Having become recently aware that canned foods are lined with estrogen-leaching BPA plastic, Greencradle customers have begun asking us more and more about the intriguing paper containers that are now so readily available as “eco-friendly” alternatives for food packaging. Everything from soy milk, to organic milk, to organic soups, to juice boxes and tomato pastes are now being sold in these novel cardboard paper boxes, sometimes referred to as Tetra Paks. It goes without saying that the packaging itself offers many advantages, including that the contents most often don’t need to be refrigerated, and can go from the fridge into a kid’s backpack with no concerns about spoilage. Notwithstanding how handy these containers may be in daily life, the question that naturally arises when holding one of these nifty boxes in your hands might be — “hmmm…how does paper make for a water-tight container?” The answer is, of course, paper doesn’t. Putting milk into untreated cardboard paper quite obviously wouldn’t amount to a combination any kid would ask for in his/her backpack. Even though we might intuitively suspect that there must be more to this sort of extraordinary “paper” than meets the eye, the fact that so many organic products now come in this type of packaging might be enough to convince us that this packaging is green enough, especially as compared to than other options. Indeed, a quick Internet search will disclose that Tetra-Paks are often praised as being more eco-friendly due to their paperboard construction, and even stand poised to carry an FSC certification for the sustainable practices used to grow the wood that goes into the paperboard.
Tetra-Paks are, however, indeed more than just sustainably grown cardboard. The paperboard is coated with a so-called polymer. According to the TetraPak’s website that coating is indeed mostly plastic, if not, also aluminum. Tetra Pak maintains that to make paper water and air proof “this is best done through the use of plastic (primarily low density polyethylene) and in longer life products, aluminium. These materials make up approximately 25% of a package’s weight on average across our packaging lines.”
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What is low density polyethylene? LDPE is a petroleum plastic derived from gasoline production. It is made up of chemicals that have been forced together, however temporarily, through chemical reactions. Aluminum is, of course, a metal that has a long history of being considered toxic by some, and even sometimes associated in studies with Alzheimers, Kidney disease, and bone disease in children. Aluminum is also the sort of metal that needs a coating to keep it from rusting, which is why SIGG used BPA coatings on their aluminum water bottles until recently. What other plastics might be in the TetraPak lining? The company that owns Tetra-Paks, which is Tetra Laval, creates PET #1 bottles (Polyethylene Terephthalate) through a subsidiary known as SIDEL. PET, like LDPE is also a plastic derived from petroleum leftover from gasoline production. PET, used for most bottled waters sold in stores, has more recently been shown to also leach estrogenic substances into the water contained therein, not unlike BPA from polycarbonate bottles (#7). One study, conducted by a German University found that PET plastics leached synthetic estrogen into the bottled water. Studies involving snails, found that snails that lived in the PET plastic bottles, as opposed to glass bottles, tended to produce twice as many embryos, presumably as a result of increased synthetic estrogenic leaching into the water. Whether the estrogenic activity was caused by phthalates, which are chemicals in certain plastics that mimic the estrogen hormone, or catalysts like antimony (which have been documented to also leach into drinking water) or other substances added to plastics to keep them from oxidizing, the presence of estrogen presents potential health issues ranging from cancer to developmental problems in kids to sexual/reproductive problems.
What is perhaps even more interesting is that German studies also found that the Tetra Paks had the same dramatic estrogenic activity leaching into the liquids, presumably from the plastic linings used to coat the paper. Because the manufacturer has only disclosed that it “primarily” uses LDPE plastics, it is impossible to tie down what exactly is the cause of the leached estrogenic hormones. However, in the German Study the Tetra Paks tested indeed not only leached estrogen, but one of the TetraPaks leached it in amounts HIGHER than nearly all of the PET plastics. The study’s researchers concluded that in Tetra-Paks the “higher contamination (from estrogen) compared to samples from glass bottles (see Fig. 3 a, p < 0.001) could be attributed to the migration of EDCs from the inner lining of the Tetra Pak packaging, which consists of a polyethylene plastic.
The issue of whether the estrogenic activity from the Tetra Paks may be BPA related likewise remain unanswered as yet, since no environmental groups have yet put Tetra-Paks on their radar. While there may be a lot of testing going on with canned foods and metals, cardboard packaging has not yet been subject to the same testing, leaving much unknown about their safety. However, even without BPA, clearly there are plastics chemicals in Tetra-Paks that leach the synthetic estrogen hormone into water. It also should be noted that actual foods and sauces with more acidic contents than water would logically only increase the amount of leaching of estrogenic substances into the foodstuffs contained therein.
The other interesting thing about Tetra Paks is that they are supposed to be aseptic, meaning sterile in terms of germs. Taking a look at the patents held by Tetra Laval also discloses some other possible issues to consider with respect to the sterile nature of the foods, and the containers. For example, in U.S. Patent number 7,604,773, effective October 20, 2009, Tetra Laval discloses that to make their packaging sterile they spray or apply Hydrogen Peroxide and high heat to the packaging, and potentially irradiate with Ultraviolet Light. Both hydrogen peroxide and heat would quite logically accelerate the leaching of plastics chemicals, including synthetic estrogens. In addition, the issue of residual Hydrogen Peroxide being left in the container, and thus, in the food, remains a concerning possibility. The other issue of a germ free food is that it too must be exposed to high heat, or ultra-pasteurization — a practice that some say interfere with important nutrients in foods, especially milk.
Given all the potential issues and unknowns raised in this type of cardboard packaging, glass would still appear to remain the safest packaging for foods, even if not the most convenient one.