Plastic food containers contain many chemicals which can leach into the food which is stored in them. The plastic itself is not the problem as the polymer molecules that it is made of are too big and stable to leach into the food which is stored in them. Plastic is a valuable aid to civilisation as we know it today. Much of what we have achieved as a society would not have been possible without synthetic materials such as plastics. Like all things, however, it should be treated with caution until we understand exactly how it can affect the things it interacts with and ultimately, us. There is enough sound scientific research now to give us pause for thought about the effect that some of the chemical additives used in plastics can have on our health, especially that of young children.
There are two types of plastic in particular which are of concern:
- Polycarbonate, a type of hard plastic which is often used to make food storage containers and baby bottles and the epoxy resin used to line tin cans to prevent corrosion and contamination of the food inside them. These types of plastics contain bisphenol-A (BPA) which can quite easily leach into the foods contained within.
- Polyvinyl Chloride (PVC), a hard plastic which can contain up to 40% plasticizing chemicals such as phthalates particularly DEHA (di(2-ethyhexyl)adipate) which make it more soft and malleable. PVC is used in many applications, from cling wrap, the rubbery plastic seals inside jar lids and screw tops for bottles to the bottles themselves. PVC is also used by itself in it’s rigid form to make plumbing supplies like drains, downpipes, guttering, irrigation systems and conduit.
Most people have heard about bisphenol-A (BPA) in recent years due to the media coverage it has received since it was discovered in baby formula in China, making over 50,000 little babies very, very sick and killing 3.
BPA was first synthesized around 120 years ago and it is now found in the majority of plastic products, including those we eat from, or store food in. It is commonly found in the plastic lining of tin cans to prevent the tin corroding and also to prevent the metals in the tin from contaminating the food. BPA is used to make baby bottles as well as plastic glasses, bowls etc as it makes the plastic clear rather than opaque and makes it slightly flexible so that it won’t shatter if dropped or stressed.
The problem with this, is that BPA is an oestrogen-mimic – it attaches to the same receptors in the body that oestrogen does and has a similar effect. Women with PCOS tend to have elevated levels of oestrogen in the first place, so compounding this with a synthetic hormone-analogue is not going to help at all. Scientists have also found that BPA can decrease sperm count and increase the rate at which breast cancer cells grow. The incidence of breast and prostate cancer is increased, fertility is reduced along with menstrual cycle disturbances and the risk of diabetes is increased.
BPA and it’s metabolites have been found in 97% of the population
In 2004 the US Centers for Disease Control (CDC) collected samples of urine from 2,157 people between the ages of six and 85 to test it for traces of BPA. 93% of those tested had detectable levels of BPA, in amounts ranging between 33 and 80 nanograms per kg of bodyweight, as well as the metabolic products of BPA as it is broken down. Children has the highest levels, followed by adolescents, then adults. Mice that were given a dose of BPA 10 times smaller (per kilogram) than the average 6 year old has today developed cancers and other diseases.
Whilst BPA is relatively easy for the body to break down and should not stay in the body for more than a few days, the CDC found that most people have glucuronide, the waste product that is formed when BPA is broken down, in their urine, suggesting that whilst exposure may be low, it is constant. Endocrinologist Retha Newbold of the U.S. National Institute of Environmental Health Sciences has said “In animals, BPA can cause permanent effects after very short periods of exposure. It doesn’t have to remain in the body to have an effect.”. She found that BPA impaired the fertility of female mice.
The EPA and the European Union Food Safety Authority consider 50 micrograms per kg of bodyweight a safe level, so the amount found by the CDC in their study is well below this, being roughly 1000 times lower, however, the effects of constant low level exposure have not yet been evaluated. Developmental biologist Laura Vandenberg of Tufts University in Boston recently published a study in the journal Reproductive Toxicology which concluded that due to the faster rate of BPA metabolism in humans, we must already be exposed to 10 times the recommended safe level to produce the amounts being found in serum and tissue samples.
A study by endocrine biologist Scott Belcher of the University of Cincinnatti found that when plastic containers are heated, for instance if used to hold hot tea or coffee, put in a microwave or a dishwasher, or used to serve hot food, BPA leaches out 55 times faster, as much as 32 nanograms per hour. “These are fantastic products and they work well … [but] based on my knowledge of the scientific data, there is reason for caution,” says Scott Belcher. “I have made a decision for myself not to use them.”
Japanese food manufacturers transitioned away from BPA in the linings of their cans to the use of a natural resin in 1997 after Japanese scientists showed that it was leaching out of baby bottles. A subsequent study measuring BPA levels in urine in 1999 found that they had dropped significantly.
Phthalates are actually a group of substances rather than just one thing and refer to the esters of phthalic acid. They are used in a wide variety of applications, from enteric coatings of nutritional supplements and pharmaceuticals to food c0ntainers and wraps, cleaning products, shower curtains and vinyl upholstery and adhesives. Some phthalates are well known to be endocrine disruptors – substances which disturb the way our hormones work. DEHP is the most commonly used phthalate for food products as it is one of the cheapest, however, studies have consistently shown that low level exposure can affect reproductive development especially in young boys, as well as an increased link between phthalate exposure and the incidence of diabetes and obesity in men. In the United States of America, it has been classified as a probable human carcinogen or cancer-causing substance. In the European Union, DEHP along with two other common phthalates, DNOP & DINP, have been banned from all products used in relation to childcare including toys.
A review of 25 food products in glass jars with PVC gaskets inside metal lids by the independant consumer testing organisation CHOICE in 2008 revealed that 12 of the products tested contained phthalate levels higher than those recommended by the EU, by as much as 230 times!
What Can We Do To Minimise Exposure?
Some things will make the leaching of plasticizing chemicals worse:
- Liquid – more surface area of a liquid will touch the plastic, than a solid, so more of the food will be exposed to the plastic
- Acids – the more acidic a food the more it will eat away (microscopically) at the surface of the container.
- Heat – when the plastic is heated either by placing hot food into it, or placing it in hot water, it is easier for the plasticizers to leach out.
- Fats – the fattier a substance is, the easier it will absorb molecules of plasticizing chemicals.
- Time exposed – the longer a food is in contact with plastic, the longer it has to absorb the chemicals.
- Re-use – plastic degrades over time, increasing the rate at which it’s components can leach into food.
If you avoid these things, then you minimise the risk of absorbing unwanted chemicals.
High quality plastic that has been designed to withstand years and years of use should theoretically be better for you. I ordered a heap of Tupperware from a colleague who was doing parties a few years ago and was really surprised that when it arrived and I first opened it, there was no bad plastic-y smell. The plastic containers I had been buying from the supermarket smelled dreadfully until they had been washed in hot soapy water a few times and aired. I presume this means that they are higher quality and better for you. The fact that they come with a lifetime warranty is also a bonus in my book, though they are murderously expensive to begin with. I have no affiliation with Tupperware nor am I a distributor.
Some plastics are safer than others. The following table from CHOICE magazine is worth printing out and saving so that you can make the safest choices when it comes to plasticware. Essentially, avoiding plastic food containers marked with the recycling symbols 3, 6 & 7 is a wise choice.
Some Easy Tips
1. Switch to refillable water containers made from Stainless Steel or Glass
Do NOT use reusable polycarbonate drink bottles – the more often you wash and reuse them, the more BPA will leach into the drinks you fill them with. This is simply not a risk worth taking.
I use either glass or stainless steel water bottles and refill them from my filter at home. It’s cheaper and I think the water tastes a lot better. I prefer not to drink bottled water if the bottle is plastic – I’ve always thought it tasted funny.
2. Buy glass or Pyrex food storage containers as your plastic ones wear out
Glass, pyrex or Corningware is much more stable chemically than any type of plasticware. It is also generally more durable. Many takeaway restaurants are happy to use your own containers to put food in if you remember to bring them.
- Pyrex: http://www.pyrex.com/ or http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dgarden&field-keywords=pyrex&x=0&y=0
- Corningware: http://www.amazon.com/CorningWare-Kitchen-Housewares/b?ie=UTF8&node=574082&pf_rd_m=ATVPDKIKX0DER&pf_rd_s=top-1&pf_rd_r=1V6D3NQXBSKXYPW4MACW&pf_rd_t=301&pf_rd_p=299621301&pf_rd_i=CorningWare or http://www.corningware.com/
- Anchor Hocking: http://www.amazon.com/s?ie=UTF8&search-alias=garden&field-brandtextbin=Anchor%20Hocking
- StainlessLUX: http://www.amazon.com/s?url=search-alias%3Dgarden&field-keywords=StainlessLUX+canister
3. Never, Ever, EVER heat food in plastic containers
It greatly increases the rate at which toxic substances leach out into your food, especially if there is fat present in the food.
4. Try and buy food that is as fresh as possible
If food has been processed, packaged or stored for a long time, it will have a greater risk of containing toxic substances which have leached into it over time. Try and buy food that is as fresh as possible as it will have the highest nutritional value (nutrients degrade as food is stored) and the least additional chemicals. Try and avoid meats, vegetables and cheeses which are wrapped in plastic wrap. Although the majority of plastic wrap is now made using LDPE (low density polyethylene) which is deemed safe, some supermarkets and independant butchers are still using plastic wrap which contains PVC.
In short, we can’t realistically avoid all exposure, for me it’s just a matter of making the safest choices when I can.
The Endocrine Society (2010, June 25). Women with polycystic ovary syndrome have higher BPA blood levels, study finds. ScienceDaily. Retrieved March 24, 2011, from http://www.sciencedaily.com/releases/2010/06/100621143602.htm
E. Kandaraki, A. Chatzigeorgiou, S. Livadas, E. Palioura, F. Economou, M. Koutsilieris, S. Palimeri, D. Panidis, E. Diamanti-Kandarakis. Endocrine Disruptors and Polycystic Ovary Syndrome (PCOS): Elevated Serum Levels of Bisphenol A in Women with PCOS. Journal of Clinical Endocrinology & Metabolism, 2010; DOI: 10.1210/jc.2010-1658 http://jcem.endojournals.org/cgi/content/abstract/96/3/E480