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You should wash your rice to reduce heavy metal contamination

Yes, washing rice involves sacrificing some of its nutritional value, but it also reduces the level of heavy metals present

Farah Qaiser

Molecular Genetics

University of Toronto

Have you ever wondered why you wash your rice  — or soak it overnight — before cooking it? Perhaps you wash your rice grains to enhance taste, reduce starch levels, or maybe that’s just the way your family has always prepped rice. Thanks to a tip from science communicator Samantha Yammine — who came across Dr. Nausheen Sadiq’s neat finding while live-tweeting a forum on Diversity and Excellence in Science — it turns out there is another reason why, as washing rice actually helps reduce the concentration of heavy metals, like chromium, cadmium, arsenic, and lead. 

Heavy metal contamination in crops can be caused by human activities, such as mining, fertilizers, pesticides, and sewage sludge. Compared to most cereal crops though, rice (Oryza sativa L.) actually accumulates more heavy materials, like cadmium or arsenic, where long-term heavy metal intake can cause health risks. For example, long-term arsenic exposure leads to skin disease, high blood pressure, and neurological effects. This is especially important to consider as rice is a staple food across the globe.

Brown rice being filtered by farmer

Heavy metal contamination in crops can be caused by human activities, such as mining, fertilizers, pesticides, and sewage sludge.

Photo by TUAN ANH TRAN on Unsplash 

In a recent study, researchers investigated the effects of different cooking methods (normal, high-pressure and microwave cooking) on the concentration, bio-accessibility and health risks posed by three heavy metals (cadmium, arsenic and lead) in two strains of brown rice. After cooking 100 grams of brown rice grains, researchers evaluated bioaccessibility (i.e. how much of the heavy metal is released for absorption) by mixing rice samples with simulated gastric fluid, and then used spectrometery to measure heavy metal concentration. Lastly, the researchers calculated the health risk posed by the heavy metals by calculating values such as the average daily dose.

Overall, the researchers found that instead of the three different cooking methods, it was the washing process which significantly reduced concentrations of cadmium, arsenic and lead, suggesting that the reduction may be due to rice morphology. For example, lead is found largely in the outer compartments of rice kernels, so lead is more likely to be removed during rice washing. 

In contrast, the three cooking methods did impact bioaccessibility i.e. how much of the heavy metal would be released for absorption by the body. Here, washing and soaking isn’t enough as rice absorbs water poorly at 25°C. This finding was also reflected in calculated values: the average daily doses of cadmium, arsenic and lead were lower in washed and cooked rice, compared to raw rice.

It’s worth noting that the European Commission has enforced limits on heavy metal levels - for example, arsenic is currently limited to 200 parts per billion (ppb) for adults and 100 ppb for infants. Both the U.S. and Canada currently have no limits in place for arsenic in food — though Canada is currently reviewing a proposal to add maximum levels for arsenic found in white and brown rice, while the U.S. FDA has previously released a (non-binding) risk assessment, suggesting the same 100 ppb levels as Europe.

So the takeaway here is that yes, your family and all those professional chefs have been right all along. Yes, washing rice involves sacrificing some of its nutritional value, but doing so means you can reduce the levels of heavy metals present in grains, and still enjoy dishes like rice cakes. And returning back to Yammine’s reporting, Saudiq actually shared that by soaking and washing rice for ~5 mins, you can get rid of 50-100% of these elements. (Thanks Sam!)

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Maria Gatta

Ecology and Conservation Biology

University of the Witwatersrand, Johannesburg

Walabíes: son muy monos, relativamente pequeños, y para los europeos, tienen una apariencia inédita. Esto es lo que llevó a la introducción del walabí de cuello rojo, una especie australiana, a principios del siglo XX a países como Inglaterra, Irlanda, y Francia. En aquellos tiempos, los walabíes se mantenían en zoos y colecciones privadas. Algunos escaparon, sobre todo durante la segunda guerra mundial, cuando la gente tenía cosas más importantes por las que preocuparse por mantener vallas.

Hoy en día, hay muy poca información disponible sobre que les pasó a aquellos walabíes introducidos. Dos científicos, Holly English y Anthony Caravaggi, decidieron investigar qué pasó con aquellos animales. Recogieron información sobre avistamientos de walabíes en los registros oficiales, las redes sociales, y los periódicos. Gracias a lo monos e inusuales que son, los avistamientos suelen ser mencionados en los periódicos locales.

En su artículo reciente publicado en la revista científica Ecologia y Evolución, los investigadores encontraron pequeñas poblaciones de walabíes viviendo a lo largo del sur de Inglaterra. Aunque alguno de estos animales es probablemente un fugitivo moderno de una colección privada o un zoo, es improbable que tales escapadas sean el origen de todos los avistamientos de la región. Por ello, los investigadores creen que las poblaciones del sur de Inglaterra se están reproduciendo en libertad.

Así que, si alguna vez estas en el sur de Inglaterra y crees que has visto a un walabí, ¡no te sorprendas demasiado!

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Marine Science

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A new study demonstrates that, in addition to a variety of other household products, LCD screens also emit these compounds

Kay McCallum

Atmospheric Chemistry

McMaster University

We spend a lot of time indoors - so it’s important that we know what’s in indoor air. Indoor chemists are especially concerned with volatile organic compounds (VOCs, a class of molecules that includes benzene, formaldehyde, and more), which can be harmful to human health and are highly reactive.

VOCs are released into indoor air from a number of sources – plants, wall paint, cooking and cleaning – and, as a recent study by a pair of researchers at the University of Toronto shows, from LCS screens like those in your phone, TV, and laptop.

To measure how LCD screens affect air quality, the researchers collected data on what types of compounds were contained in two types of samples: one of regular indoor air, and one collected near the surface of on an LCD screen like a new TV or an old laptop. They identified the chemical signatures of those compounds using a technique called proton-transfer reaction mass spectrometry. They then cross-referenced these signatures against lists of known liquid crystal monomers (the “building blocks” of LCD screens) and other compounds used in LCD screen manufacturing.

They found over 30 VOCs and 10 L liquid crystal monomers were heavily emitted into the air exposed to the screen, including extremely reactive species like isoprene and acetic acid. This finding indicates that LCD screens are an important source of VOCs in indoor environments, and that our screen-time may be exposing us to more than just new things on the internet.

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Health and Medicine

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Genetics and Genomics

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Evolutionary Biology

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Microbiology

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Shakira Browne

Zoology

University College Dublin

Fluorescence is caused by an animal absorbing light and bouncing it back out again, and in nature, it’s not a new thing. Fluorescence occurs across only a handful of mammals but they span three different continents and inhabit entirely different ecosystems. The platypus is one such animal, whose glow-in-the-dark abilities were only discovered in 2020. 

But, a discovery earlier this year by Northland College researchers that springhares fluoresce is special: it is the first documented case of biofluorescence in an Afro-Eurasian placental mammal. The study purports that perhaps fluorescence in mammals is not as rare as once previously thought. 

The researchers entered Chicago’s Field Museum of Natural History armed with a flashlight, with the goal of examining the fluorescent abilities of flying squirrels. Along the way, they accidentally discovered that springhares also glow. One specimen they examined was collected in 1905, and continued to glow in the dark for over 100 years.

The researchers subsequently tested live springhares (this time, in the dead of night—springhares are nocturnal) and found they could also fluoresce, predictably stronger than in the dead specimens. This study raises the questions: What other animals are out there, pulsating in every different shade of the rainbow after the clock strikes midnight? 

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Fernanda Ruiz Fadel

Animal Behavior and Behavioral Genetics

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Genetics and Genomics

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Ornob Alam

Population Genetics

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Astronomy and Astrophysics

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Animal Behavior and Behavioral Genetics

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This supercharged growth is likely due to nitrate aerosols in our modern atmosphere

Sarah Heidmann

Fish Ecology

University of the Virgin Islands

The growth of modern giant clams is supercharged compared to growth measured from fossil clams. A recent study from the Red Sea has shown this, finding that growth lines from modern species are larger than those of fossils from similar animals dated to the Holocene and Pleistocene.

These increased growth rates appear to be related to higher amounts of nitrate aerosols in the modern atmosphere. These come from many different sources. Some are natural, such as lightning, biomass burning, and soil processing, but most are from anthropogenic activity like burning fossil fuels and agricultural fertilization.

This fast growth may seem like a good thing, but growth doesn’t mean anything about the overall health of the clams. Additionally, aerosols may actually reduce the productivity of marine phytoplankton, which represent almost half of the world’s primary production.

The overall effects of nitrate and other aerosol pollution on global land and ocean cycles are not well understood. They may appear to reduce global warming by improving carbon dioxide uptake and reflecting the sun’s heat, but they contribute to poor air quality. We can congratulate today’s super clams on their impressive growth. But in the long run, fewer emissions on our part are probably better for them.

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