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Shorter fibers key to safer carbon nanotubes.

Monday, February 11th, 2013
Synopsis by Marty Mulvihill Feb 05, 2013

Ali-Boucetta, H, A Nunes, R Sainz, MA Herrero, B Tian, M Prato, A Bianco and K Kostarelos, 2013. Asbestos-like pathogenicity of long carbon nanotubes alleviated by chemical functionalization, Angewandte Chemie International Edition http://dx.doi.org/10.1002/anie.201207664.

A shorter carbon nanotube may be a safer one, according to a group of European researchers who varied the materials’ structural fibers and tested their health effects in mice.

Carbon nanotubes are one of the most common and exciting examples of nanotechnology with potential uses in electronics and medicine, but they are made of fibers that resemble asbestos. The modified nanotubes with shorter fibers were less irritating to the mouse lung and showed no signs of cancer when compared to traditional carbon nanotubes.

This work demonstrates the importance of researchers from different disciplines teaming up to solve problems. When applied to green chemistry, toxicologists and chemists working together can create safer materials to help avoid unintended health and environmental consequences of new chemicals.

Many scientists predict that carbon nanotubes will have many useful applications. The nanomaterials could boost performance of our electronic devices, deliver drugs directly to cells and even enable more affordable space travel through lighter materials.

At the same time, other scientists and health experts worry that carbon nanotubes could create health problems in people. In particular, the fibrous structure of these tubes closely resembles the potent carcinogen asbestos. In fact, lab and animal studies have shown that carbon nanotubes do irritate lung tissue in the same way and lead to lung cancer in exposed animals.

Asbestos has been used in building materials, auto parts and coatings as an insulator and fire retardant. Asbestos fibers are released when products containing asbestos age or are disturbed in remodeling or replacement. When breathed in, the fibers can irritate lung tissue, causing cancer and other lung disease.

Now, a group of scientists report that they can make carbon nanotubes – picture sheets of carbon rolled into a cylinder – that are much safer and have fewer asbestos-like health effects.

By chemically modifying the surface of the very small carbon nanotubes, the researchers created fibers that are 10 times shorter than typical nanotube fibers. They tested these new materials head-to-head in mice with both untreated nanotubes and asbestos fibers.

They found that the chemical treatment produces fibers that caused much less irritation in the mouse lungs and did not show signs of cancer development during the seven days after injecting the nanotubes into the lungs.

More work and further testing are needed to understand the long-term impact of the modified nanotubes, including more details about biological interactions with the new nanomaterials.

 

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The above work by Environmental Health News is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Based on a work at www.environmentalhealthnews.org.

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New Tools to Design Safer Chemicals

Thursday, December 6th, 2012

PRESS RELEASE: “A New tool to design safer products”

New publication:  A New System to Assess New Chemicals for Endocrine Disruption

A groundbreaking new paper outlines a safety testing system that helps chemists design inherently safer chemicals and processes. Resulting from a cross-disciplinary collaboration among scientists, the innovative “TiPED” testing system (Tiered Protocol for Endocrine Disruption) provides information for making chemicals and consumer products safer. TiPED can be applied at different phases of the chemical design process, and can steer companies away from inadvertently creating harmful products, and thus avoid adding another BPA or DDT to commerce.

The study, “Designing Endocrine Disruption Out of the Next Generation of Chemicals,” is online in the Royal Society of Chemistry journal Green Chemistry.

The 23 authors are biologists, green chemists and others from North America and Europe who say that recent product recalls and bans reveal that neither product manufacturers nor the government have adequate tools for dealing with endocrine disrupting chemicals (EDCs).  EDCs are chemicals commonly used in consumer products that can mimic hormones and lead to a host of modern day health epidemics including cancers, learning disabilities and immune system disorders. The authors conclude that as our understanding of the threat to human health grows, the need for an effective testing strategy for endocrine disrupting chemicals becomes imperative.

Historically, chemists have aimed to make products that are effective and economical. Considering toxicity when designing new chemicals has not been their responsibility. This collaboration between fields expands the scope of both biologists and chemists to lead to a way to design safer chemicals.

Scientific understanding of endocrine disruption has developed rapidly over the past 2 decades, providing detailed, mechanistic insights into the inherent hazards of chemicals.  TiPED uses these insights to guide chemical design toward safer materials.  And as consumers are increasingly concerned about endocrine disruption (eg BPA, flame retardants) they are demanding products that do not contain EDCs, creating a market opportunity for companies that can take advantage of the new science.

There is a companion website to the paper, www.TiPEDinfo.com. One can access the paper there and learn more about the TiPED system.

 

 

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New stain repellent chemical doubling in blood every 6 years.

Sunday, December 2nd, 2012
Nov 26, 2012

Glynn, A, U Berger, A Bignert, S Ullah, M Aune, S Lignell and PO Darnerud. 2012. Perfluorinated alkyl acids in blood serum from primiparous women in Sweden: Serial sampling during pregnancy and nursing, and temporal trends 1996-2010. Environmental Science and Technology http://dx.doi.org/10.1021/es301168c.
Synopsis by Craig Butt and Wendy Hessler
2012-1119frisbeeinrain
erikschmidt/flickr

 

As the phased-out stain repellent PFOS steadily decreases in people, its replacement is rising rapidly at levels that are doubling every six years, a Swedish study shows. Levels of perfluorobutane sulfonate (PFBS) in the women’s blood rose 11 percent per year between 1996 and 2010. Whether there are any potential health effects of these exposures — which are still far lower than PFOS levels — is unknown.

 

Context

Polyfluorinated and perfluorinated chemicals (PFASs) are applied to clothing, furniture, carpeting, cookware and food packaging to make the products stain repellent. PFASs – commonly referred to as PFCs – are a large group of chemicals that are unique because they repel both grease and water.

The PFAS chemicals used in commercial products fall into two main categories: the large fluorinated polymers that are used in clothing, furniture and carpet treatments and the phosphate surfactants that are used to coat paper.

Commercial products often contain the parent PFAS chemicals used to make the polymers and phosphate surfactants – called precursors – as impurities. PFASs break down in the atmosphere and in our bodies to form very long-lived perfluorinated alkyl acids (PFAAs).

People are exposed to PFAAs and their precursors mainly through food, air and water. Studies suggest the chemicals may contribute to kidney damage, and prenatal exposures have been linked to low birth weight.

Two of the most well-known and well-studied PFAA varieties are perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA). In addition to forming as breakdown products, small amounts of PFOS and PFOA were directly produced for specialized products. PFOS was used in fire-fighting foams as well as in the semiconductor industry. PFOA was used in the production of Teflon, but is typically not detected in the final products.

In 2002, the 3M Company – a leading manufacturer of PFOS and PFOA – voluntarily stopped manufacturing both PFOS and the chemicals that degrade to form PFOS because they were accumulating in humans globally and in animals – such as polar bears – that live in remote areas (Hansen et al. 2001; Giesy and Kannan 2001; Butt et al. 2010).

The company has substituted PFOS-based chemicals with another PFAA variety that is based on perfluorobutane sulfonate (PFBS). PFBS has four carbons whereas PFOS has eight. Otherwise, their molecular makeup is identical.

The smaller PFBS clears from the human body much faster than PFOS. PFOS has a half-life in people of 4 – 5 years, but PFBS’s half-life is only 26 days (Olsen et al. 2009).

After 3M stopped making PFOS-based compounds, production of other compounds made by another manufacturing process rapidly increased. These are called fluorotelomer-based chemicals. The fluorotelomer compounds are used for the same purpose as the PFOS-based compounds were: to make fluorinated polymers and surfactants. However, these chemicals degrade to form perfluorinated carboxylates (PFCAs), including PFOA.

Due to the increasing concern about PFOA, the eight major manufacturers have committed to eliminate PFOA emissions by 2015.

 

What did they do?

The research is part of a larger study that examined time trends of persistent organic pollutants in the blood and breast milk of pregnant and nursing women in Uppsala County, Sweden.

Blood samples were collected from first-time mothers, aged 19 – 41 years, three weeks after delivery. Samples were collected each year between 1996 and 2010, except in 2003 and 2005. For each year, several individual blood samples were pooled together for analysis. In general, three pooled samples per year were analyzed.

The study investigated levels of 13 PFAAs, including PFBS and PFOS. The study also measured perfluorooctane sulfonamide (FOSA), which is known to degrade to PFOS.

A unique aspect of this study was the ability to measure PFBS levels at very low levels.  It was this improved analytical capability that allowed the researchers to detect the PFBS  trends over time.

In addition to examining time trends, the study also investigated PFAA trends at different stages during pregnancy and after delivery.

 

What did they find?

The study showed that PFBS blood concentrations in the Swedish women increased by 11 percent per year between 1996 and 2010. The levels doubled every 6.3 years. This is the first study to show increasing PFBS levels in humans.

However, during the same time period, PFOS levels decreased by 8.4 percent per year. The study also showed decreasing levels of perfluorodecane sulfonate (PFDS), PFOA and FOSA.

In contrast, blood levels of two PFCAs – perfluorononanoate (PFNA) and perfluorodecanoate (PFDA) – increased by 4.3 percent and 3.8 percent, respectively, from 1996 to 2010.

The study also looked for longer-chain length PFCAs: perfluorododecanoate (PFDoA), perfluorotridecanoate (PFTrA) and perfluorotetradecanoate (PFTA).  But these PFCAs were not found in the women’s blood.

 

What does it mean?

Perfluorobutane sulfonate or PFBS – the chemical that replaced the PFOS-based fluorinated chemicals used as stain repellents – is building up in human blood with levels doubling every six years. This is the first study to show increasing PFBS levels in humans.

The study showed that PFBS levels in Swedish women are rapidly increasing. This means that humans are widely exposed to PFBS and its precursors. Exposure to these chemicals has increased dramatically from 1996 to 2010.

These findings were surprising because it was thought that PFBS would not accumulate in humans due to its very short half-life (26 days). But the new research shows that PFBS is building up at an alarming rate.

However, PFBS levels are still about 75 times lower than PFOS.

The study did not investigate whether there were any health effects associated with the increasing PFBS levels. There have been few toxicology studies on PFBS, and the toxic effects are generally less than PFOS and PFOA (Lieder et al. 2009).

PFBS-based chemicals were introduced as replacements for PFOS-based chemicals after 3M stopped their manufacture in 2002. In the current study, PFBS levels did not start increasing until 2002. Presumably, this increase in PFBS blood levels is a reflection of increased use of PFBS precursors in commercial products and their release into the environment after 2002.

The new study also showed that PFOS and FOSA levels are decreasing in Swedish women’s blood. FOSA is formed when PFOS precursors are metabolized in the body.

These results show that 3M’s PFOS ban in 2002 had a rapid effect on PFOS blood levels. Studies from the United States (Kato et al. 2011; Olsen et al. 2012) and Norway (Haug et al. 2009) have also shown decreasing PFOS blood levels after the 3M ban.

In contrast, PFNA and PFDA levels were shown to increase in the Swedish women. These chemicals are breakdown products of fluorotelomer-based compounds that are used in some polymers and surfactants. They have similar uses as the PFOS-related chemicals. In addition, PFNA is used in the production of polyvinylidene fluoride (PVDF) and trace amounts can be detected in the final products. Production of fluorotelomer chemicals increased after the 3M PFOS ban. The increasing blood levels of these chemicals most likely represents the increased use of their precursors in commercial products.

Because the study only monitored Swedish women, it will be necessary to confirm the trends in other regions of the world. This is because fluorinated chemical use varies in different areas of the world. For example, China began producing PFOS-chemicals in 2003. Their production in China may represent a new source of PFOS to the world.

Scientists are concerned when blood levels of a chemical increase in our bodies because it shows that our exposure is increasing. However, it is necessary to determine if the contaminant levels are enough to cause harmful effects in wildlife and people.  Future research is needed to determine if the increasing PFBS levels are affecting human health.

Resources

Buck, RC, J Franklin, U Berger, JM Conder, IT Cousins, P de Voogt, AA Jensen, K Kannan, SA Mabury and SPJ van Leeuwen. 2011. Perfluoroalkyl and polyfluoroalkyl substances in the environment: Terminology, classification, and origins. Integrated Environmental Assessment and Management 7:513-541.

Butt, CM, U Berger, R Bossi and GT Tomy. 2010. Levels and trends of poly- and perfluorinated compounds in the arctic environment. Science of the Total Environment 408:2936-2965.

Giesy, JP and K Kannan. 2001. Distribution of perfluorooctane sulfonate in wildlife. Environmental Science & Technology 35:1339-1342.

Hansen, KJ, LA Clemen, ME Ellefson and HO Johnson. 2001. Compound-specific, quantitative characterization of organic fluorochemicals in biological matrices. Environmental Science & Technology 35:766-770.

Haug, LS, C Thomsen and G Bechert. 2009. Time trends and the influence of age and gender on serum concentrations of perfluorinated compounds in archived human samples. Environmental Science & Technology 43:2131-2136.

Kato, K, LY Wong, LT Jia, Z Kuklenyik and AM Calafat. 2011. Trends in exposure to polyfluoroalkyl chemicals in the U.S. population: 1999-2008. Environmental Science & Technology 45:8037-8045.

Lieder, PH, RG York, DC Hakes, S-C Chang and JL Butenhoff. 2009. A two-generational gavage reproduction study with potassium perfluorobutanesulfonate (K+PFBS) in Sprague Dawley rat. Toxicology 259:33-4.

O’Connor, Mary Catherine. Greenpeace scolds outdoor apparel makers for chemical use. Outside Magazine Nov 12, 2012.

Olsen, GW, SC Chang, PE Noker, GS Gorman, DJ Ehresman, PH Lieder and JL Butenhoff. 2009. A comparison of the pharmacokinetics of perfluorobutanesulfonate (PFBS) in rats, monkeys, and human. Toxicology 256:65-74.

Olsen, GW, CC Lange, ME Ellefson, DC Mair, TR Church, CL Goldberg, RM Herron, Z Medhdizadehkashi, JB Nobiletti, JA Rios, WK Reagen and LR Zobel. 2012. Temporal trends of perfluoroalkyl concentrations in American Red Cross adult blood donors, 2000-2010. Environmental Science & Technology 46:6330-6338.

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Designing the next generation of sustainable chemicals.

Friday, November 2nd, 2012

Environmental Factor, November 2012 see original article here.

By Thaddeus Schug

Tom Zoeller, Ph.D., Jerry Heindel, Ph.D., and Wim Thielemans, Ph.D.  Heindel, center, goes to work creating a toxic pumpkin, while Tom Zoeller, Ph.D., left, and Wim Thielemans, Ph.D., take part in the fun. (Photo courtesy of Pete Myers)

Scientists committed to developing green solutions for replacing problem chemicals in the marketplace gathered Oct. 15-17 for a meeting on “Building the Path Forward for the Next Generation of Sustainable Chemicals,” held at the Rockefeller Brothers Fund Pocantico Center in Tarrytown, N.Y.

The meeting, sponsored by the non-government organizations Advancing Green Chemistry  and Environmental Health Sciences,  brought together a mixture of chemists, toxicologists, and biologists. Representatives from NIEHS and NTP included Division of Extramural Research and Training program administrators Jerry Heindel, Ph.D., and Thaddeus Schug, Ph.D.; Kristina Thayer, Ph.D., director of the newly named NTP Office of Health Assessment and Translation; and NTP Biomolecular Screening Branch Chief Ray Tice, Ph.D.

Designing safer chemicals

There are more than 83,000 chemicals in commerce today, many of which pose potential toxic hazards to human health and the environment. The challenge facing chemists designing replacement materials involves figuring out what kind of testing will need to be done to determine if the new chemical is safer than current ones to human health and the environment. One area of growing concern is how to ensure that the next generation of chemicals does not have the potential to act as endocrine disrupting compounds.

The meeting at Pocantico aimed to build upon a new set of testing tools — the Tiered Protocol for Endocrine Disruptors (TiPED) — developed by the group over the past two years. The protocol, which will be published online Dec. 6 in the Royal Society of Chemistry journal Green Chemistry,  is not regulatory, but rather a tool to guide chemists as they develop a new chemical, to give them confidence as to whether the substance is or is not likely to be an endocrine disruptor.

The TiPED protocol offers a five-tiered approach, starting with what should be the fastest and cheapest assays, and working through increasingly specialized tests. The initial two phases rely on predictive computer modeling and high-throughput screening, to quickly weed out problem chemicals. These tests are followed by more specific in vitro cell-based screening assays with a goal of refining, reducing, and replacing animal testing as much as possible. The last two tiers are whole animal assays, to be used for looking for integrated endpoints and less understood systemic responses.

“The idea is that if chemists hit a positive early on, they would either go back to the drawing board or, if that positive was in a specific area, such as an estrogen receptor in a high throughput assay, they would follow that up with more comprehensive assays,” said Heindel. “A hit anywhere along the tiered system means chemists need to pull back, reanalyze, or throw the chemical out.”

The project emphasizes fundamental changes in the way that scientists design new chemicals, and in the process of bringing them into the marketplace. Chemists generally have little training in toxicology, so this plan offers guidelines they can follow early on in the product development process.

Moving forward with the plan

Following a team-building exercise on the evening of Oct. 15, involving pumpkins and toxicological design criteria, the first full day of the meeting was divided into discussion sessions aimed toward refining the specific testing strategies within each phase of the screening model. A good deal of time was dedicated to establishing criteria needed to assess the quality of assays within each tier of the protocol.

The meeting wrapped up with a discussion on strategies to conduct test runs of the protocol, using test chemicals synthesized by John Warner, Ph.D., president and founder of the Warner Babcock Institute for Green Chemistry.

(Thaddeus Schug, Ph.D., is a health scientist in the NIEHS Division of Extramural Research and Training and a regular contributor to the Environmental Factor.)

Disclaimer: This report was written by members of the NIEHS staff based on materials prepared for this meeting and the discussions that took place there. It reflects the views of the authors and not necessarily those of the Rockefeller Brothers Fund, its trustees, or its staff.

 

Coach Barn of the Pocantico Center, which is also known as the John D. Rockefeller Estate  The meeting was held on the ground floor of the Coach Barn of the Pocantico Center, which is also known as the John D. Rockefeller Estate. Take a video tour.  (Photo courtesy of Ray Tice)
Ray Tice, Ph.D., and Kristina Thayer, Ph.D.  Tice, left, and Thayer take part in a discussion of the endocrine disruptor screening protocol. (Photo courtesy of Pete Myers)
Tiered Protocol for Endocrine Disruptors (TiPED) working group  The TiPED working group enjoyed the fall weather and the beautiful scenery at the Pocantico Center in Tarrytown, N.Y. (Photo courtesy of Ray Tice)

 

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Teaching Green Chemistry and Toxicology.

Thursday, October 11th, 2012

Teaching Green

Original published in Chemical and Engineering News, October 1, 2012

The Green Chemistry Commitment’s learning objectives are designed to ensure that chemistry majors have proficiency in essential green chemistry competencies.

A group of educators in the U.S. has grown impatient with the slow headway in integrating the concepts of green chemistry and toxicology into the undergraduate chemistry curriculum. They are ready to ask academic institutions for pledges to accelerate that progress through an initiative called the Green Chemistry Commitment.

Colleges and universities that sign the commitment agree to develop goals for implementing a core set of learning objectives, says Amy S. Cannon, executive director of the nonprofit organization Beyond Benign, in Wilmington, Mass., which is leading the initiative. The objectives outline the basics of green chemistry and toxicology that students should take with them to the workplace after they graduate, Cannon says.

At the top of the list of objectives is that students should have a working knowledge of the 12 Principles of Green Chemistry. These principles, developed 15 years ago, serve as a conceptual framework to guide the design, manufacture, use, and recycling or disposal of chemical products in an economically, environmentally, and socially responsible way. Additional learning objectives include having an understanding of the molecular mechanisms of how chemicals affect human health and the environment and being prepared to communicate the benefits of green chemistry to society.

“The principles of green chemistry direct chemists toward safer, less toxic, and renewable chemistry and materials,” Cannon says. “But to advance green chemistry, a significant change must occur in how we are training the current and next generation of scientists. The Green Chemistry Commitment is an effort to unite the chemistry education community around common learning objectives that have traditionally been absent from our training as chemists.”

Many institutions have already committed significant time and financial resources to introduce green chemistry concepts into lecture courses, substitute green chemistry laboratory exercises in place of traditional labs, and use green chemistry as a research framework, Cannon says. However, a widespread, systematic approach to green chemistry education doesn’t yet exist, she notes.

For example, the American Chemical Society’s guidelines for bachelor’s degree programs provide broadly defined requirements for approved departments and graduates receiving certified degrees (C&EN, Sept. 24, page 39). Green chemistry is currently listed as a potential cross-disciplinary track that could be taught as part of the overall requirements.

Green chemistry advocates argue that green chemistry should be integrated into the foundation course work on analytical, biological, inorganic, organic, and physical chemistry, Cannon says. However, the ACS guidelines are not designed to specify the content of these courses. “Rather than waiting for a mandate to teach green chemistry principles and toxicology concepts, which might be a long time in coming, we thought we should create a mechanism for the chemistry community to commit to changing the curriculum now,” she says.

The Green Chemistry Commitment is designed to be flexible so that each institution can adopt the objectives according to its resources and capabilities, Cannon explains. For example, some departments might focus on integrating green chemistry into core lecture and lab courses, whereas others might develop separate green chemistry or toxicology courses.

Each institution’s progress in meeting the objectives will be charted in an annual report that provides an opportunity to update goals to help drive continual improvement. The reports will be evaluated by the initiative’s advisory board made up of established members of the green chemistry community, and the results will be shared with other institutions.

One university that hopes to sign on to the commitment is the University of California, Berkeley. The university is a relative newcomer to green chemistry, notes John Arnold, director of the Berkeley Center for Green Chemistry and an adviser to the Green Chemistry Commitment. UC Berkeley made its first foray into green chemistry four years ago when graduate students asked for permission to start a green chemistry and sustainable design seminar, Arnold says. The university has been rapidly expanding its efforts from there.

UC Berkeley’s green chemistry program has two focal points, he explains. At the graduate level, the department offers the seminar course and a lecture course in green chemistry. Arnold says the goal is to help the next generation of leaders in chemistry begin their careers able to include green chemistry in the courses they teach and in their research.

“At the undergraduate level, we want to weave green chemistry into the fabric of what we teach, so that undergraduate students can take these concepts with them as they go into the world as doctors, lawyers, engineers, politicians, and businesspeople,” Arnold says. To help meet that goal, UC Berkeley developed new lab experiments for its general chemistry course for nonchemistry majors, which is taken by more than 2,000 students per year—about half of all freshmen.

The Green Chemistry Commitment:

◾ Theory: Have a working knowledge of the 12 Principles of Green Chemistry.

◾ Toxicology: Have an understanding of the principles of toxicology, the molecular mechanisms of how chemicals affect human health and the environment, and how to access the resources to identify and assess molecular hazards.

◾ Laboratory skills: Possess the ability to recognize, assess, and design greener alternative chemical products and processes.

◾ Application: Be prepared to serve society in their professional capacities as scientists through the articulation, evaluation, and employment of methods and chemicals that are benign for human health and the environment.

Read the remainder of the original article HERE.

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2012 American Chemical Society

 

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Building Links Between Green Chemists and Business in Education.

Wednesday, September 19th, 2012

On September 7 and 8, 2012, McGill University (Montréal, Canada) hosted a unique workshop designed to foster green innovation in the next generation. Ten MBA students from the Desautels Faculty of Management and ten PhD candidates from the departments of chemistry and civil engineering were gathered to reflect on this concept. Two guests speakers gave lectures putting green chemistry in the context of industry.

The first one, by Phil Dell’Orco, head of sustainability at GlaxoSmithKline (GSK), addressed the question of fostering and coordinating green chemistry in a large pharmaceutical company. Lynn Leger from Green Center Canada presented how her organization is constantly touring universities (in Canada and outside)

 

PHOTO: Phil Dell’Oroco, Process Engineering at GlaxoSmithKline. By Owen Egan for the McGill Reporter

to find scientific innovations and bring them to the market. She elaborated on  some of the challenges associated with the transition from research to the market. We also had a few smaller classes to introduce the concepts of green chemistry, such as the green principles and metrics, and what it takes to be successful in innovation, as well as green drivers of innovation.

Students were then divided into mixed groups (composed of both business and chemistry and engineering students) and had to work together on building a case study. They were given an innovation, coming straight from Green Centre Canada – an antibacterial compound mimicking garlic active ingredient. Students had to find a market, build a financial case and work some of the chemistry associated.

They came out of it with amazing presentations on their ideas and demonstrated outstanding ability to interact with people from a different  discipline. They all pointed out how much they appreciated being exposed to a difference academic culture and recognized the importance of building bonds across disciplines to bridge the gap towards greener innovations.

This workshop was made possible through funding from the CREATE program of  NSERC, a Canadian federal funding agency, and the Marcel Desautels Institute for Integrated Management. Steve Maguire (from the School of Management) and I created an organized the whole two-day event. And we’re very excited about it. We’ll definitely do it again next year.

Read about the workshop in the McGill Reporter.

By Audrey Moores, Ph.D.
Assistant Professor
Department of Chemistry
McGill University

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A switch to nature-based catalyst raises efficiency, reduces waste.

Thursday, August 23rd, 2012

Largeron, M, and M-B Fleury. 2012. A biologically inspired Cu(I)/topaquinone-like co-catalytic system for the highly atom-economical aerobic oxidation of primary amines to imines. Angewandte Chemie http://dx.doi.org/10.1002/anie.201200587.

Synopsis by Jean-Philip Lumb, Aug 23, 2012

A multistep process to produce intermediary chemicals for manufacturing can be done in one step with only three ingredients and little to no waste, report French chemists. Their method combines a starter catalyst with a small amount of copper and oxygen from the air to transform base compounds – called amines – into other chemical middlemen – known as imines. Manufacturers use imines extensively to produce products and drugs.

In comparison to current methods, the novel process is more efficient. It uses fewer chemicals, relies on safer chemicals, creates less waste and works under normal temperature and pressure. Additional studies will need to repeat and optimize the methods before they can be used on an industrial scale.

A major direction in the field of green chemistry is to develop ways to turn one chemical into another with no leftover atoms – and therefore little to no waste. This increases chemical efficiency. Calculating the number of atoms that go into the process and comparing them to what comes out in the end product is a way to measure chemical efficiency. These reactions – dubbed atom economy – strive to have the two equal each other.

Atom economy is a big shift away from the traditional processes that rely on additives known as activating reagents, which are added multiple times during a chemical synthesis to propel the reactions forward. Efficiency is reduced, since in each step, the activating reagent is not incorporated into the product and is lost as waste.

This is particularly troubling when producing pharmaceuticals where multiple steps are required to transform starting materials into commercial products. In these cases, activating groups increase chemical waste, since activation often requires an additional step in the overall sequence and frequently creates equal amounts of a byproduct.

Activating reagents are usually needed for oxidation reactions, which are particularly important in chemical production. During oxidation, hydrogen is removed from its parent molecule and is added to another. The process is chemically inefficient because it creates an equal amount of chemical waste for each molecule that is oxidized.

Researchers are looking to plants and animals for natural ways to improve efficiency during oxidation reactions. One way is to replace activating reagents with catalysts. Biological systems are extremely efficient and routinely use catalysts in reactions where the chemical industry uses activating reagents. Unlike activating reagents, catalysts can be used in very small quantities. This would dramatically reduce chemical waste, since small quantities of catalysts affect a reaction and they can be frequently recovered after a reaction.

In this study, researchers in France have accomplished this by replicating the activity of an important class of enzymes known as copper-containing amine oxidases (CuAOs). These enzymes control the concentration of nitrogen-containing molecules in numerous biological settings, including in people. The enzymes drive the oxidation of an amine to an imine. By carefully modulating the reaction conditions, the authors were able to produce a variety of imines from readily available starting materials under very mild conditions. Water was the only byproduct.

The authors note the reactions will need more tweaking before they can be used industrially. Nevertheless, the reaction conditions go a long way toward alleviating the typical waste associated with amine oxidation and provide a promising direction for future research.

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The above work by Environmental Health News is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Based on a work at www.environmentalhealthnews.org.

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No more butts: biodegradable filters a step to boot litter problem.

Tuesday, August 14th, 2012

 

Robertson, R, W Thomas, J Suthar and D Brown. 2012.  Accelerated degradation of cellulose acetate cigarette filters using controlled-release acid catalysis. Green Chemistry http://ds.doil.org/10.1039/C2GC16635F.

 

Synopsis by Marty Mulvihill and Wendy Hessler, Aug 14, 2012

Context

Every year over 6 trillion cigarettes are manufactured globally. Approximately 99 percent have a filter tip. After the cigarette is smoked, the used filter is called a butt and is thrown out. When littered, cigarette butts often take years to break down.

Most filters are made using cellulose acetate fibers. More than 2 billion pounds of cellulose acetate is produced every year to meet the world demand for filters. To make it, acetic anhydride is added to cellulose fibers made from wood or cotton. The reaction creates a type of plastic that provides a stronger, more rigid filter.

By itself, cellulose fibers degrade naturally in the environment. Cellulose acetate plastic degrades very slowly.

The slow degradation, along with indoor smoking bans, mean increasingly large numbers of cigarette butts are found in public places, including parking lots, parks and beaches every year. Cigarette waste is the number one reported item collected during beach clean-ups, according to the Ocean Conservancy. In some coastal towns as many as 1 in 10 cigarette butts end up polluting the waterways.

The discarded butts are more than just an eyesore. The filters contain chemical residue from the tobacco. The residue can be toxic to marine animals. Cigarette butts are commonly found in the stomachs of dead shore birds.

One way to decrease the litter would be to create cigarette filters that degrade quickly. Previous attempts used plant-based products like cornstarch, hemp, flax or cotton. One brand of biodegradable filter, Greenbutts, incorporates plant seeds that would germinate after disposal. To date, cigarette manufacturers have not widely adopted alternative filters.

The demand for degradable filters may increase as states – including New York – consider levying taxes on non-biodegradable cigarette filters. In response, there is renewed interest to make cigarette filters degrade faster.

What did they do?

A group of chemists wondered if a cellulose acetate plastic filter could be converted back into natural, degradable cellulose after it was used. If so, the cigarette butts should degrade much more quickly.

They guessed that small amounts of acid added to the filter should speed the degradation process.

First, they measured the degradation rate of cellulose acetate using a wide range of acids with different strengths. Combinations of acids were also tested to find which worked best to make cigarette filters that retained their structure and function while degrading faster.

Next, they created an effective additive based on which acids worked best. The additive needed to be acidic, non-toxic and allow the cigarette to burn normally. To find one, they looked to acids common in food, including citric acid, phytic acid and vitamin C (ascorbic acid), as well as stronger mineral acids not commonly considered safe food additives.

The new filter design was tested. A smoking machine “smoked” the cigarettes, and the butts were left outside and monitored.

What did they find?

In the first tests, the butts exposed to water and a small amount of acid broke down faster than those not exposed to acid. Strong acids worked best to efficiently speed the degradation of the cellulose acetate fibers. In particular they found that sulfuric acid was the most effective catalyst.

Sulfuric acid, however, is not safe to put into cigarette filters. The researchers devised a way to generate the stronger acid only after the cigarette was smoked. The smoker would not be exposed to any additional harmful compounds, and the filter would degrade more quickly.

To make the acid additive, the researchers combined safer chemicals – cellulose sulfate, citric acid and phytic acid – into a tablet. When the tablet got wet, these ingredients mixed and released small amounts of sulfuric acid that degraded the filter material. The tablets were coated with ethyl cellulose and cellulose acetate to shield the acid precursors from premature exposure to water.

After 14 days outside, the butts containing the acid tablet were more acidic and tested positive for the presence of sulfuric acid, while the control butts remained unchanged. At the end of the 90-day trial, the new filters were considerably more degraded than the controls. Unfortunately they had not degraded as much as expected based on the laboratory experiments.

What does it mean?

Small amounts of strong acid increase the degradation rate of the cellulose acetate fibers found in cigarette butts. Although the idea worked in principle, the outside trials did not live up to the promise of the laboratory results.

The research is important because it is a step towards making a truly degradable and functional cigarette filter. This research shows how green chemistry can improve existing technology. The researchers designed the new filters for degradation while making safer chemical choices. This approach will ultimately minimize waste and hopefully prevent some of the toxic exposures to birds and other wildlife.

Under laboratory conditions, the acid converted the filter plastic into a biodegradable material within 30 to 60 days, depending on temperature. The food grade acids and materials generated the strong acid only after the cigarette had been smoked. These preliminary results indicate that acidic additive in the filter could reduce the time it takes for cigarette butts to degrade in the environment.

Several problems will need to be resolved before large manufacturers could adopt the use of acid tablets in cigarette filters. The filter’s effectiveness – improved degradation and materials safety of materials – will need to be quantified in clinical and environmental trials. This will take more research to design and incorporate the acid precursors into the filter body.

Cost and performance are also issues. The acid materials must be incorporated into cigarettes at a low cost without harming the performance of the product.

Researchers will llkely pursue this technology as well as other approaches to a biodegradable cigarette filter in an effort to reduce cigarette butt litter.

Resources

Clean Virginia Waterways and Longwood University. 2012. Cigarette butt litter. http://www.longwood.edu/cleanva/cigarettelitterhome.html.

Novotny, T, K Lum, E Smith, V Wang, and R Barnes. 2009. Cigarettes butts and the case for an environmental policy on hazardous cigarette waste. International Journal of Environmental Research and Public Health http://dx.doi.org/10.3390/ijerph6051691.

Ocean Conservancy. A rising tide of ocean debris, International Coastal Clean-up 2009 Report. http://www.oceanconservancy.org/pdf/A_Rising_Tide_full_lowres.pdf.

Register, K. 2000. Cigarette butts as litter: Toxic as well as ugly. Underwater Naturalist: Bulletin of the American Littoral Society http://www.longwood.edu/CLEANVA/ciglitterarticle.htm.

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Mother Nature shows how to improve solar technology.

Monday, August 13th, 2012

Yang, N, Y Zhang, J Halpert, J Zhai, D Wang and L Jiang. Granum-Like stacking structures with TiO2 –graphene nanosheets for improving photo-electric conversion. Small http://dx.doi.org/10.1002/smll.201200079.

Synopsis by Marty Mulvihill, Aug 01, 2012

Researchers have improved solar cell performance by looking to leaves. The prototype mimics a leaf’s chemical layers that catch the sunlight and send the energy to plant cells. The bio-inspired solar cells were 20 times better at creating electricity than traditionally designed solar cells made from the same materials.

Solar power is an attractive energy source because it is free, readily available, clean and sustainable. To tap into this rich resource, solar power cells installed on roofs and in deserts capture and convert light to energy. But current types of cells remain inefficient and costly.

Researchers have been trying for more than two decades to build better cells by mimicking plants’ ability to harness the power of sunlight. Plants – through photosynthesis – naturally do this.

The layered design is unique because it takes advantage of an often overlooked leaf architecture that improves the efficiency of energy conversion. The results of the Chinese study are published in the journal Small.

Leaves have a specialized, layered structure called a granum, which collects light from the sun and turns it into energy the plant can use. The researchers identified two key features of the granum that could help improve solar cells: a stacked structure and a design to efficiently transfer energy.

Inside a plant granum are thin alternating layers of pigment molecules that absorb the light and molecules that turn the sun’s rays into electrical energy then used in chemical reactions. The researchers modeled their solar cell on this design. They created alternating layers of titanium dioxide – which absorbs the light, and graphene – which transports the energy.

The addition of graphene to solar cell design allows more efficient transport of the energy away from the titanium dioxide. When the graphene layers were not used, much of the energy absorbed by the titanium dioxide was lost before it could be captured as electrical energy.

Since the graphene layers improve transport of electrical energy, the researchers used many more layers of titanium dioxide, collected more light and increased the amount of light collected.

The results show the alternating, layered structure found in a plant’s granum can improve the performance of solar cells. The design has not been tested in a full-scale solar cell device. More work needs to be done to improve the safety and efficiency of the synthesis process before solar cells based on this technology could reach the market.

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The above work by Environmental Health News is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Based on a work at www.environmentalhealthnews.org.

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“Don’t put that junk on your junk”

Wednesday, July 18th, 2012


I recently said this to my favorite cyclist when discussing that he may not want to apply chamois cream containing parabens (the junk) to his junk. Male cyclists are repeatedly applying (maybe daily, for 5-7 hours at a time) these paraben containing creams to their reproductive parts. Research is showing that maybe they should reconsider.

 

You may see parabens listed as “methylparaben” “propylparaben” or “butylparaben” Etc.  Don’t let that fool you; these compounds are all structurally and functionally similar compounds, each just has an additional carbon group – the methyl, propyl, or butyl.

 

Parabens’ alias is alkyl hydroxy benzoate, not as easily recognizable, but still present on food and cosmetic labels. You can find these parabens in hair products, skin care products, or even your salad dressing! For male cyclists, they are in most creams that are applied to the groin area to alleviate chafing against the saddle of the bike.

 

Studies have shown that parabens can mimic the female sex hormone estrogen (Gomez et al 2005) and in turn can act as endocrine disruptors, inhibiting “testosterone (T)-induced transcriptional activity” (Chen et al 2007). Also, “exposure of post-weaning mammals to butyl paraben adversely affects the secretion of testosterone and the function of the male reproductive system.” Similar effects can be seen with propyl paraben (Oishi 2002).

 

What are other potential effects of this chemical on males? Recent research has shown parabens in association with  breast cancer, though causality has not yet been established (Khanna et al 2012).  This may seem irrelevant for men unless one considers the fact that breast cancer among men is actually on the rise.

 

Additionally, these chemicals may reduce male fertility. Butylparaben was shown in the lab to have an adverse effect on the male mouse reproductive system in that it damaged the late steps of spermatogenesis in the testis (Oishi 2002). Similar effects can be seen for other forms of parabens. They are also suspected of affecting the mitochondria in rat testes, reducing virility (Tavares et al 2008).

 

Male cyclists might want to look for anti-chafe chamois creams that do not contain parabens, such as creams containing lanolin, the oil in sheep’s wool. You can even make lanolin cream in your own home, following this recipe (but make sure the lanolin you use is high quality and pesticide free).

 

Alternatively, one can pay closer attention to the label on chamois cream to ensure that it does not contain parabens.

 

If you are a cyclist, know a cyclist, or love a cyclist, please share this with them.

 

By: Mana Sassanpour

 

Sources:

1. Antiandrogenic properties of parabens and other phenolic containing small molecules in personal care products. J. Chen, K.C. Ahn, N.A. Gee, S.J. Gee, B.D. Hammock, B.L. Lasley. Toxicology and Applied Pharmacology. Volume 221, Issue 3, 278–284, 2007.

 

2. Effects of propyl paraben on the male reproductive system. S. Oishi. Food and Chemical Toxicology. Volume 40, Issue 12, 1807 – 1815, 2002.

 

3. Estrogenic activity of cosmetic components in reporter cell lines: parabens, UV screens, and musks. E. Gomez, A. Pillon, H. Fenet, D. Rosain, M. J. Duchesne, J. C. Nicolas, P. Balaguer, C. Casellas. 
Journal of Toxicology and Environmental Health, Part A 
Vol. 68, Iss. 4, 2005.

 

4. Male breast carcinoma: increased awareness needed. J. White, O. Kearins, D. Dodwell, K. Horgan, A.M. Hanby, V. Speirs. Breast Cancer Research. Volume 13, Issue 5, 219, 2011.

 

5. Organ toxicity and mechanisms: effects of butyl paraben on the male reproductive system in mice. S. Oishi. Archives of Toxicology. Volume 76, Number 7, 423-429, 2002.

 

6. Parabens enable suspension growth of MCF-10A immortalized, non-transformed human breast epithelial cells. S Khanna and P.D. Darbre. Journal of Applied Toxicology. doi: 10.1002/jat.2753, 2012.

 

7. Parabens in male infertility—Is there a mitochondrial connection? R.S. Tavares, F.C. Martins, P.J. Oliveira, J. Ramalho-Santosa, F.P. Peixoto. Reproductive Toxicology. Volume 27, Issue 1, 1-7, 2009.

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