Artificial sweetener leaves lingering aftertaste in the environment


June 15, 2011


Recently, the global use of artificial sweeteners in foods has dramatically increased. A new study led by César Torres, and Rosa Krajmalnik-Brown – researchers at the Biodesign Institute at Arizona State University – examines the trail of sucralose, one of the most popular of such products, after it is digested in the human body.


ASU researchers, along with their collaborators, report in a recent issue of the journal Environmental Engineering Science, that sucralose is remarkably resistant to breakdown processes common in wastewater treatment plants, ultimately finding its way into ground and surface waters. Download Full Image


The full effects of growing quantities of sucralose in the environment are presently unknown. “Sucralose is a chlorinated sugar. Some of my work focuses on bioremediation of chlorinated organics,” says Krajmalnik-Brown. “I know that many are toxic and they are more difficult to biodegrade than the non-chlorinated counterparts. Because of this, I became interested in sucralose and its fate in the environment.”


The initial experimental work was performed by Smitha Ramakrishna, who at the time was a high school intern at the Biodesign Institute. For her innovative research, she received multiple awards including the Arizona Governor’s Future Innovator Award (2008), and the Stockholm Junior Water Prize Regional Winner (2008). She continues her studies in the field at the Department of Environmental Science and Public Policy at Harvard College, Harvard University.


Artificial sweeteners appear in a dizzying assortment of consumer products. Sucralose – a chlorinated carbohydrate popularly marketed under the brand name Splenda® – iis one of the most ubiquitous, appearing in over 4000 products sold in over 80 countries. Its widespread adoption followed approval by the U.S. Food and Drug Administration in 1999. Launches of new products containing the sweetener increased by 15 percent in 2009 and total worldwide sales increased by 14 percent in 2010.


Sucralose and other artificial sweeteners are used for a variety of reasons, most commonly as low calorie weight-loss alternatives to sugar and for those suffering from glucose-related ailments like diabetes. Prior studies have indicated that sucralose is not broken down by the human body, but passes instead through the digestive tract to be expelled in feces and urine.


While some studies suggest that sucralose has very low toxicity, making it safe for human consumption, it has recently been shown in animal models to have measurable impact on the chemical and microbiological condition of gut microflora. The full implications of these changes and their relevance to human consumption of sucralose have yet to be properly investigated.


What is currently known, is that essentially all of the sucralose consumed in foods ultimately winds up in wastewater treatment plants. Here, domestic and industrial sewage will undergo several stages of treatment, designed to degrade or remove harmful elements, before they are expelled into natural waterways. Such treatment plants use a combination of physical, chemical and biological processes to treat wastewater and remove potentially harmful organic substances.


The molecular structure of sucralose is hydrophilic, meaning that it is highly soluble in water and unlikely to settle out of solution. For this reason, chemical processes (including disinfection) or biological processes (either anaerobic or aerobic degradation) offer the only alternatives.  The new study however, shows that these processes are similarly ineffective in degrading sucralose in wastewater treatment facilities.


The effectiveness of anaerobic and aerobic treatment of sucralose was evaluated through the field sampling of wastewater and surface water. The aim of the study was to identify what elements in the treatment process could be manipulated to successfully degrade sucralose, prior to its entry into the environment. 


Sampling of wastewater was carried out at seven full-scale wastewater treatment plants in southern Arizona. Lab-scale anaerobic and aerobic biodegradation of sucralose was examined in biological batch reactors, which ran for at least 48 days. The results of the wastewater sampling showed that at each of the seven treatment facilities, no correlation could be detected between the level of treatment and sucralose concentration, indicating that sucralose was highly resistant to all forms of degradation.


In the batch reactors, degradation of wastewater sludge was examined under three experimental conditions, using sucrose, sucralose, and a combination of the two.  None of the experimental conditions yielded significant sucralose degradation.  The group also examined one of the final stages of conventional wastewater treatment, in which chlorine, O3 or UV light are used to disinfect and degrade those compounds resistant to other means of breakdown. In all three cases, degradation of sucralose was found to be negligible.


The authors stress that the resistance of sucralose to degradation may have a positive side, in that intermediary chlorinated products, which may be highly toxic to humans are not produced. Further, the resiliency of sucralose may make it useful to environmental engineers as a labeling agent to trace wastewater contributions to the environment.


The study showed that successful breakdown of sucralose would require additional interventions above and beyond conventional wastewater treatment, for example the use of filtration through activated carbon, which has been shown in other studies to enhance sucralose removal. In the meantime, the study establishes that sucralose is able to endure existing treatment and to travel significant distances from its point of discharge. With sucralose production and use increasing at such a rapid clip, it is of vital concern that long-term environmental impacts to plant and animal species as well as to humans be addressed.


Richard Harth

Biodesign Institute

480-727-0378

Lisa Robbins

editor/publisher, Media Relations and Strategic Communications

480-965-9370

ASU hosts candid talk about 'Future Energy Abyss'


June 15, 2011


American Public Media’s Marketplace™ and The Gary Comer Global Agenda, in partnership with Arizona State University’s Global Institute of Sustainability, will present Moving By Degrees – The Future Energy Abyss, at 5:30 p.m., June 16, at the Walter Cronkite School of Journalism and Mass Communication, First Amendment Forum Room, Downtown Phoenix campus.


The program will be an intimate conversation between David Brancaccio, senior correspondent, Marketplace’s Economy 4.0 and retired Shell Oil President John Hofmeister, one of the world’s foremost experts on energy and climate. They will discuss everything from climate change and energy independence to global energy leadership and the unrest currently remaking the Middle East. Download Full Image


“We’re proud to bring someone of John’s prominence and experience to our public forum to share his story,” said JJ Yore, general manager, Marketplace. “Storytelling is a vital way to share what is happening, and for the last five years, our Marketplace programs have been reporting on sustainability topics from around the world and showcasing how they affect people, business, politics and daily life.”


As Shell President, Hofmeister launched an extensive outreach program, unprecedented in the energy industry, to discuss critical global energy challenges. The program included an 18 month, 50-city tour across the country during which Hofmeister led 250 other Shell leaders to meet with more than 15,000 business, community and civic leaders, policymakers, and academics to discuss what must be done to ensure affordable, available energy for the future.


Hofmeister retired from Shell Oil in 2008, and building on his outreach program, he founded the non profit, nationwide membership association and public policy education firm, Citizens for Affordable Energy (CAE). He’s also authored a book “Why We Hate The Oil Companies: Straight Talk From an Energy Insider” (Palgrave Macmillan 2010). Hofmeister also serves as distinguished sustainability scholar, Global Institute of Sustainability and the Julie A. Wrigley Private Sector Executive-in-Residence, School of Sustainability at Arizona State University.


“Our efforts at the Global Institute of Sustainability are to advance knowledge for applied and practical solutions, engage decision-makers, span boundaries, treat science and social context equally and lead by example,” said Rob Melnick, executive dean, Global Institute of Sustainability, School of Sustainability. “I believe John Hofmeister’s experience and latest efforts embody all of those guiding principles and I look forward to hearing his story.”


With both international and domestic energy and climate policy at a crossroads, the need for public understanding around energy, climate and the economy has never been greater. Over the past several years, Marketplace has brought together top scientists, business leaders and experts in policy, journalists and students to assess and discuss the prospects for a sustainable future.


Parties interested in attending the event in-person, must make a reservation. Reservations can be made via http://sustainability.asu.edu/events/rsvp/apm" mce_href="http://sustainability.asu.edu/events/rsvp/apm" target="_blank">sustainability.asu.edu/events/rsvp/apm.


A copy of the event recording will be made available to the public for viewing via the web site movingbydegrees.org, by the end of June.


For further details on the event, please visit http://movingbydegrees.org/" mce_href="http://movingbydegrees.org" target="_blank">movingbydegrees.org or http://sustainability.asu.edu/events" mce_href="sustainability.asu.edu/events.">http://sustainability.asu.edu/events">sustainability.asu.edu/events....


About Marketplace

Marketplace reports on business, the economy and money as they affect people every day. The portfolio reaches 9.3 million listeners each week on more than 500 public radio stations through its award-winning news shows: Marketplace Morning Report; Marketplace; Marketplace Money; and Marketplace Tech Report. Moving by Degrees is an initiative from the Marketplace sustainability desk to provide noteworthy environmental and sustainability coverage. For more information on Marketplace, please visit http://marketplace.publicradio.org/" mce_href="http://marketplace.publicradio.org" target="_blank">marketplace.publicradio.org.


About The Comer Education & Science Foundation

The Comer Education & Science Foundation is a private, family foundation (a 501(c)(3) tax-exempt entity) dedicated to supporting innovative programs making a positive impact on the lives of individuals and communities. The Foundation was incorporated on June 29, 1998. The Foundation provides funding for organizations in an array of fields including education, environment, health and social services as well as neighborhood rehabilitation. For more information on The Comer Education and Science Foundation, please visit http://www.cs-ef.org/" mce_href="http://www.cs-ef.org/" target="_blank">www.cs-ef.org/.


About The Global Institute of Sustainability

The Global Institute of Sustainability is the hub of Arizona State University’s sustainability initiatives. The Institute advances research, education, and business practices for an urbanizing world. Its School of Sustainability, the first of its kind in the U.S., offers transdisciplinary degree programs focused on finding practical solutions to environmental, economic, and social challenges. For more information on The Global Institute of Sustainability, please visit http://sustainability.asu.edu/" mce_href="http://sustainability.asu.edu" target="_blank">sustainability.asu.edu.

Michelle Schwartz

Senior Manager, Marketing and Communications, Julie Ann Wrigley Global Institute of Sustainability

480-727-6302