Today, more than 4000 chemicals are used as food contact materials, and added to these are further breakdown products and impurities. For most packaging types, low-level migration into food has been confirmed. This accelerates when foods are heated, at higher ambient temperatures, with acid foods such as tomatoes or vinegar, or when foods are fatty. There are growing concerns about the potential effects of these substances on human health, which some scientists feel have not been fully explored and tested. On the issue of packaging, are informed consumers being slightly paranoid? Or are their concerns justified?
Plastics & xenoestrogens
Compared to other types of food packaging, plastics are chemically the most complex and generally raise the most concerns. Identifiable by an embossed code number ranging from 1 to 7, the safer plastics have traditionally been considered 1, 2, 4 and 5. More problematic plastics are those numbered 3, 6 and 7.
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Most of the issues with plastics involve xenoestrogens, endocrine-disrupting chemicals that mimic the body’s hormonal system. Health effects include increased risk of a range of conditions including infant brain development issues, obesity, diabetes, heart disease and asthma. Most likely to be affected are pregnant women and very young children.
In 2011, a study published in Environmental Health Perspectives showed that endocrine disruption was prevalent across 455 items with plastic codes 1, 2, 5, 6 and 7, with none of those tested receiving a clean bill of health. A total of 71 per cent of samples exhibited xenoestrogenic activity, with this number increasing to 95 per cent after dishwashing and microwaving. The study’s authors suggested that plastic packaging could be cheaply reformulated to be xenoestrogen-free.
Microwaving food in plastic containers, including those labelled “microwave-safe”, increases chemical migration and is not recommended. Avoiding all contact between plastics and food is another option for people who want to go a step further.
Bottled water
Nearly all bottled water on the shelves is packaged in PET (code 1). While it is a myth that this type of plastic leaches bisphenol-A (BPA), its clean image has been eroded by some recent findings, including the confirmation of xenoestrogenic effects.
Among the chemicals released in low concentrations by PET bottles are formaldehyde and acetaldehyde. While these sound concerning, there are far higher levels of natural formaldehyde in some fruits and vegetables, including apples and cauliflowers. Antimony compounds are used as PET catalysts, and migration levels are generally very low, although there are exceptions. In 2010, acidic British fruit juice concentrate in PET was found to have up to nine times the EU limit for antimony in tap water.
Another 2013 German study identified roughly 24,500 different chemicals in PET bottled water, all in very low or trace concentrations, with some uncertainty about which originated from the plastic and which were already in the water. The plasticiser DEHF was found to be responsible for much of PET water’s endocrine-disrupting activity.
As with all plastics, leaving a water bottle in a hot car will accelerate chemical migration and for this reason steel drinking bottles are recommended. Investing in a high-quality home water filter capable of removing fluoride is another way to avoid buying or storing water in plastic.
BPA
The notorious endocrine disruptor BPA is used in many polycarbonate plastic bottles (code 7) to make them clear and hard. Several countries have banned infant cups and bottles containing BPA, and they are subject to a voluntary phase-out from these products in Australia and New Zealand, with large retailers having already removed them.
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BPA-free product labelling is commonly found on plastic items for food contact. On the downside, this is liable to give shoppers a misleading impression because BPA-free plastics tend to have xenoestrogenic effects, and in the case of can linings, where there are no code numbers, we cannot be certain that the replacements are safe. Evidence is also emerging that some BPA replacements (such as BPS) may have hormone-disrupting effects of their own.
PVC, clingfilm & the phthalate dilemma
Phthalates are added to some plastics to make them soft or flexible. Widely believed to be restricted to PVC (code 3), UK Government tests have found them in a few other plastics, including composite materials such as lined foil. Like BPA, phthalates have xenoestrogenic properties, and are linked to a range of health symptoms.
Food is a major exposure route, with screw-top jar seals being one culprit. Avoiding phthalates is tricky, as they seem to be found throughout the processed food sector, and levels tend to be highest in meats, dairy and bread. They can get into food from tubes, milking machines, conveyor belts and disposable gloves — unless these are phthalate-free. Cutting down on processed foods is the simplest way to reduce exposure.
Another phthalate source is clingfilm and, while most domestic-use clingfilm in Australia and New Zealand is low-density polyethylene (LDPE, code 2), clingwrap for packaged foods such as meat, fruit and vegetables is more likely to be the riskier PVC that releases phthalates and other xenoestrogens. Cancer Research UK now recommends that foods are not microwaved in clingfilm.
Polystyrene nasties
With a recycling code 6, polystyrene is used for styrofoam cups and food packaging, and for the larger clear plastic water containers used for water coolers. Here the issue is low-level migration of the chemicals styrene, ethylbenzene, toluene and benzene. Of these, styrene is regarded by the World Health Organization as a probable carcinogen, and benzene is considered a suspected carcinogen. The biggest risk here is buying hot drinks in styrofoam, given that migration rates are many times higher than for liquids at room temperature. On the whole, paper cups are a far safer alternative.
Perfluorinated chemicals
Perfluorinated chemicals (PFCs) can be used for greaseproofing in packaging such as burger wrappers, microwave popcorn bags and pizza boxes.
Unfortunately, this class of chemical takes a long time to leave the body, where it is liable to accumulate faster than it is excreted and levels can easily build up. PFCs have been linked to cancer and a range of other health issues.
In the 2015 Madrid Statement, over 200 scientists called for a phase-out of PFCs. While some have been discontinued in the US, the switch from “long chain” to “short chain” PFCs does not guarantee that the substitutes are risk-free.
Foiled again
Aluminium is a known neurotoxin that tends to accumulate in the body. Though it’s considered safe in small doses by most authorities, the wisest approach would be to keep exposure to a minimum. When heating food in aluminium foil, one option is to put a layer of baking paper between the two. While it’s common to debunk the idea, aluminium exposure is a likely cause of Alzheimer’s disease, although no mechanism has so far been identified.
A small difficulty
Nanoparticles are defined as being less than 100 nanometres (a billionth of a metre) in at least one dimension. One of their many current uses includes food packaging and, although information about the extent of their use is sketchy, they are added to many PET bottles.
Elements not considered a health concern in their normal form become far more reactive as nanoparticles, are more likely to enter cells and tend to accumulate in organs and the brain. Animal studies have linked nanoparticle exposure to organ damage.
Silver nanoparticles are designed to migrate into food from a range of antimicrobial items, including packaging, cutting boards, kitchen surfaces, dishwashers, cutlery, baby bottles and fridges. As a biocide, nanosilver is a cause of cell damage and free radical production, and a priority for regulatory action.
On the whole, the nanotechnology sector, including packaging, is characterised by low regulation and a lack of safety studies. With shoppers in Australian and New Zealand wary of untested novel technologies, nano labelling on the packaging is rare.
Triclosan
Triclosan is an antibacterial chemical that has several undesirable properties, including being a bioaccumulative xenoestrogen and, like nanosilver, risking the development of antibiotic-resistant bacteria.
In addition to its presence in several soap and toothpaste brands, triclosan is used to impregnate some plastic containers, kitchen surfaces, chopping boards and kitchen utensils. As intended, very small concentrations migrate into food. Animal testing in doses equivalent to those found in the natural environment points to a significant impairment of heart muscle function.
When reading the packaging, the word “antibacterial” can indicate the presence of triclosan, nanosilver or a range of other chemicals.
Problems with paper
In 2005, Nestlé experienced a problem with a printing ink chemical migrating from cardboard packaging into baby formula, resulting in a recall. Sufficient mineral oil exposure can cause cancer and inflammation of the organs.
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Swiss researchers linked such contamination to mineral oils from printing ink, which in turn originated from recycled newspapers. Migration corresponds to time spent on the shelf, and these oils can even travel through a protective plastic layer to reach the food in very low concentrations. Inner bags with a layer of aluminium foil have been found to offer far better protection.
Using recycled feedstock in products is obviously an environmental priority, yet one solution adopted by some manufacturers is to demand that their recycled card is free from newspaper feedstock. Another simpler alternative would be a switch to non-toxic inks. Barrier films for use between the food and the packaging are also being developed.
A cautious approach to safety limits
In most cases, these chemical migrations are at levels considered very low and which usually fall under international safety limits. Unfortunately, such levels are characterised by a lack of human population tests at real-world exposure levels.
However, this “isolated dose” model is increasingly being challenged by a synergistic model involving a multiplier effect from numerous different chemicals interacting together in very complex ways. Food packaging chemicals also need to be factored into a broader picture that includes pesticide residues, food additives and household chemicals. Under this newer toxicological paradigm, there is no such thing as a completely “safe” dosage, and the strategy is to keep intake to a minimum.
Xenoestrogens, with their hormone-mimicking properties, can produce effects at very low concentrations, although governments and the food industry are being slow to recognise this.
Low regulation
At the start of 2016, the 24th Australian Total Diet Study found detectable food packaging contamination with half of the 30 chemicals tested, including phthalates at levels exceeding international migration safety limits.
Food Standards Australia New Zealand (FSANZ) pursues a low-regulation strategy for food packaging that simply requires industry to ensure that its products are “safe” without being more prescriptive. This regulatory void is becoming increasingly problematic as new technologies arrive on the scene. Remarkably, a recent survey of food companies found that 80 per cent wanted more regulation and direction from FSANZ.
FSANZ chose to exempt nanoparticles from the latest Total Diet Study because it saw their risks as being less well-defined. A safety investigation into nanoparticles commissioned by FSANZ was to have been completed by June 2015, but at the time of writing is yet to be publicly released.
Minimising exposure
If the bewildering number of food packaging concerns is causing you to pull your hair out in despair, there is hope. It’s nearly impossible to avoid processed foods entirely, and even fresh foods are often packaged, such as meat, chicken and the organic fruit and veg in supermarkets, so the many issues linked to packaging are best regarded as elevated risks.
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Cutting down on processed food, and buying unprocessed and unpackaged food will automatically reduce exposure to migrating chemicals. This has the added benefit of reducing the environmental impact from packaging.
Glass stands out from other packaging material for its relative safety, although it’s best to avoid contact between screw-top jar seals and the food. Plastic storage containers in the fridge can be swapped for glass alternatives. If feasible, prepare for being away from home by going BYO and carrying your own food container, cutlery, steel water bottle and mug.
While most low-level toxins are metabolised by the liver, they can accumulate in the body. Fortunately, there are ways to help neutralise the effects, milk thistle being one aid to the liver in detoxing while also having a liver-protective effect.
