A recent study shows that beach sand contains pathogens (bacteria) that pose a risk to adults and children and can cause illness and disease, such as skin infections and gastrointestinal (GI) disorders.

The U.S.’s Environmental Protection Agency (EPA) has formulated guidelines that determine when the pathogen levels are high enough to be dangerous for swimmers in both fresh water and sea water, but has not done so for recreational beaches. Researchers at the University of Miami and Northern Illinois University are beginning to rectify this by producing their own guidelines.

As the EPA monitored water containing fecal indicator fecal bacteria (FIB), so did the researchers because it poses as a large threat to humans (diseases such as E. coli are caused by feces-contaminated water). FIB comes from direct sewage spills and from dog and bird feces and would indicate the presence of pathogens of multiple virus strains.

“Infectious risks vary in different microorganism,” Tomoyuki Shibata tells the University of Miami. Shibata is the assistant professor in the Public Health Program and Institute for the Study of the Environment, Sustainability, & Energy at Northern Illinois University.

The researchers focused on studying sand from recreational beaches (mostly in Florida and California) because it would pose the most amount of threat to people.

In four steps, using reference pathogen guidelines from the EPA, the researchers essentially produced mathematical models, and computer simulations and measurements – per each gram of sand – of the disease-inducing pathogens to determine if the level of pathogens in the beach sand would go over the EPA’s guidelines. It turned out that it did. One fingertip dipped in the sand and inserted in the mouth contains enough FIB to cause GI. According to the researchers’ report, 19 out of 1000 beachgoers would be infected with GI.

Children would especially be susceptible to the pathogens and to becoming ill because they expose themselves to the sand more than adults.

“Parents of young children don’t need to overreact to our findings,” Shibata asserts. “They can reduce their child’s infectious risk by basic hygiene practices such as hand washing before eating or drinking and taking a shower.”

The report has been published in the American Chemical Society’s journal “Environmental Science and Technology,” and was written by Shibata and by Helena M. Solo-Gabriele, who is and the principal investigator of the study and a professor in the Department of Civil, Architectural and Environmental Engineering at the UM College of Engineering.

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Geoscientists at Newcastle University in the United Kingdom have recently confirmed that the Earth’s atmosphere switched back and forth from being hydrocarbon-rich and hydrocarbon-free- causing the atmosphere to become hazy and clear- repeatedly more than 2.5 billion years ago, during the mid-Precambrian supereon.

The alternation of haziness, resulting from microbial activity (intense enough to effect the Earth’s climate) that produced the hydrocarbons, occurred before the event in which the atmosphere underwent oxygenation- when oxygen became the principal element in the atmosphere- and sometime after the time when methane comprised much of the air.

The geoscientists analyzed marine sediments deposited 2.65 to 2.5 billion years ago in South Africa. They discovered the fossils of local microbes that produced oxygen. But if oxygen was present at the time these microbes existed, where could they have gone? The geoscientists also found carbon and sulphur isotopes, signifying that hardly any oxygen went into the atmosphere and instead stayed in the ground. It was then they ascertained that the atmosphere had not one state, but two, during which a transition took place.

“Instead of evidence for a continuously ‘hazy’ period we found the signal flipped on and off, in response to microbial activity,” Dr. Aubrey Zerkle states in the Newcastle University press release. Dr. Zerkle led the study and is a part of the School of Civil Engineering and Geosciences at Newcastle University.

“This provides us with insight into Earth’s surface environment prior to oxygenation of the planet, and confirms the importance of methane gas in regulating the early atmosphere.”

The geoscientists believe that it took so long for oxygen to dominate the atmosphere because the hydrocarbon haze blocked sunlight, affecting the evolution of microbes that depended on light to photosynthesize. Furthermore, when the amount of hydrocarbons decreased, the amount of methane (which dominated the atmosphere before the haze and haze-free switching) increased. Hence, oxygenation was delayed no matter the concentration of hydrocarbons in the atmosphere.

Evidence for the switch was further supported by models that demonstrated the transitions in action, which came from the NASA Astrobiology Institute, led by Dr. Mark Claire and Dr. Shawn Domagal-Goldman, with whom the geochemists collaborated. These models specifically showed “how the transitions could be caused by changes in the rate of methane production by microbes.”

“[These] models have [also] previously suggested that the Earth’s early atmosphere could have been warmed by a layer of organic haze,” Dr. Zerkle continues.

This discovery has changed aspects of how we come to understand the evolution of Earth and of early life, mainly of how the Earth’s atmosphere went from consisting of methane to oxygen- a concept that made scientists stumble for years.

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