Tag Archives: global warming

The sound of frogs (and other amphibians) and climate change

At least once a year I highlight some work about frogs. It’s usually about a new species but this time, it’s all about frog sounds (as well as, sounds from other amphibians).

Caption: The calls of the midwife toad and other amphibians have served to test the sound classifier. Credit: Jaime Bosch (MNCN-CSIC)

In any event, here’s more from an April 30, 2018 Spanish Foundation for Science and Technology (FECYT) press release (also on EurekAlert but with a May 17, 2018 publication date),

The sounds of amphibians are altered by the increase in ambient temperature, a phenomenon that, in addition to interfering with reproductive behaviour, serves as an indicator of global warming. Researchers at the University of Seville have resorted to artificial intelligence to create an automatic classifier of the thousands of frog and toad sounds that can be recorded in a natural environment.

One of the consequences of climate change is its impact on the physiological functions of animals, such as frogs and toads with their calls. Their mating call, which plays a crucial role in the sexual selection and reproduction of these amphibians, is affected by the increase in ambient temperature.

When this exceeds a certain threshold, the physiological processes associated with the sound production are restricted, and some calls are even actually inhibited. In fact, the beginning, duration and intensity of calls from the male to the female are changed, which influences reproductive activity.

Taking into account this phenomenon, the analysis and classification of the sounds produced by certain species of amphibians and other animals have turned out to be a powerful indicator of temperature fluctuations and, therefore, of the existence and evolution of global warming.

To capture the sounds of frogs, networks of audio sensors are placed and connected wirelessly in areas that can reach several hundred square kilometres. The problem is that a huge amount of bio-acoustic information is collected in environments as noisy as a jungle, and this makes it difficult to identify the species and their calls.

To solve this, engineers from the University of Seville have resorted to artificial intelligence. “We’ve segmented the sound into temporary windows or audio frames and have classified them by means of decision trees, an automatic learning technique that is used in computing”, explains Amalia Luque Sendra, co-author of the work.

To perform the classification, the researchers have based it on MPEG-7 parameters and audio descriptors, a standard way of representing audiovisual information. The details are published in Expert Systems with Applications magazine.

This technique has been put to the test with real sounds of amphibians recorded in the middle of nature and provided by the National Museum of Natural Sciences. More specifically, 868 records with 369 mating calls sung by the male and 63 release calls issued by the female natterajck toad (Epidalea calamita), along with 419 mating calls and 17 distress calls of the common midwife toad (Alytesobstetricans).

“In this case we obtained a success rate close to 90% when classifying the sounds,” observes Luque Sendra, who recalls that, in addition to the types of calls, the number of individuals of certain amphibian species that are heard in a geographical region over time can also be used as an indicator of climate change.

“A temperature increase affects the calling patterns,” she says, “but since these in most cases have a sexual calling nature, they also affect the number of individuals. With our method, we still can’t directly determine the exact number of specimens in an area, but it is possible to get a first approximation.”

In addition to the image of the midwife toad, the researchers included this image to illustrate their work,

Caption: This is the architecture of a wireless sensor network. Credit: J. Luque et al./Sensors

Here’s a link to and a citation for the paper,

Non-sequential automatic classification of anuran sounds for the estimation of climate-change indicators by Amalia Luque, Javier Romero-Lemos, Alejandro Carrasco, Julio Barbancho. Expert Systems with Applications Volume 95, 1 April 2018, Pages 248-260 DOI: https://doi.org/10.1016/j.eswa.2017.11.016 Available online 10 November 2017

This paper is open access.

Sunscreens: 2018 update

I don’t usually concern myself with SPF numbers on sunscreens as my primary focus has been on the inclusion of nanoscale metal particles (these are still considered safe). However, a recent conversation with a dental hygienist and coincidentally tripping across a June 19, 2018 posting on the blog shortly after the convo. has me reassessing my take on SPF numbers (Note: Links have been removed),

So, what’s the deal with SPF? A recent interview of Dr Steven Q Wang, M.D., chair of The Skin Cancer Foundation Photobiology Committee, finally will give us some clarity. Apparently, the SPF number, be it 15, 30, or 50, refers to the amount of UVB protection that that sunscreen provides. Rather than comparing the SPFs to each other, like we all do at the store, SPF is a reflection of the length of time it would take for the Sun’s UVB radiation to redden your skin (used exactly as directed), versus if you didn’t apply any sunscreen at all. In ideal situations (in lab settings), if you wore SPF 30, it would take 30 times longer for you to get a sunburn than if you didn’t wear any sunscreen.

What’s more, SPF 30 is not nearly half the strength of SPF 50. Rather, SPF 30 allows 3% of UVB rays to hit your skin, and SPF 50 allows about 2% of UVB rays to hit your skin. Now before you say that that is just one measly percent, it actually is much more. According to Dr Steven Q. Wang, SPF 30 allows around 1.5 times more UV radiation onto your skin than SPF 50. That’s an actual 150% difference [according to Wang’s article “… SPF 30 is allowing 50 percent more UV radiation onto your skin.”] in protection.

(author of the ‘eponymous’ blog) offers a good overview of the topic in a friendly, informative fashion albeit I found the ‘percentage’ to be a bit confusing. (S)he also provides a link to a previous posting about the ingredients in sunscreens (I do have one point of disagreement with regarding oxybenzone) as well as links to Dr. Steven Q. Wang’s May 24, 2018 Ask the Expert article about sunscreens and SPF numbers on skincancer.org. You can find the percentage under the ‘What Does the SPF Number Mean?’ subsection, in the second paragraph.

Ingredients: metallic nanoparticles and oxybenzone

The use of metallic nanoparticles  (usually zinc oxide and/or (titanium dioxide) in sunscreens was loathed by civil society groups, in particular Friends of the Earth (FOE) who campaigned relentlessly against their use in sunscreens. The nadir for FOE was in February 2012 when the Australian government published a survey showing that 13% of the respondents were not using any sunscreens due to their fear of nanoparticles. For those who don’t know, Australia has the highest rate of skin cancer in the world. (You can read about the debacle in my Feb. 9, 2012 posting.)

At the time, the only civil society group which supported the use of metallic nanoparticles in sunscreens was the Environmental Working Group (EWG).  After an examination of the research they, to their own surprise, came out in favour (grudgingly) of metallic nanoparticles. (The EWG were more concerned about the use of oxybenzone in sunscreens.)

Over time, the EWG’s perspective has been adopted by other groups to the point where sunscreens with metallic nanoparticles are commonplace in ‘natural’ or ‘organic’ sunscreens.

As for oxybenzones, in a May 23, 2018 posting about sunscreen ingredients notes this (Note: Links have been removed),

Oxybenzone – Chemical sunscreen, protects from UV damage. Oxybenzone belongs to the chemical family Benzophenone, which are persistent (difficult to get rid of), bioaccumulative (builds up in your body over time), and toxic, or PBT [or: Persistent, bioaccumulative and toxic substances (PBTs)]. They are a possible carcinogen (cancer-causing agent), endocrine disrupter; however, this is debatable. Also could cause developmental and reproductive toxicity, could cause organ system toxicity, as well as could cause irritation and potentially toxic to the environment.

It seems that the tide is turning against the use of oxybenzones (from a July 3, 2018 article by Adam Bluestein for Fast Company; Note: Links have been removed),

On July 3 [2018], Hawaii’s Governor, David Ig, will sign into law the first statewide ban on the sale of sunscreens containing chemicals that scientists say are damaging the Earth’s coral reefs. Passed by state legislators on May 1 [2018], the bill targets two chemicals, oxybenzone and octinoxate, which are found in thousands of sunscreens and other skincare products. Studies published over the past 10 years have found that these UV-filtering chemicals–called benzophenones–are highly toxic to juvenile corals and other marine life and contribute to the fatal bleaching of coral reefs (along with global warming and runoff pollutants from land). (A 2008 study by European researchers estimated that 4,000 to 6,000 tons of sunblock accumulates in coral reefs every year.) Also, though both substances are FDA-approved for use in sunscreens, the nonprofit Environmental Working Group notes numerous studies linking oxybenzone to hormone disruption and cell damage that may lead to skin cancer. In its 2018 annual sunscreen guide, the EWG found oxybenzone in two-thirds of the 650 products it reviewed.

The Hawaii ban won’t take effect until January 2021, but it’s already causing a wave of disruption that’s affecting sunscreen manufacturers, retailers, and the medical community.

For starters, several other municipalities have already or could soon join Hawaii’s effort. In May [2018], the Caribbean island of Bonaire announced a ban on chemicals sunscreens, and nonprofits such as the Sierra Club and Surfrider Foundation, along with dive industry and certain resort groups, are urging legislation to stop sunscreen pollution in California, Colorado, Florida, and the U.S. Virgin Islands. Marine nature reserves in Mexico already prohibit oxybenzone-containing sunscreens, and the U.S. National Park Service website for South Florida, Hawaii, U.S. Virgin Islands, and American Samoa recommends the use of “reef safe” sunscreens, which use natural mineral ingredients–zinc oxide or titanium oxide–to protect skin.

Makers of “eco,” “organic,” and “natural” sunscreens that already meet the new standards are seizing on the news from Hawaii to boost their visibility among the islands’ tourists–and to expand their footprint on the shelves of mainland retailers. This past spring, for example, Miami-based Raw Elements partnered with Hawaiian Airlines, Honolulu’s Waikiki Aquarium, the Aqua-Aston hotel group (Hawaii’s largest), and the Sheraton Maui Resort & Spa to get samples of its reef-safe zinc-oxide-based sunscreens to their guests. “These partnerships have had a tremendous impact raising awareness about this issue,” says founder and CEO Brian Guadagno, who notes that inquiries and sales have increased this year.

As Bluestein notes there are some concerns about this and other potential bans,

“Eliminating the use of sunscreen ingredients considered to be safe and effective by the FDA with a long history of use not only restricts consumer choice, but is also at odds with skin cancer prevention efforts […],” says Bayer, owner of the Coppertone brand, in a statement to Fast Company. Bayer disputes the validity of studies used to support the ban, which were published by scientists from U.S. National Oceanic & Atmospheric Administration, the nonprofit Haereticus Environmental Laboratory, Tel Aviv University, the University of Hawaii, and elsewhere. “Oxybenzone in sunscreen has not been scientifically proven to have an effect on the environment. We take this issue seriously and, along with the industry, have supported additional research to confirm that there is no effect.”

Johnson & Johnson, which markets Neutrogena sunscreens, is taking a similar stance, worrying that “the recent efforts in Hawaii to ban sunscreens that contain oxybenzone may actually adversely affect public health,” according to a company spokesperson. “Science shows that sunscreens are a key factor in preventing skin cancer, and our scientific assessment of the lab studies done to date in Hawaii show the methods were questionable and the data insufficient to draw factual conclusions about any impact on coral reefs.”

Terrified (and rightly so) about anything scaring people away from using sunblock, The American Academy of Dermatology, also opposes Hawaii’s ban. Suzanne M. Olbricht, president of the AADA, has issued a statement that the organization “is concerned that the public’s risk of developing skin cancer could increase due to potential new restrictions in Hawaii that impact access to sunscreens with ingredients necessary for broad-spectrum protection, as well as the potential stigma around sunscreen use that could develop as a result of these restrictions.”

The fact is that there are currently a large number of widely available reef-safe products on the market that provide “full spectrum” protection up to SPF50–meaning they protect against both UVB rays that cause sunburns as well as UVA radiation, which causes deeper skin damage. SPFs higher than 50 are largely a marketing gimmick, say advocates of chemical-free products: According to the Environmental Working Group, properly applied SPF 50 sunscreen blocks 98% of UVB rays; SPF 100 blocks 99%. And a sunscreen lotion’s SPF rating has little to do with its ability to shield skin from UVA rays.

I notice neither Bayer nor Johnson & Johnson nor the American Academy of Dermatology make mention of oxybenzone’s possible role as a hormone disruptor.

Given the importance that coral reefs have to the environment we all share, I’m inclined to support the oxybenzone ban based on that alone. Of course, it’s conceivable that metallic nanoparticles may also have a deleterious effect on coral reefs as their use increases. It’s to be hoped that’s not the case but if it is, then I’ll make my decisions accordingly and hope we have a viable alternative.

As for your sunscreen questions and needs, the Environment Working Group (EWG) has extensive information including a product guide on this page (scroll down to EWG’s Sunscreen Guide) and a discussion of ‘high’ SPF numbers I found useful for my decision-making.