I used to think that “microwave-safe” simply meant that the container would not melt or warp when used in the microwave. However, many plastics contain harmful ingredients that can leach into food, especially when heat or oils are present, and should never be used in a microwave. So, in addition to being structurally intolerant to heat, some plastics actually become harmful to our health when used in the microwave.
I learned this the hard way. When my kids outgrew their Tupperware “sip ‘n’ seal" cups and lids I thought they would work well for coffee in the car. Eventually, the plastic taste in my coffee became so strong I discarded the cups, never realizing I had been endangering my health.
During this time I had a series of health problems with mammogram and Pap test recalls… but I didn’t connect the two until I attended a lecture on environmental connections to breast cancer, sponsored by our local breast cancer support group.
We watched a film entitled “Exposure: Environmental Links to Breast Cancer” then participated in a discussion with the producer and director of the film. They described many different types of environmental chemicals that have been connected to increased rates of cancer, including ingredients in plastic that contacts our food, some of which can disrupt the action of hormones in the body. I believe this film may still be available – I found a source online (www.womenshealthyenviroments.ca) or you could check with your local library if you are interested in seeing this film.
So, when it comes to plastics, some are safer than others. A numbering system, 1 to 7, has been developed to help sorting plastics for recycling, but the numbers also help us know which plastics are considered safer. You've probably noticed these numbers surrounded by a triangle, embossed or printed on the plastic container, usually on the bottom.
Basically, types 2, 4 and 5 are considered safest, with types 1 and some 7’s considered safe with some precautions. Here are the details:
PET (or PETE) – Polyethylene Terephthalate
Thin, clear plastic
Used in water bottles, cooking oil, peanut butter jars, soda pop bottles
Safe for one use only
Do not heat or reuse (or leave in a hot environment, such as in a car)
Can be recycled once into other products
HDPE (High density polyethylene)
Thick, opaque plastic
Used in milk/water jugs, juice bottles, containers for detergent, shampoo, motor oil, toys
Limit how often they are refilled
Can be recycled as with type 1 plastic
PVC (Polyvinyl chloride)
Can be rigid or flexible
Used for bibs, mattress covers, commercial plastic wrap, some food and detergent containers
Recommended to avoid. Manufacture of PVC creates dioxin, a potent carcinogen
PVC may also contain phthalates to soften it. These are hormone-disrupting chemicals linked to reproductive problems and birth defects. (It seems likely that I mistakenly exposed myself to this type of chemical)
Difficult to recycle
LDPE (Low density polyethylene)
Soft flexible plastic
Used for grocery bags, household plastic wrap, garbage bags
One of the safer plastics but best to recycle and reuse when possible to reduce impact on the environment
PP (Polypropylene)
Hard but flexible
Used to make ice cream and yogurt containers, drinking straws, syrup bottles, salad bar containers, some dishware, diapers
One of the safer plastic, but recycle when possible as with type 4 plastic.
PS (Polystyrene)
Rigid
Used for styrofoam coffee cups, meat trays, opaque plastic spoons and forks
Avoid. Can leach styrene, a known neurotoxin with other harmful effects
Other (includes polycarbonate, bioplastic and acrylic)
Polycarbonate – used for 5-gallon water bottles, sports bottes, clear plastic cutlery, linings of food cans
Bioplastics – uused for biodegradable garbage bags
Safety grab bag:
Polycarbonate is made from BPA (bisphenol-A), a harmful synthetic estrogen (hormone disruptor). Usually labeled “Not for microwave use”. Best to avoid.
Bioplastics are considered safe for their stated use. Must not be recycled with other plastics (due to programmed degradation)
Acrylic (Plexiglass) – non-BPA, usually labeled “hand-wash”, “BPA-free”, safe to use but microwavable
Tritan (SAN) – BPA-free clear plastic. Looks similar to polycarbonate but does not contain BPA.
Melamine – considered less safe, not microwavable. Melamine is toxic if ingested with food.
Often type 7 plastics are not labeled. Check if BPA-free labeling.
So, to uncomplicated things a bit, here are some basic recommendations to follow to reduce potential exposure to harmful ingredients in plastic and protect the environment at the same time…
Choose glass, metal or food-safe ceramic to heat and store food whenever possible
Plastics labeled as recycle types 2, 4 and 5 are safest, with type 1 acceptable for single use only. Type 7 plastics need further investigation. Avoid food contact with other types of plastic.
Avoid exposing any plastic to high temperatures as much as possible (do not microwave or put in dishwasher)
Even with safer plastics (2, 4 and 5) acidic food, fat/oils and heat will promote breakdown of plastic and leaching of plastic ingredients into food
Recycle or discard cracked or worn plastic items as these are more likely to leach chemicals
Always recycle plastic except for biobased plastics
Avoid buying processed and packaged foods if possible. Buy from bulk and use reusable containers from home as much as possible
Use reusable shopping bags and lunch containers (stainless steel, glass, ceramic or wax paper) whenever possible
If you are interested in a chart of plastic types to download or print, a good one is available here.
References: healthychild.com, babygreenthumb.com, davidsuzuki.org
