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.

世卫组织周五表示，大多数食品中含有的微量三聚氰胺对人体是无害的，但该组织与美国和欧盟共同制定了监管者应实施的严格限量标准。

最近，世界各国的奶制品都被检测出受三聚氰胺污染。在中国还致使30万婴幼儿生病，至少6名婴幼儿死亡。

世卫组织周五在加拿大渥太华召开一次食品安全专家会议，与会人员决定，虽然食品中根本不应存在三聚氰胺，但每公斤体重每天最多可以容忍0．2毫克三聚氰胺的摄入。

世界卫生组织负责食品安全问题的官员约尔根·施伦德表示，这一标准比欧盟0．5毫克的限量更低。美国食品和药物管理局最初将限量定为0．63毫克，后来将每天可容忍的摄入量降低为0．063毫克。

各国政府将参照世界卫生组织的标准制定本国的最低食品安全标准。

三聚氰胺是一种用于塑料产品的富氮化工原料。当9月份中国的婴幼儿配方奶粉中发现三聚氰胺，人们才首次意识到这个问题的严重性。此后，世界各国的奶制品中都发现含有微量的三聚氰胺。

上个月，美国食品及药品管理局检测后发现，美国一个主要生产商制造的婴幼儿配方奶粉中含有微量三聚氰胺，另一个主要奶粉制造商的配方中含有与之相关的化学物质三聚氰酸。

施伦德强调世卫组织设定的50公斤（110磅）体重的人每日对三聚氰胺的容忍量10毫克，并不是一个“安全”标准，只表示在不产生健康高风险的情况下人体的可消耗量。

三聚氰胺用于某些食品包装，并有可能通过摩擦导致食品含有三聚氰胺，同时也用于某些食品加工设备的清洁液中。