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
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
For my third and final interview in the Virginia Tech series, I had the privilege of interviewing Dr. Felicia Etzkorn (pictured left), pioneer of the green chemistry course at Virginia Tech. The green chemistry course was her idea back in 2003. She and her colleague, Dr. Tim Long, decided to team-teach it just for fun. A couple of years later Dr. Etzkorn decided she was going to approach it more seriously. As a result, she had to write a course proposal for Virginia Tech’s course catalogue. The course was approved by three different curriculum committee levels. Afterwards, she developed course material and lectures, and taught the class for three years, from 2007 – 2009. She is excited to be teaching it again this Spring 2012.
and heat the mixture to get the polymer following lab procedures. Then the students made small toys by pouring polymer into clay molds they made in art class (pictured right – the brown items: shells, lips et.c are the PLA polymer, the grey figures are clay molds.). Since it does biodegrade the students were even encouraged to compost it. They were really enthusiastic about green chemistry.
No more butts: biodegradable filters a step to boot litter problem.
Tuesday, August 14th, 2012Robertson, 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.
What did they do?
What did they find?
What does it mean?
Resources
More new science from EHN
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.
14 August No more butts: biodegradable filters a step to boot litter problem. Environmental Health News.
13 August Catalyst could zap methane emissions. Chemical & Engineering News.
9 August Liquid protein challenges importance of water. New Scientist.
3 August Mother Nature shows how to improve solar technology. Environmental Health News.
31 July California releases draft rules to reduce chemicals of concern in consumer products. Bloomberg BNA.
Green chemistry
Tags: biodegradable, biofeedstocks, plastics, replacements, water
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