As a young child, I was plagued with a a skin condition until my middle school years. When my mother applied ointments on me, I posed questions in protest. What she putting on my skin? How does it work? Although I didn’t find the answers at the time, this was the reason Vanity, Vitality, and Virility, by John Emsley, piqued my interest. The book takes a deep dive into the worlds of our industries, particularly ones which some of us may not be the same without – take the example of me and my ointments – and encourages the reader to explore the ingredients and their functions in our sunscreens, snacks, and  medicines. My skin condition, a type of eczema, would cause white patches to form on my face when I was small. Although genetics factored into acquiring the disease, a variety of skin conditions are caused by overexposure to certain UV rays. The most common form of UV radiation is sunlight, which emits three types of UV rays, UVA, UVB, and UVC. These rays are present from the 400 – 100 nm range on the electromagnetic spectrum, a range invisible to the human eye. However, although the vast majority of UVC rays are absorbed by our ozone layer, UVA and UVB rays do affect our bodies. UVA rays can cause our skin to slowly turn brown, while UVB rays “…produce a quicker response, and it goes fiery red.” (Emsley 18).  Our cells have evolved over time to protect our skin from these rays. A chemical pigment called melanin is the most effective, which is produced in the upper layers of the skin by melanocytes. Melanocytes are also responsible for the dark colour of hair. Melanin cells are triggered into producing this pigment when exposed to UVA rays, and produce it via the amino acid tyrosine. Tyrosine combines with other molecules and creates the melanin polymer. The more UVA rays absorbed, the more melanin generated; this demonstrates a correlation between the amount of UVA rays absorbed by a human and their skin tone, which accounts for the variation in skin tone around the world. In countries where exposure to sunlight is high, inhabitants have evolved over time to produce higher amounts of melanin. In countries with low exposure to sunlight, the inhabitants take more time to produce melanin, and are at a larger risk of skin conditions such as sunburn, or even skin cancer. For example, Australia has one of the highest skin cancer rates in the world. This is due to its short distance from Antarctica, where a hole in the ozone layer allows more UV rays to reach the planet’s surface, and Australia’s high population of fair skinned people, who cannot produce melanin fast enough to protect themselves from immediate overexposure. For many, the skin care products we have today are an absolute essential for any day in the sun. Sunscreens are primarily composed of 5% microfine titanium dioxide, 5% UV absorbing chemicals, 10% oils, and 5% of emulsifying agent, and the rest being distilled water. The microfine titanium dioxide is present as nanosize, invisible particles, of which the optimal size is “…around 50 nanometres”. (Emsley 22). These reflect UV rays which come in contact with the skin. The UV absorbing chemicals can deactivate the UV rays once our skin absorbs them. They do this by interfering with the free radicals, molecular remnants of broken chemical bonds which react violently, produced by UV rays meeting the skin. It was once thought that because our cells produce urocanic acid, an amino acid, as natural protection against UV light, we could benefit from adding it to cosmetics as a moisturizing agent; it was used consistently in the 1960s, but it is now known that . Antioxidants such as vitamin C and vitamin E can accomplish similar tasks, because they can interact with free radicals and stop a reaction before crucial molecules are damaged. The emulsifying agent is present in order to keep the solution together, and prevent separation. Before reading the book, I found the word “fat” to be quite a trigger word in the context of food.  I understood fat intake as an easy way to gain weight and become unhealthy. Emsley leads us to an avenue of chemistry which has provided an understanding of how my understanding was both right and wrong. He discusses where fats come from, why certain fats are essential to our well being, and how some fats negatively impact our health. An increase in weight is not directly caused by fat intake. What matters is the amount of energy it releases. The calorie is a unit which measures the amount of energy needed to raise the temperature of 1 gram of water 1 degree celsius. When the body has a surplus amount of energy, it creates its own body fat, which shows as pores of skin all over the body. Emsley suggests that to maintain good health, one should “…take in twice as much unsaturated fats as saturated fats”. (Emsley 36). Unsaturated fats are typically found in vegetable oils, such as olive, sunflower, soya, and others. Fats and oils come from the same kind of chemicals – derivatives of fatty acids. Fatty acids are comprised of a chain of carbon atoms, where one carbon at the end is attached to an acid group. Saturated fats have chains which are “…neatly in line with each other,”  (Emsley 39) and pack together well, hence their solid phase. When two hydrogens on the carbon chain are removed, two of the carbons form a double bond and an unsaturated fat is formed. Talk about mono unsaturated and other fatty acids. Research has shown that there are two fatty acids which cannot be eliminated from the diet, because they play a role in producing a group of key body chemicals known as prostaglandins. Prostaglandins are found in nearly all animal tissues, and are necessary for certain hormone effects on animals, such as the feeling of pain. If lacking in them, the loss of organ function could easily occur. blah blah Include which foods these fatty acids can be found in. Other examples of fats contributing to health can be found in triglyceride molecules – collections? of three fatty acids attached to glycerol – such as polyunsaturated fats. These molecules have multiple double bonds between carbons; noteworthy polyunsaturated fats are the omega 3 and omega 6 fatty acids. These contribute to certain metabolic processes, and are required in generating arachidonic acid, which is the source of chemicals involved in the body’s defences. They were also included as a supplement to formula milk, as their inclusion makes the solution more like breast milk. Although these fatty acids may be beneficial, there are many which are unfavorable – such as trans fats. Trans fats are another type of triglyceride, which have a trans double bond in their chain. Trans fats come into play during the process of hydrogenation. Hydrogenation is a method of converting oils to fats, by “…reacting them with hydrogen gas at elevated temperatures…” (Emsley 47). Food industries often do this in order to create a particular texture, or increase shelf time. However, in 1994 a study was done by a Harvard professor which found evidence linking trans fats to heart disease. Furthermore, they restrict the formation of cyclooxygenase, which is involved in blood regulation. Not only chemistry played a large role in the knowledge of how foodstuffs affect our bodies, but it has facilitated a pivotal change in agriculture as well, via fertilizers. In the 1800s, chemists realized that atmospheric nitrogen is a vast resource, and converting it to ammonia could lead much more efficient farming. However, there was extensive struggle in reacting nitrogen with hydrogen to produce ammonia, no matter how much the reactants were heated. In the early 1900s, German chemist Fritz Haber discovered that the reaction could be orchestrated if iron was present as a catalyst. Afterwards, a process engineer named Carl Bosch proved it could be “…made to work commercially…” (Emsley 68). As a result, in 1909, the first Haber Bosch chemical plant was constructed. Unfortunately, the ammonia they supplied was first used by Germany to create explosives for World War I and World War II. In 1945, however, the ammonia began going towards ammonium nitrate fertilizer, and this fertilizer allowed a much larger output of fruits and vegetables on smaller plots of land. Today, around “…2 billion people worldwide…” require the fertilizer to feed their families.