Organic vs. Inorganic UV Filters
This nomenclature itself causes confusion as it relates to the chemical structure of the active constituents found in each type of sunscreen.
“Inorganic” means the compound does not contain carbon-carbon bonds as with mineral sunscreen ingredients: titanium dioxide and zinc oxide. Whereas “organic” UV filters like oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate are chemical compounds that contain lots of carbon molecules. Therefore the inorganic mineral sunscreens are actually more “natural” than the sunscreens with chemical/synthetic or organic active ingredients.
Same-Same But Different
Both types of sunscreen filters can reduce UV radiation but there are a couple of important differences to take into consideration. Mineral zinc oxide and titanium dioxide reflect UV rays while chemical ingredients absorb UV rays to dissipate them. Studies have shown that, when common chemical sunscreen ingredients oxybenzone, avobenzone, and octocrylene absorb UV radiation, a small amount is converted to heat.
Therefore, if you have sensitive or delicate skin, mineral sunscreens are likely a better choice as the synthetic ingredients have a greater risk of causing allergic reactions, rashes, redness, flushing (especially with pre-existing rosacea) or even blistering. Inorganic mineral filters also provide broad-spectrum protection, photostability, non-irritability, and have a lower environmental impact than their chemical counterparts.
Oxybenzone and octinoxate have been found to be toxic to coral and marine ecosystems not only through swimming in oceans but also via wastewater/sewage treatment plant outflows. The link is so great that in 2018 the state of Hawaii passed a bill banning sunscreens that contain these 2 ingredients. Additionally, animal studies have raised concern that chemical sunscreens may disrupt normal hormone patterns as they are absorbed into the bloodstream and can pass into urine and breast milk at levels exceeding what is recommended for toxicology testing. At this stage, all this means that the FDA-set threshold for topical medications to undergo safety studies has been surpassed and further research is needed to determine the effects this chemical exposure actually has on human health.
So what’s the better choice?
Inorganic mineral filters, which reflect and scatter UV light, have been termed as physical or barrier sunscreens and, at this time, seem to be the better choice for you and the planet. While historically, these options have gotten a bad rep due to their application (flashbacks of chalky white sunscreen that sits on the skin), this is a thing of the past and many new formulations utilizing mineral nanoparticles exist.
Nanoparticles are commonly used in cosmetics and can actually boost sun protection without indication of skin penetration or damage when energized by the sun/heat. Nanomaterials can, however, cause lung damage when inhaled in large quantities so you may want to avoid spray sunscreens using titanium dioxide or zinc oxide of any particle size until the proposed FDA testing on the matter is complete.
Ultimately, protective clothing, hats and monitoring the amount of time spent in the sun are the most reliable ways to protect the skin from UV rays, as there is shockingly little evidence to show that sunscreens alone prevent skin cancer.
For more information, please refer to the EWG’s 2019 Guide to Sunscreens: https://www.ewg.org/sunscreen/