Mary Cundiff, Ph.D.
October 2026
(7 Minutes)

This article is Part I of a two-part series and was inspired by the Science VS. Podcast

Sunscreen has become an integral part of modern life. We generally agree that protecting our skin from the sun is important: excessive ultraviolet (UV) exposure can cause sunburn, premature skin aging, and skin cancer.

At the same time, the current wellness boom has brought increased attention to potentially “toxic” chemicals in everyday products, and sunscreen has become one of the more controversial examples. We want to be vigilant about protecting our skin from UV radiation, but we also want to know that the products we use to do so are safe. That raises an increasingly common question: Is sunscreen toxic?

Before getting into the science behind sunscreen ingredients and what we know about their safety, it helps to understand how we got here.

The History of Sunscreen
The sunscreens we use today are the product of thousands of years of sun-protection practices, followed by more recent scientific discoveries and plenty of trial and error that eventually gave us modern sunscreen formulations.

Before Sunscreen: Melanin as Natural Protection
For much of early human history, topical sun protection likely wasn’t necessary in the way we think about it today. Early Homo sapiens evolved in Africa roughly 300,000 years ago, where high levels of UV radiation favored darker skin pigmentation. Darker skin contains more melanin, a pigment that helps protect cells from UV-induced DNA damage. (We’ll get into the biology of melanin later in this article.)

As populations of Homo sapiens migrated out of Africa roughly 60,000–70,000 years ago and settled in regions with lower UV exposure, particularly northern climates, skin pigmentation gradually changed in response to different environmental pressures.

Ancient Approaches to Sun Protection
By the time of the ancient Egyptians and Greeks (roughly 3100–300 BC), people were applying substances to their skin for both cosmetic purposes and sun protection.

Lighter skin became culturally desirable in some societies, and Egyptians used ingredients such as rice bran, jasmine, and lupine in preparations intended to limit tanning or alter the appearance of the skin. The Greeks used olive oil both as a skin treatment and as protection from the elements.

Interestingly, modern research has investigated some of these traditional ingredients for biological properties relevant to UV exposure and skin health. Rice bran contains compounds capable of absorbing UV radiation, while jasmine-derived compounds and lupine have also been studied for effects on the skin. Oils such as olive oil can provide limited UV protection (SPF ~8), although they should not be considered substitutes for modern sunscreen.

The Discovery of UV Radiation and Skin Damage
The cultural association between fair skin and social status continued for centuries and remains influential in some cultures today. But by the late 1700s and 1800s, our understanding of the skin itself was beginning to change. Dermatology emerged as a medical discipline, UV radiation was discovered, and scientists began investigating the relationship between sunlight and skin pigmentation.

By the late 1800s and early 1900s, researchers were establishing connections between UV exposure, sunburn, and skin cancer. These discoveries helped inspire some of the earliest attempts to develop topical products specifically intended to protect human skin from UV radiation.

When Tanning Became Fashionable
Then, Western beauty standards shifted.

In the 1920s, Coco Chanel famously helped popularize tanned skin after photographs circulated of her returning bronzed from a Mediterranean trip. Whether she actually “invented sunbathing” is debatable, but she became strongly associated with a broader cultural shift toward tanning as a symbol of leisure, health, and privilege.

By the early 20th century, tanned skin increasingly replaced pale skin as a desirable beauty standard in many Western societies. With that change came demand for products that allowed people to spend more time in the sun.

In 1935, Eugène Schueller, the founder of what would become L’Oréal, developed Ambre Solaire, an early commercial tanning product marketed as helping users tan while reducing the risk of burning. The Ambre Solaire brand still exists today.

World War II and “Red Vet Pet”
World War II created another practical need for sun protection. Military personnel stranded in deserts or on life rafts could experience intense, prolonged sun exposure, prompting the U.S. military to look for an effective protectant that was waterproof, inexpensive, and suitable for widespread use.

One solution was red veterinary petrolatum, commonly known as “red vet pet.” It worked, but it was thick, greasy, dark red, and not exactly something most people would voluntarily wear to the beach.

Benjamin Green, an airman and pharmacist who served during World War II, experimented with making a more consumer-friendly version. By combining the protective substance with ingredients such as cocoa butter and coconut oil, his formulation eventually contributed to the development of Coppertone.

The Birth of SPF
But how do you know whether a sunscreen actually works?

That question led to the development of SPF, or sun protection factor. Swiss chemist Franz Greiter is widely credited with helping develop the SPF concept in the 1960s. Years earlier, after reportedly getting sunburned while climbing Piz Buin in the Alps, Greiter had developed an early sunscreen called Gletscher Crème, or Glacier Cream. His company, Piz Buin—named after the mountain—still exists today.

As sunscreen products became more sophisticated, manufacturers developed increasingly effective and water-resistant formulations, regulators became more involved, and standardized methods for measuring sun protection emerged.

By the 1980s, SPF had become a standard way of describing sunscreen performance. The FDA defines SPF based on the amount of solar energy required to produce sunburn on protected skin relative to unprotected skin.

By the 1990s, SPF 15–30 products were increasingly common, and organic UV filters such as avobenzone and octyl methoxycinnamate, also known as octinoxate, were widely used.

Sunscreen Enters a New Era of Scrutiny
By the 2000s, the conversation surrounding sun protection began to change again. Scientists weren’t only asking how well sunscreen prevented UV damage. They were also asking what repeated use of sunscreen ingredients might mean for human health and the environment.

On one end of the spectrum, researchers were finding an association between indoor tanning devices and melanoma. On the other end of the spectrum, they were also finding that high levels of sunscreen in seawater could contribute to coral bleaching. Because of this, in 2018, Hawaii passed legislation restricting sales of sunscreen that include oxybenzone and octinoxate for their concerns on coral reef ecosystems. On top of that, a study in JAMA found that several commonly used sunscreen ingredients—including avobenzone, oxybenzone, octocrylene, and ecamsule—could be absorbed and detected in the bloodstream at levels that triggered additional FDA safety testing.

Importantly, exceeding this threshold does not mean that these ingredients were shown to be toxic or harmful. Rather, the results demonstrated that sunscreen ingredients can be systemically absorbed and highlighted the need for additional research into their long-term safety.

Where Does That Leave Us Today?
The modern history of sunscreen is no longer just about preventing sunburn. It is also about balancing effective UV protection with questions about ingredient safety, environmental effects, formulation, and long-term exposure.

As more people learn about the importance of protecting their skin from UV radiation, they are also becoming more conscious of what is in the products they use. That has left sunscreen in an unusual position: it is one of our most important tools for reducing UV exposure, yet some of its ingredients are also the subject of ongoing scientific and public debate.

So, after thousands of years of trying to protect ourselves from the sun, we arrive back at our original question:

Is sunscreen actually toxic?

To answer that, we need to look beyond the label and examine what happens to sunscreen ingredients once they are on, and potentially inside, our bodies.

Tune in next month for part II of this article!