Water is not just valuable, it is essential. Yet Formulators are aways so quick to qs to 100%. Barbara Brockway investigates the vitality of water and the different ones out there
A professor once offered a prize to the student who could bring to his next lecture the most expensive water they could find. The student who won was not the one who brought him a bottle of mineral water costing £16 for 1 litre but the one who offered him her mother’s moisturising skin cream. Dry weight analysis on the cream showed that it was 65% w/w water. The professor cruelly concluded that her mother had paid £160 for just 39ml of water. This water cost over £4,100 per litre. Of course there are even more expensive products with just trace amounts of water that would make their water content even more expensive, but the professor’s point was well made – water can be very expensive. But as Oscar Wilde famously wrote “Nowadays people know the price of everything and the value of nothing”... so having pointed out the high price of water it is important to now consider its value.
Water is so crucial to life that space missions searching for signs of life on Mars concentrate on looking for signs of water. Fortunately for terrestrial life, water covers 70% of the earth’s surface and has been estimated to be over 1.4m cubic kilometres.(1) With all this water around us there’s a danger of us becoming complacent and taking it for granted. Experts on human behaviour, population dynamics and global economics predict that the demand for water will soon outstrip its availability, making water wars a serious threat. The United Nations predicts that by 2025 two thirds of us will experience water shortages and in 2050 it believes 7 billion people in 60 countries will be water-stressed.
Economists are already talking about the trade in virtual water (ie the volume of freshwater used to produce a product(2,3)) and countries are trying to control this indirect trade in their water. Israel, for example, is discouraging the export of oranges in an attempt to conserve the virtual water which would otherwise be needed to grow the oranges. Personal care companies who are discussing their carbon footprint may soon find themselves calculating how much virtual water goes into their products. The Body Shop already touched on this in 1999 when it attained Millennium Product status with its Eau No travel range of products that required minimal water in manufacture and use. These products were developed in an attempt to raise awareness of the need for water conservation and to encourage tourists to respect the environment at their destination.
WATER IN SKIN & HAIR
Of the 150 litres of water that the average person in the UK uses per day, only 1.6 litres are used for drinking (Chenoweth, 2008). In the US it has been estimated that the average sedentary adult man should consume at least 2.9 litres (women 2.2 litres) of fluid per day, in the form of non-caffeinated, non-alcoholic beverages, soups and foods; interestingly, solid foods contribute approximately 1 litre water per day and there is an additional 0.25 litres of water made when we metabolize food. It is believed that a significant number of people in areas where there is no obvious water shortage may be chronically mildly dehydrated.(8)
It is generally accepted that to be well hydrated we need to replace the approximately 2 litres of water a day lost through breath, transepidermal water loss (TEWL), sweat, urine and faeces. The rate of TEWL varies from person to person and is influenced by many factors such as the local humidity, but 0.5 litres a day is a safe estimate of how much water is lost through TEWL by normal adults in comfortable surroundings.(4)
The BBC tested the idea that drinking water is better for our skin than drinking tea, coffee and soft drinks etc. It asked one girl from a pair of twins, who had a habit of drinking two litres a day of bottled water, to satisfy her thirst instead by drinking watery drinks. Five days later, despite their different drinking habits, the moisture and elasticity levels in the twin’s skin were unchanged. While this type of experiment on just two people is hardly scientific it does illustrate nicely that all drinks, apart from alcohol, can count equally towards maintaining healthy skin.(6)
And in case you’re one of the people in the cosmetics industry who is concerned about the small moleculer sizes involved with nanotechnology it’s worth bearing in mind that the critical diameter of a water molecule is just 32nm, yet funnily enough everyone is perfectly happy to use it.
As with skin the amount of water in hair is dependent on the relative humidity. When hair is at room temperature (and at 70% humidity) it contains around 15% water. The intact cuticle on undamaged hair prevents water from readily leaving or entering the hair shaft. However, when hair is washed and soaked, the water more easily enters between the polypeptide chains, swelling the hair. In undamaged hair nearly all the swelling is due to free water being absorbed between the cortical fibres. The amount of swelling increases in damaged hair especially when bleaching or perming has damaged significant numbers of disulphide bonds. The degree of swelling is a useful index for hair damage. Some of the free water in hair will become bound by hydrogen bonding to the proteins and these bonds help increase the elasticity of the hair, but unfortunately wet hair is weaker than dry hair. Some conditioners work by increasing the amount of bound water that remains in hair when it dries. The bound water also helps to reduce static.(5)
IN SEARCH OF MOISTURE
As we age, the structure of our tissues changes so that they are less able to hold water and our bodies become less hydrated. The water in our total body mass falls from around 72% for younger adults to only about 60% for adults aged over 60.(7) It would be nice to think we could replace this lost water simply by drinking more or soaking in a bath, but that would be like turning stale bread into fresh bread by wetting it. Unfortunately stale bread is hard because the starch has re-crystallized (starch retrogradation) and added water can no longer get to the binding sites found in fresh bread so the original texture would not be recovered. The ageing process in skin is more complicated than bread staling but skin also undergoes changes that result in a loss of water binding sites.
Not only does aged skin contain less water, it is also less able to control the rate of water loss. The stratum corneum needs to be kept hydrated at greater than 10% water to maintain its flexibility and integrity. When it dries it readily becomes cracked, brittle and rigid leading to rough, dull and dry skin. Moisturisers are designed to help skin look and feel better by enabling it to retain water and control water loss. Moisturisers could in theory add water back to skin as skin is not completely waterproof; which is why when we soak ourselves for any length of time, some water starts to seep in and cause the skin to expand and form temporary wrinkles. (10) In practice however, the water in the emulsion starts to evaporate as soon as it is applied to skin and it is usually lost within 15 minutes. Moisturisation is achieved through the increase in skin barrier function due to surface lipids, dominated by emulsion lipids, which immediately increase when the emulsion is applied to the skin. The surface lipids normally remain high for at least two hours after application before gradually declining. During this lipidisation phase, epidermal hydration parameters are slightly but consistently improved.(9)
Moisturisers can also contain hygroscopic molecules that behave like the complex mixture of natural moisturising factors (NMF) found in skin. These molecules need to be small enough to penetrate a little way into the skin where they can catch water and act as tiny reservoirs. NMFs make up 20-30% of the dry weight of skin and consist of amino acids and their derivatives such as pyrrolidone carboxylic acid (PCA) and urocanic acid (UCA) together with lactic acid, urea, citrate and sugars.(11) It should therefore not be surprising that moisturisers containing combinations of glycerin, amino acids, non-reducing sugars such as trehalose, urea and sodium PCA have been shown to be very effective.
Hygroscopic molecules can be a problem when formulating anhydrous products such as bath bombs. If they are not suitably protected from moist air, components such as glycerin in a bath bomb will attract moisture and cause a slow bleed of carbon dioxide, shortening the product’s shelf-life. On the other hand large hygroscopic molecules have also proved useful as plumping agents used to make lips larger and more attractive as well as to fill in our fine lines and wrinkles. The sodium hyaluronate (hyaluronan), chondroitin sulphate and large proteins packaged in Active Concepts’ plumping Nanovectors are designed to enter the upper layers of skin and rapidly expand as soon as they come in contact with moisture.
Hygroscopic macromolecules, especially the glycosaminoglycans (GAGs) are also involved in normal skin hydration. Hyaluronan is arguably the most important and the largest GAG. Sodium hyaluronate is made up of repeating units of the disaccharide, N-acetylglucosamine and glucuronic acid and can have molecular weights up to and around 1 million to 1.5 million. This molecule retains very large amounts of water and controls molecular movement in the extracellular matrix where it is also involved in cell movement and proliferation.(12) As we age the levels of hyaluron fall. Anti-ageing products therefore often contain sodium hyaluronate, but it is accepted that its large size means it cannot penetrate skin to fulfil all its natural functions but will hold moisture and perhaps help broken skin heal. Other large macromolecules such as those found in algae extracts including carrageenan and alginates, the gums such as guar gum and synthetic polymers like polyquaternium-51 and dimethylacryl-amide/acrylic acid/polystyrene ethyl methacrylate copolymer also retain large amounts of water and can be included
in formulas to act in a similar way to hyaluronate.
WATER CONTENT & CONTROL
Aqua is very often the first name on INCI listings. It is the cheapest of all the ingredients so formulas can be made less expensive by increasing the amount of water. The food industry cleverly included alginates into low fat spreads to make the spread less fatty and therefore healthier but also less expensive. There was however a downside for the food industry. The higher water activity in these ‘healthier foods’ meant that spreads had to be preserved against microbiological spoilage. The cosmetics industry already preserves its products so it can take advantage of the same principle without worrying about spoilage. For example, alginates can be included in emulsions to help moisturise skin but they also allow for more water in a formula and can reduce the cost of materials.
Controlling the water activity in products is one way to improve stability and reduce or even eliminate the need for preservatives. Lipid oxidation and non-enzymic browning as well as microbial growth all depend on the availability of free water. Even ascorbic acid breakdown is prevented when the water activity (aw) reaches levels less than 0.4. Amongst all the common spoilage bacteria it is Staphylococcus aureus that is capable of growing at the lowest water activity (aw 0.86) so, as the jam makers among us know, controlling water is one route to preservative-free.(13)
SOURCES OF SUPPLY
Usually it is demineralised water that is used in a formula because variations in trace levels of substances in water can cause problems. There are many examples of problems that can be traced to minute changes in water composition. For example natural banana conditioner with natural banana pulp will turn black if the level of iron in water is too high; easily illustrated by cutting a banana with an iron knife. Although it is a myth that swimming pool water can turn hair green, when blond hair, particularly chemically bleached or damaged hair, is exposed to high concentrations of copper in tap water or swimming pools it can result in green hair and the metal content of water can affect the performance of hair dyes.(14)
Companies occasionally have their own special proprietary treated water and a few more niche companies are keen to use water that has first been energised with the Vortex Energiser, a special tapered coil that causes an energising vortex. Whether there are any measurable benefits from using these different sources of waters does not seem to take anything away from the increasing requirement for water from exotic locations. Mineral and spa waters undoubtedly contain trace amounts of essential elements that are good for the skin and several prestige skin care companies are investigating the benefits of water from unique Eastern European locations, often near spa towns famous for the health giving properties of their spa water. Even water from UK towns such as Harrogate have found a place in natural skin therapies.
Soliance in France has data supporting the benefits of using its Spring Sea Water (Eau de Source Marine), which is pumped from a natural reservoir near the coast of North Brittany more than 22 metres below ground. Salt is removed as the sea water percolates through the rock leaving the water naturally rich in minerals and trace elements.
Waters from thermal springs, Mont-Blanc glacial water and pure Tasmanian water are now commercially available. Because of prevailing winds, this water originates from Antarctica and retains many of the characteristics of the water in the Antarctic snows. These waters bring with them not only a full mineral composition but, like The Body Shop’s Eau No range, they can be used to raise awareness of the effects of climate change.
For those developing 100% organic products, the author asked the Soil Association whether there was an approved source of organic water. Maarten van Perlo replied: “Water is not something that can be grown so it’s impossible to produce it organically.” It seems a terrible shame that formulators have to resort to using flower waters, reconstituted aloe vera and organic rice starch waters in order to get around not having sources of water approved for 100% Organic certified products.
PROTECTING PEPTIDES
Finally it is important to remember that many of the latest active ingredients are peptides that mimic skin’s peptide messengers. Often it is the shape of the hydrated peptide that is important so they normally cannot be used in lipsticks and anhydrous products. Salvona’s unique encapsulation process will hold these peptides in a hydrated micro-environment surrounded by a shell that disperses easily in waxes and oils. These systems allow active peptides to be incorporated into every type of cosmetic. They can also be engineered to release their varied contents in the presence of moisture such as TEWL and perspiration, making them ideal delivery systems for all types of fragrances and actives including antiperspirants.(15)
Water is not just valuable, it is essential. Yet we unthinkingly qs with water. A slight increase in water could destabilise and make a low water product vulnerable to spoilage but then again it could be the answer to how you can lower costs. If the professor’s point was right and the water in your prestige product does work out to cost the consumer over £4,100 per litre then maybe using exotic water in place of demineralised water would help justify the cost. If you are worried about your product’s carbon footprint and the virtual water needed then remember special waters may be available locally. As the world moves towards water shortages it is vital to know the value of water as well as its price.