Leaving your water bottle in the car on a hot day can give you cancer! This was the message of a recent email I, and no doubt many of you, received. The claim is that as the plastic bottle heats up it leaches potentially carcinogenic chemicals into the water.
Public reactions to the email seem to swing from those who immediately discarded it as scare mongering, those who believed it utterly and resolutely determined to avoid all plastics from now on and the bulk of us somewhere in the middle who thought it sounded plausible but surely if it were true the food standards people would be taking steps to warn and protect us. I made it my mission to find out what I could to uncover the real story.
The truth is that we really don’t know enough about chemical leaching from plastics and much more research needs to be done. Plastics are ubiquitous in modern society and are hard to avoid in the packaging, manufacturing, storing and reheating of foods and drinks. It’s little wonder when you consider what incredible materials they are: pliable, lightweight, hard to break and, depending on the plastic, resistant to a range of temperatures from the freezer to the microwave. But does such versatility come at a price?
Reassuringly there are several plastics commonly used for our foods that have no evidence of harm if used in the way they were intended. The key to knowing which ones are safe is in the recycling code on the bottom of the container. Three out of the seven codes have question marks over their safety, while the remaining four have no known risk. The single-use water bottle of the email claim falls on the safe side as these are almost always recycle number 1 (PET). However this assumes you discard the bottle after drinking the contents. These bottles are not designed for repeated use and although no strong evidence that chemicals can leach as the bottle ages, it seems prudent to play safe and not take the chance.
The major concern is over a chemical called bisphenol-A (BPA), used to make polycarbonate plastics (identified by recycle number 7), epoxy resins and some other products. BPA was first synthesised in 1891 so it has been around for a long time, although it was not approved for use in food containers until 1963. However in the last few decades our use of plastics has grown enormously and consequently we are exposed to more BPA than ever before.
On a global scale it is estimated that around 2.8 million tons of BPA are produced every year. It is so widely used due to it’s hard to beat qualities for creating a hard, clear, and almost unbreakable plastic. For that reason polycarbonate plastics are used to make drinks bottles, food containers and most worryingly baby bottles and children’s sippy cups. In food manufacturing epoxy resins are used to line some food cans to help prevent corrosion and food contamination.