NanoSapiens » Chemistry

Chromium-6 and clean water | Rebecca Sutton

Rebecca Sutton — Tue, 25 Jan 2011 13:30:01 +0000

As the Environmental Working Group found, carcenogenic contamination is a real issue. We need to go back to the source

The Environmental Working Group welcomes informed scrutiny of our recent study on hexavalent chromium (chromium-6) in tap water. We detected this probable human carcinogen in the water of 31 of 35 American cities tested.

We now know that chromium-6 exposure is not limited to communities like Hinkley and Kettleman City, California, victims of extreme industrial pollution and corporate malfeasance. Our results show that communities across the United States, and probably around the world, may be exposed to low levels of this toxin. Worldwide, known hotspots of chromium-6 contamination include Glasgow, Oinofita, Greece and parts of India, China and Australia.

The US Environmental Protection Agency reacted swiftly to our study with a four-point plan to help water utilities nationwide monitor and assess chromium-6 levels, and EPA chief Lisa Jackson has pledged to move quickly to set a nationwide safety standard.

California officials recently lowered the proposed safe level from 0.06 parts per billion (ppb) to 0.02 ppb. The amount EWG found in tap water from one American city, Norman, Oklahoma, was nearly 650 times higher than this. State scientists concluded that the lower goal is necessary to account for the special sensitivity of infants and young children to carcinogens. EWG and many other scientists and public health advocates have urged exactly this approach. Establishing this public health goal is the first step in setting a mandatory safety standard, which, under California law, should have been done by 2004.

The author of a recent opinion piece here argued that the proposed safe level would achieve an insignificant reduction in lifetime cancer risk. Public health agencies disagree. Safety goals are intended to protect people over a lifetime of exposure, not just to chromium-6 but to the many other cancer-causing compounds that commonly contaminate tap water, including chlorination byproducts linked to bladder cancer, and arsenic linked to skin, bladder and lung cancer. Many of these compounds also contaminate food, air and soil, or turn up in consumer products. Over a lifetime, people’s exposures to all these sources add up.

Stringent safety standards aren’t a luxury. Forty-one percent of all Americans will be diagnosed with cancer during their lifetimes. About 21% will die from it, according to the US National Cancer Institute; in 2009 alone, 1.5 million people were diagnosed. Health officials can hardly be too protective when it comes to tap water, which is widely consumed and commonly contaminated. We don’t know how many cancer cases are linked to chemical exposures, but in an April 2010 study the President’s Cancer Panel found that environmental causes of cancer are “grossly underestimated” and “needlessly devastate American lives”.

The case of chromium-6 is particularly troublesome. Both animal and human studies have shown it to be a potent carcinogen. As far back as 1987, researchers documented an increased risk of stomach cancer and a “significant excess of overall cancer mortality” among Chinese villagers whose water had been polluted by chromium-6. In 2008, a gold-standard study (pdf) by federal scientists found increases in gastrointestinal tumors in rats and mice exposed through drinking water. Based on that data, the US National Toxicology Programme found that chromium-6 shows clear evidence of carcinogenic activity.

Certainly, the actions necessary to address the problem will carry significant costs. But the accumulating evidence makes clear that simply ignoring it is not an option. The first step is to identify those water supplies that contain unsafe levels of chromium-6, and the EPA deserves credit for following up promptly on our findings. The second step is to find ways to minimise contamination where it is found.

But providing safe drinking water is not just a matter of treatment or purification. As a nation, we need to protect our water supplies at the source. We spend 1,900 times more to treat drinking water than we do to protect it in the first place. Our priorities are back to front.

Rebecca Sutton

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The Disappearing Spoon by Sam Kean; Periodic Tales by Hugh Aldersey-Williams — review

Robin McKie — Sun, 23 Jan 2011 00:06:17 +0000

Two lively tales of the periodic table and the scientists behind it are full of entertaining nuggets

After the rise of Adolf Hitler, two of Germany’s leading liberal scientists, Max von Laue and James Franck, sent their Nobel medals to the great Danish physicist Niels Bohr for safe-keeping. Everything seemed fine until 1940 when Copenhagen was overrun by the Germans. Bohr found himself in a tight spot. It was illegal to export gold from Nazi Germany and discovery of the medals, bearing Franck and Laue’s names, could have led to executions.

Colleagues suggested burying the medals. Instead Bohr chose to use aqua regia, a corrosive mix of acids that was known, since the days of alchemy, to dissolve precious metals. Troops later ransacked Bohr’s institute but found no gold – just some uninteresting beakers containing brown liquid. These survived the war and their gold was extracted to be sent to Sweden to be cast into new medals for Franck and Laue.

Clearly alchemy can pay off, even for a quantum physicist. The authors of these two books make much of this story in their peregrinations through the periodic table while also waxing lyrical about the Nobel prize’s constituent metal. For Sam Kean in The Disappearing Spoon, gold is aloof “because it doesn’t bond with other elements”, while Hugh Aldersey-Williams praises its incorruptibility, which inspires “a torrent of other ideals: the golden section and the golden rule”..

Empires have been built on gold, of course – medieval Spain, for example. By contrast, Britain’s rested on carbon (coal) and iron, while modern America relies on carbon (oil) and silicon. Ours is an elemental world, though it is only relatively recently that we have come to understand the behaviour of these basic building blocks of complex materials.

It was the 18th-century French chemist Antoine Lavoisier who first showed elements were chemically irreducible units of matter; he compiled an early list that included hydrogen, nitrogen, sulphur and oxygen. Scientists added more but could find no pattern to these additions until, in 1869, Dmitri Mendeleev produced his periodic table. In it, he categorised elements by atomic weight and chemical properties. Crucially, he left gaps for elements yet to be discovered.

These omissions made many scientists suspicious until, in 1875, they isolated gallium, whose atomic weight and chemistry had been predicted by Mendeleev. The great Russian was vindicated while chemists’ lives were enriched by a substance of beguiling behaviour, as is suggested by the title of Kean’s book. Gallium looks like aluminium but melts at a mere 29C. Make a spoon of it, give it to guests to stir their tea and watch it melt and form a metallic puddle at the bottom of their cups. Laugh? They have to mop it up.

The final void in the table was filled, in 1939, with francium, the last naturally occurring element to be uncovered. Physicists then started bombarding existing elements with high-energy particles to create synthetic ones. These, as Kean points out, are the first new elements to appear on Earth since the creation of the solar system billions of years ago and have found widespread use, ranging from plutonium, in nuclear bombs, to americium, which is employed in domestic smoke alarms.

Other elemental nuggets provided by Kean and Aldersey-Williams include the revelation that tellurium is the smelliest of the elements and will leave scientists reeking of a garlic-like odour for weeks should they let a piece touch their skin. By contrast, beryllium tastes like sugar while rhodium, ounce by ounce, is the most expensive to buy – hence the disc made of it in 1979 for Paul McCartney after he became the bestselling songwriter and musician of all time.

Not all these periodic tales are so appealing. The 17th-century alchemist Hennig Brand boiled down gallons of his own urine to produce a residue that glowed in the dark. This was the element phosphorus. Brand carried out his work in Hamburg which, 270 years later, had 1,900 tonnes of incendiary phosphorus bombs dropped on it by Allied bombers. The resulting firestorm destroyed much of the city, including the district where Brand had discovered the element, and “melted between 40,000 and 50,000 people,” according to the historian Jorg Friedrich. Sadly, phosphorus is still employed to make weapons, as Israel demonstrated during a raid in Gaza in 2009. “The smokescreen that phosphorus produces remains moral as well as literal,” notes Aldersey-Williams.

Strangely, these different elements make up a very small part of the cosmos. Ninety per cent – more or less – of matter in the observable universe consists of hydrogen while the other 10% is helium. The other elements account for a mere 0.04% of total matter and could be dismissed by an overenthusiastic mathematician while rounding up his figures. We live in an odd part of the cosmos, it would seem.

It is provocative stuff, and both books do justice to their topic, though both struggle to forge a proper narrative from all these disjointed tales of elemental discovery. The Disappearing Spoon is cleverly conceived, easily digested but a little too glib for my liking. Periodic Tales follows a more composed, personalised approach – including a quite splendid account of the author’s visit to a homeopath in a bid to buy his plutonium “cures” – and proves to be the more enjoyable and polished of the pair: not pure gold, perhaps, but a glistering effort.

Robin McKie

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Virtual Screening: Principles, Challenges, and Practical Guidelines

Fri, 14 Jan 2011 05:00:00 +0000

A comprehensive and up-to-date overview, this is both a desktop reference and practical guide for virtual screening applications in drug discovery. Clearly divided into three major sections, the first on principles provides a detailed description of the methods required for and applied in virtual screening, while the second discusses the most important challenges in order to improve the impact and success of virtual screening. Finally, the third,

Concise Physical Chemistry

Donald W. Rogers — Fri, 14 Jan 2011 05:00:00 +0000

This book is a physical chemistry textbook that presents the essentials of physical chemistry as a logical sequence from its most modest beginning to contemporary research topics. Many books currently on the market focus on the problem sets with a cursory treatment of the conceptual background and theoretical material, whereas this book is concerned only with the conceptual development of the subject. Comprised of 19 chapters, the book will address

Regulated Bioanalytical Laboratories: Technical and Regulatory Aspects from Global Perspectives

Michael Zhou — Fri, 14 Jan 2011 05:00:00 +0000

This book provides useful information for bioanalytical / analytical scientists, analysts, quality assurance managers, and all personnel in bioanalytical laboratories through all aspects of bioanalytical technical and regulatory perspectives within bioanalytical operations and processes. Readers learn how to develop and implement strategies for routine, non-routine, and standard bioanalytical methods and on the entire equipment hardware and software