Is plastic safe?

Monday, April 16, 2007
It wasn't so long ago we wrapped our sandwiches in greaseproof paper but now, everything comes wrapped in plastic. We cook with it, we eat from it, we store food in it. But is plastic safe?

Our passion for plastic took off in the fifties — a Tupperware party used to be the height of sophistication. Nowadays we use a whole range of plastic products for our food. But is it safe? Can plastic leak harmful or cancer-causing chemicals into our food?

To find out, our reporter Michael Slater pays a visit to the Sydney labs of the CSIRO to meet packaging expert Dr Bob Steele.

Plastic is made from oil, coal and gas — things we certainly wouldn't want to eat. Some plastics contain dangerous chemicals, so this, plus rumours of cancer, have made us a tad nervous about putting it near our food, especially when cooking.

Michael: So is there any threat to the public using plastic, particularly if you're heating food in the microwave?
Dr Steele: Not really. All the plastics we see and are used commonly with food contact have been thoroughly tested over many years for their food contact suitability and their safety.

Sounds good, but there's a catch. You see, you just can't put any old plastic pot in the microwave. Use the wrong plastic and your food could get contaminated.

"Materials that are not intended for heat should never be used," says Dr Steele.

Put a margarine, ice-cream, or yoghurt tub in the microwave and you'll get a melt-down — these plastics are designed for the fridge and freezer and not high heat.

Are you someone who heats food in the microwave still in the shopping bag? Is that safe?

According to Dr Steele, "We don't know what this plastic is. It's not identified and we don't know what its' history's been. It may be made from recycled materials and the issue with recycled materials is that the components that it's been in touch with during that processing line can come back and can contaminate that mince meat."

The contamination happens when the plastic leeches through to the food so shopping bags and microwaves don't mix.

But what about takeaway containers? They've had hot food in them. Surely they are okay?

"The issue is that there will be an exchange of food component with the plastic and the plastic with the food, so you'll quite often see, especially if you've got a Bolognese sauce or something, it's gone a bright red. So those compounds can contaminate your next food that you want to heat up in there," says Dr Steele.

The best advice on this one is to carry your food home from the Thai takeaway in its plastic container, but reheat it in something else. But what should that something else be?

A lot of containers these days trumpet the fact they're microwave safe, but can we believe what's on the label?

For the answer Michael Catchpole, who heads the Plastics and Chemicals Industries Association, can help out.

Michael Slater: This container says microwaveable so I'm assuming it's safe, should I believe it?
Michael Catchpole: I think you're quite safe to believe it Michael, yes, because the manufacturer will have had tests done. There would have been independent testing on the material itself so that we can assume that a very specific stamp like that, that that product can be used in the microwave.

So microwaving food in plastic is perfectly safe as long as you use the right kind of container. And if you want to minimise the contact between your food and plastic, use glass or china for heating it up instead.

So that's plastics and cooking, but what about plastic wrap? The rumour mongers say it'll give us cancer, but are they right?

Is plastic wrap cancerous?

Plastic wrap's been around for over sixty years. It's great for separating and storing food, keeping the bugs and bacteria out and the goodness in. But in recent years there have been a number of scares about cling wrap — some people even believe it could give you cancer.

Dr Steele says he's not surprised: "Concerns obviously arise because you've got new things and you don't know what the effects are going to be."

The concern is all about the ingredient that makes cling wrap the stretchy, bendy stuff it is — it's called a plasticiser.

"Plastic packaging for the cling wrap used to be made of polyvinyl chloride and the plasticisers that were used there were based on adipates and there was some concern about the excessive migration of these adipates into the food," says Dr Steele.

Adipates are synthetic chemicals. Now having these leaking into your food was a real worry, because in some studies some adipates have triggered tumours in mice. But nowadays every kind of cling wrap is made from a plastic called polyethylene and experts say the amount of plastic that leaks from this wrap into our food is too minute to matter.

But if you've still got your doubts, why not use a paper towel? It'll certainly stop foods exploding all over the microwave, although it may lose strength and collapse if it gets wet.

Is it safe to put plastic water bottles into the freezer?

When it's hot outside, you need to keep hydrated by drinking plenty of water and plastic water bottles are light and easy to use on the go. A lot of people also put their bottle in the freezer to keep it cool for later in the day. But what happens to water when it's frozen in a plastic bottle? Are harmful chemicals released? And is the water safe to drink once it's thawed out?

"I can't think of any health concerns that should arise, it's much more a case of just good hygiene practice, but from the plastic itself no, it's not a health threat," says plastics expert Michael Catchpole.

So, go forth and freeze! It's perfectly safe.

As a rule, plastic is like any other food storage device — more often than not, it's the contents, not the container that'll make you sick.

So when it comes to food, most of the experts agree that plastics are perfectly safe as all of the dangerous chemicals were removed many years ago. But if you want to play it super safe around the microwave, use glass or china — but be careful when you pick them up because they can get really hot.

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