Sunscreen is no trivial matter
There is a myth that advances that sunscreen is good for you no matter what and it's a lie. Till recently, telling someone to wear sunscreen was the best advice you could give. I mean what could possibly go wrong with sunscreen? It protects your skin from being burnt (UVA rays), and more importantly from developing skin cancer (UVB rays); only positive things can come out of wearing sunscreen. Well, no. Sunscreen can be bad. Here's why:
1- Chemical Sunscreen versus Physical Sunscreen
To understand the sunscreen problem, we first need to understand sunscreen, period. There are two types of sunscreen: chemical and physical, both protect your skin from UV rays differently. With a chemical sunscreen rays are altered before penetrating the skin through ultraviolet filters that make them non-harmful. Chemical sunscreens are the most common on the market and include a combination of two to six of these active ingredients: oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate (most of these are not recommendable but more on that later).
With a physical sunscreen (or mineral sunscreen) rays do not penetrate the skin but instead are mirrored from the skin. They use as their active ingredient zinc oxide or titanium dioxide, which are derived from chalky, reflective materials. While this is beneficial in blocking the sun's rays, the application of these materials can be unappealing because it results in white, chalky appearance. For this reason, many sunscreen manufacturing companies work to scale down the particles for chemical sunblocks. Titanium dioxide is scaled down to between 10 and 100 nanometers (nm), while zinc oxide is scaled down to 30 to 200 nm. This makes each particle go on the skin less noticeably, however the effect of nanotechnology in sunscreen on human organism is subject to debate (again more on that later).
2- The Sunscreen Problem
Both chemical and physical sunscreens can be problematic for the environment and the human organism.
Ecologically, a study led by Roberto Danovaro of the Polytechnic University of Marche in Italy (reported here by National Geographic), estimated that 4,000 to 6,000 metric tons of sunscreen were washed off swimmers annually to penetrate oceans worldwide, and that up to 10 percent of coral reefs are threatened by sunscreen-induced bleaching. The research found that amongst the several brands of sunscreens that were tested all had four ingredients in common: paraben, cinnamate, oxybenzone, and a camphor derivative (all found in chemical sunscreens).
When scattered in the sea these chemicals, even in the smallest doses, activate a virus in an algae called zooxanthelae that is vital to reef coral building. Without zooxanthelae coral reefs can’t do photosynthesis and develop color. The coral bleaches and eventually dies along with all the aquatic life dependent on it. Another 2015 study published by the Archives of Environmental contamination and Toxicology directly linked oxybenzone to the declining health of coral reefs that are popular with tourists.
As for the effects on the human organism, another debate has focused on the potential hormonal problems that can be caused by oxybenzone, given it is an endocrine disruptor. The chemical has also been associated to allergic reactions triggered by sun exposure. In a study of 82 patients with dermatitis, over one quarter showed photoallergic reactions to oxybenzone.
In addition, commonly found ingredients in chemical sunscreen are known to be carcinogen such as paraben, or even to increase DNA defects such as PABA (p-Aminobenzoic acid).
The problem with physical sunscreen is not the ingredients but rather the nanotechnology that can be applied to it. Nanoparticles from titanium dioxide found in sunscreen can accumulate in coastal waters and be ingested by marine animals, according to the Australian Journal of Science and Technology. In humans there is a slight chance that nanoparticles are absorbed by the skin. Although the effects of ingestion on aquatic animals are unknown, a study made on mice showed that when injected in the skin titanium dioxide caused inflammation. Some scientists argue that the extremely small size of the nanoparticles can enter the epidermis and the bloodstream and possibly cause harm. Others have dismissed the possibility of skin absorption altogether (usually proponents of nanotechnology as in this academic paper). All in all it seems different studies have led to contradicting results.
3- The Sunscreen Solution
Now you understand that protecting yourself from UVA and UVB rays while protecting the environment from the harmful ingredients found in sunscreen is no easy task. First, in order to not contribute to coral bleaching it is imperative to turn to organic (biodegradable) physical/minerak sunscreens that preferably use zinc oxide as their active ingredient. We also recommend you check for the label “Reef Safe” and "Non-nano" when purchasing sunscreen. Also, beware of oil based products, especially those that use lavender, tea tree, jojoba and other oils that act as natural insecticide as these kill coral cells as well.
Here is a suggested list of healthy and eco-responsible sunscreens: