semiconductor chips, but also in fire fighting foam, photo imaging, hydraulic fluids and textiles.

PFOS has been the most difficult chemical to list because it is still widely used, Cooper said.

He said developed countries have signaled that they intend to phase out the production and most of the use of PFOS over the course of the next 10 years because it will take awhile to develop alternatives. Developing countries have indicated they would do that within 15 years.

The new chemicals targeted for elimination are:

— alpha hexachlorocyclohexane, still produced as an unintended byproduct of lindane

— beta hexachlorocyclohexane, still produced as an unintended byproduct of lindane

— hexabromodiphenyl ether and heptabromodiphenyl ether, used in flame retardants

— tetrabromodiphenyl ether and pentabromodiphenyl ether, used in flame retardants

— chlordecone, an agricultural pesticide

— hexabromobiphenyl, or HBB, a flame retardant

— lindane, used in creams for treatment head lice; also has been used in insecticides.

— pentachlorobenzene, used in PCB products, dyestuff carriers, as a fungicide, a flame retardant

For elimination or restriction:

— PFOS — perfluorooctane sulfonic acid, its salts and perfluorooctane sulfonyl FLUORIDE