Tag Archives: plastics

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

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

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

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

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

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

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

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

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

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

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

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

See original post in Environmental Health Sciences

What do you think? Is SynBio the next big scary thing?

The Sins of Syn Bio

How synthetic biology will bring us cheaper plastics by ruining the poorest nations on Earth.

By Jim ThomasPosted Wednesday, Feb. 2, 2011, at 10:00 AM ET

This article arises from Future Tense, a collaboration among Arizona State University, the New America Foundation, and Slate. A Future Tense conference on whether governments can keep pace will scientific advances will be held at Google D.C.’s headquarters on Feb. 3-4. (For more information and to sign up for the event, please visit the NAF Web site.)

An aerial view of rainforest. Here’s a grim prediction to chew on. This biotech craze dubbed “synthetic biology“—where hipster geeks design quirky life-forms: That technology is going to wind up costing lives—likely a lot of them. I’m not suggesting a direct kill by rogue viruses. These will be economic deaths. The dead will not be noteworthy: farmers, pastoralists, and forest dwellers who live in poor nations that depend on plant commodities. Here’s a grim prediction to chew on. This biotech craze dubbed “synthetic biology“—where hipster geeks design quirky life-forms: That technology is going to wind up costing lives—likely a lot of them. I’m not suggesting a direct kill by rogue viruses. These will be economic deaths. The dead will not be noteworthy: farmers, pastoralists, and forest dwellers who live in poor nations that depend on plant commodities.

Syn bio is feted as the next big thing, but we should be clear-eyed about what makes syn bio such a big deal and about whom it will harm. Its advocates predict that synthetic bio will lead to the “New Bioeconomy,” in which we harness biology to perform tasks now accomplished by manufacturing. Read more.

Distinctions between biopolymers and bio-based polymers important (Media review).

Posted by Evan Beach at Nov 08, 2010 04:00 AM | Permalink

The origins of bio-based plastics need to be clarified in a Vancouver Business Journal article that highlights the use of the materials in industrial applications.

A recent story in the Vancouver Business Journal provides an overview of the challenges manufacturers face when trying to work with plastics that incorporate natural molecules – so-called bio-based plastics. Companies are exploring new ways to handle the raw materials and optimize the molding process.

The article draws attention to an important trend in the world of plastics and green chemistry, but could have been more precise in the language used when referring to the polymers involved. Polymers are large molecules made of smaller, repeating molecules that are chained together.

The reporter does a good job of explaining the difference between two major types of bio-based polymers: “biodegradable” and “compostable” polymers. The distinction can be important  when manufacturers or consumers choose an environmentally friendly disposal method for a particular material. International standards define a biodegradable polymer as one that breaks down into smaller fragments due to the action of bacteria and other microorganisms. To be “compostable,” a polymer must degrade completely into carbon dioxide, water, minerals and biomass; and it has to do this quickly without hurting the overall compost process.

He could have also clarified that biopolymers and bio-based polymers are different.  “Biopolymer” refers to polymers that occur in nature or are produced by biological action. Cellulose, starch, proteins and polyesters made by bacteria (known as PHAs) are examples of biopolymers.

Then there are the synthetic polymers – like polylactic acid (PLA). These materials usually biodegrade and are made from biological raw materials, but are prepared by chemical methods.  PLA is made up of small molecules found in nature, but the polymerization process is a human invention. Similarly, nitrocellulose, which was historically used in photographic film, is a chemically modified version of a natural material, but does not occur naturally. PLA and nitrocellulose would be more accurately referred to as “bio-based” or “bio-derived” polymers.

These distinctions may seem minute, but they help clarify for manufacturers, regulators and consumers to what extent a material is truly natural.

Soy plastics targeted for electronic circuit boards.

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

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

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

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

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

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

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

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

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

A safer flame retardant protects an everyday plastic.

Xiang, H, C Sun, D Jiang, Q Zhang, C Dong and L Liu. 2010.  Flame retardation and thermal degradation of intumescent flame-retarded polypropylene composites containing spirophosphoryldicyandiamide and ammonium polyphosphate. Journal of Vinyl and Additive Technology 16:161-169.

Synopsis by Evan Beach, Sep 10, 2010

Polypropylene plastic (PP) was less flammable yet remained strong when mixed with two chemicals considered safer than those currently used as flame retardants, report Chinese researchers. The chemical blend achieved the highest flame retardancy rating in standardized tests without significantly impacting the strength of the plastic.

PP, which is coded as number 5 in plastic recycling, is used in numerous consumer products including carpets and thermal underwear.

The new flame retardant is a step forward in finding an alternative to traditional systems that are based on halogen-containing chemicals and antimony trioxide, say the researchers who developed the chemical blend. Alternatives are desired to prevent toxic, corrosive gases from forming during fires. Also, several classes of halogen-based flame retardants – like polybrominated diphenyl ethers – are raising concerns about persistence in the environment, toxicity and accumulation in animals and humans.

One of the additives, ammonium polyphosphate, is well known as a flame retardant, but by itself it cannot protect PP. The scientists invented a second additive –  spirophosphoryldicyandiamide (SPDC) – that created synergy in the polymer blend. In the presence of a flame, the two additives formed a protective char layer that shielded the inside of the plastic from heat and prevented flaming drips. The combination also reduced heat, carbon monoxide gas and smoke.

Cost might limit the practicality of the new system. However, perfomance was adequate when the more expensive SPDC chemical was limited to just 25 percent of the flame retardant combination. The total amount of additives in the experiments was 30 percent of the plastic by weight.

The researchers showed that the new additives are safer compared to halogenated chemicals during fires. But, the overall green benefits of their technology are still not calculated. Further testing of the blends’ leaching, persistence and toxicity is necessary.  Also, several highly toxic starting materials – like dicyandiamide and phosphorus oxychloride – are needed to make SPDC. These would be dangerous to workers and surrounding communities in the event of an accident.

Article misleads on BPA alternatives.

By Laura Vandenberg Aug 02, 2010 06:00 AM | Permalink

In reviewing a proposed bill to ban BPA from food and beverage containers, a San Francisco Chronicle article presents a one-sided view of available alternatives.

San Francisco Chronicle article describes efforts by U.S. Representative Dianne Feinstein to pass a bill banning bisphenol A (BPA) from food and beverage containers. Unfortunately, the reporter relies on information provided by industry officials to explain the availability of BPA-free alternatives. This one-sided approach misinforms readers.

Reporter Carolyn Lochhead states that “With no viable alternative for can liners, an immediate ban would be equivalent to banning canned foods.” An industry spokesman adds that “banning [BPA] would make food less safe because there is no viable alternative to line cans and jars.”

These statements stretch the truth. There are, in fact, food cans on the market without BPA in their epoxy linings. Some BPA-free cans are made with a vegetable-based lining that was used by the canning industry before the switch to BPA-based resins. These have been used for more than a decade.

Lochhead interviewed only a few sources for her story: Representative Feinstein; a U.S. Food and Drug Administration representative; and the director of the American Chemistry Council, an industry lobbying group. The important voice that is missing is an independent scientist. A scientist who works on BPA could have pointed out the alternative cans that exist and provided better accuracy in reporting the effects of BPA on animals and humans.

Human exposure to BPA is widespread through food can linings, polycarbonate plastics, some thermal papers and dental sealants, among other sources. A 2008 study by the US CDC showed that almost everyone has this chemical in their bodies. Reducing or eliminating BPA in consumer products can have a significant impact on human exposures. A 2003 study found that BPA levels in urine collected from Japanese college students in 1999 dropped compared to levels measured from similar students in 1992. During this period of time, the authors report that some can linings were changed from a BPA-based resin to a lining that eliminated or reduced the use of BPA.

BPA has been linked to numerous adverse health effects in exposed animals, including malformations of the male and female reproductive tract, changes in the development of the brain, alterations in the immune system, development of prostate and mammary cancers, and changes in behavior, among others. BPA studies in humans, while limited, also suggest that this chemical could have adverse health effects.

BADGE, made from BPA, reacts with food.

BADGE, made from BPA, reacts with food.

Jul 19, 2010

Coulier, L, EL Bradley, RC Bas, KCM Verhoeck, M Driffield, N Harmer and L Castle  2010.  Analysis of reaction products of food contaminants and ingredients: Bisphenol A diglycidyl ether (BADGE) in canned foods. Journal of Agricultural and Food Chemistry 58:4873-4882.

Synopsis by Evan Beach

Leftover residues of a compound made from bisphenol A (BPA) for use in food can linings reacts with sugars, proteins and other parts of food to form new molecules, researchers report.

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A main component of food can linings forms new chemicals when it reacts with different parts of food, according to research published in the Journal of Agricultural and Food Chemistry.

BADGE – which is short for bisphenol A diglycidyl ether – is manfactured from bisphenol A and is a building block of certain types of resins that coat food and drink cans. Like its parent compound, BADGE has endocrine disrupting properties.

The researchers from The Netherlands and Great Britain found that BADGE residue left over from manufacturing of the can coating can react with sugars, proteins and other small molecules – for example ethanol in beer.

The findings show how critical it is to understand the extent of chemical migration from resin linings into the can’s contents and what happens to the compounds once they interact with the food and beverage.

This is important because of the implications for food safety. The European Union bases its regulations for how much BADGE can migrate from food primarily on the reaction between BADGE and water.

However, the study’s authors found that the BADGE-water reaction only accounted for as much as 26 percent of the “disappearing” BADGE  they added to samples of canned tuna, apple puree and beer. Some of the remaining BADGE could be detected as BADGE-glucose and BADGE-amino acid reaction products. Even when the additional BADGE products were considered, it was still not possible to account for all of the BADGE added to the food.

The researchers suspect that BADGE can form products with larger, high-molecular-weight carbohydrates, fibers and proteins that would be difficult to detect directly with the methods they used. This was the case for proteins. When the authors mixed BADGE with insulin, a large protein, the BADGE was effectively invisible. But when they broke down the protein into its component parts, then the BADGE products could be detected.

Although large molecules like the insulin-BADGE product would probably be too large to be absorbed by the body at first, it is possible that after they break down into smaller molecules in the stomach, then exposure to BADGE would be likely.

The BPA-like chemical backbone of BADGE was not changed by reactions with food molecules. The authors did not discuss whether the structural similarity of these products to BADGE and BPA might lead to similar harmful effects attributed to BPA or if the BADGE products might be related to levels of BPA that have been detected in most of the U.S. population.

For the study, BADGE was added to two types of canned food – tuna in sunflower oil and apple puree – and three drinks – an ale, a stout, and a lager. Spiked and nonspiked controls were recanned, homogenized and then analyzed three weeks later using liquid chromotagraphy.

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.

Mice moms, sons end up diabetic after short BPA exposure during pregnancy.

Mice moms, sons end up diabetic after short BPA exposure during pregnancy.

Jul 01, 2010

Alonso-Magdalena, P, E Vieira, S Soriano, L Menes, D Burks, I Quesada and A Nadal. Bisphenol-A exposure during pregnancy disrupts glucose homeostasis in mothers and adult male offspring. Environmental Health Perspectives http://dx.doi.org/10.1289/ehp.1001993.


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2010-0630bloodsugarmeter
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Brief exposure to low levels of bisphenol A during pregnancy may contribute to diabetic symptoms in the mother and her sons – but not daughters – finds a study with mice. BPA, which acts like estrogen and can interfere with normal hormone activity, caused changes in the mothers that resembled gestational diabetes. The mothers gained weight and could not properly regulate insulin, sugars and fats, even four months after the pregnancy. Their male pups showed similar deficits in metabolism, even though they had only been indirectly exposed for a brief period as fetuses.

Context

Intricate body systems process and store energy from food. When needed, sugars and fats are released. These mechanisms are delicately balanced. When they go awry, metabolic problems such as diabetes and obesity can occur. At no time are these systems more vulnerable than during pregnancy, when the energetic demands of the fetus compete with the mother’s regulation of her own body (Haig 1993).

Normally, insulin release causes sugars to be stored in cells for later use. During pregnancy, the body becomes increasingly resistant to insulin. This ensures that enough sugar remains in circulation to feed the growing fetus. Typically, the mother compensates by secreting more insulin so that blood sugar levels are kept in check.

These check and balance systems are easily derailed. When the mother’s body fails to adjust its insulin release, gestational diabetes – which afflicts up to 10 percent of pregnant women – may occur. Most cases of gestational diabetes resolve soon after birth, but many serious consequences may remain for both the mother and child. The children are often dangerously large at birth, and both mothers and offspring may find themselves at increased risk of obesity and Type II diabetes.

Because estrogen may play an important role in regulating the normal changes in metabolism during pregnancy (Nadal et al. 2009), anything that disrupts the body’s normal estrogenic activity may also throw the blood sugar regulation systems into upheaval, causing metabolic symptoms, and possibly contributing to diabetes or obesity.

The environmental chemical bisphenol A (BPA) – found in products throughout the modern world – is a compound that mimics natural estrogens. Concern first surfaced because it can leach from widely-used polycarbonate plastics, which were used a food packaging and water bottles. Recently, several reports brought attention to its overwhelming prevalence in canned goods (Consumer Reports 2009National Workgroup for Safe Markets 2010).

From food to household electronics to sales receipts, BPA is so commonly used in consumer goods that 95 percent of Americans have measureable levels in their blood. During pregnancy, BPA can pass from mother to the developing fetus.

Alarm bells were first raised about the chemical’s safety when animal studies showed that BPA could affect development of the reproductive system and the brain. More recently, concern has turned to whether BPA exposure may also impact metabolism. Several recent studies have linked BPA to diabetes, obesity and other symptoms of impaired metabolism in humans (Lang et al. 2008) and animal models (Alonso-Magdalena et al. 2006).

What did they do?

The researchers examined whether there were long-term metabolic effects on the mother and her pups exposed to BPA for a week during pregnancy.

Researchers injected pregnant mice with BPA from days 9 to 16 of pregnancy, which roughly corresponds to the development stage of middle to late pregnancy in humans. Some of the injected mice received a low dose of 10 micrograms per kilogram (μg/kg) of BPA each day while others received a high-dose of 100 μg/kg each day. Currently, the U.S. Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA) consider anything below 50 μg/kg per day to be a low, and thus, “safe” dose.

The researchers measured glucose in the blood to determine if the pregnant mice processed sugars and responded to insulin – a hormone that helps the body store sugars after a meal. After birth, they continued to monitor the mothers and their offspring for their ability to metabolize sugar and insulin. They also examined how well the animals processed fats and how well their pancreases worked. The researchers compared these measures from BPA-treated mice to untreated mice and determined the physiological differences between the two groups.

What did they find?

Pregnancy typically entails some degree of insulin resistance, and this effect was amplified in the BPA-exposed mice, particularly in those receiving the lower dose of BPA. When compared to the untreated pregnant mice, their cells were less able to efficiently process and store sugars and their liver and muscle tissues showed a reduced insulin response similar to that seen in diabetic conditions.

Four months after giving birth, the BPA-treated mothers were heavier than the controls, even though their diets were the same. The mice in the high-dose group – but not the low-dose groups – had clear deficits in their cells’ ability to use insulin to store sugars. In both BPA-treated groups, levels of triglycerides – a type of lipid or fat – in the blood were elevated.

The mouse pups born to BPA-treated mothers also showed differences from control mouse pups. The low-dose pups were heavier at birth than controls – as is frequently the case with babies born to mothers with gestational diabetes. Yet, the high-dose pups actually weighed less than the controls.

As they aged, the BPA groups showed similar metabolic problems to their mothers. Although no significant differences were seen at three months of age, by six months, male – but not female – offspring in both BPA groups showed clear abnormalities in their ability to use insulin to store sugars. This deficit was consistently apparent in the blood tests and when the pancreatic cells were examined.

What does it mean?

Exposure to low levels of BPA at a crtical time in pregnancy may influence metabolic function during and after pregnancy, setting the stage for long-term gestational diabetes in the mothers and development of diabetes in sons as they age.

This study adds to a growing body of research evidence that, when taken together, suggests BPA causes health problems in animals and quite possibly in humans. Much of the research has focused on reproductive and developmental risks.

This study is one of a number of recent ones investigating whether BPA might have effects on metabolic conditions such as diabetes and obesity. But, it is the first to examine the mother’s risk of developing diabetes during pregnancy. While the recent studies have found some conflicting results, this new study’s methodological strengths mke the findings of particular concern.

Earlier this year, another group of researchers reported that prenatal and early postnatal BPA exposure in mice did not appear to lead to problems with blood sugar regulation, although they did find faster rates of growth during early development (Ryan et al. 2010).The new study improves upon earlier work, however, in that it is particularly comprehensive in its methods and approaches problems of insulin resistance and blood sugar regulation using a number of different methods. From sugar metabolism tests to measures of gene expression to blood chemistry, the multiple lines of evidence in this study all point to BPA having profound negative effects on the body’s ability to properly control blood sugar.

Beyond its methodological strengths, this new study adds two important nuances to our understanding of how BPA may impact metabolism. First, the study showed that even if BPA exposure occurs during a very brief period, the disruption in blood sugar regulation can be long-lasting. The female mice received BPA for only a seven day window during pregnancy, and yet were affected even months later, with higher weights and abnormal blood sugar and lipid levels.

In humans, of course, we are exposed continuously throughout our lifetimes as we ingest BPA in our food and pick it up through plastics and other sources every day. How this constant exposure might affect our bodies’ abilities to regulate blood sugars and other body systems remains an open ended question. However, these early results in mice are enough to merit additional research.

Second, the new study shows intergenerational effects. Males who were exposed to BPA as fetuses through their mothers displayed long-term metabolic problems resembling diabetes, even though they were never exposed to the chemical after birth. Because the body’s systems develop very early in life – often before birth – early exposures can cause permanent changes in body functions. In this case, through the ability to act as a pseudo-estrogen, BPA seems to permanently “program” body responses to sugar, causing an inability in the mice process the sugar – a condition that may mirror some of the most troubling current human health problems.

Aspects of the findings are also puzzling. Surprisingly, only male offspring were affected in this way by BPA exposure. The researchers hypothesize that perhaps the female offspring’s own estrogen production protected against the dysregulation, but further investigation would be needed to address that question.

In addition, low and high-dose BPA exposures didn’t yield the same findings. While both levels of exposure clearly produced negative health effects, it remains uncertain why the mice might respond differently to the two doses. The lower dose more closely approximates average human exposure levels. Ideally, future experiments will need to simulate the typical method of human exposure – ingestion through food – rather than injection.

Still, many questions remain unanswered, and more research is needed to fully understand how BPA impacts regulatory systems.

Resources

Alonso-Magdalena, P, S Morimoto, C Ripoll, E Fuentes and A Nadal. 2006. The estrogenic effect of bisphenol A disrupts pancreatic beta-cell function in vivo and induces insulin resistance. Environmental Health Perspectives 114(1):106-12.

Calafat, AM, Z Kuklenyik, JA Reidy, SP Caudill, J Ekong and LL Needham. 2005. Urinary concentrations of Bisphenol A and 4-Nonylphenol in a human reference population. Environmental Health Perspectives 113:391-5.

Concern over canned foods. 2009. Consumer Reports, December.

Haig, D. 1993. Genetic conflicts in human pregnancy. Quarterly Review of Biology 68(4):495-532.

Lang, IA, TS Galloway, A Scarlett, WE Henley, M Depledge, RB Wallace and D Melzer. 2008. Association of urinary bisphenol A concentration with medical disorders and laboratory abnormalities in adults. Journal of the American Medical Association 300(11):1303-10.

Nadal, A, P Alonso-Magdalena, S Soriano, AP Ropero and I Quesada. 2009. The role of oestrogens in the adaptation of islets to insulin resistance. Journal of Physiology 587(Pt 21):5031-7.

National Workgroup for Markets. 2010. Silver lining: An investigation into bisphenol A in canned foods (PDF).

Ryan, KK, AM Haller, JE Sorrell, SC  Woods, RJ Jandacek and RJ Seeley. 2010. Perinatal exposure to Bisphenol-A and the development of the metabolic syndrome in CD-1 mice. Endocrinology 151(6):2603-12.

Chemicals with unknown toxicity form when polypropylene plastic is heated.

Chemicals with unknown toxicity form when polypropylene plastic is heated.

Jun 25, 2010

Reingruber, E, M Himmelsbach, C Sauer and W Buchberger. 2010. Identification of degradation products of antioxidants in polyolefins by liquid chromatography combined with atmospheric pressure photoionisation mass spectrometry. Polymer Degradation and Stability 95:740-745.

Synopsis by Evan Beach
New chemicals – with unknown toxic properties – are present after heating commercial polypropylene plastics during manufacturing.

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The chemical composition of an everyday plastic could be more complicated than what a list of raw ingredients would suggest, report a group of Austrian chemists.

Their discovery concerns chemicals that manufacturers add to stabilize polypropylene (PP) plastics. The synthetic antioxidant additives break down when exposed to high temperatures typical of the manufacturing process, especially when they are combined with a common mineral filler called talc.

The results of this study add to the body of knowledge about chemicals found in everyday plastics. The findings could be used to more thoroughly assess the implications for environmental and human health.

Antioxidants are added to protect the structure of the plastic.  They are designed to react quickly with oxygen, sacrificing themselves to protect the PP chemical chain.

The discovery of the new chemicals is of concern since they may occur in commercial products where they could migrate out of the plastic and potentially into humans.  Talc-filled PP plastic is typically found in car parts, household appliances, and building materials.

The researchers did not measure the toxicity of the newly discovered chemicals, but their molecular similarity to the controversial product additives BHT and BHA suggests that they merit further study. While still widely used, the synthetic chemicals BHT and BHA have known health effects. They are used as antioxidants in many products, including food, cosmetics, pharmaceuticals, plastics and some petroleum-based greases and lubricants. BHT has been shown to cause mutations, tumors and endocrine effects in test animals. It has been responsible for allergic responses in people. BHA can also mimic the female hormone estrogen.

The researchers tested six commercial antioxidant additives, four of which had structures similar to BHT. In the presence of heat and talc, the additives lost parts of their chemical structures in predictable ways. This predictability means that chemists might be able to anticipate what will happen when new additives are exposed to heat and design for safer breakdown processes.

The chemists showed that although most of the pure additives were stable at 239 degrees Fahrenheit, all of them broke down when talc was present. Some also broke down when blended with the PP.  PP generally melts above 266 F. If the additives were blended into melted plastic, the high temperature would lead to their degradation, and thus, the new low-molecular-weight chemicals.

The observed decrease in molecular weight could lead to faster migration out of the plastic.  This question and the issue of toxicity could be resolved by further study.

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7 November Plastics, by the numbers, they’re everywhere. The bottom line: since plastics are a fact of life, learn how to pick and choose your plastics if you want to protect your health. Santa Cruz Sentinel, California.

4 September How to be poison-free going back to school. Parents, it is time to start stocking up on the latest school supplies, and many children’s supplies, such as lunchboxes, backpacks and binders, are often made out of PVC (#3 plastic). Collingwood Enterprise Bulletin, Ontario.

31 August Chemicals leach from packaging. Open a cereal box or a carton of juice, breathe in an asthma drug from an inhaler, or pop a pill out of a plastic pouch’s metal foil. Even when the wrapping comes off, you inevitably ingest some of the container. It is not a question of whether packaging components will leach into a product, it’s a question of how much. Chemical & Engineering News.

30 July ‘BPA-free’ bottles leach chemical: study. Health Canada scientists have found bisphenol A leaching into liquid in plastic baby bottles marketed to parents as being free of the toxic chemical. Canwest News Service.

22 June Battle of the bottles. Scientists are debating whether bisphenol A in plastic can actually harm humans, but when it comes to their babies some Irish parents don’t want to take any chances. Ireland’s Food Safety believes there is no need for parents to be alarmed about products containing BPA. Dublin Irish Independent, Ireland.

7 November Researchers raise alarm after chemical leak found in common plastic. Medical researchers at the University of Alberta say that two chemicals leaking from plastic laboratory equipment were so biologically active they ruined a drug experiment. Toronto Globe and Mail, Ontario.

23 April Conflicting reports target key chemical ingredient. For many consumers, the recent flurry of news reports about plastics and health hazards has been conflicting and confusing. San Diego Union-Tribune, California.

18 April Beverage bottlers waiting for word on bisphenol A. Although growing numbers of Canadian retailers are pulling plastic water bottles and baby bottles that contain the chemical BPA from their shelves, the beverage industry is generally in a holding pattern until Health Canada officially deems the chemical unsafe. Vancouver Sun, British Columbia.

13 March How safe are your bottles ? The decision to use hard plastic water bottles just got more complicated. Louisville Courier-Journal, Kentucky.

8 February Baby bottles linked to health risk. Most plastic baby bottles sold in the United States could be hazardous to a baby’s health, according to a new report by a coalition of environmental groups. Bergen County Record, New Jersey.

11 November Artificial turf full of toxins that can cause cancer. Every new expanse of artificial turf contains plastic grass and about 120 tons of finely chopped tires that emit a small amount of toxic, cancer-causing, mutation-triggering chemicals and metals. New Haven Register, Connecticut.

11 November Got plastic panic? There are solutions. Plastic is durable, flexible, inexpensive and virtually unbreakable. By those measures, it’s a consumer’s dream – and yet it just might be harming us. Canwest News Service.

2 November Several plastic bottles found unsafe to reuse. Studies have indicated that food and drinks stored in plastic bottles can contain trace amount of Bisphenol A (BPA), a synthetic chemical that interferes with the body’s natural hormonal messaging system. Phoenix Arizona Republic, Arizona.