Your guide to safe synthetics and natural alternatives
Product inventor Jack Constantine
Preservatives are substances added to food and other products to keep them fresh for longer. They ensure that perishables aren't affected by microbial spoilage, retain a long shelf life, and that consumers are protected from any potential infection. The result is an insurance policy, giving you peace of mind every time you touch a product.
Throughout history, people have found innovative ways to keep food, drink and cosmetics clean, fresh and safe to use without the use of fridges, freezers, chemicals or handy tupperware containers. Take a trip back in time to see how the history of preservation has unfolded.
Early civilisations relied heavily on preserving food for scarcer times. The ancient Egyptians would dry grains and store them in sealed containers to ensure they kept for the longest period possible, while the ancient Greeks and the Romans packed their meat and fish in salt to keep it edible for months after it was caught.
Wood smoking food has been traditional and natural way of increasing the shelf life of a foodstuff for millennia. Since the Neanderthal era, people have used fire to preserve their food and feed their families for longer and there is evidence of early humans smoking food atop their chimneys and tipis. Smoked salmon, a delicacy enjoyed as part of a champagne breakfast, was first eaten by nomadic Native American tribes centuries ago.
Fast forward a hundred years or so and summer fruits was steeped in alcohol to prolong their shelf life. This practice really took off in the Victorian era when the dried, alcohol-steeped fruit was enjoyed in the form of the traditional Christmas pud. In fact, the Ford family from Michigan, USA, lay claim to an unusual heirloom baked in 1878: a Christmas pudding cooked by their great grandmother that has been passed down through the generations and, impressively, is still edible.
Canning was a technique first developed in France during the Napoleonic Wars (1799-1815), when French brewer Nicolas Appert created a means of sealing food in glass jars to feed the French army. His technique was developed into a process of packaging food in airtight cans made of tinned wrought iron.
As well as keeping soldiers fed, the great explorers of the age would take canned food on expeditions all over the globe, allowing them to explore farther than ever before. Unfortunately, not all canning methods were safe at the time, as demonstrated by an ill-fated expedition to the Arctic in 1845 led by John Franklin. When the bodies of the crew were recovered, lead poisoning from the solder used to seal canned food was found to have been a factor in their deaths.
In many ways and at many points in our evolution, natural preservation has been the key to human preservation. During the Second World War, eggs and milk were rationed, and their powdered alternatives offered because they had a far longer shelf-life. In the same way salted beef and pork were presented as corned beef and Spam - a form of salted ham.
While powdered goods were scorned by many, they contained the same essential nutrients as their fresh counterparts, at a time when they were not readily available. During the war, for example, most adults were limited to one fresh egg per week. Dried alternatives could be added to cakes and bakes in powdered form, or rehydrated with water to be used in liquid form.
Freezing prevents micro-organisms from accessing moisture in food, which keeps perishables fresh for longer. Subterranean icehouses can be traced back to medieval times when they were used to provide cool storage for most of the year. Up until around the 1950s, ice was imported into the UK from Scandinavia, creating a lucrative trade for entrepreneurs.
The introduction of the first practical, domestic refrigerators in the twentieth century signalled the end of the lucrative ice shipping business. Initially, the public were reluctant to leave behind their iceboxes - non-mechanical cold closets packed with ice - but by the 1940s, the domestic refrigerator had mostly been embraced by consumers who delighted in their practicality.
Of course, there were limitations to what could and couldn't be preserved and for how long until scientists introduced parabens in the 1930s. These non-toxic, odourless, colourless, and inexpensive chemical preservatives revolutionised the industry because products that once had a shelf life of months could be stored for years, which drastically reduced wastage.
Parabens are still widely used today because of their reliability, non-toxic nature and long history of safe use.
Free water, also known as 'water activity,' refers to water that microbes can use to reproduce. Like all living things, micro-organisms need water and nutrients to grow, and so water-based products like shower gels provide the perfect environment for bacterial reproduction. To keep perishables safe and fresh, free water must either be reduced or microbial growth must be controlled with a preservative. Synthetic preservatives like parabens can be used to stop microbes from developing in water-based products. Absorbent natural materials like clay and water-soluble compounds like salts and sugars can also be used to reduce the amount of water that microbes are able to access. Solid, naked products have minimal water content which means they don’t need added preservatives.
On average, 5 million aerobic bacteria live on each square centimetre of your skin. These are able to clear any pathogenic micro-organisms in 20 minutes, providing the skin is clear of cuts or abrasions. A good preservative should limit interference with these important micro-organisms.
To protect consumers, the European Union monitors the use of synthetic preservatives, both by classifying which materials can be used as preservatives and limiting the maximum usage of these. Manufacturers, however, are not limited by the number of preservatives they can use in a product.
Preservatives have different methods of keeping a product clean, and the effectiveness of each synthetic can be boosted when two preservatives that work in different ways are teamed up. Much like a doubles tennis team, one preservative can defend at the net while the other covers the back of the court, both waiting to tag-team microbes.
For example, preservatives like methylparaben and phenoxyethanol punch holes in bacterial cell walls or membranes, much like pulling the plug out of a bath. This means that the bacteria is unable to reproduce. Others like propylparaben and benzyl alcohol prevent microbes from forming cell walls properly so the bacteria can't close itself in to reproduce. This means a second generation of microbes can't form.
Parabens are a family of chemical preservatives that are used to prevent the growth of harmful bacteria and mold in perishable goods like preservatives. During their long history of use, numerous studies have assessed their safety and effects on the skin in extensive detail.
Paraben controversy is derived from a piece of research by the University Of Reading, UK, in 2004, in which scientists took biopsies of breast tumours and found parabens inside. This formed the basis of a theory that parabens, which can weakly mimic the hormone oestrogen, could disrupt hormones and increase the risk of breast cancer. However, the study has since been widely criticised.
Critics pointed out that the researchers involved did not examine healthy tissue for traces of parabens, and that they also could not guarantee that the equipment used to conduct the study had been cleaned using paraben-free materials. Evaluating the 2004 conclusions, and subsequent studies led by the same chief researcher, European safety body The Scientific Committee of Consumer Safety concluded that there was insufficient data to establish a link between the use of underarm cosmetics and breast cancer.
In fact, parabens have been subjected to such rigorous testing that experts now believe that they are safer than other synthetic alternatives. Rachel Rawson, senior clinical nurse specialist at Breast Cancer Care, confirms: "There is currently no conclusive evidence to suggest that the use of products containing parabens is directly linked to the development of breast cancer." Dr Stefanie Williams of European Dermatology London adds: "[Parabens] are well established skincare preservatives and, for the vast majority of customers, won’t cause any problems."
Of the 75,000 metric tonnes of synthetic preservatives used in 2015, only 17% were parabens. We know little about the other 83%, but they include substances like formaldehyde - antiseptic gas that is used to preserve biological specimens as well as in cosmetics - and methylisothiazolinone - an antimicrobial substance used in cosmetic preservation, moisturisers and baby products. These preservatives have caused concern in recent studies for irritation of the airways and the skin.
Proven safe alternatives to parabens, then, are limited. As D.C. Steinberg wrote in Cosmetics & Toiletries: Preservatives for Cosmetics (1996), "The ideal preservative does not – and probably cannot – exist." Yet Dr Edmund Fowles of EF Chemical Consulting LTD, puts parabens into perspective, explaining: "I feel absolutely sure that parabens are safe. As a result of all the fuss about the potential risks, there has been exhaustive research, which has covered all angles. Paraben-free cosmetics simply use a different type of preservative, which will have been much less rigorously researched, so how can we say that it’s better?"
Although confident that the materials are safe for use, Lush co-founder Helen Ambrosen is keen to reduce the amount of synthetic preservatives used on environmental grounds (as well as for human health). She says, "Synthetic preservatives that are available to the cosmetic industry, like parabens, stop things decaying in the environment, so when people use them they are going down into water systems and so on. There's an argument for preserving products with materials like honey, which will not harm the environment in any way as they will break down naturally."
If expertly used, a number of ingredients can keep formulas fresh naturally - eliminating the need for synthetic preservatives. These materials can reduce the water content of a product and create an environment that is inhospitable to micro-organisms, but simultaneously add benefits to a formula, making it lovely to use on your hair and body.
Honey is the product of blossom nectar transformed into a rich, glutinous ingredient by honey bees. Batches from different areas have unique flavours, colours and properties, which are determined by regional flora, meaning a great variety of honeys can be sourced - and have been for thousands of years. In fact, evidence of early humans harvesting honey has been found on an 8000-year-old rock painting from Valencia, Spain.
Honey combines a high sugar content with a very low water content, which creates an inhospitable environment for micro-organisms and gives the material renowned antibacterial and antimicrobial properties. Archeologists have uncovered pots of honey in ancient Egyptian tombs that are still perfectly edible, meaning the jar of honey in your kitchen cupboard will definitely outlive you - unless you eat it first.
Glycerine is a byproduct of soap manufacturing, and can be either synthetic, or derived from plants or animals. The substance was accidentally discovered in 1779 when Swedish chemist K. W. Scheele heated a mixture of olive oil and lead monoxide, and declared the thick, resulting liquid the "sweet principle of fat." A century later, M. E. Chevreul, a pioneering French investigator of fats and oils, named it after the Greek word for sweet: glykys.
Glycerine has over 1,500 uses, meaning this clear viscous material more than lives up to its reputation for versatility. Glycerine absorbs free water into its structure, creating an inhospitable environment for microbes, and making it an ideal substitute for water in products such as shower gels. Glycerine also has hydrating properties on the body and the ability to carry ingredients like fruit juices deeper into the skin.
Salt is derived from both seawater and from a mineral known halite and has been harvested by humans for thousands of years. Ancient Egyptian art from as far back as 1450 BC shows salt making taking place, while Roman soldiers were paid in the highly coveted mineral. Our word 'salary' is derived from salt.
Salt is also a valuable currency when it comes to preserving products, keeping micro-organisms at bay through a process called osmosis. Adding salt to a product formula attracts water molecules away from micro-organisms, which means they aren’t able to survive and the product can keep itself clean. And, as well as being antimicrobial and exfoliating, salt also has a natural antiseptic and astringent effect, which helps to keep you clean and healthy.
Natural, plant-derived butters have plenty to offer: rich, hydrating qualities on the skin and deterrent effects on microbial growth. Human civilisations have a long relationship with natural butters, with shea traceable as far back as Cleopatra's Egypt, when it was carried in large clay jars for use on the skin. Cocoa has also long been prized commercially - initially as a drink by the Mayan and Aztec civilisations.
Cocoa butter (which is obtained from the seeds of the cacao tree) and shea butter (which is extracted from the nut of the African shea tree), are natural emulsifiers meaning they bind oil and water together to create a tight emulsion that deters microbial growth. They also melt at body temperature to create a barrier on the skin that locks in hydration.
Clays like kaolin are soft mineral substances which are the product of volcanic ash that has been subject to environmental influences, and can be pulverised into fine, dry particles like talc. They have been a popular cosmetic ingredient for millennia: the ancient Greeks would use clay as a facial soap and skincare ointment, while the ancient Egyptians applied naturally tinted clay minerals on the lips and cheeks for colour.
Clays and powders are used more sensibly in modern cosmetics for their absorbent and deeply cleansing effects on the skin, as well as added exfoliating properties. These materials are also highly valuable as natural preservatives: hiding excess water that may be active within a formula. By carefully mixing up ingredients in a process called dispersion, micro-organisms cannot grow and reproduce, enabling products to stay fresh and clean for longer.
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Bees are the chemists of the natural world, taking watery, sugary nectar and transforming it into unspoilable honey. Slowly scientists and beekeepers are gaining precious insight into this complex process of self-preservation.
Busy worker bees forage for nectar amongst the flowers and store the substance in a separate stomach compartment, only consuming the little they need for energy. The rest of this precious cargo is carried back to the hive and given to a recipient bee via a mouth-to-mouth transfer.
Repeated regurgitation between more bees in the colony concentrates this sugary solution further, before it is deposited in droplets along the inner hive wall. Excess water evaporates and it dries out further and thickens into recognisably rich and sticky honey.
Bees must reduce nectar's very high water content to create a preservable foodstuff for the winter. The recipient bee processes the nectar inside her mouth and stomach, using an enzyme to break down the substance's complex sugars into simple, more digestible ones.
The inner hive is already a toasty 95 degrees fahrenheit, but the bees optimise the evaporation process by repeatedly fanning the honey with their wings day and night. Their combined efforts create the infamous buzzing noise we hear coming from beehives and gradually reduce the water content of the honey to around 18%.
This process of collection and evaporation is an endless cycle in a bee’s relatively short life which is dedicated to building a store of sweet and nutritious honey with which to feed the next generation.
