When purchasing food related plastic items, be sure to check the recycle number at the bottom. Each recycle number corresponds to certain types of plastic material. They are not only the guide for recycling, but also an easy way to distinguish harmful plastics:
Plastic #1: PET (polyethylene terephthalate)
Mostly used for disposable mineral water and drink bottles. It’s apt to melt at the temperature of 70°C, and then tend to leach some harmful substances. Such plastic products may release carcinogen DEHP after 10 months of use. So do not heat them! Nor reuse them! Do not expose them to direct sunlight! And do not store alcohol, oil, etc.
Plastic #2: HDPE (high density polyethylene)
HDPE, as a version of polyethylene, also has the same odorless and non-toxic physical properties as PE. It can be used for food containers. It has low water absorption and high hardness, and is often used for liquid packaging such as cleaning supplies, milk bottles and bath products and white medicine bottles, etc. However, due to the properties of easy aging, brittleness, stress cracking, and difficulty in printing, HDPE is not so common in food packaging. It’s not recommended to reuse such boxes for storing food items.
Plastic #3: PVC (polyvinyl chloride)
PVC is one of the most widely used plastics as it has excellent plasticity and cheap price. Raincoats, building materials, plastic films and some plastic boxes are usually made of PVC. But this plastic can only withstand a temperature of 81℃, and it is easy to leach out bad substances at high temperatures. So do not use it for storing any portable or edible items.
Plastic #4: PE (polyethylene)
PE is safe for food at room temperature, most common in making cling film etc. However, it releases harmful substances at high temperatures, which enter the human body with food and may cause breast cancer, birth defects and other diseases in newborns. Do not put any plastic wrap or container made of PE into the microwave oven or expose it to heat otherwise.
Plastic #5: PP (polypropylene)
PP is safe and the top pick for food. PP has a melting point up to 167°C and thus it’s the only microwave-safe plastic! PP plastic boxes can be reused after careful cleaning. PP is the most common food packaging material. More and more water bottles and baby feeding bottles are made of PP, instead of PC. It should be noted that some PP microwave lunch boxes carries PE lids. In that case, don’t put the lid together with the bottle into the microwave.
Plastic #6: PS (polystyrene)
PS can be used for food like bowls of instant noodle boxes and fast food boxes. But do not microwave them. the release of chemicals due to high temperature. After loading acid (such as orange juice) and alkaline substances, carcinogens will be decomposed. Avoid using fast food boxes to pack hot food. Don’t use the microwave to cook instant noodles.
Plastic #7: PC (polycarbonate) & other types
Simply put, don’t buy nor use any containers made of PC for whatever food items (though it’s not precise to dismiss all #7 plastics by judging from the recycle number). Water bottles and baby nursers made of PC used to be quite popular about a decade ago. But they are phasing out in most countries now, because this plastic releases the toxic substance bisphenol A (BPA). BPA is known as environmental hormone and harmful to the human body.
Absolutely stay away from any plastic containers made of plastic #3 (PVC) and #7 (PC & others). Do not reuse nor heat plastic #1, #2, #4 and #6 for food. It’s safe to choose plastic boxes or containers made of virgin plastic #5 (PP).