Tag Archives: plastics

IBM, Stanford Unveil Green Chemistry Breakthrough

Scientists from IBM and Stanford University have unveiled discoveries that could lead to the development of new types of biodegradable, biocompatible plastics. The result of a multi-year research effort, the breakthrough also could lead to a new recycling process that has the potential to significantly increase the ability to recycle and reuse common PET and plant-based plastics in the future. Todays announcement may have sustainability implications across a wide range of industries including biodegradable plastics, plastics recycling, healthcare and microelectronics. IBM and Stanford scientists are pioneering the application of organocatalysis to green polymer chemistry, which represents a fundamental shift in the field. This discovery and new approach using organic catalysts could lead to well-defined, biodegradable molecules made from renewable resources in an environmentally responsible way.

See the YouTube video: Stanford & IBM on Green Chemistry and plastics.

Plastic from algae: How green?

Plastic from algae: How green?

Posted by Evan Beach at May 18, 2010 08:30 AM | Permalink

A story in Discovery News on new algae-based plastic highlights green benefits but misses the challenges.

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An article in Discovery News offers a rare look at how algae can be used to make something other than fuel or animal feed: plastic.

The story would have been more informative if the reporter had discussed the challenges that remain before algae fuels or plastics can become widespread. It is still not clear how algae can be produced sustainably on a large scale.

Reporter Alyssa Danigelis describes a new plastic that can be made with up to 50 percent algae. The company developing it hopes it will be 100 percent algae in a few years. Danigelis draws attention to the major green benefits of this new technology: it uses what would probably be a waste material from biodiesel production, it should not have any impact on the food supply, and further research and development could lead to a compostable material.

The 50 percent algae product also contains polypropylene (PP), a plastic often encountered in everyday life, for example, in microwaveable food containers. Such blends of natural and synthetic materials are not completely biodegradable but they often help to reduce consumption of limited resources.

By using algae left over from fuel extraction, this new plastic supports the idea of a “biorefinery.” The oil, coal and gas industries don’t just produce fuels – they produce the chemical building blocks for everything from industrial solvents to pharmaceuticals, leaving almost nothing to waste. Similarly, biofuel production will be more competitive if all of the raw materials are used productively. Plastic from algae is a step in that direction.

However, water, nutrient and energy demands can be extremely high and these issues are just as serious as whether the technology will compete with food production. Until the science is worked out, the “greenness” of algae – beyond its actual color – is not yet certain.  The story could have made this more clear.

Improved outlook for a biodegradable plastic.

Improved outlook for a biodegradable plastic.

May 12, 2010

Agarwal, S and C Speyerer. 2010. Degradable blends of semi-crystalline and amorphous branched poly(caprolactone): Effect of microstructure on blend properties. Polymer 51(5):1024-1032.

Synopsis by Evan Beach

A new way of concocting a promising “green” plastic called polycaprolactone (PCL) makes it clearer and more biodegradable – critical features for alternatives to PVC plastic or other conventional packaging materials.

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PCL was transformed into a more transparent plastic when two different varieties of the same starting material were combined in the laboratory. The blends broke down faster when buried in a compost.  The results show that the new blends improve traits – transparency and degradability – necessary to develop PCL into a viable plastic product.

PCL degrades easily and thus has been studied for decades as an alternative plastic for use in agriculture, medicine, pharmacy, biomedical and as an environmentally friendly material for packaging. Because it has some disadvantages –  for example it cannot form a transparent film – it must be blended with other plastics in industrial applications.

PVC, like many other plastics, is not biodegradable, and therefore, it persists in the environment. PVC is rigid unless other chemicals are added to the formulation. Phthalates are among the most commonly used additives to make PVC flexible. Human health concerns have been raised about exposures when these chemicals migrate out of the plastic, especially effects on the male reproductive system.

Ironically, PVC is often chosen for blending with PCL because the two polymers can be mixed very easily. This takes away from the environmental benefits of PCL, since in the blended plastic, after the PCL degrades, the PVC persists just as it normally would on its own.

The new PCL plastic reported in this study does not use PVC. It can be fine-tuned so that the transparency increases from 8 percent to 45 percent and the plastic films break down much more quickly than ordinary PCL. The blends were less flexible and stretchy, but the researchers did not discuss whether the impact this would have on a potential packaging material.

The technique that led to the new plastic was a method of changing the structure of the PCL chain. Ordinary PCL and the new PCL contain the same repeating units, but the new PCL is not perfectly linear. It has branches, forcing the chains to take on a different overall shape. There are many different ways to make branched-chain PCLs, so more research could increase the number of options for manufacturers who want to use environmentally friendly plastics.

Story on animal testing confuses plastics issues.

Story on animal testing confuses plastics issues.

Posted by Evan Beach at Apr 16, 2010 10:00 AM | Permalink

The Valley Vanguard draws attention to some interesting fronts in endocrine disruption, but confuses issues related to plastics and chemical additives.

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A March 22 article in the Valley Vanguard reports on a clash between the animal rights organization People for the Ethical Treatment of Animals (PETA) and researchers at Saginaw Valley State University (SVSU). The reporter’s description of the SVSU research program provides an excellent, succinct summary of the differences between studies that focus on animal death or reproduction and those that explore fetal development in a more detailed way.

The article does erroneously link dioxins and the phthalate plasticizer DINP to water bottles, though.

Most water bottles are made from polyethylene terephthalate (PET) plastic (recycling #1), which is highly unlikely to contain dioxins or dioxin precursor chemicals. Urban legends have spread the myth that extreme cold or heat can release dioxins from water bottles, but PET contains no chlorine, the essential ingredient required for formation of the environmental contaminants. Dioxin formation is linked to burning of chlorine-containing PVC plastic (recycling #3), which is used in many everyday products but rarely water bottles.

The effects of DINP are also discussed in the article. DINP is a phthalate plasticizer commonly used as an additive for PVC plastic, not PET, so it should not be found in an ordinary water bottle. The confusion may arise from the similarity in names: PET contains building blocks called terephthalates and DINP is an orthophthalate. But as far as harmful effects are concerned, the connection stops there. DINP, DEHP, and other orthophthalates are associated with the hormone-disrupting effects described in the story. Readers who wish to avoid DINP exposure should stay away from soft, flexible PVC products (e.g. vinyl shower curtains, floor tiles, and children’s toys).

The PETA versus SVSU conflict is given a balanced presentation. However, it could have been better and more interesting if the story had further explored the larger question about non-animal testing methods. To provide greater depth into the issue would have informed readers about why other methods couldn’t be used for this particular research. One way to do this would be to include the viewpoint of a third party who doesn’t have a stake in the dispute.

Story shines light on new, but controversial, degradable plastic.

Story shines light on new, but controversial, degradable plastic.

Posted by Evan Beach at Apr 16, 2010 09:30 AM | Permalink

An article in The Telegraph is one of the few media stories to focus on the ongoing controversy about so-called ‘oxo-degradable plastics.’

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A public relations battle has erupted between different parts of the plastics industry over a new kind of degradable plastic.  Manufacturers that produce plastics from starch, sugar and other biological sources challenge claims about the environmental benefits of the new plastics.  They are pitted against companies that make the chemical additives involved. Both of these parties have financial interests at stake.

The Telegraph brings an unbiased voice to the debate by reporting on a new British government-funded scientific review.  The government report is not a “study” in the usual sense – no experiments were done by the authors – rather it is a summary of the work of dozens of scientists from around the world.

The article does an excellent job of covering most of the major issues involved. But, the reporter could have done more to highlight areas where there is uncertainty due to a lack of scientific evidence one way or the other.

The oxo-degradable technology involves adding small amounts of a metal-based additive that make plastics sensitive to the damaging effects of oxygen.  It can be added to everyday plastics like polyethylene (PE) that ordinarily are highly stable.  According to the government report, there is no question that plastics containing the additive can break down in the presence of light and heat, whereas without the additives the plastics persist.

But beyond that, there is a great deal of uncertainty. In particular, do the oxo-degradable plastics break down when buried in soil or in landfills?  Will microorganisms attack and digest the carbon in the plastic to make carbon dioxide? Some biodegradable plastics  – like polylactic acid (PLA) – do this without additives.

The Telegraph highlights many of the concerns raised by the government review.  For example, oxo-degradable plastics could disrupt plastic recycling facilities, might persist in a landfill, could break down too slowly to have any impact on littering and the small fragments might harm wildlife. The article also reports on product labels that might lead a consumer to dispose of the plastics in improper ways.

What the reporter could have clarified is the state of the science. The review emphasizes that its major limitation is the “lack of hard evidence produced by systematic, well-controlled studies carried out by independent parties.”  In other words, the jury is still out on many of the key issues.

The reporter mentions this uncertainty in the beginning, but only clearly communicates the lack of research with respect to bioaccumulation of plastic fragments in animals.  It would have been helpful to explain that there is not enough science to judge the other environmental issues as well.  The report found that not enough research had been done to determine whether the plastics could be degraded by microbes or break down when buried in a landfill. Similarly, if light and heat broke the plastic down into a fine powder, there is no research to show if it might act as a sponge for other pollutants. Oxo-degradable plastics may or may not be environmentally friendly by all these measures, and without further study, it’s too early to know which side of the industry is right.

The article also left out perhaps the most surprising recommendation of the government review: that the best way to dispose of an oxo-degradable plastic is to incinerate it.  If it goes up in flames, all other questions of degradability – bio- or otherwise – become moot, and the environmental impacts would be essentially the same as an ordinary plastic.

The Telegraph should be commended for bringing issues related to oxo-degradable plastic to readers’ attention, as this coverage will help inform consumers to make environmentally-friendly decisions when choosing products.

Thought-provoking story describes alternatives to bisphenol A.

Thought-provoking story describes alternatives to bisphenol A.

Posted by Evan Beach at Feb 27, 2010 09:30 AM | Environmental Health Sciences

A February 23rd article in the Washington Post provides a well researched overview of potential substitutes for bisphenol A (BPA) in food containers. It raises important issues about scientists’ state of knowledge about exposures to chemicals in packaging materials and the food supply.

BPA is widely used in food can linings, and exposures through canned food are thought to be related to the frequency with which BPA is detected in the urine of the US population.  This application of BPA has also proven to be one of the most difficult in terms of finding a substitute technology.  The Washington Post article provides an excellent summary of the properties needed for high performance steel can linings and industry efforts to replace BPA-containing materials.

One of the most striking parts of the story is the revelation that one food company that switched to BPA-free steel cans is still finding trace amounts of BPA in its products. The source of contamination remains unknown.  This adds to growing evidence that estrogenic chemicals are so widely used in manufacturing supply chains that it has become difficult to pinpoint how and where in the process they are able to migrate into food and drink. For example, a 2009 study found that bottled water showed estrogenic effects after it was stored in Tetra Pak liners.  It is still unclear whether this was a result of the packaging materials themselves or some other aspect of the manufacturing process.

These findings suggest that our problems will not be solved just by replacing BPA in food can linings.  As discussed in the Post article, BPA is used in thousands of consumer products, increasing the chances of cross-contamination.  What’s not mentioned, though, is that BPA is not the only estrogen mimic showing up in food.  The problem is more systematic, begging the question, will the potential alternatives discussed in the story be any safer?

It is very difficult for a chemist sketching new molecules in a notebook to predict whether those structures will lead to a toxic product or a safe product.  This has led to situations described by NIEHS director Linda Birnbaum as like “jumping from the fry pan into the fire” when it comes to substitutes, as she said in reference to alternative flame retardants.

A possible solution to this issue is greater cooperation between environmental health scientists and green chemists, who are seeking to better understand the connections between chemical properties and toxic endpoints.  Progress in this area would make it easier to recognize chemical hazards as a design flaw.

The Post article did a good job bringing up difficult issues regarding chemicals in the food supply, and provided a rare focus on the quest for replacements.  Other journalists could follow suit and begin asking more pointed questions that dig deeper into how chemicals can be made safer.

“Science versus theology: the bisphenol A debate continues” – Pumphandle blog entry by Sarah Vogel

View the original Pumphandle blog post here.

Science versus theology: the bisphenol A debate continues

March 2, 2010 in Environmental Health | by The Pump Handle

by Sarah Vogel

If you thought the scientific debate about bisphenol A was over or even quieting down, you haven’t been reading the latest issues of Toxicological Sciences. (What are you doing with your spare time?) Last month in an editorial piece published in the journal, Richard Sharpe queried: “Is It Time to End Concerns over the Estrogenic Effects of Bisphenol A?”  His answer was an unequivocal ‘yes’, based on the latest study from Ryan et al. (published in the same issue) that found no reproductive effects from bisphenol A exposure in rats.  The study, according to Sharpe, “throws cold water on this controversy.”

Not so fast.  On Wednesday, February 17, 2010, the journal published a second letter to the editors, “Flawed Experimental Design Reveals the Need for Guidelines Requiring Appropriate Positive Controls in Endocrine Disruption Research,” by Fred vom Saal and 23 other researchers.  In a position quite contrary to Sharpe’s, the letter pointed to an important design flaw in the study.

This latest iteration of the controversy is about a fundamental and persistent challenge in the research on bisphenol A and other endocrine disrupting chemicals—what is the appropriate study design.  Issues of animal selection, route of exposure, animal feed and housing, and appropriate use of positive controls all point to the complexity of studying extremely low levels of endocrine disruptors.

These are not trivial issues.  Proper study design is essential to conducting good science, and charges of inappropriate design have been used to discredit research findings of adverse effects of as well as no effects of bisphenol A at low-doses.

This most recent letter critical of the Ryan et al. paper points to a flaw in the selection of dosing levels for the positive control.  To understand the argument requires a basic understanding of a positive control.

Let’s start with a very different example recently shared with me.  Say you have an unknown substance in the garage that you think might be a fertilizer.  To test this hypothesis you take two dishes of seeds and treat one with water and the other with the unknown substance and see what happens.  When there is no growth in the seeds of either treatment, you could conclude that the substance isn’t a fertilizer.  But what if the seeds you had started with were already dead?  So, you decide that a better way to test the unknown substance is to take three dishes of seeds and treat one with water, one with the unknown substance and a third with Miracle-Gro. This way if the seeds grow with Miracle-Gro you know they’re alive and reactive to fertilizer.  And if the seeds grow with the unknown substance and the ones in the water don’t, you know it’s a fertilizer. In this example, Miracle-Gro is the positive control and water the negative control.

But what happens if it turns out that when testing your seeds, you find that you have to use 10 times the amount of Miracle-Gro that is recommended to make the seeds grow?  What if your unknown substance is a fertilizer, but over the years of sitting in your garage has become less potent?  Your seeds might grow if you were to use a ton of the substance but because you didn’t have that much you only tested a small amount.  So in your study you use water, a small concentration of your fertilizer and a ton of Miracle-Gro.  You find that only the seeds doused with Miracle-Gro response positively.  This could lead you to incorrectly conclude that the unknown substance is not a fertilizer.

How does this apply to the critique of the Ryan et al. paper?  In their study the researchers used a positive control, ethinylestradiol (EE), the hormone used in birth control.  However, they had to use extremely high doses to trigger the reproductive endpoints of interest (e.g. sexually dimorphic behavior, age at puberty, reproductive function).  They basically had to douse these rats with this estrogen to elicit a positive response—that is, to make the positive control work.  If they had used lower concentrations they would have observed no effects.  At the lowest concentration of EE used, 5 µg/mg, Ryan et al reported no effects in the animals.  The letter by vom Saal et al. noted that the pharmacologically effective dose of EE in oral contraceptives used in humans is less than 0.5 µg/mg.  So the rats used in Ryan et al.’s lab were not sensitive to levels of EE above the concentration used to avert pregnancy in women.

Given that it took such high concentrations of the positive control to elicit a positive effect, the researchers should have selected much high concentrations of BPA. This is because as demonstrated by the positive controls, the animals are insensitive to estrogen.

The details of this scientific debate can be confusing, particularly for the non-scientists.  But what it unsettling about Sharpe’s commentary is that he turned what should have been a scientific debate into a theological discussion.  Sharpe used the recent findings by Ryan et al. to paint a simplistic picture of the bisphenol A debate as a struggle between rational facts observed by scientists and exemplified in the Ryan et al. article, and “believers” of false hypotheses propagated by “nonscientific” media, blogs and website. According to Sharpe, these “believers” argue that bisphenol A has estrogenic effects at low doses, whereas scientists prove otherwise.

Simplifying a complex scientific debate using theological arguments ironically achieves the exact opposite intent of Sharpe’s editorial.  Rather than pulling this debate out of the mire, Sharpe drags it back in, and in the process, pulls it away from the rich scientific debate that needs to occur, particularly in the pages of scientific journals.

It is a credit to the 24 bisphenol A researchers that they did not take offense to this characterization of their work and careers.  They chose to stick to the scientific aspects of the debate and provide recommendations for appropriate use of positive controls.

In publishing the recent letter to the editor, Toxicological Sciences pushes scientific progress forward one small step by encouraging healthy and constructive skepticism and scientific debate.  Now we must wait for the next installment: a response from Ryan et al.

Sarah Vogel received her PhD from  Columbia University in the Department of Sociomedical Sciences’ Center for the History and Ethics of Public Health and Medicine; her dissertation was entitled “Politics of Plastic: the economic, political and scientific history of bisphenol A.” She holds master’s degrees in public health and environmental management from Yale University. She authored the case study “Battles Over Bisphenol A” at DefendingScience.org.