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YOU ASKED: Why do we refrigerate our eggs?

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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

YOU ASKED: What are the different types of starch and how do we digest them?

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You Asked: Why do they spray wax on apples?

applePick an apple off a tree, buff it a little and it will shine! That’s because the fruit is coated with a layer of natural wax that protects it from drying out and helps to prevent fungi from getting a foothold. The wax is a mixture of up to fifty different compounds, most of which fall into the chemical category known as esters. There are also alcohols like heptacosanol and malol as well as hydrocarbons such as triacontane, C30H62. This compound can also be isolated from petroleum and is sometimes applied to fruit to supplement its natural wax. In that case chemophobes kick and scream about a petroleum derivative being applied to their fruit but there is no difference between triacontane produced by an apple isolated from petroleum.

Natural wax also contains compounds in the triterpenoid family. Ursolic acid has a variety of biochemical effects that have been demonstrated in laboratory experiments. For example, it can inhibit the proliferation of various cancer cells and also has weak aromatase inhibitor activity. Aromatase is an enzyme that leads to the synthesis of estradiol, the body’s main estrogen that is implicated in some cancers. This of course does not mean that the amount of ursolic acid in the peel of an apple can have a beneficial effect on human health, but it is at least another plus for eating apples.

After apples are picked they are washed before they appear in the supermarket to remove dirt and chemical residues. This process also removes the wax. Since the waxy layer prevents moisture in the apple from escaping, its loss shortens the storage time for the fruit. Producers therefore spray the fruit with a thin layer of wax to prevent such moisture loss as well as to make the apple look more appealing. The applied layer is very thin, only about 3 mg of wax coat an apple.

Several different types of wax are used, mostly Carnauba wax that comes from the leaves of the Brazilian palm, Candelia wax from a dessert plant, as well as food grade shellac from the Indian lac bug. There are also some synthetic esters made by combining sucrose with fatty acids. Polyethylene, the same plastic used to make disposable shopping bags can also be applied in a very thin layer. Interestingly, this can be termed as being vegan because it is made from ethylene which in turn is made from ethanol that is produced by the fermentation of corn. A trace of an emulsifier morpholine oleate is added to allow the wax to be spread in a thin layer. Some concerns have been raised that the wax seals in pesticide residues that cannot be removed by washing but studies have shown that the prior washing removes most traces of pesticide residues. As far as the wax itself goes, it presents no health issue since it is not absorbed and passes right through the digestive system. Wax coatings can also be used on organic produce with the proviso that they must come from a natural source like beeswax or Carnauba wax or wood resin. While there is no worry about eating the wax on fruits, they should be well washed mostly to remove bacteria that may have stuck to the surface.

A video has been circulating in which boiling water is poured over an apple resulting in the formation of white splotches as a voice drones on warning people not to eat waxed apples because of the pesticide residues. The message is that the boiling water reveals the pesticide residues. That is not the case. The heat cracks the wax coating allowing air to enter between the wax and the skin of the apple resulting in white patches due to the way the air pockets reflect light.

It is not just apples that are waxed. Citrus fruits, rutabagas, cucumbers, many tomatoes, melons and peppers also are treated with wax. Even jellybeans are coated with beeswax to prevent them from drying out and to increase their appeal.

Joe Schwarcz PhD

You Asked: How can homeopathic teething “remedies” that essentially contain nothing have an adverse effect on infants?

question markThe FDA in the U.S has raised alarm about homeopathic teething pills that may have caused seizures in babies and possibly even caused some deaths. But how can homeopathic “remedies” do this, given that they contain nothing? The bizarre tenet of homeopathy is that a substance that causes symptoms in a health person can relieve those symptoms in a sick person as long as it is diluted to an extent that contains almost zero or a just a trace amount of the original substance. Homeopathic teething remedies are made by diluting a solution of belladonna in an extreme fashion.

Why belladonna is the preferred substance is bizarre since according to homeopathic doctrine, to relieve pain, it should cause pain when used at a high concentration. While atropine, the active ingredient in belladonna can cause many adverse symptoms, it doesn’t cause pain. In any case, when diluted homeopathically, it should have no effect.

Now it seems some homeopathic companies are not very adept at making dilutions and the effects on the babies were likely caused by an overdose of belladonna. Dilution is really a very simple process, so it is hard to see how they could get it so wrong. It seems homeopaths are not only incompetent when it comes to understanding chemistry and medicine, some are also incompetent at carrying out dilutions. Obviously homeopathy is not always just benign nonsense.

Joe Schwarcz PhD

You Asked: Does the Magnetic Laundry System work?

question markMagnets are fascinating. Imagine the amazement of the ancient Greeks who discovered that some naturally occurring stones, later named magnetite because they were found in a region of Greece called Magnesia, attracted iron. The stones also quickly attracted superstitious beliefs. Magnetite was said to have had magical powers, the ability to heal the sick and frighten away evil spirits. Archimedes, in an undoubtedly apocryphal story, is said to have used magnetite to remove nails from enemy ships and sink them. Magnets never sank ships, but they were used to guide them. We are talking about the compass.

Thousands of years ago the Chinese also noted the properties of naturally occurring magnetite. When made into the shape of a needle and floated on water, the magnetite always lined up in a north south direction! By about 1000 AD, the Chinese had developed the compass that became the key to navigation. But magnets have also been used to navigate people away from reality. In the 1800s physician Anton Mesmer had people hold onto magnetized rods to attract disease out of their body. Mesmerism, as his antics came to be called, often worked. The success of the treatment had nothing to do with the magnets, rather it was based on the belief of the patient. Magnets are great placebos. Today, magnetized bracelets can be purchased to energize the gullible. And you can buy magnetic laundry disks for insertion into washing machines to allow laundry to be done without the use of detergents. The claim is that the magnets ionize water and thereby increase its cleaning ability. Nonsense.

Advertising for these products often attacks commercial detergents accusing them of containing cancer causing chemicals and hormone disruptors. The claim is that the magnetic disks reduce health risks by eliminating exposure to these substances while also saving money since there is no need to purchase detergents. Furthermore, use of the disks prevents the release of toxic substances into the environment. That all sounds very “green.” References are given to a patent for the laundry disks, as well as to a study supposedly demonstrating their cleaning efficacy.

It is important to understand that the only requirement for obtaining a patent is novelty. In this case, since nobody before had the idea of putting magnets into a washing machine, the patent was not hard to get. When it comes to the patent, there is no need to show that the magnets actually do anything, just that their use in this context is novel. How about the study carried out by a testing lab that examined the cleaning efficacy? Technicians actually took bundles of clothes, washed them in a magnet equipped washing machine and demonstrated they came out cleaner than they went in. Surprise, surprise! Water is an excellent solvent and cleans remarkably well even without any detergent. The “study” had no control. That is, there was no comparison between laundering with just water and laundering with the magnetized water.

Is there any rationale that the magnets can actually do something? Water is diamagnetic, which means that it will be repelled by a magnet. But the effect is very, very, small. If a vial of water is placed on a piece of floating Styrofoam and a strong magnet is brought close, it will slowly move away from the magnet. An interesting phenomenon, but nothing to do with cleaning ability. But there is something about the advertising for the laundry disks that is not contestable. They are guaranteed to last for fifty years, a guarantee that is indeed safe since magnets do not rot. That is more than what can be said about the claims of their miraculous cleaning properties.

Joe Schwarcz PhD

You Asked: Is it true that getting angry can affect the heart?

stressAccording to a study in the European Heart Journal, a single angry outburst can have immediate adverse effects. That’s because anger causes an increase in blood pressure and a release of the stress hormones adrenaline and cortisol. Indeed, the risk of a heart attack or angina is nearly five times higher in the two hours following an anger outburst than at other times, and the risk of stroke is four times higher. Let’s not get too carried away with this though, because at any given moment the risk of a heart attack or stroke is very low, so even a five fold increase in risk isn’t that great. To put the numbers into perspective, researchers estimate that if 10,000 healthy people have one anger outburst a month over a year, one of them will suffer a heart attack or a stroke as a result of the outburst. Among people who have other risk factors such as smoking, being overweight, high blood pressure or high cholesterol, there would be four cardiovascular events over a year with one monthly outburst. But among people who get angry more often, which is not an unusual scenario, the risk rises significantly. For example, if 10,000 people who also have other risk factors have five angry outbursts a day, some 600 of them will have a heart attack or stroke.

Joe Schwarcz

You Asked: Can coffee explode in the microwave oven?

coffeeA sensational sounding e-mail about “exploding coffee” has been making the rounds. It describes the misadventures of an unfortunate soul who heated up water for coffee in a microwave oven. When he picked up the mug, it “exploded!”

Explode is probably too strong a term, but spurting and frothing is a real possibility. This is due to a phenomenon known as superheating. First, we have to understand what boiling is all about. At the surface of a liquid molecules are always evaporating. If we leave a glass of water out, it will eventually disappear.  If we heat the liquid, its molecules move faster, become more energetic and more molecules go into the vapour phase. As a consequence, the liquid disappears more quickly. At the boiling point, molecules all over the liquid, not only at the surface are energetic enough to go into the vapour phase. They do this most readily by evaporating into airspaces that exist in the container. All containers have imperfections where air gets entrapped when a liquid is introduced. As these air pockets fill with vapour, they expand and begin to rise. That is why we see streams of bubbles which originate at the sides or the bottom of the container.

In a microwave oven, the container is not heated, only the water.  So the container actually cools the liquid in contact with it, meaning that the liquid in the center is always hotter, sometimes by as much as 10 degrees C. But the liquid in the center cannot boil, because there are no air bubbles for it to evaporate into.  By the time the liquid near the edge of the container reaches the boiling point, the liquid in the middle is considerably hotter; it is superheated.

The addition of sugar or a tea bag now can spur vigorous boiling. This is because the surface imperfections introduce trapped air bubbles into which the superheated liquid vaporizes. Sometimes just picking up the container can have an explosive effect as the superheated liquid comes into contact with air bubbles on the periphery. Accidents can be prevented by putting a plastic spoon into the mug or glass while it is heating in the microwave. In this case the scare-mongering note about “exploding coffee” may actually has some basis in fact.

Joe Schwarcz PhD
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