Smarter Living: Shopping Wise
Food Storage Containers
Photo: Kathy Warner/Flickr
Storing leftovers has long been a way to stretch out the pleasures of holiday meals over the following days and many a kitchen cabinet is well stocked with plastic tubs, cling wrap and other containers. Although they cut down on food waste, some containers pose more of a burden on the environment and potentially to your health, than others. Storing food in reusable containers helps reduce environmental impacts associated with single-use containers, but knowing more about different types of containers (including the type of resin for plastic containers) can help you make better choices.
Plastics are typically classified by one of seven resin codes, indicating the type of resin used (the code is usually found inside a small triangle on the bottom of containers and bottles), as follows:
- #1 polyethylene terephthalate (PET or PETE) -Products: Soft drink bottles, water bottles and some medicine containers
- #2 high density polyethylene (HDPE) - Products: Bottles for milk jugs, detergent, shampoo and motor oil, (also some toys)
- #3 polyvinyl chloride (V or PVC) -Products: Piping, shower curtains, (and some clip-wraps)
- #4 low density polyethylene (LDPE) -Products: Wrapping films, grocery bags
- #5 polypropylene (PP) -Products: Syrup bottles, yogurt tubs, bottle caps
- #6 polystyrene (PS) - Products: Single-use coffee cups, clam-shell take-out containers, packing peanuts
- #7 other (usually polycarbonate but can mean any resin not listed above, including compostable plastics) - Products: Medical storage containers, some Nalgene water bottles
While most industrial processes are associated with certain byproducts, manufacturing plastic resin creates more toxic emissions than manufacturing glass. According to the Berkeley Plastics Task Force, producing a 16 oz. PET bottle generates more than 100 times the toxic emissions to air and water than making the same size bottle out of glass.
The Task Force stated in a 1996 report that the plastic industry contributed 14% of the most toxic industrial releases -- including styrene, benzene and trichloroethane-- into the air. Other major emissions from plastic production processes include sulfur oxides, nitrous oxides, methanol, ethylene oxide, and volatile organic compounds.
Petroleum - A Non-Renewable Resource
Plastics are made of petroleum, a non-renewable resource that requires new fossil reserves to be extracted continuously. Because fossil fuels take millions of years to form, they are a finite and, ultimately, an exhaustible energy resource. The USA, the world's second largest oil extractor, has only 4% of the world's oil reserves but uses nearly 30% of all oil extracted each year. By choosing to switch from plastics to renewable and recyclable packaging, we can conserve this valuable resource and reduce our dependence on oil.
According to the Environmental Protection Agency, in 2008, the United States disposed of just over 30 million tons of plastic. While plastic recycling continues to grow, increasing 580% from 1990 to 2001, with 2.1 million tons of plastic recycled in 2008 the reality is that recycling rates still remain very low (with only about 7% of plastic recycled annually). In addition, consumers often believe the coding symbols on plastic containers mean the item is recyclable when, in fact, the symbols only identify the resin base of the plastics, not all of which are accepted by all recycling programs. Companies need to be urged to use recycled plastics and citizens should encourage their states to pass and enforce bottle bills and other legislation supporting increased recycling.
Substantial threats to health arise during plastic manufacturing, use, and disposal, both from ethylene monomers, one of the basic building blocks for plastic, and from the problem chemicals added to give plastic products their desirable performance properties. Some examples of chemicals associated with plastics manufacture are described below.
[sidebar1]Dioxins, which are highly toxic in even at low doses, are emitted into the atmosphere and waterways when most plastics are manufactured and incinerated. While dioxin levels in the United States environment have been declining for the last 30 years, they break down so slowly that some of the dioxins from past releases will still be in the environment many years hence. In its 2000 final draft reassessment of the health effects of dioxins, the U.S. Environmental Protection Agency (EPA) concluded that dioxins have the potential to produce an array of adverse health effects in humans. The EPA report estimated that the average American's risk of contracting cancer from dioxin exposure may be as high as 1 in 1,000 -- 1,000 times higher than the government's current "acceptable" standard of 1 in a million. Dioxins are also endocrine disruptors, substances that can interfere with the body's natural hormone signals. Dioxin exposure, moreover, can damage the immune system, and may affect reproduction and childhood development.
Many cling-wrapped meats, cheeses and other foods sold in delis and grocery stores are wrapped in PVC. To soften #3 PVC plastic, as well as other plastics, into their flexible form, manufacturers add various toxic chemicals known as "plasticizers" during production. Traces of these chemicals, known as adipates and phthalates, can leak out of PVC when it comes in contact with foods.
Phthalates are known to interfere with the production of male reproductive hormones in animals and likely to have similar effects in humans. Their effects in animal studies are well recognized and include lower testosterone levels, decreased sperm counts and lower sperm quality. Exposure to phthalates during development can also cause malformations of the male reproductive tract and testicular cancer. Young children and developing fetuses are most at risk. In a move to address these concerns, in 2008 Congress banned the use of six phthalates in children's toys and products.
Many #7 polycarbonate bottles (including baby bottles), microwave ovenware, eating utensils and plastic coating for metal cans are made with bisphenol-A, a chemical invented in the 1930's during the search for synthetic estrogens. Bisphenol-A can leach into food in cans or from polycarbonate bottles as they age.
Many studies have evaluated bisphenol-A as a hormone disruptor, a chemical that alters the body's normal hormonal activity. Exposure among test animals to this chemical early in life is associated with:
- Pre-cancerous changes in the mammary and prostate glands;
- Altered development of the brain causing behavioral abnormalities and earlier onset of puberty;
- Reproductive abnormalities such as lower sperm counts, hormonal changes, enlarged prostate glands, and abnormalities in the number of chromosomes in eggs,
- Obesity and with insulin resistance, a condition that commonly precedes the development of diabetes.
There is concern that BPA may cause similar health problems in humans. More than 90 percent of the general population has BPA in their bodies, at levels close to those which have been shown to cause harm in animal studies.
PET plastic water bottles have been shown to leach antimony into water. A recent study conducted by University ofHeidelberg researcher Bill Shotyk, and published in volume 8, issue 2 of the Journal of Environmental Monitoring, found antimony levels in PET water bottles were higher than levels found where the water was sourced. According to Shotyk, consumers should not be concerned about drinking water bottled in PET plastic, as the levels found in water are below safe drinking standards. Nonetheless, it’s important to remember that leaving water in any plastic bottle for a prolonged period of time allows for chemical leaching to occur.
What to look for
Glass, Ceramic and Stoneware
Glass, ceramic and stoneware are the safest options when it comes to food packaging and storage because they do not leach any questionable chemicals when in contact with food. Unlike plastic recycling, which can produce toxic chemicals, glass recycling is more environmentally friendly.
Safer plastics—#1PET, #2HDPE, #4LDPE, and #5PP
When choosing plastic containers, even those you'll use over and over again, choose those that are accepted for recycling in your area. #1 PET is best known for its high recyclability. While some #1 PET reusable containers exist, research shows that reusing single-use bottles can cause bacteria to build up in screw threads. Many reusable containers are made from another commonly recycled plastic, #2 HDPE.
Number #4 LDPE and #5PP plastics, although not as widely recycled, are also good choices since, as with #2, most research has not shown leaching of any carcinogens or endocrine disruptors. Some bread and frozen food bags and squeezable bottles are made out of #4 plastic and some ketchup bottles and yogurt and margarine tubs are manufactured from #5 plastic.
Biobased compostable plastic
Biobased, compostable plastics, made from corn (Polylactide or PLA), or other plants, are decomposed by bacteria when composted in a commercial composting system. While bags made of PLA look, feel and smell like normal plastic bags, in about twelve days in a commercial composter, more than half the bag will have broken down, unlike conventional plastic bags, which may take up to 100 years. Unfortunately, many cities lack composting facilities, meaning that many these plastics will end up in landfills, an environment that will drastically slow their decomposition. However, biobased plastics, like biofuels, are a developing market that, if developed appropriately, can offer some potential renewable alternatives to fossil-fuel-derived, non-renewable plastics. Ideally, you should purchase biobased compostable plastics made from agricultural residues (like bagasse, the waste from sugarcane production), which otherwise would be treated as waste.
Be wary of other varieties of compostable plastics which are made from plant-derived material mixed with petroleum-derived products that do not break down completely and may wind up in the food chain.
Aluminum and Stainless Steel
Food storage containers made of aluminum are an alternative to plastics because aluminum is recyclable, relatively inexpensive and offers even heating capability. However, aluminum extraction is extremely energy intensive, so reuse containers like old pots, seek new containers made with recycled content, and recycle containers when they’ve reached the end of their useful life.
Containers made from stainless steel are also a good choice, not only because the material is 100% recyclable, but also because stainless steel is easy to clean without any harsh chemicals. Stainless steel is also inexpensive, attractive, and will not react with foods during cooking.
What to look out for
Riskier Plastics—#3 PVC, #6PS, and #7Other (Usually Polycarbonate)
Sometimes found in clear food packaging, PVC, the second most commonly used plastic in the world, is a toxic plastic dangerous both to our health and to the environment. Its manufacture and incineration releases dioxins, a potent carcinogen and hormone disruptor. Vinyl chloride, the primary building block of PVC, is a known human carcinogen that also poses a threat to workers during manufacture.
In contact with foods, especially hot, fatty foods, PVC can also leach chemicals such as adipates and phthalates, which have been shown to cause birth defects and damage to the liver, kidneys, lungs and reproductive systems in mice. In addition, most community recycling programs do not accept PVC, so the vast majority of vinyl ends up in landfills or incinerators. While many companies have agreed to restrict or phase out PVC, we still have a long way to go before this "toxic" plastic is banned from use.
Polystyrene, #6 PS, is usually found in foam containers and cups and sometimes in clear disposable takeout containers, plastic cutlery and cups. It's best to avoid this plastic because PS may leach styrene into food it comes in contact with. Styrene, considered a possible human carcinogen by the World Health Organization's International Agency for Research on Cancer, may also disrupt hormones or affect reproduction.
Polycarbonate (one of the many plastics marked as #7, “other” – don’t confuse with compostable plastics that are also marked as #7), usually found in baby bottles, 5-gallon water bottles, and lining in food cans, can release its primary building block, bisphenol-A (BPA), into liquids and foods. A study conducted at Prefectural University of Kumamoto, Japan, concluded that polycarbonate bottles containing hot liquids leach more bisphenol-A than new bottles.
Though many companies are beginning to move away from BPA, parents have a right to be concerned as 95% of all baby bottles on the market are still made of polycarbonate, which contains BPA. The National Environmental Trust recommends switching to polycarbonate-free baby bottles, like those manufactured from glass or from polypropylene (#5) plastic.
Plastics in the Microwave
While a "microwave-safe" or "microwavable" label on plastic containers only means that they shouldn't melt, crack or fall apart when used in the microwave, the label is no guarantee that containers don't leach chemicals into foods when heated. The USDA also warns on its website against microwaving in single-use containers not intended for that purpose, such as takeout platters and margarine tubs. According to the FDA, microwave-safe plastic wrap should be placed loosely over food so that the steam can escape and should not directly touch your food.
For safety's sake, it's best not to heat foods in plastic and use ovenproof glass or ceramic containers with covers. Never use plastic storage bags, grocery bags, newspapers or aluminum foil in the microwave.
Here are a few suggestions you can follow to reduce plastics and toxic exposure in your home:
- Avoid single-use, disposable packaging
- Buy food in glass or metal containers
- Avoid heating food in plastic containers
- Bring your own containers to salad bars, yogurt shops, etc. —anywhere you'll be served in plastic
- Avoid plastic cutlery and dinnerware, especially when cooking or heating food; use stainless steel or wooden utensils and look for recycled paper products
- Use wood instead of plastic cutting boards and spray your wooden board with a mist of vinegar, then with a mix of hydrogen peroxide, to kill bacteria
- When purchasing cling-wrapped food from the supermarket or deli, slice off a thin layer where the food came into contact with the plastic and store the rest in a glass or ceramic container, or non-PVC cling wrap (see Shopping Suggestions)
- You can also write a letter to manufacturers of food and drink packaged in plastics, indicating your concern about plastics—especially if their packaging is #3, #6 and #7. Tell them you are actively seeking products packaged in safe, reusable glass, metal and recycled paper. Ask manufacturers for a mailing address by calling their toll-free question/comment line, usually listed on the back of the product; alternatively, you can find their mailing address on their website.
Friends of the Earth: Plastics Fact Sheet
National Institutes of Health: Tenth Annual Report on Carcinogens
Science News: Food for Thought: What's Coming Out of Baby's Bottle?
US Food and Drug Administration, November-December 2002 FDA Consumer: Plastics and the Microwave
Environmental Protection Agency: Municipal Solid Waste in the United States: 2008 Facts and Figures
Richard Lindsay Stover et al: Report of the Berkeley Plastics Task Force
NRDC Switchboard: More evidence that BPA is toxic and industry tactics exposed
last revised 11/22/2011