Is Your Sunscreen Contaminating the Water Supply?
Meredith Rutland Bauer — New and Improved
Sunscreen use has been recommended by dermatologists and pediatricians for decades for its ability to save our skin from cancer-causing solar radiation. But scientists and consumers are also becoming increasingly aware of how chemical compounds found in typical sunscreens could have a harmful impact on ocean life, like coral and plankton. And now researchers are starting to question whether these sprays and lotions could have unintended consequences for our drinking water, as sunscreen leaves people’s bodies through shower drains, public pools, and dips in rivers or lakes.
“The impact on drinking water supplies is something we know very little about scientifically,” says David Andrews, a senior scientist at the Environmental Working Group, a nonprofit that researches cosmetic chemicals and advocates for safer products. There's no consensus yet whether current water filtration methods are sufficient to keep sunscreen chemicals out of the public drinking supply.
Common chemical-based sunscreen almost always contains some combination of these six active ingredients: oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate. The one that gives Andrews the most pause is oxybenzone. This chemical is suspected to be an endocrine disruptor, which interrupts the body’s normal flow of hormones and can lead to cancer, birth defects, sexual development delays, and other health issues, according to EWG.
Andrews says the bulk of scientific research on oxybenzones focuses on what happens when sunscreen is absorbed through the skin, or on the chemical’s potential to damage sea life in saltwater environments. But the consequences of humans ingesting sunscreen via drinking water are still a big question mark, he says.
So how would sunscreen get into drinking water?
Juan Guerreiro, deputy director of wastewater treatment and disposal for the city of San Diego says when someone showers and sunscreen washes off their body, the water goes to a wastewater treatment plant where it’s processed and eventually deemed safe enough to dump back into streams, rivers, lakes, and oceans. Once treated and dumped, some of that wastewater eventually ends up being recaptured by drinking water treatment plants, which send it along to be consumed as tap water.
With coastal populations rising and sunscreen use increasing, wastewater treatment plants are seeing more sunscreen come into their systems, says Guerreiro. Even though the amounts are minuscule compared to the volume of water these plants deal with every day, compounds like oxybenzone are an issue of increasing concern within the wastewater industry.
“These compounds haven’t been [recognized as] an issue in the past, therefore wastewater treatment plants aren’t designed specifically for these products,” Guerreiro says.
Few studies have looked at the prevalence of sunscreen ingredients in the wastewater that eventually ends up back in rivers and lakes—but those that have indicate that oxybenzone is a particularly tough chemical to scrub out.
For example, a 2010 study from Cornell University published in Water Research suggested that oxybenzone cannot be removed via a prevalent wastewater treatment method. “Pharmaceuticals and personal care products … are now routinely detected in raw and treated municipal wastewater,” according to the study.
Subsequent studies have supported the Cornell findings, both the prevalence of personal care-related chemicals in treated wastewater and the difficulty in removing them. A 2011 study from the University of Texas at Austin concluded that at least some amount of oxybenzone was likely making its way into drinking water supplies via treated wastewater.
A 2013 study, also from UT, suggested alternative treatment methods could reduce the amount of oxybenzone released with treated wastewater—but current industry standards weren’t making the cut. “Conventional wastewater treatment plants do not effectively remove pharmaceuticals and personal care products,” the study stated.
Despite the findings that current treatment methods do not scrub oxybenzone from our water supplies, some experts aren’t that worried about sunscreen’s impact on freshwater systems or drinking water. For one thing, the ratio of sunscreen to water is quite small, given the massive amount of fluid that runs through wastewater treatment plants each day. Christine Owen, water quality senior manager of Tampa Bay Water in Florida, says that the industry standard for drinking water plants uses several types of intense filtration designed to remove a variety of personal care products that are more dangerous and show up in much larger amounts than sunscreen ingredients—including items like prescription drugs, estrogen, or contaminants from fracking operations.
“By the time you get through all that, you’re not going to see contaminants” in drinking water, she said.
Even Guerreiro, who acknowledges the growing concern around oxybenzone, isn't exactly panicked. To balance apprehension, he cites a 2012 report from the Southern California Coastal Water Research Project that looked at the amount of sunscreen ingredients in Southern California’s wastewater. “For both oxybenzone and benzophenone, the levels observed in treated wastewater were lower than the concentrations at which toxic effects to fish and other organisms (such as algae or daphnia) become a concern,” the report read.
Still, Guerreiro notes oxybenzone has already been officially labeled a “contaminant of emerging concern,” environmental jargon for anything that isn’t federally or locally regulated but could be a problem down the road. Researchers at his wastewater plant are aware of it and keep up to date on all emerging contaminants, just in case the plant needs to take more steps to treat them.
As the worldwide sunscreen market grows, and temperatures rise, it's likely the issue of sunscreen ingredients in freshwater will receive more scrutiny, and our treatment methods may change because of it. For now, Guerreiro says, he’s decided to start buying zinc-based sunscreen for his 1-year-old, which doesn’t contain chemicals like oxybenzone. And he’s been talking with his wife about whether the adults in their family should also start using alternative sunscreens, so they can enjoy the sun without unintended consequences to themselves or the environment.