Back in September, I wrote about the plastic AT&T Yellow Pages bag that showed up on my doorstep unsolicited. Here’s the update. I called the Yellow Pages, found out to whom I should write, and sent this letter (PDF file).
Not long afterwards, I actually received a telephone call from Jim Troup, the head of environmental issues for AT&T Yellow Pages. We had a long conversation about plastic bags, Yellow Pages recycling, and different types of degradable bags the company has tried. He told me he is researching alternatives to the plastic bags, and that they actually did an experiment up in Redding, California, with a bag made of a plastic called D2W. He called this plastic “chemo-degradable” rather than “bio-degradable” and said that AT&T was still looking for something fully biodegradable and would let me know when they’d made a decision.
Weeks went by, and I forgot about D2W plastic, until I received a comment and email from blogger Jessica at Bwlchyrhyd asking about this very product. So I figured I’d better look into it. D2W is a plastic made by a British company called Symphony Environmental Limited. It breaks down due to additives in the plastic that are added during the “extrusion stage of manufacture, when polymer granules are heated and melted to form packaging films.” The web site calls these additives “metal salts.” The metal salts cause the plastic polymers to break down to such a degree that eventually, micro-organisms can take over and finish the job biologically. The end product is “some H2O, some CO2, and a small amount of biomass.” Here is a more detailed description of the degradation process.
Sounds great, right? Not so fast, pardner. Let’s look at all the pieces of this description logically in light of what we know about all the problems of plastic.
First, what exactly are the “metal salts” that are added to the plastic, and can they leach out of the plastic while it’s degrading? I contacted Symphony to find out the answer to this question and received this Word Document, Technical Paper “Heavy metals” and essential trace elements (Word Doc), which states that “the commonly used transition metal compounds in commercial oxo-biodegradable plastics are manganese, iron, cobalt and nickel.” The paper goes on to explain why we should not be concerned about “heavy metals” being added to the plastic. Not being a chemist myself, I sent the paper to Solvig, a chemistry teacher I know, who wrote me the following:
The metal compounds are used to catalyze the breakdown of the plastic in the presence of light, heat and oxygen. Catalyst tends to be active in trace (extremely low) concentrations, but I don’t know if that is so in this particular product. If on the other hand there is a high concentration of nickel in the product, we will end up with high concentrations of nickel in the compost.
How would the nickel be taken up from the soil? The amount of nickel taken up by plants has little to do with its concentration in the soil. The accumulation of nickel in various parts of the plant remains constant whatever the concentration of nickel of the soil. [However,] the uptake of nickel from the soil by other organisms such as bacteria or other critters is not discussed.
They finish by saying: If you added degradable polyethylene film as mulching to the soil it would take 500 years to increase the nickel content of the soil by 1ppm. However, they don’t explain what they mean by that. How much biodegradable plastic are they talking about??? Just one little container, or a composting plant’s worth.
In an ideal world all the biodegradable plastic would be broken down in a composting plant, and the amount of nickel and cobalt released would depend on the amount of plastic in relation to the amount of other food and garden waste it is mixed with.
My feeling is that there is no danger of poisoning people when this stuff is broken down, but I don’t know since I don’t know what the concentration of metal is. Let’s stick with the precautionary principle and avoid single use items whether biodegradable or not.
So that’s question #1: Will the metals present in the plastic prove toxic to us in the long run? At this point, I don’t think we know. So many other additives in plastic, like phthalates and Bisphenol-A were once thought safe and are now being found to leach into our water and food.
Second, the web site description says that the metal salts are added during the “extrusion stage of manufacture, when polymer granules are heated and melted to form packaging films.” Let’s remember that D2W film is still being made from ordinary petroleum-based plastic granules, the same pellets commonly called “nurdles” that are being found in our oceans and taken up into the food chain. These raw plastic pellets do not contain any additive to help them break down. If they blow off a ship into the ocean, which they often do, they will remain there basically forever, attracting pollutants like PCB and DDE and concentrating them even as they enter the bodies of fish and other marine animals.
Any plastic film made from petroleum-based plastic contributes to the pollution of our oceans simply through the transportation of the raw material to the manufacturer. To state my opinion less formally, if we can’t find some way to keep these little buggers from blowing about and washing down storm drains, we oughtn’t be making things out of them.
Third, it takes energy and materials to create any disposable products, including products that biodegrade. Symphony’s answer to the question of reusable bags (PDF) is this:
Long-term re-usable shopping bags are not the answer. They are much thicker and more expensive, and a large number of them would be required for the weekly shopping of an average family. They are not hygienic unless cleaned after each use. Whilst sometimes called “Bags for Life” they have a limited life, depending on the treatment they receive, and become a very durable form of litter when discarded.
Shoppers do not always go to the shop from home, where the re-usable bags would normally be kept, and consumers are unlikely to have a re-usable bag with them when buying on impulse items such as clothing, groceries, CDs, magazines, stationery etc.
However, for those who believe in long-term re-usable bags, they can be made from extended-life oxo-biodegradable plastic and will last for five or more years.
I disagree that long-term use reusable bags are not the answer. And the comment about reusable bags not being hygienic is just plain ridiculous. We are so germ-phobic that we can’t have our produce touch material that’s been previously used? Do we not realize that fruits and vegetables are plants that grow in dirt fertilized by manure?
I believe that reusable bags should be the number one alternative for carrying home purchases and perhaps some type of degradable bag could be a distant second for those who forget to bring their bags to the store and are willing to pay for a disposable one. I think we ought to be charging fees for one-time use bags and containers in the first place, which would help to remind folks to bring their bags with them.
What do you think?