It's summer, when the blistering Sun can be felt from above and all we want to do is dive into the closest body of water. You may even associate the distinct smell of sunscreen and seawater with the gentle coastal breezes of the season.

However, some experts are suggesting that that smell is also cue for a new wave of harm to the environment, and even possibly to sun-bathers everywhere.

New research has shown that common ingredients in sunscreens can become toxic after washing off in the ocean, threatening essential marine and harming ecosystems as a whole. These same toxins could be seeping into users' skin, causing some to worry that this tool of cancer prevention is actually raising their risk.

Poisoned Plankton

The American Cancer Society, the US Centers for Disease control and Prevention (CDC), and the Skin Cancer Foundation all recommend that beach-goers be liberal with their sunscreen, as skin cancer remains the most common form of cancer in the United States, with more than 3.5 million cases of the disease diagnosed annually.

However, according to a study recently published in Environmental Science & Technology, a journal from the American Chemical Society (ACS), titanium dioxide and zinc oxide, nanoparticles can be found in most sunscreen lotion brands, are harming local ecosystems.

When health-conscious sunscreen users wade into the ocean for a quick cool-off, they may actually be shedding these particles into the ocean. The particles then react with ultraviolet (UV) light while in the water, forming new compounds such as hydrogen peroxide.

According to researchers Antonio Tovar-Sanchez and David Sánchez-Quiles, high amounts of hydrogen peroxide can harm phytoplankton, the microscopic algae that feed everything from small fish to shrimp to whales. These essential creatures are also a significant source of oxygen on Earth, providing nearly half the world's total supply.

The pair of researchers found that on an average summer day at Majorca Island's Palmira becach there was a massive spike in hydrogen peroxide levels in coastal waters, largely due to the 10,000 beachgoers that hit that specific shore each day.

This could be a significant threat to aquatic life, they say, but more work will need to be done to measure the exact impact.

Poisoned People?!

Other experts are suggesting that the same sunscreen meant to protect you from cancer-causing UV rays might actually be increasing your chances instead. That's according to a number of studies that stretch as far back as 2000, where it was found that sunscreen users were actually more likely to develop skin cancer than non-users.

Another study, published in 2004, supported this claim, finding that a number of compounds found in some sunscreens were encouraging tumor growth.

These studies have recently resurfaced, and some experts are up in arms about what appears to be a sunscreen conspiracy.

However, Ronald Siegle, of the Skin Cancer Foundation, is telling people not to be fooled by the hype.

"The 'worst' answers [to the sunscreen question] come from individuals or special interest groups who may have a pertinent question but whose theories are untested or, if tested, unsubstantiated by other studies," he said in a recent release. "This is what some people might call 'junk science,' and what some media outlets might call good stories for a slow news day!"

The expert goes on to explain that while free-radical causing chemicals like oxybenzone and  retinal palmitate has been seen to encourage the growth of tumors, the best known example of this was seen in mice, not humans.

"We can't automatically assume that research findings on rodents are relevant in humans," he said, adding that a 2004 study considered by the FDA when it was initially approving new sunscreens was never even published in a peer-reviewed journal, which suggests that its findings were not deemed worthy of publication. 

lastly, remember those harmful nanoparticles we mentioned earlier? While they could indeed be washing into our oceans to harm phytoplankton, they won't be getting into our skin anytime soon.

"Sunscreen is applied to the top layer of skin, made up of dead cells, and multiple studies have shown that nanoparticles cannot even penetrate living skin," said Seigle. "The general consensus is that they pose no risk to human health."