The World Health Organization said Friday that tiny traces of the chemical melamine are not harmful in most foods, but it joined the U.S. and EU in setting a strict limit that regulators should impose before pulling products off the shelf.

    Melamine was recently found to have contaminated milk products around the world and has been implicated in the sickening of nearly 300,000 babies in China and killing at least six infants there.

    A meeting of food safety experts held by WHO in Ottawa, Canada, decided on Friday that while there is no good reason to have any melamine in food products at all, a maximum of 0.2 milligrams of melamine per kilogram of body weight can be tolerated per day.

    Jorgen Schlundt, WHO's director for food safety, said that threshold is lower than the European Union's limitation of 0.5 milligrams. The U.S. Food and Drug Administration, which originally set its limit at 0.63 milligrams, later reduced its tolerable daily intake to 0.063 milligrams.

    WHO's guidance is used by governments to set their minimum food safety standards.

    Melamine, a nitrogen-rich chemical used in the production of plastics, was first discovered to be a major problem when it appeared in Chinese infant formula in September. Since then traces have been found in milk products around the world.

    Last month the FDA said tests found traces of melamine in the infant formula of one major U.S. manufacturer and cyanuric acid, a related chemical, in the formula of a second major maker.

    Schlundt stressed that the threshold the WHO has set — which stipulates that a 50 kilogram (110-pound) person could tolerate 10 milligrams of melamine per day — is not a "safe" level for melamine, but merely the amount a human being can consume without higher health risk.

    Melamine is used in some food packaging and can rub off into packaged food products. It also is part of a cleaning solution used on some food processing equipment.

    世衛(wèi)組織周五表示，大多數(shù)食品中含有的微量三聚氰胺對人體是無害的，但該組織與美國和歐盟共同制定了監(jiān)管者應(yīng)實施的嚴格限量標(biāo)準(zhǔn)。

    最近，世界各國的奶制品都被檢測出受三聚氰胺污染。在中國還致使30萬嬰幼兒生病，至少6名嬰幼兒死亡。

    世衛(wèi)組織周五在加拿大渥太華召開一次食品安全專家會議，與會人員決定，雖然食品中根本不應(yīng)存在三聚氰胺，但每公斤體重每天最多可以容忍0．2毫克三聚氰胺的攝入。

    世界衛(wèi)生組織負責(zé)食品安全問題的官員約爾根·施倫德表示，這一標(biāo)準(zhǔn)比歐盟0．5毫克的限量更低。美國食品和藥物管理局最初將限量定為0．63毫克，后來將每天可容忍的攝入量降低為0．063毫克。

    各國政府將參照世界衛(wèi)生組織的標(biāo)準(zhǔn)制定本國的最低食品安全標(biāo)準(zhǔn)。

    三聚氰胺是一種用于塑料產(chǎn)品的富氮化工原料。當(dāng)9月份中國的嬰幼兒配方奶粉中發(fā)現(xiàn)三聚氰胺，人們才首次意識到這個問題的嚴重性。此后，世界各國的奶制品中都發(fā)現(xiàn)含有微量的三聚氰胺。

    上個月，美國食品及藥品管理局檢測后發(fā)現(xiàn)，美國一個主要生產(chǎn)商制造的嬰幼兒配方奶粉中含有微量三聚氰胺，另一個主要奶粉制造商的配方中含有與之相關(guān)的化學(xué)物質(zhì)三聚氰酸。

    施倫德強調(diào)世衛(wèi)組織設(shè)定的50公斤（110磅）體重的人每日對三聚氰胺的容忍量10毫克，并不是一個“安全”標(biāo)準(zhǔn)，只表示在不產(chǎn)生健康高風(fēng)險的情況下人體的可消耗量。

    三聚氰胺用于某些食品包裝，并有可能通過摩擦導(dǎo)致食品含有三聚氰胺，同時也用于某些食品加工設(shè)備的清潔液中。