Cancer
Sunscreen Basics
2025-09-06
Sunscreen Basics
Sunscreen is one of the most effective tools to prevent skin cancer, sunburn, and premature aging. But not all sunscreens are equal — and not all claims are reliable.
Summary
Choose a broad-spectrum SPF 30+ or higher, apply generously, and reapply often. Physical blockers like zinc are highly reliable, while chemical filters are also safe when tested properly.
What SPF Really Means
- SPF 30 filters ~97% of UVB rays.
- SPF 50 filters ~98% of UVB rays.
- No sunscreen blocks 100%.
- The biggest factor is application — most people apply only half the recommended amount.
Types of Sunscreens
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Chemical filters (oxybenzone, avobenzone, octocrylene, etc.)
- Pros: Lighter feel, easier to spread, often invisible on skin.
- Cons: May irritate sensitive skin; some degrade faster in sun/heat.
-
Physical/mineral blockers (zinc oxide, titanium dioxide)
- Pros: Very stable, broad-spectrum, effective immediately, lower irritation risk.
- Cons: Thicker texture, can leave a white cast (though tinted formulas help).
👉 Zinc sunscreens are often recommended by dermatologists, especially for sensitive skin and children, because their UV protection is consistent and reliable.
Which Sunscreens Can You Trust?
- Independent testing by Choice (Australia) and Consumer Reports (US) shows not all products match their label claims.
- Zinc-based sunscreens generally perform well, including those marketed as “reef safe.”
- Some brands — like Kokua Sun Care (Hawaii, zinc-based, backed by pro surfer Kelly Slater) — build reputations on transparent testing.
⚠️ Always look for independent reviews and third-party testing, not just the label.
Sunscreen and Coral Reefs
- Myth: Sunscreen causes coral bleaching.
- Truth: Coral bleaching is primarily caused by warming oceans from climate change.
- Some chemical UV filters (oxybenzone, octinoxate) may harm coral larvae in lab studies at high concentrations.
- Real-world reef exposure is far lower, but many people choose reef-safe (zinc-based) sunscreens when swimming in sensitive areas.
How to Use Sunscreen Effectively
- Apply at least a teaspoon per limb (~30–40ml for full body).
- Reapply every 2 hours, or after swimming, sweating, or toweling off.
- Use daily when the UV index is 3 or higher (common in Australia year-round).
- Combine with hats, clothing, and shade for full protection.
FAQs
Q: Is zinc sunscreen better?
A: Zinc is stable, broad-spectrum, and very reliable. But high-quality chemical sunscreens are also safe and effective. The best sunscreen is the one you’ll actually use consistently.
Q: Do higher SPF sunscreens last longer?
A: No. SPF is about the level of protection, not duration. All sunscreens need reapplication.
Q: Can darker skin tones skip sunscreen?
A: No. While melanin provides some protection, darker skin can still develop sun damage, aging, and skin cancer.
Q: Can sunscreen prevent melanoma?
A: Yes. Regular daily use of SPF 30+ significantly lowers the risk of melanoma and other skin cancers.
References
- Cancer Council Australia — sunscreen advice
- WHO — UV radiation and protection
- Consumer Reports — best sunscreens
Related Guides
- #sunscreen
- #skin cancer
- #SPF
- #zinc
- #sun safety
- #patientguide