When I say a long time, I mean a really long time - maybe up to 170,000 years ago. Clothing is often made from soft, organic materials, things that degrade rather quickly. So we have very few artifacts to help us track clothing throughout human history. Because of that, the earliest evidence suggesting that humans wore clothing isn’t actually clothing; it’s a bug. Clothing lice are bugs that live specifically on clothing. A study showed that they diverged from their louse ancestors between 83,000 and 170,000 years ago. That implies that modern humans may have been wearing clothing for tens, if not hundreds, of thousands of years.

For as long as we’ve been wearing clothing, it has helped protect us. Initially, clothing likely helped with climate. Through various ice ages and global migrations, clothing kept us warm, even when fire and shelters couldn’t. It enabled our ancestors to survive in harsher climates than they otherwise would have.

To get to where we are today, clothing has undergone countless technological, stylistic, and functional advancements. And although clothing still helps regulate our temperatures, it also protects from other factors - namely, cancer. The sun emits ultraviolet radiation, which is just like visible light but has higher energy. Because of its higher energy, ultraviolet radiation, also called UV, can actually damage our DNA, leading to cancer. UV is a major risk factor for skin cancer, and is why we wear sunscreen, which can either reflect ultraviolet rays or absorb them before they damage our cells. As it turns out, some clothing can do that, too!

Unfortunately, most manufacturers don’t display UPFs, making it difficult to know which clothing provides real protection. There is a lot that goes into the UPF of a textile. It ranges from the chemical composition to the moisture content and the way the fabric is woven.

For example, you may have heard that darker fabrics absorb more heat. That’s because they have more pigment in their material. Those pigments can absorb radiation and convert it into heat. So it’s really not heat being absorbed, it’s radiation being converted to heat. That includes UV radiation, increasing the UPF of a fabric. Although it’s counterintuitive to wear black on a hot summer day, more pigment technically means more UV protection. Moisture content is also really important! Some fabrics take in and retain more water from the air, causing their fibres to swell. This closes gaps in the fabric and leads to more UV reflection. The tightness of the weave also plays an important role in the UPF. Tightly woven fabrics like satin provide greater protection, whereas loosely woven fabrics let more UV through. Nowadays, clothes can be treated with solutions to coat them with reflective molecules, also increasing the UPF of the fabric.

Carcinogens in clothing are a deeply layered topic. They’re found in all stages of a garment’s lifespan. As fast fashion and mass production rise, so too does the use of harmful chemicals in clothing production. From a plant being grown with toxic pesticides, factory finishes on a new piece of clothing, to how it’s disposed of after it’s thrown away.

To meet the high demand for new clothing, it’s essential to maintain crop health. That means companies will treat plants with pesticides to reduce crops lost to insects or rodents. The use of many of these pesticides has been linked with increased risk of cancer. This is particularly harmful because not only do these chemicals remain in fibres as they’re turned into clothes, but workers are also exposed to excessive amounts of carcinogenic chemicals daily.

The making and processing of clothing is also rife with risk. A lot of fabric nowadays is made with synthetic pigments. Some synthetic pigments are made with something called “aromatic amines”. These are some of the same chemicals found in tobacco smoke, and can lead to damaged DNA, linking them with carcinogenicity. The finishing process is possibly even worse. Shockingly, some garments are treated with formaldehyde to prevent wrinkling, which never fully washes out. Formaldehyde is used to embalm and preserve organisms. One of its main functions is to kill things and prevent decomposition. On top of that, it directly damages DNA, leading to cancer-causing mutations. Some clothes are treated with that…

Even after clothing is disposed of, it can still contribute to cancer. After clothes are thrown out, many are burned. This process releases any carcinogens in the garment freely into the air.

The history of clothing goes back tens of thousands of years. Throughout all of that rich history, apart from cultural or social significance, the main purpose of clothing has been protection. Nowadays, what we wear doesn’t always keep us safe. Overall, clothing can be a double-edged sword. On the one hand, it can protect us from UV radiation, a risk factor many of us are regularly exposed to. On the other hand, the production of clothing, from start to end, is riddled with the use of cancer-causing chemicals. Even the end of a garment’s life often produces carcinogens. This exposes both the people who produce clothing and those who wear clothing. Luckily for us, we can use this information to balance the risks we’re exposed to. Knowing how our clothing is made and what makes it safe can help us choose items that fit the risks we’re comfortable with.

I hope you learned a little something today, but for next week, it doesn’t matter what you wear because we’re taking a look inside the body as we discuss cancer imaging.

See you next week!

If you missed last week’s letter, you can read “It’s In Your Genes” to learn a little more about spontaneous and hereditary cancer.