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Making Safer Products: A Chemical Design Protocol for Chemists

AGC session at Green Chemistry & Engineering Conference 2012 

Tuesday, June 19, 3:20 -  5:20 / McKinley Room

 

Using Scientific Findings From the Environmental Health Sciences to Avoid Endocrine Disruption in the Chemical Design Process

Pete Myers, Environmental Health Sciences

Karen Peabody O’Brien, Advancing Green Chemistry

A central goal of green chemistry is to avoid hazard in the design of new chemicals. This objective is best achieved when information about a chemical’s potential hazardous effects is obtained as early in the design process as feasible. Endocrine disruption is a hazard that to date has been inadequately addressed by both industrial and regulatory science. To aid green chemists in avoiding this hazard, we propose an endocrine disruption testing protocol for use by green chemists in the design of new materials.

Endocrine Disrupting Chemicals – Principles of Endocrinology for Chemical Design and Public Health Protection.

R. Thomas Zoeller, Department of Biology, University of Massachusetts, Amherst

Epidemiological and experimental studies continue to show adverse effects of endocrine disrupting chemicals (EDCs) from exposure levels far below what risk assessments indicate are safe. Because EDCs interfere with hormone action, it is essential to design experiments and interpret their results in terms of the very large literature that informs us about the role of endocrine systems in health and disease. Principles of endocrinology important to this field include hormone-receptor interactions, the spatial and temporal characteristics of hormone action in relation to development and adult health, and the regulatory circuits that control delivery of hormones to the proper targets at the proper time. These principles should inform basic research and regulatory science as well as to guide chemists in the design of safe chemical products.

The Relationships Between Exposures to Endocrine Disrupting Chemicals and Adverse Human Health Effects.

Laura N. Vandenberg,

 Department of Biology and the Center for Regenerative and Developmental Biology, Tufts University

A growing number of studies overwhelmingly suggest that environmentally relevant doses of EDCs influence human health and disease. Hundreds of human and animal studies challenge traditional concepts in toxicology, in particular the dogma that “the dose makes the poison”, because EDCs can have effects at low doses that are not predicted by effects at higher doses.  Additionally, a large body of evidence indicates that hormones and EDCs produce non-monotonic dose responses (NMDRs), defined as non-linear relationships between dose and effect where the slope of the curve changes sign within the range of doses examined. These data indicate that the effects of low doses cannot be predicted by high dose studies. Thus, fundamental changes in how chemicals are tested are needed to protect human health.

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Polymer Clay Jewelry Chemistry

This interview was inspired by my latest infatuation with my etsy shop. My inspiration for starting an ‘store’ on etsy was Inedible Jewelry. They are a polymer clay jewelry business in the lovely city of Charlottesville, making replicas of everyday foods with PVC. The ladies of Inedible Jewelry, Jessica and Susan Partain, are at our local farmer’s market every weekend selling their latest miniature creations.  Taking the opportunity to see their studio and learn more about the chemistry behind polymer clay, I set up an interview with Jessica Partain in her workshop (see picture to left).

I interrupted her in the middle of placing holiday orders, in her studio filled with doll-house sized desserts, drinks, fruits, vegetables, etc. The main material used to make these bit-sized creations is PVC.  I started the interview asking about the chemical concerns with PVC over the past decade. Jessica explained: “While the formulation of PVC itself has not changed, both of the polymer clays that I work with (97% Premo, 3% Sculpey, both manufactured by polyform products) were reformulated in 2008 to be phthalate-free and lead-free.” Phthalates, which are also endocrine disruptors, used to be a concern for the sculptors before the reform because baking the clay would release them, consequently allowing them to be  inhaled by the artist. Jessica also explained: The clay she uses is also ASTM certified, making the product safe. “They’ve run it past medical experts and biochemists looking specifically for potentially harmful interactions between the material and the artist.” This made me proud of my fellow medical experts and biochemists, doing good in the world.

Jessica and Susan have also always used a separate toaster in a well-ventilated room for their polymer baking, making creations such as the cupcake earrings to the right. They use a separate toaster to ensure that they would not combine their cooking with their polymer. One concern that still remains is when the clay is burnt, from baking for too long or from baking at too high a temperature – releasing toxic HCl gas.

As a loyal customer, I asked her: “What do you do with annoying customers like myself, who also ask all these difficult chemistry questions before a purchase.” She answered: “Well, you are one of two people asking me these questions in past 22 years; and the other person who asked did not have much basis for her questioning.” I felt like a major nerd at that moment – 8 years of intense science back ground can do that to you.

Although most customers do not ask about the chemistry behind polymer clay, many worry about the metals used in the jewelry. I then asked “Is this because they are worried about the toxic chemicals in metals?” That was strike two for Nerd Mana. The real reason is because many people are allergic to certain metals. To combat this problem, Inedible Jewelry uses 925 Sterling Silver for their necklaces.925 indicates the silver is 92.5% silver, and 7.5% copper. Jessica explained that the copper allows for 925 Sterling Silver to hold its shape because 100% silver is too malleable. All her metals are nickel free to avoid allergic reactions that lead to inflammation.

AGC loves the work of Inedible Jewelry and is impressed with their knowledge of chemistry and toxicology as it applies to their work. We all have a necklace with a polymer clay pendant. So far our collection includes: a peppermint, a gingerbread man, and a rainbow cake (mine!). The equally festive peach pies are pictures to the left where each miniature peach slice is crafted by hand.

 

Written by Mana Sassanpour

 

The Toxins in Baby Products (and Almost Everywhere Else)

Read original post at The Atlantic (online)

By Elizabeth Grossman

Jun 2 2011, 11:15 AM ET

Carcinogenic flame retardants were supposed to be gone by now, but, like endocrine-disrupting plasticizers, they persist

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A dangerous flame retardant known as “Tris” has reappeared in products designed for babies and young children, among them car seats, changing table pads, portable crib mattresses, high chair seats, and nursing pillows. (Tris, once used in children’s sleepwear, was removed from these products in the 1970s, after it was identified as a carcinogen and a mutagen, a compound that causes genetic mutation.) Also found in these products, according to the same recent study, which appeared in Environmental Science & Technology, is another flame retardant, pentaBDE. This compound was banned in Europe in 2004, when its U.S. manufacturers voluntarily discontinued it after it was found to be environmentally persistent, bioaccumulative, and to adversely affect thyroid function and neurological development.

The study also identified new compounds whose ingredients include some of the older toxic substances—and it found all of these and other flame retardants in 80 percent of the 101 infant and children’s products tested. That these chemicals, associated with adverse health impacts including cancer and endocrine disruption, are so widespread raises serious questions about the U.S. system of chemicals management and how we evaluate product safety.

With the potential health hazards of widely used synthetic chemicals coming under increasing scrutiny, and with a growing call from medical and scientific professionals for policies that protect children from such hazards, the question of what takes the place of a threatening chemical has become increasingly important. It also prompts questions about whether it is better to substitute another chemical for the one posing problems or to redesign a product so it can achieve its desired performance, perhaps without such chemicals.

Together these flame retardants and plasticizers raise profound questions about how we think about designing new materials and the wisdom of regulating chemicals one at a time.

The brominated and chlorinated flame retardants (BFRs and CFRs) found in these children’s products offer one cautionary example. Another group of chemicals known as phthalates, used to increase the flexibility of one of the world’s most widely used plastics, polyvinyl chloride (PVC), offers another. Together, these compounds account for the vast majority of all plastics additives used worldwide.

In the case of the flame retardants used in upholstery foams, carpet backings, textiles, and hard plastic appliances and other products since the 1970s, new compounds introduced to replace the hazardous ones have in fact resembled their predecessors. The result, despite “early warnings and periodic reminders about the problematic properties of these chemicals” is a “continuing pattern of unfortunate substitution,” wrote Linda Birnbaum, director of the National Institute of Environmental Health Sciences and National Toxicology Program, and Ake Bergman, professor of environmental chemistry at Stockholm University, in Environmental Health Perspectives in October. They were introducing a statement of concern about BFRs and CFRs signed by nearly 150 scientists from 22 countries.

While cushions and electronics can function without flame retardants, PVC cannot work without plasticizers. Phthalates—oily, colorless liquids based on benzene chemistry—have been the plasticizers of choice since PVC was commercialized in the early 20th century. Without phthalates, PVC would be brittle and of limited use. In some bendable PVC products, phthalates can make up as much as 40 to 50 percent of the finished plastic—and in 2008, nearly 540 billion pounds of PVC were produced worldwide.

Phthalates are also used in other vinyl-based products, to create thin and flexible films (they’ve been used in nail polish and other cosmetics), as lubricants (hence their use in lotions), as solvents, and to extend the life of fragrances, among many other applications. They are found in everything from food packaging to insect repellant to bath and teething toys. Some phthalates have been shown in animal studies to cause birth defects, and a number of popular phthalates have been identified as endocrine disrupters that interfere with male reproductive development. Concerned, Europe restricted use of about half a dozen phthalates in 2008, and the U.S. restricted them in products intended for use by children under age 12. Similar regulations exist elsewhere, including Canada, Japan, and Taiwan. On May 4, the French National assembly voted to ban phthalates altogether, based on concerns about endocrine disruption.

Like the BFR and CFR flame retardants, phthalates are released from the materials to which they’re added. That phthalates could migrate from PVC has been known since the 1960s, when the Air Force found that this could cause problems on spacecraft and phthalates were detected leeching from plastic tubing used in blood transfusion and dairy equipment. We can take phthalates into our bodies by breathing them, ingesting them, and by absorbing them through our skin. A study published in March of this year found that when people eliminated certain packaged foods from their diets, levels of the corresponding phthalates in their urine dropped by more than 50 percent.

So with growing concerns about phthalates and increasing restrictions on their use, a search is on for alternatives—ideally non-toxic compounds that will not migrate out of the plastics. But PVC itself, even without the phthalates, raises questions about product safety. While it may be possible to find a non-toxic plasticizer, vinyl chloride, the main ingredient of PVC chloride, is a human carcinogen that also causes liver and nerve damage. PVC also poses hazards when burned, as incomplete combustion can result in dioxins, also carcinogenic compounds. In April, the Environmental Protection Agency proposed increasing emissions standards for plants that product PVC, citing inhalation risks to people who live in communities where these manufacturing facilities are located. There are currently 17 such plants in the U.S., mostly in Louisiana and Texas.

Together these flame retardants and plasticizers raise profound questions about how we think about designing new materials and the wisdom—from an environmental health perspective—of regulating chemicals one at a time rather than by examining their characteristics and behavior. They also point to the need to look at a product’s entire lifecycle when considering its health impacts. There are many arguments to be made about the costs and benefits of using these materials, and moving away from such widely and long-used materials presents many challenges. Yet as Paul Anastas and John Warner, often considered to be the founders of green chemistry, point out, there is no reason a molecule must be hazardous to perform a particular task. To solve the kinds of problems posed by materials like PVC, “we need to design into our technologies the consequences to human health and the environment.”

Image: mbaylor/flickr

Newly identified chemicals leach into food packages, pose regulatory challenge.

Synopsis by Emily Barrett
— last modified Feb 07, 2011 09:25 AM

Muncke, J. Endocrine disrupting chemicals and other substances of concern in food contact materials: An updated review of exposure, effect and risk assessment. Journal of Steroid Biochemistry and Molecular Biology http://dx.doi.org/10.1016/j.jsbmb.2010.10.004.

It is well-known that eating fresh fruits and vegetables can reduce extra fat, salt and calories; but now there are additional reasons to choose fresh foods over processed ones.

Increasingly, evidence shows that the plastics and wrappers used for packaging can inadvertently leach unwanted chemicals into food. Several recent studies found high levels of bisphenol A – an environmental chemical that can disrupt hormonal processes – in canned foods and in packaged foods for people and pets.

Now, another study suggests that the problems go far beyond just one culprit or one health effect. Among the many toxic chemicals that can migrate from packaging into food are the endocrine disrupting phthalates and organotins and the carcinogen benzophenone. These compounds are heavily used in food packaging and have known health effects, yet are not routinely tested or regulated in food.

Although some regulations exist to guarantee safe food packaging, the current system does not address concerns posed by endocrine disrupting chemicals. The associated health effects of exposure to hormone altering compounds are many and varied, including immune disfunction, metabolic disorders (diabetes, thyroid) and reproductive problems.

A number of other notable regulatory flaws include not testing mixtures and a lack of understanding of different effects on different populations – from children to developing fetus to adults to the elderly.

Currently, chemical toxicity tests are only required when compounds reach certain levels in food. In the U.S., it is 0.5 parts per billion (ppb) for general toxicity and 1 ppm for reproductive toxicity.

The guidelines, though, do not consider the collective numbers and toxicity – alone or in combination – of all of the chemicals that can leach from the packaging. In a chemical mix, individual health effects may be magnified. Printing, ink, adhesives, recycled cardboard and the plastic containers can all introduce unwanted chemicals into a single food product, creating a mix with additive or synergystic effects. What’s more, the chemicals may degrade over time or form new compounds that migrate into food. These can go entirely unmeasured since it is nearly impossible to identify and test for them all.

Kids may be at particular risk. Not only are their bodies still developing and hence susceptible to environmental insults, but they tend to eat more packaged foods, a more limited diet and more food for their body weight than adults do. There are similar concerns for pregnant women and their fetuses, as well as obese adults, whose bodies may process these chemicals differently from their trimmer counterparts.

More stringent and broader regulations as well as testing programs may be necessary to further identify and reduce exposures – especially in children and women of reproductive age – to a broad swath of chemicals found in canned, packaged and other processed food.

See original post in Environmental Health Sciences

Soy plastics targeted for electronic circuit boards.

Zhan, M and RP Wool. 2010. Biobased composite resins design for electronic materials. Journal of Applied Polymer Chemistry 118:3274-3283.

Synopsis by Evan Beach
New materials made from soybean oil have excellent electronic properties and offer a low-carbon-footprint alternative to conventional plastics that are used in printed circuit boards.

Soybean oil can be mixed with conventional chemicals and converted into a strong, rigid plastic that could be used for high-speed, energy-efficient, electrical components, report researchers at the University of Delaware.

The greasy liquid could provide a cheap, abundant and renewable alternative to some of the plastics, resins and other petroleum-based materials now used to make the parts. The use of renewable ingredients in the new plastics may reduce greenhouse gas emissions and slow depletion of petroleum resources. In principle, other plant oils besides soy would work in the same way.

One target area for the new plastic is circuit boards – the internal units that relay signals in computers, radios and other electronics. They are often made from materials called epoxy resins, a family of plastics that frequently rely on bisphenol A (BPA) for stiffness. BPA is known to interact with the hormone system, most famously as an estrogen. The use of BPA has raised health concerns over harmful effects seen in animals at low doses. Human exposure is widespread and studies suggest the chemical may contribute to obesity, behavior problems and altered fertility and reproduction in people.

The researchers wanted to modify soybean oil so the individual oil molecules would create a chain and the other added ingredients would lend rigidity. They mathematically predicted that structures similar to benzene – six carbon atoms linked together in a planar ring – would give the desired properties. Bisphenol A, for example, contains two benzene rings in its structure.

The researchers manufactured the soybean-based material to validate the theory. A key ingredient needed was phthalic anhydride, which is best known as a raw material for phthalate plasticizers that are used in a variety of products and have been linked to health effects in animal studies. At levels of 10 – 20 percent, it improved both the mechanical and electrical properties of the soy-based plastics.

All of the soy-based materials had lower dielectric constants than epoxy resins – about 3.6 to 3.8 compared to 4.2 to 4.7. A low dielectric constant is important for high signal speed and low “crosstalk” of signals between lines in a circuit. The materials also have very low dissipation factors – a measure indicating that circuits could operate using less power.

Further research is needed to improve the environmental impacts of the soy plastics. It would be ideal to progress away from adding chemicals such as phthalic anhydride that have known health effects and moving toward a 100 percent biobased material. More benign sources of benzene ring structures also should be considered.

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.