GLOBAL – A University of Massachusetts-Lowell paper titled “Sustainability of Bio-Based Plastics: General Comparative Analysis And Recommendations For Improvement” published in the Journal of Cleaner Production 23 (2012, 47-56), has been labelled an inaccurate, out of date ‘literature report’ by NatureWorks LLC as opposed to a contemporary scientific study.
The university paper, by Clara Rosalia Alvarez-Chavez, Sally Edwards, Rafael Moure-Eraso, and Kenneth Geiser, claims that bio-based plastics are not fully sustainable, and concludes that “none of bio-based plastics currently in commercial use or under development are fully sustainable.”
The paper, which was first submitted to the Journal for peer-review in February 2011 and published in the March 2012 edition (though avilable online since October, evaluated the sustainability of bio-based plastics according to the impact on occupational and public health as well as on the environment throughout their life cycles. It said that, although bio-based plastics are more sustainable than petroleum-based plastics in some aspects, environmental and occupational health and safety hazards are present in their production cycle.
The Health and Safety impact comparative analysis found that PHAs, PLA and starch (TPS) are preferable, while starch, urethanes, PHA, zein and soy protein have less environmental impact.
Where PLA is concerned, the authors claim in their studies that GMOs (genetically modified organisms) are used in feedstock crops for PLA, and that the production process involved the use of hazardous and potentially harmful chemicals.
The authors also offered a range of recommendations for improving the sustainability of bio-based plastics, including the use of non-GMO feedstock, avoiding hazardous additives, energy and water efficiency, using by-products instead of primary food feedstock to lessen food supply impacts, and improved end-of-life management.
In an interview with Steve Davies, NatureWorks’ Director of Marketing and Communications, he said the study is “a little out of date” and explained why:
What are NatureWorks' main objections to the study?
Davies: The first half of the paper gives a broad context of plastics in general and talks about bio-based plastics in that context, and it is quite exciting when bioplastics is shown on a spectrum compared to a whole range of plastics, and they conclude, for many reasons, that bio-based plastics is preferred.
Then in the second half of the paper, the authors dissect the chemistry and the production techniques for bioplastics. And that’s where our problems lie.
One of the first challenges we’ve seen is that many in the trade media have simply seized the sensationalized headline of “bioplastics = non-sustainable” and they’ve missed the whole first half of the paper where the researchers highlight the problems and challenges with conventional plastics, and say that bio-based plastics is preferable. That is our first concern.
With the second half of the paper, which talks about the details on how bioplastics are produced, we have three PLA-specific concerns.
The University of Massachusetts-Lowell report was not based on actual industrial practice, certainly for Ingeo PLA. (see Table 1)
The paper notes what it terms as the toxicology of the organotin compounds it claims are used during the industrial manufacture of PLA. We do not use any organotin compounds anywhere in our production of Ingeo PLA grades. So that concern does not apply.
The paper also describes a concern with a chemical known as 1-Octanol used to start the chemical reaction as a polymerization initiator. Again, we have never used that chemical in the production of Ingeo.
So 1-Octonal has NEVER been used in production.
What about organotin compounds? Have they ever been used in production?
Davies: It’s certainly not used today and it’s not been used recently. We’ve never disclosed the exact catalysts so it’s not appropriate for me to say whether or not it’s been used in the past, but it’s not been used in recent history, in the last couple of years.
|Table 1: Quote (4.1.2. PLA and starch)|
“During the industrial manufacturing of PLA, an organotin-based catalyst system (tin octanoate) is used in very low concentrations (100-1000ppm) (Henton, et al., 2005)... 1-Octanol is also used in the ring opening catalysis step to control molecular weight and accelerate the reaction (Drumright et al., 2000; Sodergard and Stolt, 2002).”Journal of Cleaner Production 23 (2012, 47-56)
The authors are certainly not current on what’s being done, at least in NatureWorks. And while the paper is general on PLA production, as you know we are the biggest PLA producer so we want to be clear about our production technique.
We don’t use those two chemicals.
The study also recommends further technologies/answers to reduce the formation of co-products (by-products) during the production of lactic acid, which is the main building block that we use (in PLA production). And also here, they are simply not current on what we are doing today.
In 2008, we implemented some significant changes in the fermentation technology to make lactic acid and with those technology changes we’ve significantly reduced the amount of co-products produced.
Does NatureWorks use calcium hydroxide in production?
Davies: While ammonium hydroxide will react to produce ammonium sulfate, which is a form of fertilizer, it is a nasty chemical to deal with.
We’ve gone a completely different route.
What we did in 2008 was to go back to the root cause and change the lactic acid fermentation technology to one that substaintially reduced the formation of the lactic acid co-products. Although we still use a little sulfuric acid and calcium hydroxide, it is significantly less.
And that’s the reason why the environmental footprint of Ingeo has improved; we’ve published that information.
So again, they are a little out of date on that.
The researchers claim: “An unknown health hazard in the production of PLA and starch is the use of GMOs (genetically modified organisms) in crops to produce higher yields or to improve starch properties… PLA may also use GMOs during fermentation of glucose.” What is your comment on that?
Davies: On that, they are also a little out of date. In the US, most corn that is bought, for example our feedstock in Nebraska, is today a mixture of GM and non-GM. That’s just the way the agricultural practice is performed in the US.
We fully understand that that’s a concern too in parts of the world, so for more than eight years we have been sourcing non-GM corn for customers that are interested and we bring that into our process. We have third-party certification from the field all the way to our facility to ensure that it is non-GM.
The researchers seem to be a little unaware of the sourcing options that we offer. That leads to the other problem, that they didn’t check their work with NatureWorks and so many of the recommendations that they make at the end of their paper are things that have long been done.
For example, they recommend that the industry start to look at lingo-cellulosic feedstock. Well, we, and our parent company (Cargill), are working on that. They recommend that wherever possible, producers use non-GM crops and we’ve been offering that option for a long time.
They are a little out of date with industrial practice.
According to the Journal of Cleaner Production, the paper was received in revised form in September 2011.
So when you say they’re “a little out of date” where feedstock sourcing, production etc is involved, what sort of time-frame are you suggesting that they’re out of date by, weeks, months?
Davies: About a decade out of date!
They’re looking at what catalysts are recommended etc etc, from maybe 10 years ago. Some of their sources are from 2000-2002. and they’ve assumed that that is what’s still happening.
At times their data is just basically wrong. For example, they claim 1-Octonal is used in the process when it has never been used.
It’s not a question of being out of date, it’s just not used.
Similarly, with regard to the sourcing options for non-GM corn, we’ve been doing that since 2004.
You’ve just said that some of the data is wrong. Why do you think the University researchers might have made some errors in their report?
Davies: I think what they set out to do was laudable. They’re obviously huge fans of green chemistry.
For example they start out by saying that bio-based plastics are better than fossil-based ones, and they wanted to understand how we can further improve green plastics.That’s what they set out to do, and it’s a laudable goal.
But I think where they went wrong is in not taking the time to talk to industry.
It was more of a ‘literature report’ (desk research report), it seems.
One of the recommendations that the authors made was to “work with governments and municipalities to put in place infrastructure so that bioplastics can be successfully composted and/or recycled”. What is your comment on that?
Davies: Again, I think their recommendation was spot-on. It is a very high-level recommendation, and of course, that is what we have been doing for the last five years.
We’ve worked with the US Composting Council, the association of composters in the country. We’ve run one-day workshops at their annual conference to educate them about what bioplastics are doing and to get their concerns on the table.
We also work with the Biodegradable Products Institute (BPI) that certifies compostability.
We’re working with both institutes to make sure that composting standards are the right ones, and to address the identification concerns (i.e. identify green plastics from conventional ones)
Our frustration with the report’s suggestion, that we work to put in place an infrastructure for composting bioplastic, is that this is what we have been doing for years!
We’re doing the same thing for recycling - Another North American example is the Association of Postconsumer Plastics Recyclers – the industry’s recycling organization. We’ve largely kept our plastic out of bottles; we don’t want to contaminate that recycling stream because we understand the industry’s concerns. And we’re working to recycle post-consumer waste right now.
What about outside of the US?
Davies: The approach is completely unique by geography because the practices are different. In Germany for example, we’ve been working with the recycling industry. A new business was just formed in February 2012 in Germany called RE|PLA Cycle GmbH – this is an independent business which was formed to buy back from the Green Dot system any PLA that is being collected.
Our interaction with this company is to work with them to find end markets for the recycled PLA that they are collecting.
Any final points?
Davies: No material or process is impact neutral. Every material and process involves tradeoffs.
No one polymer is ample for all applications. Biopolymers, as have been shown in third party reviewed research, score extremely high on some aspects of manufacture as compared to fossil carbon plastics.
On other items, for example land usage, they score lower - and in that instance it’s because fossil carbons have nothing to do growing crops.
Based on all of the factual production information available today and the best independent research basing a biopolymer on renewable resources is good for society, business, and the environment.