Tag Archives: bioaccumulation

Smelling good without stinking up the environment.

Boethling, RS. 2011. Incorporating environmental attributes into musk design. Green Chemistry http://dx.doi.org/10.1039/c1gc15782e.

Synopsis by Wim Thielemans, Dec 01, 2011

Chemists developing compounds used to create fragrances can weed out chemicals that don’t meet toxicity and environmental standards early in the design process, finds a study that predicted the toxicity and persistence of a variety of musk chemicals using a sophisticated computer program.

The program – developed by the U.S. Environmental Protection Agency – uses molecular structure and other chemical attributes to predict if a compound will easily break down in the environment. The results are published in the journal Green Chemistry.

While the tools are not perfect, they help for early screening. One important use would be to compare the environmental effects of chemical classes or individual molecules to determine whether to proceed or block a chemical’s development. Further analysis and testing on the musks given the go ahead would still be needed to avoid producing a harmful molecule that might not be tagged as dangerous at this stage of development, because the computer modeling did not consider many potential mechanisms of toxicity, for example, whether or not the molecule is a potential endocrine disruptor.

The findings show that chemists can avoid making certain types of musks that may be harmful. Musks add scent to consumer products and can harm the environment. Predicting a compound’s later performance at a very early stage – even before the molecules are made – would make design and development of safer fragrance musks much cheaper.

Fragrances are used in a wide variety of products from the obvious perfumes to soaps, detergents, shampoos and toothpastes. The natural and synthetic musk compounds produce the rich and deep smells that form the base of some fragrances. The long-lived musks are chemically heavy and evaporate slowly. Their scents surface well after their use – at least 30 minutes – and may linger for a day. They also help hold lighter smells for a longer period of time.

These same longevity properties mean the compounds tend to end up in municipal wastewater and its solid sludge, which is often reused as fertilizer. Through these routes, musk compounds are released into the environment. They can accumulate in soils, wildlife and people. Several synthetic musks are toxic to fish, algae and aquatic invertebrates.

Chemists still design new synthetic musks. They use tools to predict the compounds’ future performances as a fragrance. A similar tool to predict their toxicity, their accumulation in the environment and their persistence in the environment is needed. A compound persists in the environment if it does not biodegrade.

The new research from the U.S. EPA looked at 106 synthetic and natural musk chemicals. The predictions on the environmental impact of these musks were compared to experimental data.

The study found and identified specific types of musks that were less problematic than others. It also verified that existing tools and knowledge could be used to screen new molecules for their potential to be toxic, not break down and accumulate.

According to the author, the research shows “that it can be convenient and useful to include environmental properties in that screening prior to any testing or manufacture of a chemical.” The tools and knowledge exist, and it is time to apply them to chemical production for “economic as well as environmental sense.”

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

ORD Chief Sees Need For EPA To Craft Green Chemistry ‘Design’ Guidance.

Bridget DiCosmo InsideEPA.com. Originally Posted: Mar. 14

2011 EPA’s research chief Paul Anastas is calling for the agency to begin crafting a guidance for how to design benign industrial chemicals and chemical processes, and establish metrics and criteria for both design and assessment of what specific chemical properties should be considered in reducing a substance’s ability to manifest hazard.

Anastas told the Society of Toxicology’s (SOT) 2011 annual meeting in Washington, DC, March 8 that the agency should set as a goal development of a set of design parameters that establish criteria about the properties of new chemicals that render it intrinsically less hazardous than comparable substances currently in the marketplace. “The goal is to develop a set of design rules that can inform and be useful — just inform and be useful — for molecular design and reduced hazard,” Anastas said, during the meeting. Anastas’ presentation to SOT, “Molecular Design for Reduced Hazard,” floated a set of “design protocol” criteria for modifying chemical properties in new chemicals that could potentially pose hazard that should be considered within such a framework, such as reduced bioavailability of a chemical, or its ability to reach the system of an organism.

“One of the grand challenges of molecular design is thinking about this in a systemic way,” Anastas said. The need to transition ORD’s current risk assessment paradigm into a more systemic and sustainable approach has been a long-standing priority of Anastas’ at the agency, culminating recently in the development of a newly integrated research program, Chemical Safety for Sustainability, which includes green chemistry in its planned research agenda

The approach Anastas is suggesting appears to be different from that currently used by the agency’s toxics office, which uses a set of alternatives assessment criteria, including bioaccumulation potential of substances, to qualify products for its Design for Environment (DfE) labeling program. But for the most part that methodology is based on specific toxicity endpoints, like carcinogenicity, rather than using chemical properties to evaluate the mechanistic potential of a chemical to cause adverse effects.

Anastas said that the pharmaceuticals industry considers a general, uniform set of criteria meant to circumvent hazard in its drug manufacturing processes, saying the industry approach “couldn’t be more different from the vast majority of industrial chemicals in design purposes.”

Anastas’ remarks also take the agency some way toward adopting a definition of green chemistry — an approach some environmentalists and public health advocates have previously called for EPA to adopt in order to limit chemicals’ toxicity.

Read the entire story at Inside EPA.com

Pigments may be a new source of PCBs.

Pigments may be a new source of PCBs.

Jul 09, 2010

Hu, D and KC Hornbuckle.  2010.  Inadvertent polychlorinated biphenyls in commercial paint pigments. Environmental Science and Technology 44(8):2822–2827.

Synopsis by Evan Beach
Environmental engineers report that common paint pigments – more types than previously thought – are contaminated with PCBs and may be an ongoing source of exposure for people.

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Researchers at the University of Iowa have discovered that PCBs are present in many more kinds of paint pigment than previously known. While the U.S. Environmental Protection Agency knew about some of the contamination, the extent of the problem is a surprise.

The researchers suggest that the contaminated pigments used in a variety of paints, inks, cosmetics, plastics and other consumer goods are probably a source of ongoing exposures in humans.

PCBs are persistent and bioaccumulating toxic chemicals that have been largely banned from use in the United States since the 1970s. They can still be detected in air, water and people.

In the study, the scientists measured PCB levels in paints produced by Sherwin Williams, PPG and Vogel. The PCBs were only found in paints with certain kinds of colored pigments, belonging to two of the major classes of synthetic dye molecules.  From that information, the researchers were able to pinpoint the mechanisms by which PCBs could be formed unintentionally during manufacturing.

PCBs contain the element chlorine. During manufacturing, PCBs could form from reactions involving raw materials or solvents that contain chlorine. The use of chlorobenzene solvents, for example, led to PCB contamination in pigments with no chlorine in their chemical structure.

From a green chemistry perspective, this information could be used to design a new manufacturing process free of chlorinated materials.

The researchers pointed out that the levels of PCBs found in the paint samples were below regulatory thresholds, but the ubiquity of pigments in urban areas and the ability of PCBs to bioaccumulate may increase exposures.

There are hundreds of possible structures for PCBs, and some are more toxic than others. The researchers detected a wide variety of structures, including some of the most toxic, dioxin-like PCBs.

The connection between modern pigments and global PCB pollution is suggested because some of the PCBs found in the paint samples were not produced on a large scale before bans took effect. Those PCBs have been found by other researchers worldwide in air and surface water as well as waste streams from pigment manufacturing.