Food is something most of us are pretty fussy about on holiday - either because we want to indulge ourselves and eat well or because we don't want to get ill. But certain places are considered "safe", including, undoubtedly, the US.
The biggest worry most tourists are likely to have is severe weight gain, such is the size and calorific value of the portions. But one potentially serious health issue that many Britons have followed closely at home is probably not given a second thought when they go on holiday - genetically-modified food.
Only three years after the first large-scale commercial harvest, GM crops now cover a quarter of US cropland - around 90 million acres - and are fully integrated into the American diet.
But only about a third of Americans are aware that GM foods are being sold. "There's a kind of schizophrenia here," says Charles Margulis, GM campaigner at Greenpeace. "On the one hand, we are extremely health conscious, but on the other we have very high sugar, high fat, high red meat diets. The GM issue is just another contradiction."
There are four main genetically-modified crops in the US - corn, soya, rape seed and cotton seed - and 60-70% of processed food in the US is likely to contain GM ingredients.
The multinationals that control the biotechnology insist they cannot separate GM crops from non-GM crops at source and are fighting the call for labelling.
A holiday-maker will find it practically impossible to eat or drink without consuming something that is genetically modified.
"Some potatoes are also GM so avoid fast-food french fries," says Margulis. "And a small percentage of tomatoes are GM, so processed tomato-based foods like ketchup may also be contaminated.
"Corn syrup is ubiquitous in virtually any sweetened drink," he explains, "so Coke and other sodas are likely to be made with a combination of non-GM and GM corn syrup."
Is the answer for the anti-GM tourist to avoid the US as a holiday destination? Sadly the influence of the US biotechnology companies growing GM crops goes much further than the US. Their crops are exported to Europe for animal feed and ironically, the more the US and European public protests about the issue, the more likely it is that GM crops will be dumped on poorer countries, as happened last September when Russia received illegal shipments of Novartis GM maize from the US.
"Exotic" environments - so vital for tourism - could also be threatened. Scientists are currently assessing the potentially harmful effect on Mexico's biodiversity of the recent arrival of 5 million tons of US maize - up to 35% genetically modified. A Cornell University study showed that 44% of the larvae of the monarch butterfly fed with milkweed contaminated with GM Bt-maize pollen died within 48 hours.
"The fall migration of monarch butterflies from Canada to central Mexican forests is a natural wonder," Dr Jane Rissler, senior staff scientist with the Union of Concerned Scientists, points out. "The loss of monarchs - and perhaps many other incredible species around the world - is too high a price to pay for engineered corn."
The Consumers Union website has a comprehensive list of everyday GM products sold in the US. The True Food Campaign can be contacted at 0171-865 8100.
