Making a cleaner, greener, environmentally safe sunscreen
by Yousong Ding
Ingredients in many sunscreens are bleaching coral and harming marine life. www.shutterstock.com
As the temperatures rise and Americans swarm to the beach, they slather on sunscreen to protect against the sun’s harmful UV radiation that causes skin cancer. As they splash and swim, few give thought to whether the chemicals in the lotions and sprays are safe for marine organisms such as the fish and corals living in these coastal zones.
The bad news is that mounting evidence suggests that certain chemicals in these radiation filters are bleaching the corals and killing fish. The good news is that there is a greener, cleaner and safer alternative in the works.
The sunscreens widely available belong to two major categories: physical and chemical. Physical sunscreens contain tiny minerals that act as a shield deflecting the sun’s rays. On the other hand, chemical sunscreens use many synthetic compounds that absorb UV light before it reaches the skin.
Killer chemicals
But these lotions wash off in water. For example, for every 10,000 visitors frolicking in the waves, about 4 kilograms of mineral particles are washed into the beach water each day. These minerals catalyze the production of hydrogen peroxide, a well-known bleaching agent, at a concentration high enough to harm coastal marine organisms. In fact, up to 14,000 tons of sunscreens are released into the water each year. Active ingredients in these sunscreens, minerals and synthetic organic compounds, are putting 10 percent of the global reefs under stress, including 40 percent of coral reefs along the coast.
One of these ingredients is oxybenzone, a synthetic molecule commonly used in chemical sunscreens and known to be toxic to corals, algae, sea urchins, fish and mammals: A single drop of this compound in over 4 million gallons of water is already enough to endanger organisms. Unfortunately, its concentration in coastal water is already significantly higher than its toxic limit, though not yet deadly, and might be accelerating coral bleaching. To save their marine ecosystem from further destruction, legislators in Hawaii passed a new law banning chemical sunscreens containing oxybenzone and another harmful ingredient, octinoxate. The law will take effect January 1, 2021.
Sunscreen from algae
A flask of the cyanobacterium Synechocystis sp. PCC 6803 that was used to produce shinorine. The green color comes from the chlorophyll, which is a natural part of the bacterium. Shinorine is clear. Dr. Guang Yang, CC BY-NC-ND
Protecting ourselves from UV rays is nothing new. Many organisms including microbes, plants and animals have evolved ways to guard themselves. These organisms produce small molecules that absorb UV rays and block radiation from entering cells and damaging the DNA. Unlike physical and synthetic chemical sunscreens, these naturally available compounds are environmentally friendly and biodegradable. As such, these natural products have the potential to be safer compounds for commercial sunscreens.
In my laboratory in the College of Pharmacy at the University of Florida, we are interested in combing the world for naturally occurring chemicals that have applications in health, agriculture and environment. Recently, my colleagues and I have discovered a more efficient way to harvest shinorine – a natural sunscreen produced by microbes called cyanobacteria.
Shinorine belongs to a family of natural products, called mycosporine-like amino acids, and is made up of two amino acids and one sugar. Many aquatic organisms exposed to strong sunlight, like cyanobacteria and macroalgae, produce shinorine and other related compounds to protect themselves from solar radiation. The cosmetics industry is already infusing products with shinorine as a key active ingredient. Commercial supplies of shinorine come from marine red algae that grows slowly in large tidal pools that experience frequent environmental changes. That means that conventional extraction method is time-consuming and unpredictable.
To ramp up shinorine production, we sought a fast-growing strain of cyanobacteria that would thrive under predictable conditions. This took a lot of work! We decoded the genetic blueprints – genomes – of more than 100 varieties of cyanobacteria from marine and terrestrial ecosystems and selected one, Fischerella sp. PCC9339, to cultivate in the laboratory.
To our delight, after four weeks this strain produced shinorine, but unfortunately not enough. To produce more we then transferred a set of genes that encode the instructions to make shinorine, into one freshwater cyanobacterium (from Berkeley, California), Synechocystis sp. PCC 6803, which grows fast with just water, carbon dioxide and sunlight. Using the engineered cyanobacterium, we produced a quantity of shinorine comparable to the conventional method – but we did it in just a few weeks instead of one year that’s needed to cultivate red algae.
By advancing the method to produce more shinorine and other UV-absorbing natural products, we hope to make “green” sunscreens more available – to protect our skin and the lives of the creatures we are so eager to see.
Yousong Ding is an Assistant Professor of Medicinal Chemistry at the University of Florida.
This article was originally published on The Conversation, a content partner of Sci Fi Generation.
whenever I pass by a tow truck, I feel a slight flutter in my stomach.
four years ago, my car battery died on the third floor down of my apartment garage. the first tow truck was too big to even enter the garage. the second tow truck came closer but still didn't cut it, so we ended up having to call a pickup over and hook my car up to it. in the hour or so that we were waiting for the pickup driver, the tow truck driver and I started chatting. he was about my age, and working to put himself through a junior college. we were from completely different backgrounds, but there was just something that made the conversation click, and i found his crooked smile to be endearing. after we got my car out, I rode with him to the dealership, and before we parted ways he thanked me and said he hadn't met someone who he could have such easy conversation with in quite some time.
since that day I've forgotten his name, his face, and even the towing company he worked for, but i can't forget that spark (I think I might have even scanned missed connections on craigslist for a few days after). now whenever I see a tow truck, I can't help but peer through the window hoping I might recognize his face.
but what then? would we exchange numbers? would we go on a date?
I've been thinking about this a lot, and it's brought me to two somewhat conflicting conclusions:
Conclusion 1: I'm ready to give chemistry a shot, even if nothing else seems to fit the criteria that I (and all of us) have in my head. clicking with someone is the hardest criteria to satisfy because of its intangible nature, and I can't underestimate the importance or the difficulty of that one trait. so, if I met tow truck man today, I would go on a date with him.
Conclusion 2: There is no one person in the world that's right for me. just like when looking for an apartment, every potential match is a combination of dials - except instead of desired location, price, and proximity to public transport, the dials read intelligence, background, physical attractiveness, and chemistry. all relationships are different because of the values on each dial, and all can be great in different ways.
based on conclusion 1, I'm holding chemistry as the most important dial. but, I have to take into consideration the balance of all the other dials to make it sustainable. maybe there isn't "the one", but some number of individuals have to fall within this ideal range.
i'm putting both these conclusions to the test. I've been seeing someone who is definitely in the 90s on the chemistry and physical attractiveness scale, but low on the intelligence and background scale. it's been fun the last two weeks, but I already sense it falling apart (for one thing, the "goodnight, pretty lady" texts have stopped). chemistry only opens the door; intellectual stimulation and a common upbringing are what deepens the connections. yet, it's so easy to fall for someone based just off the way they look and how your body reacts when you're near them...
