Not lovin' it: U.S. chicken McNuggets 'contain SILLY PUTTY chemical'

Chicken nuggets sold in U.S. branches of McDonald's contain a chemical used in Silly Putty.

'McNuggets' sold to American fast food lovers contain dimethylpolysiloxane, an anti-foaming agent used in Silly Putty.

They also have more calories and fat than those sold in the chain's British restaurants, according to a CNN study.

Four American McNuggets total 190 calories, 12 grams of fat and two grams of saturated fat. The equivalent portion in Britain clocks in at 170 calories, nine grams of fat and one gram of saturated fat.

Transatlantic tastes: McDonald's Chicken McNuggets contain more calories, fat and chemicals than their British counterparts

U.S. McNuggets also contain a petrol-based chemical called tertiary butylhydroquinone (tBHQ) as well as dimethylpolysiloxane. British McNuggets contain neither.

A spokeswoman for McDonald's put the transatlantic differences down to the local methods of food preparation.

Lisa McComb, McDonald's global media relations manager, said that in the U.S. McNuggets are coated and then cooked, while in Britain they are cooked and then coated.

The result, she explained, is that British McNuggets absorb less oil and have less fat.

Labeling also plays a part in giving nuggets sold in Britain the appearance of being healthier than those sold in the U.S., she said, as ground celery and pepper are listed on the American packaging as simply 'spices'.

'You would find that if you looked at any of our core food items, you'd see little, regional differences,' she said. 'We do taste testing of all our food items on an ongoing basis.'

Ms McComb added that dimethylpolysiloxane is used for safety reasons to prevent the oil from foaming.

Marion Nestle, a New York University professor and author of What To Eat, told CNN that tertiary butylhydroquinone and dimethylpolysiloxane in the McNuggets probably pose no health risk to consumers.