Mineral blockers - you ask, what are those? There is basically 2 categories of sun protection: sunscreens and sunblocks. Sunscreens, commonly recognized as “organic filters” such as avobenzone, homosalate, octisalate, octocrylene, absorb the sun’s UV rays and convert them to heat within the skin to keep you protected. Sunblocks or mineral blockers, such as zinc oxide and titanium dioxide, actually create a physical block between the sun and your skin, so the rays never penetrate.
Ingredients to Know
Let's keep going with this definition exploration, continuing with chemical sunscreen ingredients that I like to avoid are:
Oxybenzone: It is the most widely used and most suspected of disrupting the endocrine system since it bioaccumulates in the body. Some studies have found this ingredient in breast milk.
Benzophenone: According to the National Oceanic and Atmospheric Administration (NOAA) this ingredient can cause mutations in corals by disrupting their DNA. Corals contain the most diverse ecosystem on the planet, they are necessary for the marine ecosystem's proper functioning as they are a source of essential elements for the marine food chain and provides habitat for many species.
Also beware of these ingredients: Oxybenzone, Benzophenone-1, Benzophenone-2 Benzophenone-8, OD-PABA, 4-Methylbenzylidene camphor, 3-Benzylidene camphor, nano-Titanium dioxide*, nano-Zinc dioxide* (*note: the nano precursor is what is problematic as there simply is not enough research done that shows the long term effects, both on the body, as well as for the environment of using nano-sized particles of these ingredients).
These ingredients perform a chemical reaction when they come in contact with UV rays and absorb them. They are preferred by the masses because they are easy to use (meaning they soak in quickly and leave no residue) but most folks don't realize the ingredients are derived from toxic petrochemistry.
So what do I like to see you ask?
Considered as true shields, these act as mirrors that bounce UV instead of absorbing them and because they are not bioaccumulative in the body, nor do they affect the endocrine system, they naturally minimize the negative effects on health, comparatively to chemical sunscreens.
Look for: Titanium dioxide and zinc oxide. (Note that titanium dioxide can be in nanoparticles form that bioaccumulates in the body and is therefore harmful to health. Always look for a non-nano mention).
Both ingredients offer sun protection but titanium dioxide may be carcinogenic if inhaled so do avoid aerosol products made with titanium dioxide.
What About 'Broad Spectrum'?
What Does SPF Really Mean?
And ... get this ... there isn't actually a hard rule for how SPF is calculated. For example, if it takes you 10 minutes to burn and you use SPF 30, you can stay out, protected for 300 minutes (take the amount of time it takes YOU to burn and multiply if by 30 - the SPF factor). However, say it takes ME 20 minutes to burn and I use SPF 30, I can stay out, protected for 600 minutes! How do we figure out how long it takes us to burn? Generally, the paler the skin, the quicker we are to burn. Regardless, I like to err on the side of caution and apply every 2 hours. Again, how to calculate SPF? Take the amount of time it takes YOU to burn and multiply that by the SPF factor.
SPF 30: 97%
SPF 50: 98%
SPF 100+: 98.3%
Between SPF 50 and SPF 100, there is literally no difference (0.30% - not even a whole percentage!). Choosing a sunblock between 30 or 50 should be your aim; the higher SPF is simply a powerful marketing ploy that suggests that it's far more powerful BUT in reality is only slightly more effective. And remember, a high SPF does not guarantee broad spectrum!