The problem or benefit of having a scientific background (and a skincare company) is that I’m constantly reading about skincare ingredients and products. There is so much misleading information in the green beauty industry that it takes time to find reliable sources for many of my questions and concerns. In the past few months, I have been immersed in professional cosmetic formulation resources and scientific literature about sun safety. After years of making and using my own sunscreen, I no longer recommend making and using DIY sunscreen.
Here’s the gist of it! The sun produces UVB and UVA rays. The UVB have shorter wavelengths that affect the surface of the skin and can cause sunburns and skin cancer. The UVA have longer wavelengths that penetrate deeper in the skin and while they are not the main sunburn culprits they can cause cellular damage, aging and skin cancer.
Sunscreens are classified according to their active ingredients. Chemical filters absorb some of the UVA and UVB radiation. These include avobenzone, homosalate oxybenzone, octisalate, octocrylene and octinoxate. Physical filters scatter and reflect UVB and UVA radiation. These include zinc oxide and titanium dioxide. A few sunscreens contain both chemical and physical filters.
Chemical filters have been having some bad rap lately since studies have indicated that a few may mimic hormones or cause skin allergies. If these concerns are valid or not is a totally different story. Also, there are more chemical filters that absorb UVB rays than absorb UVA rays. Physical filters are the ones DIY recipes and many green beauty brands use. They are great at reflecting both UVB and UVA, and have lower toxicity concerns. However, they are tricky to work with, especially in a home setting.
Let’s talk about zinc oxide, the physical filter most used in DIY sunscreens. Zinc oxide comes in different size particles and each of those sizes spread very differently giving different levels of protection. Normally, you don’t know which size particle they are using in a particular DIY recipe. The second major problem is clumping. Zinc oxide is really hard to disperse in a base, and practically impossible at home with a regular blender. Because it’s hard to disperse and tends to clump together, you are looking at an uneven distribution and patchy coverage. Lab photos that I have seen show cottage cheese type coverage with some patches protected and others not.
Do you see the issue here? In good conscience I cannot recommend making sunscreen or buying sunscreens that are not approved by Health Canada. In Canada, sunscreens are considered drugs not cosmetics and are regulated and tested (in humans) as such.
How to help keep sunburns, cellular damage, and skin cancer at bay?
1) Get a Broad Spectrum Sunscreen – SPF that stands for Sun Protection Factor and it only tells us about the UVB protection that a sunscreen will give, NOT UVA. Independently of the SPF always get a Broad-spectrum or Full-spectrum sunscreen that protects against UVB and UVA.
2) Application Time – Physical sunscreens work as soon as you apply them but chemical ones need about 20-30 minutes to absorb into the skin and do its magic. Apply every 2h and more frequently if you are active.
3) Application Amount – SPF is based on a specific amount of sunscreen during testing. If you are applying less, you have less sun protection. There’s no set amount for children but the Skin Cancer Foundation recommends that adults use at least an ounce (30 ml, 2 Tbsp.) of sunscreen per application.
4) Physical protection – Best protection is always physical protection. Seek shade at peak hours, use protective clothing, hats and sunglasses.
Enjoy the sun but be safe!