Summer is finally here- which means hitting the beach, going to the pool, and just enjoying the sun. It also means it’s sunscreen season! Picking a broad-spectrum (UVA and UVB) option and applying regularly, about every 2 hours when it’s really sunny, is important to avoid sunburn, excessive tanning, and long-term skin damage. But while we’re busy looking out for our own health, it can be easy to overlook the effects that sunscreen can have on the environment.
In general, there are two types of sunscreen: organic and inorganic. Organic sunscreens refer to the ones whose active ingredients are chemical compounds (not if they’re produced in a pesticide free way!), and they work through absorbing UV radiation. These often have multiple chemicals since each chemical can only absorb certain kinds of UV. Common components of these sunscreens are Oxybenzone (also known as benzophenone-3), Octinoxate, and Octocrylene. Inorganic sunscreens, on the other hand, are physical sun protectors, and they usually use Zinc and Titanium compounds to reflect a broad spectrum of solar radiation.
These compounds also have varying impacts on the environment.

While there still isn’t enough research to say specifically which ones are the worst, we know a few things:
1. Exposure to multiple types of chemicals tends to be more damaging to aquatic life than one or two in isolation, since they tend to work in the same ways and so the effects amplify each other;

2. Oxybenzone is a particularly concerning chemical: because it associates itself with fats, it has been shown to accumulate in the fat stores of both humans and fish. It also acts as an endocrine disruptor, meaning that it disrupts normal hormone function in the body, particularly for the hormone estrogen. This can harm reproduction in aquatic creatures. It has also been detected in humans globally at all ages, including in vitro;

3. At high enough concentrations, corals exposed to any type of sunscreen tend to bleach, which means that they expel the algae that live in their structures, and are at a very high risk of dying because they then lose the nutrients that the algae provide. Octinoxate and Oxybenzone are known to increase bleaching, and some research indicates that Zinc sunscreens do too;

4. Effects tend to be reasonably localized to the area where sunscreen enters the water, but can over time cause harm in low-concentration areas because they accumulate inside plants and animals. Hawaii has banned oxybenzone and octinoxate because its beaches have so many tourists and the beaches are very close to important reef ecosystems.

So what to do? As always, it’s hard to balance convenience, personal health, and environmental consciousness. However, there are a few tricks to avoid sunburn and help out the environment:

  • Avoid spray-on sunscreens: a lot of it is wasted as it misses the body, and aerosols are also bad for the environment.
  • Wait at least 20 minutes after applying sunscreen before going swimming: this lets it absorb properly and be useful, instead of washing out almost as soon as you hit the water.
  • Choose physical sunscreens over chemical: zinc and titanium occur naturally in the environment (although our addition increases normal amounts), whereas chemical ones don’t and are thus riskier. Fun fact: titanium makes the zinc sunscreen more transparent, so don’t worry about it looking too smear-y!
  • Cut open your sunscreen bottle when it’s ‘finished’: there’s often a lot still hiding in the bottle, so you can reduce waste and it makes it easy to wash out the bottle for recycling!

Allison Lalla (summer student)