Cosmetics

Parabens and Breast Cancer

Chemical Institute of Canada — Fri, 20 Jan 2012 03:04:57 GMT

Sometimes researchers remain stubbornly wedded to their ideas even when their own work begins to unravel the fabric they have woven. I believe such is the case with Dr. Phillipa Darbre of the University of Reading in England. Back in 2004 Darbre achieved tabloid fame with her allegation that antiperspirants were implicated in breast cancer because they accosted breast tissue with preservatives known as parabens. These compounds have estrogenic properties and estrogens have indeed been implicated as significant players in breast cancer.

Darbre showed the presence of parabens in cancerous tissue taken from breast cancer patients and suggested a cause and effect relationship, buttressing her argument by pointing out that most breast cancers occur in the quadrant of the breast closest the armpit where shaving nicks would allow entry of antiperspirants most readily. The study was small, only some twenty patients, and she had no controls. She had no idea whether parabens were also present in the breast of healthy women. Furthermore, she never determined if her subjects had actually used antiperspirants. The study was castigated by many breast cancer researchers with suggestions that even a high school science fair participant would recognize the need for controls. They pointed out that breast tumours have long been known to occur more frequently in the top quadrant of the breast closest the armpit simply because that area has the highest concentration of tissue.

Stung by the accusations, Darbre has cranked out a series of papers demonstrating the estrogenic effects of parabens and measuring their concentration in various tissues. Her latest paper, published in the Journal of Applied Toxicology, not one of the world’s most impactive journals, furthers her attempts to forge a link between these chemicals and breast cancer. This time she has investigated more patients, 40 of them, and took 160 samples, analyzing them for different parabens. She did not study any samples from healthy women, in other words, still no controls. She did, however, compare parabens concentrations in tumour areas and elsewhere.

There was no relationship between amount of parabens detected and tumour location, an observation that runs contrary to parabens playing a decisive role. This time she did determine whether the patients had used antiperspirants and as it turns out seven out of the forty had not. So the parabens were coming from elsewhere; no great surprise here because these chemicals are widely used in a variety of cosmetics and foods. Darbre clearly states that the presence of a chemical in breast cannot be taken to imply causality, which of course is true. But she then goes on to discuss all sorts of reasons why her negative results do not rule out this possibility. For example, she says, absolute levels of parabens may not be the main determinant of risk because of variations in individual susceptibility. Small amounts may trigger it in some people, not in others, so there may be no correlation. An attempt to rationalize her preconceived notions. And what about the possibility that parabens play no role at all? Has she considered that? But a seductive hypothesis with which one has become identified is rarely given up even when confronted by cruel facts.

Formaldehyde in Baby Shampoo-Crunch the Numbers, Crunch the Scare

Chemical Institute of Canada — Mon, 14 Nov 2011 02:12:54 GMT

It is a very small molehill. But to the folks at the Campaign for Safe Cosmetics (CSC) it seems more like Mount Everest. This organization’s recently released report features a cute baby smothered in lather, sitting in a bathtub under the headline “Baby’s Tub Is Still Toxic.” What is this all about? Acrylic monomers leaching out of the tub? Lead in the water? Chemicals out gassing from the shower curtain? Reactions to mould on the grout? Nope. The warning is about the trace amounts of formaldehyde or formaldehyde-releasing compounds added to some baby shampoos to prevent bacterial contamination.

Reading this report may send any mother who has used a baby shampoo preserved with formaldehyde into a state of panic, fearing they may have doomed their offspring by exposing them to a “known carcinogen.” Well, let’s throw in a little science before we throw out the baby shampoo. Yes, formaldehyde is a likely carcinogen. But that categorization was made on the basis of inhaling the chemical in significant amounts under occupational exposure. Embalmers and pathologists have indeed experienced a slight increase in cancer rates attributed to formaldehyde, mostly of the nasal cavity. However, data indicate that no tumours have been found when occupational exposure was below 2.4 mg of formaldehyde per cubic meter of air.

Now let’s crunch a few numbers. A shampoo preserved with a formaldehyde-releasing agent such as “quaternium-15” has a formaldehyde yielding potential of 0.4 mg per gram. And let’s say that about 10 grams of shampoo, a rather generous amount, are used to wash baby’s hair. So we have the possibility of releasing 4 mg of formaldehyde into the air. But wait! Formaldehyde is very soluble in water, so very little will evaporate. But let’s really play it safe and assume that half, or 2 mg, will evaporate. Now, assuming that the volume of air in a bathroom is about 10 cubic meters, and that there is zero ventilation, the concentration of formaldehyde will be 0.2 mg per cubic meter, or one tenth the amount that has never caused a tumour even with continuous exposure! Of course, here we are not talking about continuous exposure. Nobody bathes a baby for eight hours a day. Therefore any suggestion that formaldehyde in shampoo presents a cancer risk is unfounded. Actually, mommy’s breath may be a greater risk. Formaldehyde is a product of human metabolism and breath can contain concentrations of formaldehyde at 0.4 mg per cubic meter. Maybe the greatest benefit of fear mongering about formaldehyde in shampoo is to make mommy breathless.

While inhalation of formaldehyde from shampoo is a non-issue, problems due to skin exposure cannot be so readily dismissed. Formaldehyde is a known allergen and can trigger rashes and inflammation, but these effects are also dose dependent. Skin sensitization can occur when the concentration in a solution is above 0.2%. And how much is present in baby shampoo? If all the formaldehyde were instantly released from quaternium 15, the concentration in baby shampoo would be 0.04%. But quaternium-15 is a slow releaser, so the effective concentration is far less than that. There may be some babies that react to these remarkably small amounts, but far fewer than would react to the bacterial contaminants in a poorly preserved product.

As can be seen, once appropriate calculations are made, the clamor to remove formaldehyde as a preservative from baby shampoos amounts to no more than unscientific noise. But as far as marketing goes, the public is right even when it is wrong, and manufacturers are working towards using alternate preservatives such as benzyl alcohol, potassium sorbate, sodium benzoate or methylisothiazolinone. Of course one can dredge the scientific literature and come up with risks for these as well. Dig deep enough and at some dose you can find some sort of risk with any chemical.

Furthermore, if we want to eliminate all risks from formaldehyde, we’ll have to get rid of particleboard, permanent-press fabrics, varnishes, paints, carpeting, curtains, nail polish as well as many types of insulation and paper products, all of which are manufactured with formaldehyde and can out gas the compound. In some cases, as with the notorious trailers that were supplied to victims of the Katarina disaster, out gassing can be enough to cause severe eye irritation and respiratory symptoms. To curb formaldehyde exposure we would also have to forget about fireplaces, gas cookers, driving cars and of course, smoking. Even then we would be ingesting some formaldehyde because it occurs naturally in virtually all foods.

When it comes to the use of products for the hair, there is one area where formaldehyde poses a real concern. Some of the “Brazilian” hair smoothing products contain sufficient formaldehyde to pose an occupational hazard to hair dressers. Here the chemical is not used as a preservative, it is one of the active ingredients needed to form links between protein molecules in hair. And unfortunately the presence of formaldehyde in these products can be hidden by using alternate names for the chemical on the label. Methylene glycol, methanal, oxomethane and formalin are some of these. Often these products declare themselves to be “formaldehyde-free.” You certainly wouldn’t want a baby lying all day in a hair dressing salon where such products are used to “smoothen” hair. But washing baby’s hair with baby shampoo, any kind of baby shampoo, is a completely different story. So let’s get formaldehyde out of Brazilian hair products but let’s not throw out the baby with the bath water. Trace amounts of formaldehyde in shampoos prevent bacterial contamination, a significant problem, at minimal risk.

If you want to worry about a real risk in the tub, consider that about 150 children in North America, the majority under four years old, end up in emergency rooms mostly because of tub falls, many of which could be prevented with the use of a vinyl mat. Now that really matters! But I suspect that the folks behind the Campaign for Safe Cosmetics might then make an issue of the phthalate plasticizers that leach out of the mat.

Ethyl or methyl, what’s the difference? When it comes to sculptured nails, a lot.

Chemical Institute of Canada — Mon, 10 Oct 2011 00:20:20 GMT

It’s a fingernail biting problem. You would like to have nice, long, shapely nails but yours just won’t grow properly. Time for a little chemical help. You know you can avail yourself of the latest acrylic technology at your local nail salon, but you have a lingering concern about safety. You’ve heard about the nasty things that methylmethacrylate can do. Redness, swelling, itching, blisters, lifting of the nail from the nailbed, irritation of eyes, nose and the bronchial tract. Who wants to take a chance with wicked things like that? Nobody. Certainly not the Canadian or the U.S. governments. That’s why methylmethacrylate is banned from use in sculptured nail products.

But your salon advertises sculptured acrylic nails! Are they defying the law? No. Not all acrylics are created equal. They’re not using methylmethacrylate, they’re using ethylmethacrylate. May not sound very different, but the extra carbon atom in this compound’s molecular structure makes a huge difference in terms of its toxicity. Ethylmethacrylate doesn’t have the same potential for skin or respiratory irritation as methylmethacrylate. But what do these chemicals do anyway?

Sculptured nails are distinct from glue-on nails, which have their own issues. The glue-on nails are made of polymethylmethacrylate, a plastic that commonly goes by the name of Plexiglass. This material is inert and doesn’t cause problems, but the glue with which it is stuck on, a cyanoacrylate, can cause irritation in people who have become sensitized to it. Sculptured nails are also made of polymethylmethacrylate, but the formation of the plastic actually takes place on the nail. A flexible template is inserted under the natural nail plate and the elongated sculptured nail is then built on top of the nail and the template extension. The process involves mixing two components, one a powder, the other a liquid, and applying the mixture to the nail with a brush in layers. In minutes the plastic hardens, it can be sanded and then covered with nail polish.

Now for the interesting chemistry that’s involved here. The powder is polymethylmethacrylate, a polymer that is formed by joining methylmethacrylate molecules into a long chain. The role of the liquid with which the powder is mixed is to cross-link the long polymethylmethacrylate chains. Sort of like using rungs to make a ladder. The liquid contains individual molecules of ethylmethacrylate. When mixed with the powder, and prompted by an “initiator,” also contained in the powder, the ethylmethacrylate molecules join together to form a chain that ties together the polymethylmethacrylate chains. The result is a hard plastic. Before it was banned in 2003, methylmethacrylate was used as the cross-linking agent and it created numerous problems. Today people still have a concern about acrylic sculpted nails because few appreciate the difference between the terms ethyl and methyl. But when it comes to chemistry, the difference between that “e” and “m” is huge.

Acrylic Fingernails

Chemical Institute of Canada — Wed, 17 Aug 2011 00:05:57 GMT

There’s lots of interesting chemistry in acrylic fingernails. Actually you have two types of acrylic fingernails. You have the type that is made of acrylic and is attached to the fingernail with cyanoacrylate glue, which is also a type of acrylic. And you also have the gel type that is painted on to the fingernail and is hardened by exposure to ultraviolet light. That involves some fascinating chemistry with the polymerization actually taking place on the finger.

This kind of a reaction is initiated by the formation of highly reactive molecular species known as free radicals. Once formed, a free radical adds to a molecule of methyl methacrylate, which then becomes very reactive and adds to another molecule to form a “dimer” which then latches on to another “monomer,” and pretty soon all the small molecules are zipped into a long chain. You now have a hardened acrylic nail. But why do you have to sit with your fingers under an ultraviolet lamp? Because it’s the UV light that generates the initial free radicals that get everything started. Ultraviolet light is energetic enough to break chemical bonds, which is exactly what it does to a “photoinitiator” that is incorporated into the mix. Under the effect of UV it breaks apart into free radicals. These then start the cascade of reactions resulting in a polymer. Of course ultraviolet light is energetic enough to break other chemical bonds as well, including ones in DNA. That’s why excessive exposure to the sun causes skin cancer. And that brings up an interesting question. Is there a risk of cancer by exposing the skin on the hands to ultraviolet light while waiting for the acrylic gel to harden?

Some concern about this possibility was generated by two Texas dermatologists in a paper submitted to the Archives of Dermatology in 2009. They reported diagnosing skin cancer on the fingers of two women, aged 55 and 48, both of whom had had previous exposure to ultraviolet nail lights. The first one had a 15 year history of twice monthly UV nail light exposure, the second had about eight treatments in one year, but that was several years before the first cancer appeared. Such case reports are interesting but they are not very meaningful statistically. Ultraviolet light cured acrylic nails have been popular for some twenty years with millions of women using them. Any significant risk of skin cancer on the hands would have already been noted epidemiologically. Actually, UV exposure from nail lights is quite small in comparison to exposure from other UV sources such as sunlight. Living in Texas exposes one to significant UV.

Calculations show that exposure from a nail lamp is equivalent to spending an extra 1.5 to 3 minutes a day in sunlight between salon visits, the time depending on whether the lamp has one or two bulbs. Basically the two case reports do not make for a compelling case and should not cause panic. The time spent under the lamps just isn’t long enough to present a significant risk. It is also interesting to note that since the paper originally appeared there have been no further reports of skin cancers linked to nail lights. One would have expected other dermatologists who read the paper to chime in with case histories that they noted, as is often the case after such publications. No further reports have been published. So there’s no need to fret about acrylic fingernails, at least not because of UV exposure. But in addition to the acrylic monomers and photoinitiators, there are cross-linking agents, reaction accelerators, plasticizers and pigments. So irritation and allergic reactions are always a possibility.

Preservatives in Cosmetics

Chemical Institute of Canada — Fri, 15 Apr 2011 05:44:00 GMT

What a strange world this is. On one hand people are terrified of bacteria. They shell out without abandon for all sorts of antibacterial cleansers. They’re wiping their kitchens, their bathrooms and their hands with a myriad products formulated to destroy bacteria. But when it comes to applying makeup to their face, mascara to their eyes or deodorants to their armpits, then heck with the bacteria. Bring’em on. Don’t dare adulterate my personal care products with “preservatives,” they say.

Consumers increasingly seek out products advertised as “preservative free,” or “formaldehyde-free” or “parabens-free.” I wonder if they would be as eager to buy these products if the label stated “contents susceptible to bacterial contamination which may result is skin rash or eye infection.” Do people think that cosmetic manufacturers add preservatives just to boost their expenses? No, they add these chemicals to increase the safety of their products. Most cosmetics are oil and water emulsions, just the kind of medium that bacteria need to proliferate. When you rub on moisturizer, you can readily pick up some nice pseudomonas or staphyolococcus bacteria that naturally inhabit the skin and introduce them into the jar when you take your next dab. In the nice cozy moist environment and comfy temperature of the bathroom, these bacteria can happily multiply, waiting to escape the next time a finger dips into the jar. Put the contaminated cream near the eye, and an infection can follow. Put it on the skin, and you may be looking at a rash. If you have an open cut, bacteria can enter the bloodstream and you could be looking at a systemic infection.

Various parabens and formaldehyde releasers added to products in very small amounts, less than 1% of total weight, not only prevent such health problems, but also help prevent spoilage due to bacterial action. So why do people want their cosmetics to be free of such chemicals? Because they have read in alarmist books or pseudoscientific websites that formaldehyde is a carcinogen and that parabens interfere with hormonal function and have been linked to breast cancer. Well, yes, technically formaldehyde is a carcinogen, because if the dose is high enough, it can cause cancer in test animals. But that is a very different situation from its effects when a tiny dose is applied to the skin. Parabens do have estrogenic properties, but depending on which specific paraben we’re talking about, the effects are a thousand to a million times less than that of estradiol, the body’s own estrogen. Furthermore, parabens also have aromatase inhibiting activity, which actually reduces the conversion of testosterone to estrogen. Aromatase inhibitors are actually used in the treatment of breast cancer.

The bottom line is that the trace amounts of parabens that consumers are exposed to from cosmetics are not a health issue. But if the public wants “preservative-free,” then that is what producers will provide. So they are either leaving out preservatives, or loading up their cosmetics with “natural” preservatives of questionable efficacy derived from roses or honeysuckle. Another marketing trick is to use a preservative such as phenylpropanol which is found in flowers and fruits and can therefore be labeled as natural, even though it is actually produced synthetically in the lab. Not that this matters. Phenylpropanol is a safe preservative and whether it is extracted from a plant or made in the lab is irrelevant. There is no difference between the two. But in business the customer is right even when he is wrong. I wonder how long before we see a product marketed as “ingredient-free?” Would sell well, I bet.

Whitening Teeth

Chemical Institute of Canada — Wed, 28 Jul 2010 02:34:45 GMT

Everyone wants pearly whites. And carbamide peroxide can deliver the goods. You’ll find it in most tooth-whitening products for the simple reason that it can deliver hydrogen peroxide, H₂O_2,to the tooth surface. Hydrogen peroxide itself is a liquid and difficult to apply to teeth, but when it’s mixed with urea it forms a gel of carbamide peroxide that can easily be painted on teeth, placed into trays fitted to the teeth, or incorporated into whitening strips. Thickeners such as carbopol and glycerin are often used to achieve the right consistency. Actually, hydrogen peroxide isn’t the real active ingredient. It is the hydroxyl free radical that it yields that can break down colored molecules.

Tooth discoloration is mostly the result of colored substances in foods and drinks that embed themselves over time in the calcium phosphate that makes up the tooth’s outer coating, the enamel. Tannins in tea and coffee, anthocyanins in blueberries, and polyphenols in red wine are just some of the compounds that can discolor teeth. A further complication is that dentin, the mix of proteins and calcium phosphate that lies beneath the enamel, yellows naturally with age. The molecules responsible for tooth discoloration tend to have a network of carbon-carbon double bonds. Such unsaturated systems, as they are called, absorb all colors but reflect yellow. Hydroxyl radicals are highly reactive and can disrupt these double bonds, leading to whitened teeth.

Applying various peroxide products to the teeth is generally quite a safe and simple procedure, although some people experience heightened sensitivity to cold after their dentist applies products containing high concentrations of hydrogen peroxide. Products developed for home use generally contain only 3 to 6 percent hydrogen peroxide and do not cause sensitivity, but they may take weeks to lighten discolored teeth. We may not yet have an ideal system for treating stained teeth, but carbamide peroxide is surely a great improvement over historical methods, including gargling with urine or rubbing the teeth with a mixture of chalk and ground rabbit skull.

A Problem with Baby Shampoo?

Chemical Institute of Canada — Fri, 01 May 2009 15:44:45 GMT

I like to listen to the radio when I cook. And I was just in the midst of chopping my veggies when the lead item on the newscast caused my ears to perk up: “Carcinogenic chemicals found in baby shampoos!” I knew I had better get ready for the onslaught of phone-calls and the emails because the words “carcinogen” and “baby” in the same sentence add up to a formula for panic. But first things first. The chicken was already in the pot and I had to finish chopping my parsnips, carrots, onions and celery for the soup.

Once the soup was nicely simmering, I began to Google. The consumer group, Campaign for Safe Cosmetics, I learned, had commissioned a laboratory analysis of a number of children’s shampoos and bath products, and was now trumpeting the discovery of undeclared formaldehyde and dioxane. Since both of these chemicals are classified as probable human carcinogens, it comes as no surprise that the airwaves and newspapers were soon filled with stories about “baby products tainted with cancer causing chemicals.” What do I make of it all? Much ado about not much.

How do these chemicals end up in these consumer items in the first place? Formaldehyde is an indirect additive, released at a controlled rate from imidazolinyl urea, DMDM hydantoin or quaternium 15. Its purpose is to keep bacteria at bay. Dioxane is another story. This is a trace contaminant that is formed during the manufacture of certain detergents, such as those that may be included in baby shampoos and bubble baths. Concern arises because in addition to being likely carcinogens, formaldehyde and dioxane, are also potential allergens. Of course the pertinent question is whether or not the amounts found in these products present a risk. As we well know, dose matters.

As far as allergens are concerned, the dose that matters can indeed be very small. Some cosmetic products may contain up to 600 parts per million of formaldehyde, and that can cause skin irritation. Such reactions are rare, but possible. But reactions to bacterial contaminants that may form in the absence of preservatives are a bigger concern. It always comes down to a risk-benefit analysis. We don’t ban peanuts because allergy to them they may threaten the lives of some consumers.

People may accept the risk of an allergic reaction, but when the specter of cancer rears its head, well that’s another story. Indeed, formaldehyde can cause cancer, at least in animals that inhale it at a high dose over a long period. There is also some evidence that embalmers, pathologists and people who work with formaldehyde-containing resins may have a slightly increased risk of cancers of the lungs, nose and throat. But these exposures are astronomically greater than that presented by products such as shampoos which are applied, and then washed away. Even when formaldehyde is applied to the skin of mice at concentrations of up to 10% over their lifetime, no effects on longevity are noted.

Dioxane, based on animal studies, is a carcinogen. When administered to rats in large amounts in their drinking water, it can cause cancer. However, studies carried out on people who have extensive occupational exposure to dioxane have not shown any increase in cancer rates. So why should we tremble at the trace amounts of dioxane in some cosmetic product, amounts which in any case evaporate almost immediately when applied to the skin? We shouldn’t. But what about the possibility that tiny amounts may be absorbed through the skin and build up in the body? That seems to be very unlikely. A study of over 2000 people of all ages, randomly selected, has failed to detect any dioxane in their blood. So what’s our bottom line? Exposure to trace amounts of formaldehyde or dioxane from cosmetic products is not a big worry. If you’re going to get all antsy about such things, you might as well worry about, well, chicken soup!

That’s right. My chicken soup is loaded with carcinogens. Not man-made additives, but naturally occurring compounds. Furocoumarins like 8-methoxypsoralen are present in parsnips and celery. Not only are they potential carcinogens, they can cause nasty skin reactions. Carrots contain caffeic acid, another carcinogen. I commonly add basil, which contains estragole, a known rodent carcinogen. The same can be said for alpha-methylpyrroline in black pepper. I’m sure an analysis of my cooked chicken would reveal some heterocyclic aromatic amines, nasty carcinogens. And then there is the formaldehyde. It occurs naturally in the onions and shiitake mushrooms I use to flavour the soup. In fact, shiitake mushrooms, can have a whopping 400 parts per million of formaldehyde!

What is the point here? To trigger headlines about toxic chicken soup? Of course not. We need to realize that we are constantly exposed to thousands and thousands of chemicals on a daily basis, both natural and synthetic. Some, whether natural or synthetic, have the ability to trigger cancer under certain conditions. But the nature of those conditions is critical. The risk to an embalmer working with a concentrated formaldehyde solution day in and day out, or to a rodent reared on formaldehyde-laced drinking water, is not the same as that to a human exposed to traces of formaldehyde in a shampoo. And I don’t worry one bit about the formaldehyde I’m ingesting in my soup, even though I bet my exposure is far greater than from any shampoo.

If these notions drive you to drink, remember that alcohol is an established carcinogen. And if you would rather relax with a cup of coffee, well, then enjoy the acrylamide, chlorogenic acid and furfural, along with a host of other natural carcinogens.