« Older Entries

You Asked: What are “oxo-biodegradable plastic” shopping bags?

question markPolyethylene shopping bags are a big convenience but they also present a big problem. While they can be recycled, many just get carelessly discarded and end up in the environment not only as an eyesore but as a danger to wildlife. Estimates are that only about 3% of plastics that can be recycled actually are. Polyethylene does not degrade easily in the environment and the bags can end up as pollutants for decades. Some clever chemistry can, however, help the situation.

If certain salts of iron, manganese, nickel or cobalt are incorporated into the polyethylene, polypropylene or polystyrenene molecular chains during manufacture, they will catalyze the breakdown of the polymers. But the breakdown requires the presence of oxygen because the mechanism of the degradation involves “oxidation,” which means forming bonds between some of the carbon atoms in the polymer and oxygen atoms supplied by oxygen in the atmosphere. Exposure to ultraviolet light speeds up the reaction

Once the chain has been “oxidized,” the bonds between the oxygen bearing carbons and their neighbours are significantly weakened and begin to break apart. The resulting short chains are then biodegraded by microbes basically to carbon dioxide and water. Depending on the extent of UV and oxygen exposure, and ambient temperature, oxo-biodegradable plastics visually disappear in as little as two months, although the process can take up to a year and a half. These bags will not degrade in a landfill and therefore will not generate methane, a potent greenhouse gas. They cannot be composted, but they can be recycled just like other polyethylene bags. The big advantage is a reduction in all those bags that end up fluttering from trees or floating in the ocean. Of course, until the plastic breaks down, it can still pose a risk to wildlife but there is no doubt that the oxo-biodegradable plastic is preferable to the conventional variety in terms of impact on the environment.

 

Dr. Joe Schwarcz

Small beads can make for a large problem

dangerScience can make for a strange bedfellow. I had just finished recording a video showing off one of my favourite sweaters and expounding on the ingenuity and the environmental benefit of it being made from recycled polyester bottles when an article appeared on one of my newsfeeds about how “your clothes are poisoning our oceans and food supply.” The message was that the very fabric I was so high on may be unravelling the fabric of society.

I must say I was puzzled by the headline, but on glancing through the story, the details of the problem quickly came out in the wash, as it were. Synthetic fabrics are not exactly inert and release microscopic bits of fiber when washed. The particles may be microscopic, but their number is anything but. Researchers at the University of California found that a synthetic fleece jacket releases hundreds of thousands of microscopic fibers, about 2 grams in total, with each wash. Wastewater treatment removes some of this debris, but most of it ends up in rivers, lakes and oceans where it can be consumed by wildlife. The fibers then can bioaccumulate up the aquatic food chain, right up to people consuming fish. Whether this presents a risk is not known, but bits of plastic are not a desirable dietary component. The clothing industry is sensitive to the problem and is working on coatings for fabric that would reduce shedding. Also in the works are washing machines that prevent the release of microfibers by using pressurized carbon dioxide instead of water.

The shedding of microfibers from synthetic fabrics is not the only way tiny pieces of plastic, invisible to the naked eye, end up in water systems.” Microbeads,” introduced into consumer products such as toothpaste and exfoliating skin products as abrasives, are a bigger concern. Six varieties of the tiny beads are used. Those composed of either polyethylene, polypropylene or expanded polystyrene are more likely to float, whereas the ones made of polyvinyl chloride, nylon or polyethylene terephthalate (PET) are more likely to sink. McGill biologist Anthony Ricciardi has found microbeads in significant numbers in sediment at the bottom of the St. Lawrence River, meaning possible contamination of fish that feed on the riverbed.

Microbeads range in size from 10 millionths of a meter to one millimeter. Their round shape makes them much less irritating than irregularly shaped, abrasive exfoliants like apricot kernels or walnut shells that have sharp edges. Also, because the particles are tiny spheres, they act as little ball bearings, allowing for easy spreadability of creams and lotions as well as a smooth texture and silky feel. There’s more. Imperfections in the skin tend to be visible because of the contrast between how they reflect light compared with the surrounding tissue. Microbeads with their ability to scatter and diffuse light can minimize the appearance of fine lines and improve skin tone. When it comes to toothpaste, though, they make a minimal contribution to polishing the teeth and may actually become embedded in gum tissue. Why are they there? Since the microbeads can be produced in various colours they can also increase the visual appeal of a product.

A single container of face wash can contain hundreds of thousands of the microspheres. While the virtually indestructible plastic beads are not themselves toxic, once they enter the water, they attract potentially toxic substances such as PCBs, triclosan and nonylphenols. Like the microfibers, microbeads can then become part of the aquatic food chain, eaten by fish and then by people. Once consumed, the beads may also leach out plastic additives like colourants, plasticizers and ultraviolet light stabilizers.

Researchers have found fish both in the oceans and the Great Lakes contaminated with microbeads. Besides carrying toxins, the beads can cause internal abrasions and can stunt growth of the fish by giving them a false sense of being full. One-third of fish caught off the south-west coast of England have been found to contain microbeads and  Belgian researchers studying seafood from German farms and French supermarkets found that an average portion of mussels can contain about ninety microplastic particles, and an order of oysters about fifty. The beads have also been found to lodge in the guts of crabs as well as in their gills.

The number of microbeads that end up in the environment is staggering. In New York State alone some 19 tons go down the drain every year. Most wastewater plants are not equipped to filter out such fine particles and while they could be retrofitted, the expense would be prohibitive. Drinking water poses less of a problem because municipal water treatment plants can filter out the tiny particles although a sampling of German beers found microbeads in every bottle, with the water used being the likely source. Both Canada and the U.S. have moved to ban microbeads and manufacturers have started the process of phasing them out. Researchers agree that there are still too many unknowns to fully assess the environmental damage caused by microplastics but given that they do not contribute significant benefits they should be eliminated.

But the problem of plastic waste in the oceans is greater than can be accounted for by microfibers and microbeads. Other tiny particles form from the breakdown of plastic bags, bottles and all sorts of containers that get discarded end up in waste streams that empty into the ocean. “Biodegradable” on a label means that the plastic has been shown to degrade under ideal composting conditions, but these do not exist in the natural environment. Estimates are that the ratio of plastics to fish by weight in the oceans is 1:5 and with our current callous attitude towards “reduce, recycle, reuse,” it is set to increase to 1:1 by 2050.

Given these concerns, I don’t think I can wear my “made from a plastic bottle” sweater with the same pride as before. And I may even feel a bit of apprehension tossing it into the laundry basket.

 

Joe Schwarcz

Plastic Cheese and Fake Mayo

plastic cheeseOn a recent trip to the U.S. I perused the menu and decided on a cheese sandwich. When I queried the waitress about the kind of cheese involved, I was told, “American!” I replied I was interested in the type of cheese, not its citizenship. “You know, American, the plastic kind” came the irritated response. I now knew I had to prep the taste buds for “processed” cheese.

“Would you like it with just mayo?” “Not just mayo,” I replied, “I’d like lettuce and tomato as well.” “Yes, but with just mayo or real mayo?” Sensing my confusion, the waitress turned on her heels and returned with a jar sporting the label “Just Mayo.” Looked real to me. I decided not to torment the poor lady further and decided that “Just Mayo” would be just fine with my plastic cheese.

“American cheese” really is plastic. But don’t start conjuring up images of cheese makers grinding up recycled plastic bottles. A plastic is simply any material that can be molded into a desired shape, and processed cheese does fit that definition.

It was back in 1916 that cheese merchant J.L. Kraft, plagued by complaints of inconsistent quality, hatched a scheme to mix a variety of cheeses and blend them with water to produce a uniform product. For a smooth consistency Kraft had to devise a method to prevent the fat, protein and the water from separating. Sodium monohydrogen phosphate turned out to be an ideal “emulsifier,” and ensured that people who like their cheeseburgers can count on a slice that will always taste the same and melt in a uniform fashion. And yes, processed cheese does melt, as anyone who has ever made a grilled cheese sandwich can attest.

That is contrary to the implication of a widely circulating video portraying processed cheese as some sort of Satanic product because it does not melt in the heat of a flame. One viewer was prompted to wonder if this is why “cancer is on the rise,” and another asked why Kraft puts plastic in its cheese. No, there’s no plastic. But there are emulsifiers that bind the cheese’s components tightly and do not lose their hold with a sudden increase in temperature. They do, however, let go with prolonged heating at a lower temperature. There is nothing devilish here, just some clever chemistry. Nutritionally, processed cheese is comparable to whatever cheese was used to make it, usually cheddar. It does tend to be higher in sodium, but if there is any risk to be had from processed cheese, it is to the palate.

Now what about “Just Mayo?” Isn’t it real mayonnaise? Not according to the U.S. Food and Drug Administration. “Mayonnaise” is defined as a condiment that must contain a specific amount of vegetable oil and egg yolk. But what if you shorten the name and call it “Just Mayo?” Does it still have to contain eggs? No, says Josh Tetrick of Hampton Creek, maker of the new-fangled spread that advertises itself as being healthier, more environmentally friendly, and more humane than “real mayonnaise” The term “mayo” is not defined, Tetrick maintains, and he says he does not sell his product as mayonnaise. “It’s Just Mayo!”

The “more humane” refers to the way egg-laying chickens are raised in small cages. True, the peas that are grown to produce the protein extract used to emulsify the oil and vinegar in Just Mayo have a peaceful life, and presumably do not suffer when their pods are wrenched apart. The “environmental friendliness” is based on the ratio of energy input to food energy output for eggs being about 39-to-1, whereas Just Mayo’s plant ingredients that replace eggs weigh in at a ratio 2-to-1.

Hampton Creek may be on firm footing when it comes to promoting the benefits of “no eggs” in terms of environmental footprint, but when it comes to implication of health benefits, the company is trampling in mud. Both Just Mayo and Hellman’s “real mayonnaise,” contain 90 calories per serving from 10 grams of fat. The 5 milligrams of cholesterol in the real mayo is inconsequential. Curiously, Just Mayo lists its protein content as zero, yet its promotional material describes how the company’s biochemists have investigated numerous plants to come up with a protein that can rival egg yolk as an emulsifier. Obviously not much of this protein is needed in the product. And how did the sandwich taste? Like plastic cheese with fake mayo.

 

Joe Schwarcz

Dr Oz and phthalates

phthalateThe title of the segment on the Dr. Oz Show was “The Secret Ingredient Companies are Hiding in Your Food.” What could that be? Some opiate to keep you coming back for more? Tetrahydrocannabinol to increase appetite? No. The segment was all about chemicals called phthalates. And companies are not hiding their presence any more than they are “hiding” the presence of numerous substances that are not added to our food supply on purpose but can be detected through sophisticated analytical methods. These include pesticide residues, corrosion inhibitors, PCBs, detergents, chloroform, cadmium, radium, mercury, aflatoxins, bacteria and a host of others. Some of these are man-made, some occur naturally, but all are potentially toxic if present in a high enough dose. They end up in our food supply for the simple reason that if substances come into contact with each other, there will be a transfer of material from one to the other. If chloroform forms in water as a result of chlorination, which it does, some will be transferred to food that comes into contact with the water. Flourinated compounds used to produce grease-proof packaging can leave residues in food, aspergillus fungi can contaminate apple juice with their toxic metabolite patulin, wine may harbour residues of isinglass, a fish protein used to remove fine particles, and the potential carcinogen acrylamide forms when bread is baked.

None of these substances appears on food labels, not because there is some conspiracy to hide them, but because they are unavoidable. So it is with the phthalates. They do end up in our food supply because these chemicals have widespread applications. They lend flexibility conveyor belts, tubes used in milking machines and to plastic water pipes. They help the dispersal of pesticides, they’re found in caulking and in printing inks used on food packaging.

It’s no surprise to anyone familiar with chemical analysis that phthalates can be detected in our urine. Their presence, though, did come as a big surprise to the ten women Dr. Oz selected to have their urine analyzed for phthalates. None of the women had ever heard of phthalates before, which is quite surprising given the amount of publicity they have received. Their faces filled with panic when Oz revealed that they all tested positive for phthalates, chemicals that had been associated with endometriosis, weight gain, respiratory problems as well as brain and behaviour changes in children.

But here is the crux of the problem. Associations do not prove cause and effect. Just because women are more likely to suffer from endometriosis if they have higher levels of phthalates in their urine doesn’t mean that phthalates are the cause. Perhaps they have greater phthalate exposure because they eat more fatty foods like dairy and meat which are known to have higher amounts of phthalates. Perhaps they used more scented products most of which contain phthalates to inhibit the evaporation of the scent and they were somehow reacting to some of the numerous chemicals that make up scented products.

None of this is meant absolve phthalates from all blame because there are sufficient laboratory studies, animal experiments and human epidemiological data that suggest the need for further investigation. But there is no need for panic. There are numerous other substances that could be detected in our urine that could also be vilified in the same fashion as the phthalates. How many? At least 3,079 compounds can be detected, of which 2,282 come from diet, drugs, cosmetics or environmental exposure. Enough chemicals there for Dr. Oz to discuss and panic audiences for many years.

 

Joe Schwarcz

Tempest in a K cup

K cupsA question came up about the risks of chemicals leaching out of those convenient coffee K cups. Yes, chemicals do leach out. That of course is the idea, you want to leach out the hundreds of compounds that contribute to coffee flavour and aroma and you also want a good shot of the stimulant caffeine. However, the likely reason for the question was concern about chemicals leaching out from the plastic. Yes, that happens too.

Anytime two surfaces come into contact, especially if one is a liquid, there will be transfer of chemicals. I don’t know exactly what plastic is used in these cups since the company maintains that this is proprietary information. By its texture, it seems the plastic is either polystyrene or polypropylene. It certainly is not polycarbonate which would be a source of bisphenol A (BPA). Traces of styrene, the compound from which polystyrene is made, may leach out. But styrene also occurs naturally in coffee beans, so all coffee will have some styrene. This is really not much of an issue because styrene is quickly metabolized and excreted.

If anyone has concerns about styrene, they had better stay away from cinnamon which can have as much as 39,000 ppb of styrene as opposed to the 5 ppb that may be leached out from polystyrene. They will also have to stay away from beer which has up to 25 ppb of naturally occurring styrene. If the K cup is made of polypropylene, there is no issue whatsoever. No compound of any consequence leaches out of this plastic. Basically what we have here is a tempest in a Kcup. If there is to be a concern, it centers in the environmental unfriendliness of these little cups which may pose a big problem in terms of where they end up.

Joe Schwarcz

Colourful conman

Spectro-ChromeLet me tell you about Dinshah P. Ghadiali and his Spectro-Chrome.  Dinshah, as he like to be called, was born in India in 1873 and at least by his own account was a remarkable man.  He began school at the ripe age of two and a half and by eleven he was an assistant to a professor of mathematics at a college in Bombay.  This prodigy began to study medicine at the age of fourteen, but then we hear no more about his progress in this area.  Probably because he saw no need to pursue these futile studies once he had independently discovered the key to health.  Colour therapy.

Dinshah apparently came upon this discovery when he exposed a young girl “dying of colitis” to light from a lamp fitted with an indigo colored glass filter.  Within three days, the girl was well and a career was launched.  Dinshah opened an Electro-Medical Hall in India where he began to refine his treatment.  By the time he came to America in 1911, he had a theory to go along with his colored lights.  Every element, he said, exhibits a preponderance of one of the seven prismatic colors.  Oxygen, hydrogen, nitrogen and carbon, the elements that make up 97% of the body, are associated with blue, red, green and yellow.  In health these colors are balanced but fall out of balance in disease.  Therapy is simple; to cure disease administer the lacking colors or reduce colors that have become too brilliant.

Of course, Dinshah had exactly the method to use.  His Spectro-Chrome was a box with a lightbulb and an opening that could be fitted with various colored filters.  It was accompanied by The Spectro-Chrome Therapeutic Sytem guide detailing the appropriate colors to shine on a patient.  Green light, for example, was a pituitary stimulant and germicide while scarlet was a genital stimulant.  Any disease, save broken bones, was amenable to color therapy.  The Spectro-Chrome was especially suited for use by intelligent people, Dinshah said, because “drugs quickly upset the nervo-vital balance of persons of high mental and spiritual development.”  A pretty clever trap.  The gullible, thinking themselves to be intelligent, ate it up.

To many people the argument about the benefit of color therapy seemed convincing.  After all, they knew that premature babies were treated with blue light to cure them of jaundice, that sunlight was needed for the synthesis of vitamin D in the body and that plants absolutely required light for growth. Add to this the notion that chemists had shown that elements when heated emitted different colors of light, and Dinshah’s preposterous notions seemed to make sense.  His slogan of “No diagnosis, No Drugs, No Surgery” also sat well with a public largely unsatisfied with current medical care. The non-invasive therapy and the promise of a cure for virtually any ailment was very appealing.

Iit wasn’t long before Dinshah ran into trouble with the establishment.  He was labeled a fraud and a charlatan by the American Medical Association but managed to cunningly portray himself as a humanitarian who was being persecuted by the money-grabbing, ineffective, jealous physicians.  To protect himself legally, Dinshah came up with some incredible lingo.  He didn’t talk of cures, he spoke of “normalating” the body.  Instead of treating patients he claimed “to restore their Radio-Active and Radio-Emanative Equilibrium.”  This would be done with his light exposures, or “tonations.”  Tonations would be carried out with the patient lying with his head to the north, so as to align the earth’s and the body’s magnetic field, of course.

In 1931 Dinshah had his first run-in with the law over the Spectro-Chrome.  He was arraigned on second degree grand larceny after being charged by a former student who claimed that the Spectro-Chrome did not perform as promised.  Dinshah trotted out numerous satisfied patients in his defense, incredibly including some physicians.  A surgeon, Kate Baldwin, claimed that she had successfully treated glaucoma, tuberculosis, cancer, syphillis and a very serious burn case.  The government countered with experts who testified that the Spectro-Chrome was nothing other than an ordinary lamp and that the successes were all due to the placebo effect.  The prosecution could not prove the intent to defraud and Dinshah was found not guilty.  He went back to selling more Spectro-Chromes, now claiming that he had been vindicated.

After the passage of the Food and Drug Act of 1938 which gave the FDA some teeth in regulating theraputic devices, the government began to assemble evidence against Dinshah.  Finally in 1945 he was charged with introducing a misbranded article into interstate commerce, a violation of the criminal code.  Once again he trotted out his satisfied patients, but this time there were no supporting physicians.  His fate was virtually sealed when one of his star witnesses, whom Dinshah had “cured” of seizures, had a fit on the witness stand.  The jury also heard how patients he had claimed had been cured had actually died.  The prosecution brought a witness who Dinshah had repeatedly profiled in his advertising as having been cured of paralysis.  She could not take a single step when the master urged her.  And finally the court heard how the celebrated burn victim, described as a miracle cure by Dr. Baldwin in the previous trial had in fact died of her injuries.  Another witness described how he had called Dinshah after his diabetic father had lapsed into a coma and was told to just shine the yellow light on him.  He did, until the man died.  Dinshah was heavily fined, his books and lamps were seized and he was put on five years probation.

The Dinshah legacy is still with us.  Through the Dinshah Health Society of Malaga you can buy plans to build an inexpensive Spectro-Chrome from a light bulb, cardboard and colored plastic sheets.  They apparently do not sell the finished product, but another company on the Internet does advertise Color Light Therapy Lamps “as recommended by Dinshah.”  These look suspiciously like theater spot lights with colored gels.

It seems that today there is still enough ignorance about what light is, about disease processes and about how the body functions to allow the gullible to be victimized. The colorful Dinshah may have lived in what we think are enlightened times, but his pseudoscientific ideas smacked of the dark ages.

 Joe Schwarcz

How an Asian bug led to the first synthetic plastic

bakeliteDuring the first years of the twentieth century the demand for shellac outstripped the supply. People did not develop a sudden penchant for shiny furniture, but electricity was starting to take the world by storm and electrification required the use of insulating materials. Shellac was a very effective insulator! The problem was that it was hard to come by. Shellac is the resinous secretion deposited on some species of Asian trees by Laccifer lacca beetles.  Workers scrape off the resin, heat it and filter it to produce the commercial product. Leo Baekland, A Belgian chemist who had emigrated to America, was aware of this problem and sought a solution.
Money to fund the research was not a problem for Baekland.  He had already struck it rich by inventing Velox photographic paper which was the first paper that could be printed with artificial light. Velox was a silver chloride contact print paper, meaning that the negative would be placed on top of the paper, followed by light exposure.  Previously strong sunlight was needed to form a print, but now even gaslight would do. Kodak capitalized on this and actually introduced Velox as the “first of the true gaslight papers.” George Eastman, head of Kodak, had purchased the Velox idea from Baekeland who approached him one day hoping to sell the invention for $25,000. But before Baekland ever mentioned any amount, Eastman offered him the staggering sum of a million dollars.
Baekland bought an estate In Yonkers, N.Y. and converted a barn into a lab.  This is where he took up the challenge of making artificial shellac. He was aware of the fact that German chemist Adolf von Baeyer had learned back in 1872 that phenol, a solvent distilled from coal tar, reacted with formaldehyde to form a resin that gucked up laboratory glassware. To von Baeyer this was a curse, but to Baekland it presented an opportunity. Indeed, he developed a reactor in which the reagents could be combined and heated under high pressure to produce a material that was very similar to shellac and could be readily moulded. In all modesty, he called this first truly synthetic plastic, Bakelite. It turned out to be an excellent electrical insulator, but that was only the beginning. Bakelite could be formulated into buttons, knife handles, billiard balls, radios, telephones and records. The synthetic plastic industry was born, and all because Leo Baekland wanted to reproduce the chemical secretions of an Asian bug.
Joe Schwarcz

Soft drink bottles are made of a plastic called polyethyleneglycol terephthalate, or PET. While this plastic is fine for storing soft drinks, why is it not recommended for storing home-made wine?

While PET has a very low permeability when it comes to carbon dioxide, it readily allows oxygen to pass through. And oxygen is the enemy of wine! When we talk about storing soft drinks, permeability to carbon dioxide is the critical factor. A beverage that loses carbonation loses its appeal. In this case oxygen permeability is not an issue. While oxygen passing into a plastic soft drink bottle from the air may react with some of the flavor components, the effect would be minor given that we don’t store soft drinks for extended periods. But of course we do store wine to age it. And this is where oxygen becomes a problem. Grape juice contains a variety of compounds called polyphenols which can react with oxygen and produce a variety of colors and flavors. This really is the same chemistry that occurs when an apple is cut and exposed to the air. Reaction between polyphenols and oxygen produces the brown discoloration. Not only will the apple slices look different, they will also taste different. The same thing can happen with wine. White wine is more susceptible to such changes because it lacks some of red wines colored compounds, the anthocyanins, which can act as antioxidants. Sulfur dioxide is also an effective antioxidant, which explains why compounds such as sodium bisulfite are used to preserve wine. Burning sulfur inside wine barrels to produce sulfur dioxide is an age-old method of preservation. Now back to our plastic bottles. As we have seen, empty soft drink bottles are too permeable to oxygen and are not appropriate for storing wine. But wine can be purchased in plastic containers, although I suspect a true eonophile would look warily upon this method of marketing. So how do the marketers solve the problem of oxygen permeability? By sandwiching a layer of an oxygen-impermeable plastic between layers of food-grade polyethylene or polypropylene. Ethylene-vinyl alcohol copolymer is ideal for this purpose since it allows very little oxygen to pass through. A bit of ingenious chemistry. So while it is not a good idea to store your wine in old soda bottles, it is quite acceptable to purchase wine in plastic containers.

Joe Schwarcz

« Older Entries
Blog authors are solely responsible for the content of the blogs listed in the directory. Neither the content of these blogs, nor the links to other web sites, are screened, approved, reviewed or endorsed by McGill University. The text and other material on these blogs are the opinion of the specific author and are not statements of advice, opinion, or information of McGill.