Despite a new law banning the sale of over-the-counter sunscreens containing chemicals deemed harmful to coral reefs, they are still turning up in the waters of Hanauma Bay Nature Preserve on Oahu.

Craig Downs, one of the authors of a study recently published in the scientific journal Chemosphere, said water from the bay was collected as early as 2017 as well as during its closure last year due to the COVID- 19 pandemic, and after the lockdown was lifted and the sunscreen ban went into effect in January.

Downs, director of the Haereticus Environmental Laboratory in Virginia, said oxybenzone, a chemical found in sunscreens, was still present in water samples this year, though not as high as in 2017, along with others of concern such as octocrylene, which is not included in Hawaii’s ban.

The study’s focus, however, is on the harmful impacts of oxybenzone on the coral reef at Hanauma and the Hawaiian monk seals and turtles that visit the preserve. It also examines the role of beach showers there as another likely source of sunscreen pollution, in addition to swimmers and snorkelers entering the water.

Runoff from the beach showers discharges directly into the beach and the bay, according to Downs, rather than going through the municipal wastewater system.

As part of the study, sand samples collected near the beach showers were analyzed and researchers found traces of UV-filter chemicals, including octisalate and homosalate. During rainy season, this source, too, potentially washes out to sea.

If this is true at Hanauma Bay, he said, it is likely true for other popular bays across the state, including Kapalua and Napili bays on Maui and Kahaluu Bay on Hawaii island.

A simple remedy would be to hook the showers up to the municipal system.

“The real tragedy is our coral reefs in (Hanauma) Bay have been declining and have never recovered,” Downs said. “My guess it’s about 90% of the glory of what it was back in the ’50s.”

This is not how it should be for an established marine life conservation district, which became clear when Hanauma Bay got an eight-month reprieve from visitors due to the closure last year.

“During the lockdown when you get to the tabula rasa (pristine) state, with no one coming in — holy cow, the beauty’s being reborn,” he said.

Downs advocates for further protection of coral reefs and wildlife at Hanauma Bay, which he said that as a marine life conservation district should, according to the state’s Clean Water Act, remain in its “natural pristine state as nearly as possible with an absolute minimum of pollution or alteration of water quality from any human-caused source or actions.”

There are also potential health ramifications, he said, because studies have shown that oxybenzone and other benzophenones have harmful impacts on pregnant women and young children.

Hawaii’s sunscreen law, which Gov. David Ige signed in 2018 and went into effect in January, bans the sale of over-the-counter sunscreens containing oxybenzone and octinoxate to protect Hawaii’s marine environment.

Visitors, however, may still bring sunscreens with the banned chemicals into the state.

Downs said most visitors likely buy sunscreens at home and pack them for their trip to Hawaii. In addition, a few stores continue to violate the law by selling sunscreens with the banned chemicals, without much enforcement.

The Honolulu Department of Parks and Recreation said it is important to note the study was conducted before the ban went into effect and that numerous management improvements have been put in place to reduce the number of visitors to Hanauma by about half.

“We appreciate the efforts to further our understanding of human impacts to the natural environment, in particular at the Hanauma Bay Nature Preserve,” DPR said in a statement. “The City will review this announcement and make improvements where they are needed.”

The Hawaii Institute of Marine Biology has studied the nature preserve prior to and during the pandemic. The institute’s Kuulei Rodgers said in a statement that there are very few monk seals and turtles at Hana­uma Bay, possibly one or two at most at a time.

“There is no strong evidence to state sunscreens threaten coral reefs,” she said. “Our coral reef ecology lab has not seen the effects of sunscreen use on bleaching in our monitoring efforts.”

Rodgers added that coral reefs in the outer bay are in excellent condition compared to the rest of the state as a counterpoint to the possibility of beach showers as a source of sunscreen chemical pollution.

“If there were effects from sunscreen it would be evident,” she said in her statement. “We have evidence in the various reports that the inner reef with low coral cover is directly related to the number of visitors, not sunscreen. The corals growing on vertical surfaces, in deeper areas, and in the lower use sectors like Witches Brew are in good condition.”

DPR said the beach showers at Hanauma Bay drain into ground wells, and staff have not observed water from showers draining directly into the ocean.

Lisa Bishop, president of the Friends of Hanauma Bay, is pleased with limits on visitors to the bay of about 1,500 per day, with shortened hours and a reservation system. In previous years, Hanauma Bay received a peak of 10,000 to 13,000 visitors a day.

To protect the bay and progress made during the months of respite from visitors, however, she would like a sunscreen chemical ban added to requirements. This is doable, she said, because the site has only a single point of access, which is managed.

Bishop said the state Department of Land and Natural Resources already set a precedent by banning the use of chemical sunscreens at Kealakekua Bay on Hawaii island. DLNR issues permits with this requirement in place for commercial tour boat operators.

On Friday, the Maui County Council passed a bill prohibiting the sale, distribution or use of nonmineral sunscreens in an effort to protect the environment. If signed into law, it would take effect in October.

Downs, who supported the bill, said government leaders should look to Maya Bay in Thailand — a beach made famous by the 2000 Leonardo DiCaprio movie “The Beach” — as an example of taking necessary protective measures. The bay was closed in 2018 so it could recover from the damaging impacts of thousands of tourists a day, and is only set to reopen in January, with tighter restrictions.

“COVID has allowed us to restart things and I think we can restart things better,” Downs said. “Before the hordes of all these tourists come in and muck up the place again, I think the city can put some regulatory constraints on how tourists interact with nature so we can keep our coral reefs safe.”

Researchers from the National Oceanic and Atmospheric Administration, along with the Spanish Research Council, Sorbonne University in Paris, and University of Tehran in Iran, among others, are listed as part of the study’s team.