McDonald's Corp yesterday declined to release the exact amount of two food additives contained in its Chicken McNuggets sold in China - chemicals that, if taken in excess, may cause nausea or vomiting.

The Chinese operation also failed to rule out the possibility that the two ingredients could be found in other items listed on its menu in China.

The State Food and Drug Administration said on Tuesday it had launched a nationwide inspection on McDonald's Chicken McNuggets after a recent CNN investigation found that McDonald's all-white meat Chicken McNuggets sold in the United States contains the preservative tBHQ, a petroleum-based tertiary butylhydroquinone, as well as dimethylpolysiloxane, an anti-foaming agent.

The fast food chain said the amount of its two additives, also found in McNuggets in China, is within the limits of China's national standard and poses no risk to consumers' health.

The food administration said it will release the inspection results later and called on domestic catering providers to use additives strictly according to national limits.

According to China's standard on food additives, both chemicals are legal in limited amounts.

The tBHQ is allowed to be used in fats, oils and fried foodstuff with a maximum level at 0.2 grams per kilogram. The dimethylpolysiloxane can be used in edible oils within the limit of 10 milligrams per kilogram and 0.2 grams per kilogram during processing of meat products.

Although the two food additives were proven to be allowable in China, health experts remained concerned that frequently eating food with the additives might have an accumulated impact and bring potential risks for health.

McDonald's has been slapped for not mentioning the two additives on its product packages to raise public awareness.

One gram of the tBHQ can cause "nausea, vomiting, ringing in the ears, delirium, a sense of suffocation, and collapse, says "A Consumer's Dictionary of Food Additives."