The SPF Files: Why Sunscreen Exists and What the World Says About It

The SPF Files is a four-part series on sunscreen: its science, its formulation challenges, and the cultural forces reshaping how we use it. This is Part 1.

The sun is the most constant presence in human life — and arguably one of the most misunderstood hazards we face daily. For most of human history, a tan was seen as a marker of labour, class, or geography. The idea that invisible radiation could silently damage our DNA, accelerate ageing, and contribute to the most common cancer in the world is a relatively modern scientific discovery; and the science of photoprotection was born directly from that realisation.

This first article in The SPF Files series lays the scientific and regulatory foundation: what UV radiation is, how it interacts with human biology, what SPF actually measures, and how different countries and regions have chosen to govern sunscreen.

A Brief History of Photoprotection

The first commercially formulated sunscreen is generally attributed to chemist Franz Greiter, who introduced Gletscher Creme (Glacier Cream) in 1938 after a severe sunburn while climbing Piz Buin in the Swiss Alps. He later proposed the concept of the Sun Protection Factor (SPF) in 1962 — a measurement system that became the global reference for sunscreen efficacy and remains in use today, though the science around it has evolved.

In the United States, wartime necessity drove early development: pharmacist Benjamin Green created a sticky red petrolatum mixture for soldiers in the Pacific theatre during World War II (a crude, but functional as a barrier to UV). From the late 1970s onward, the FDA began reviewing sunscreens under its over‑the‑counter (OTC) drug monograph framework, a structure that remained largely static until reform efforts intensified in the last decade.

Parallel developments in Europe, Japan, and Australia unfolded under entirely different frameworks, generating a global patchwork of regulation, permitted ingredients, and labelling systems that still complicates life for any brand marketing sunscreen internationally.

The story of sunscreen is also a story of regulation lagging behind science. Many UV filters used in products today were approved decades ago, and some of the most photostable and effective filters developed in Europe are still not approved in the United States.

Understanding UV Radiation: UVA, UVB, and UVC

The sun emits radiation across a broad electromagnetic spectrum. Of direct relevance to human skin health is the ultraviolet (UV) range, which the World Health Organization divides into three bands by wavelength: UVA, UVB, and UVC.

Source: Own.

UVA: The Silent Ager

UVA radiation (around 320–400 nm) makes up roughly 95% of the UV that reaches the Earth’s surface. Because these wavelengths are longer, they penetrate more deeply into the skin, reaching the dermis where collagen and elastin live and driving photoageing: wrinkles, sagging, and uneven pigmentation. UVA also contributes to DNA damage and skin cancer, and its intensity is relatively constant all day, all year; even on cloudy days and through ordinary glass.

Formulators further split UVA into UVA‑II (320–340 nm) and UVA‑I (340–400 nm), because different filters cover these sub‑bands with different efficiency, which becomes crucial when you are targeting “broad spectrum” performance.

UVB: The Burning Band

UVB radiation (about 280–320 nm) represents a much smaller fraction of surface UV, but it is the primary cause of sunburn and directly damages DNA. Its intensity fluctuates strongly with time of day, season, latitude, and altitude, which is why the UV Index is expressed as a daily peak and can reach extreme values in places like Australia and New Zealand.

SPF was historically designed to quantify this UVB protection, not UVA. That is the origin of many misunderstandings and the reason separate UVA rating systems had to be created.

UVC: The Blocked Band

UVC radiation (100–280 nm) is the most energetic and, in high doses, the most biologically destructive, but under natural conditions it is almost completely absorbed by the stratospheric ozone layer. It is not a target for cosmetic sunscreen formulation.

What SPF Actually Measures

SPF measures how much UVB radiation a product filters compared with unprotected skin. It is defined as the ratio of UV energy required to produce a minimal visible reddening on protected versus unprotected skin.

In consumer terms:

• SPF 15 filters about 93% of UVB
• SPF 30 filters about 97%
• SPF 50 filters about 98%
• SPF 100 filters about 99%

The differences look small on paper but matter more in practice than most people realise, yet no SPF blocks 100% of UVB.

Critical limitation: SPF measures UVB protection only; it says nothing about UVA coverage. A product labelled SPF 50 with minimal or no UVA‑active filters could still allow substantial UVA‑driven photoageing and DNA damage. This blind spot is exactly why “broad spectrum” standards and separate UVA ratings (stars, PA+, etc.) were developed — and why they differ from region to region.

A second limitation is application quantity. SPF testing assumes 2 mg of product per cm² of skin, which is roughly a heaped teaspoon just for the face and neck. Real‑world studies show people typically apply half or even a quarter of that amount, which can drop the actual protection far below what is printed on the label.

The Melanin Myth

Melanin, produced by melanocytes, is the skin’s built‑in photoprotective system. It absorbs and dissipates UV energy as heat, providing a degree of natural SPF.

However, the idea that darker skin does not need sunscreen is both inaccurate and harmful. While deeper skin tones do enjoy more baseline protection from sunburn, they are not immune to skin cancer, photoageing, or UVA‑driven hyperpigmentation. These concerns are especially salient in APAC, South Asian, Middle Eastern, and Latin American populations.

The Global Regulatory Patchwork

There is no globally unified sunscreen rulebook. How a product is classified, which filters are allowed, what claims you can make, and how you test them all differ by market. For formulators and brands, this is one of the biggest strategic and operational challenges.

Here is a simplified view of major markets:

Source: Details drawn from public regulatory summaries and industry guidance on UV filters and SPF labelling. Updated to federal and national regulations, including TGA Order 2019, FDA Proposed Order 2021, EU Reg. 1223/2009, and ANVISA RDC 629/2022.

For any brand seeking truly global reach, regulatory misalignment is one of the biggest bottlenecks. A filter approved in the EU and widely used in South Korea may be unavailable in the US or restricted in Australia, forcing brands to create region‑specific formulas instead of a single global hero product.

Key Takeaways for the Global Consumer

• The Approval Gap: While the EU boasts a modern list of ~27 filters, the US is just now entering a transition phase. As of early 2026, the FDA has proposed adding Bemotrizinol — the first new filter in decades — to the US monograph, though it is not yet widely available in domestic formulas.
• Safety vs. Speed: Australia’s TGA enforces the strictest manufacturing standards in the world (GMP), meaning sunscreens there are essentially manufactured with the same oversight as pharmaceutical drugs.
• UVA Standardization: The PA system (PA+ to PA++++) that originated in Japan has become the gold standard for UVA transparency across Asia, whereas the US and Australia rely on the binary “Broad Spectrum” pass/fail claim.
• The SPF Ceiling: While you might see “SPF 100” in Brazil or the US, many regions (like the EU and Japan) cap labels at 50+ to prevent a “false sense of security” and encourage proper reapplication.

What Comes Next

With the scientific and regulatory groundwork laid, Article 2 — Inside the Lab — will step into formulation reality: how to design sunscreens that are effective, stable, safe, sensorially elegant, and compliant in multiple markets at once. What can go spectacularly wrong, yet what can go brilliantly right with the right filters, and partners.

Key Sources & Further Reading

• WHO — UV Radiation & Health Fact Sheet (2022) https://www.who.int/news-room/fact-sheets/detail/ultraviolet-radiation
• WHO — Radiation and Health (2024) https://www.who.int/teams/environment-climate-change-and-health/radiation-and-health
• IARC Monographs Vol. 100D — Radiation (2012) https://publications.iarc.who.int/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Radiation-2012
• FDA — OTC Sunscreen Monograph M020 & Proposed Order (2021) https://www.fda.gov/drugs/news-events-human-drugs/otc-monograph-reform-otc-sunscreen-drugs-12152021 Federal Register full text: https://www.federalregister.gov/documents/2021/09/27/2021-20780/amending-over-the-counter-monograph-m020-sunscreen-drug-products-for-over-the-counter-human-use-over
• FDA — Proposed addition of Bemotrizinol (BEMT) — December 2025 https://www.afslaw.com/perspectives/alerts/fda-proposes-first-new-sunscreen-active-ingredient-two-decades
• TGA — Understanding the Regulation of Therapeutic Sunscreens https://www.tga.gov.au/resources/guidance/understanding-regulation-therapeutic-sunscreens https://www.tga.gov.au/products/medicines/therapeutic-sunscreens/overview/sunscreen-regulation-australia
• EU Regulation (EC) No 1223/2009 — EUR-Lex https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=celex:32009R1223
• EU — Regulation (EU) 2022/1176 — Oxybenzone & Octocrylene concentration restrictions (2022) Summarised at: https://www.ul.com/news/eu-updates-annexes-v-and-vi-cosmetics-regulation
• EU — 4-MBC ban (Regulation EU 2024/996) — filter banned from May 2025 https://www.intertek.com/blog/2025/08-04-eu-regulations-for-sunscreen-products/
• ANVISA Brazil — RDC 629/2022 & updated framework RDC 907/2024 https://www.gov.br/anvisa/en/regulation-of-products/personal-hygiene-products-cosmetics-and-fragrances
• Pantelic, Wong, Kwa & Lim — UV Filters US vs EU review — JAAD (2023) PubMed: https://pubmed.ncbi.nlm.nih.gov/36442641/ Journal: https://www.jaad.org/article/S0190-9622(22)03141-3/abstract
• Heppt et al. — Ultraviolet Filters: Dissecting Current Facts and Myths — Journal of Clinical Medicine (2024) https://pmc.ncbi.nlm.nih.gov/articles/PMC11121922/
• Lautenschlager, Wulf & Pittelkow — Photoprotection — The Lancet (2007) https://pubmed.ncbi.nlm.nih.gov/17693182/
• Standards Australia — AS/NZS 2604:2021 Referenced on TGA pages; available via SAI Global