Poisons and Policy: Arsenic and Aflatoxins
Sep20

Poisons and Policy: Arsenic and Aflatoxins

In the past 24 hours, do you recall hearing anything about arsenic in rice? If you're in the United States, the answer is very likely, "yes!" A great many pixels were spilled yesterday when Consumer Reports and the US Food and Drug Administration released -- almost simultaneously -- analytical data on inorganic arsenic concentrations in 200 samples of commercial rice products, particularly those grown in the southern US. You can't do any better in understanding this story than reading, "Arsenic and Rice. Yes, again," on Deborah Blum's Elemental blog at Wired Science Blogs. Professor Blum has been discussing arsenic in the diet for a few years, an interest she developed while composing her superb book, The Poisoner's Handbook: Murder and the Birth of Forensic Science in Jazz Age New York. Deborah's post puts in perspective the risks of inorganic (and organic) arsenic concentrations in food products such as rice relative to drinking water. Arsenic occurs in nature but exists in higher concentrations in water from areas where arsenical pesticides have been used in cotton farming or poultry deworming (the latter discussed in 2006 at NYTimes). While she closes in being critical of the FDA for lack of clear consumer guidance, let it suffice to say that no character in Blum's book was killed by poisoning with rice from Louisiana. Pick your poison What caught my attention yesterday was a completely different report from the US FDA -- actually a FDA ruling released by the Iowa Department of Agriculture and Land Stewardship. Corn containing one of the most potent natural toxins and carcinogens -- a class of compounds called aflatoxins -- can be legally blended with other corn for use in animal feed.  A standing rule of the FDA, when invoked, allows farmers to blend corn containing up to 20 parts per billion of aflatoxins with corn containing lower concentrations (or none) of the toxin family. Here's where 20 parts per billion falls in the FDA's guidelines according to the Iowa Dept of Agriculture statement: The FDA has established guidelines for acceptable aflatoxin levels in corn based on its intended use.  Corn containing aflatoxin in concentrations of greater than 20 ppb cannot be used for human consumption and cannot be used for feed for dairy animals or for immature livestock of others species. Corn containing aflatoxin at 100 ppb or less can be used in breeding cattle and swine and mature poultry.  Corn with 200 ppb or less can be used with finishing swine greater than 100 lbs. in weight and corn with 300 ppb or less can be used in finishing beef cattle. Where is this aflatoxin coming from...

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How Do You Like Your Caffeine?
Mar08

How Do You Like Your Caffeine?

Inhaled or oral? Natural or synthetic? Two interesting reports came across the interwebs over the last couple of days. Earlier this week, the US Food and Drug Administration issued a warning letter (press release) to makers of Aeroshot brand of inhaled caffeine. No, it's not an asthma medicine (although oral theophylline is). It's billed as a non-caloric caffeine delivery system, 100 mg per hit. That's roughly the amount in two 12 fl oz/355 mL cans of Mountain Dew or one gulp more than a 8.4 fl oz/250 mL can of Red Bull energy drink. However, the company claims that only 15-25 mg are delivered - perhaps half the amount in a Coca-Cola. The FDA has concerns about the dual promotion of the product for swallowing and inhalation, the relative safety of inhaled caffeine, and the potential for children and adolescents to use the product in combination with alcohol. The company's FAQ specifically notes that the product is not marketed for use in children. Readers will recall that Four Loko caffeinated alcohol drinks were withdrawn from the market in late 2010 and replaced with alcohol-only versions. On another front, Analytical Chemistry published a paper by a group led by Maik Jochmann at Essen, Germany on an isotopic ratio method for determining whether caffeine in a consumer product is derived from plants or synthetically. While public demand for naturally-caffeinated products doesn't seem to be especially a big deal in the US, the FDA only requires listing of caffeine content for products with added synthetic caffeine. (Note: I only just found out this afternoon that C&EN Online had covered this paper back on February 29th. My apologies to all for not linking to it. That report is here.) The authors show here that 13C ratios can indeed be used to determine the source of caffeine. In general, 13C represents 1.11% of Earth's carbon. However, plants incorporate less 13C in making caffeine via C3 carbon fixation from atmospheric carbon dioxide. I'm still a bit unclear as to whether the method can determine the difference between naturally-occurring caffeine from products spiked with purified, plant-derived caffeine (I don't think so). In the paper, I learned something new and of relevance to the American South (where I live): the international standard for 13C/12C ratios is Vienna Pee Dee Belemnite (VPDB). In 1957, the late Scripps Institution of Oceanography geochemist Harmon Craig, defined terrestrial carbon isotope ratios from a fossilized cephalopod in the Pee Dee limestone formation of South Carolina. Although none of the original specimen remains, secondary standards are now used for calculations. To complete our history lesson, you should know that the Pee Dee River...

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Supporting chemistry education in public schools
Oct13

Supporting chemistry education in public schools

Dear beloved, good-looking, and erudite readers of Terra Sigillata, Our blog is once again participating in a drive for DonorsChoose, an online charity established to fund small, public schoolteacher-initiated projects that are not otherwise supported by their school districts. The annual DonorsChoose Blogger Challenge - Science Bloggers for Students - is a friendly competition among blogs and blog networks to use their reach to put our collective money where our mouths are. As public school budgets are cut and cut, we have to maintain the quality of scientific experiences for our young people. Your generosity can help! How does it work? You click on my donor challenge, "Chemistry With Kroll," or on the graphic above. You see projects that I have selected to represent for our annual drive. You choose to donate a few doubloons to a project or two that move you (i.e., donors choose, get it?). No donation is too small (Okay, $1 is the smallest). When the project is funded, fulfilled, and executed, you get feedback from the teachers and students - pictures and notes that I challenge you to not bring a tear to your eye. Not all of these projects are for science directly; some are to fund just the basic tools needed to get teachers to a point where they can teach science. Most are in high poverty areas of my home state of North Carolina but I've added a few others from around the country. I'd love for you to support my projects but please feel free to donate to any project anywhere on the DonorsChoose site! I've participated in this project in 2006, 2007, 2008, and 2009 (click years to see my previous giving pages). You fine people have given almost $14,000 to support 39 projects that have reached 4,100 students. Pretty amazing for a little blog effort, eh?   Heartiest thanks and accolades for physical chemist, philosopher, and ethicist, Prof. Janet W. Stemwedel, for getting the ball rolling on this effort way back in the summer of 2006. Here's her post for this year explaining the whole blogger challenge. And if you care to tweet about this, Janet has established the hashtag...

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Compilation of synthetic marijuana posts (Spice, K2)
Oct02

Compilation of synthetic marijuana posts (Spice, K2)

Welcome to readers arriving from Reddit - scroll down through the post for links to our more detailed discussions on cannabimimetics. (updated 8 October) Recent media coverage of our writings on the chemistry, pharmacology, public health risks, and regulation of synthetic marijuana herbal incense products has led us to put together a compilation of posts we've written here on the topic over the last year-and-a-half. Synthetic marijuana is a term used to describe a collection of herbal products labeled as incense or potpourri to which one or more marijuana-like chemicals have been added. Unlike with the naturally-occurring marijuana or cannabis plant, Cannabis sativa, these herbal products contain chemicals made in the laboratory. These chemicals, called cannabimimetics for their ability to mimic the effects of cannabis, are potentially more powerful than the chemicals made by the marijuana plant. Their side effects have led to a surge in emergency room visits and poison control center reports. Many of these chemicals were first made in 1990s in the laboratory of Professor John W. Huffman, a now-retired chemistry professor at Clemson University for the purpose of identifying the parts of a molecule responsible for the psychotropic effects of marijuana. These research tools were referred to by the prefix "JWH-" followed by a number (e.g., JWH-018) and recreational chemists in Europe began making and selling these agents around 2004, mixed with legal aromatic herbs and sold predominantly by the name "Spice." Now illegal in most of Europe, Scandanavia, and the former Soviet republics, these compounds began to be sold in the US over the last three years. A similar wave of prohibition is now occurring across the US and the federal drug regulatory agency, the Drug Enforcement Administration (DEA), has temporarily moved five cannabimimetics to the most restrictive class of controlled substances, Schedule I. The following list is a compilation of our writing on the topic here at Terra Sigillata.   What’s the buzz?: Synthetic marijuana, K2, Spice, JWH-018 First appearing in February 2009, this is our classic, first-stop post explaining the background on these products and the compounds they contain. DEA already admits defeat on synthetic marijuana ban? This post from March 2011 describes how the US DEA prohibition on five synthetic cannabimimetics is already being circumvented by creative marketers. “Synthetic marijuana” chemist John W. Huffman interviewed on regional NPR program This January 2011 post discusses a Charlotte, NC, NPR interview with Professor Huffman from his home in western North Carolina. Strong chemistry in NC bills banning legal highs NC legislators aim to clean up “bath salt” omission This pair of February 2011 posts provide uses my local North Carolina examples of state...

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“Alex, I’ll take ‘Public Chemistry Literacy’ for $1,000”
Jun21

“Alex, I’ll take ‘Public Chemistry Literacy’ for $1,000”

Trebeck: "Okay, Public Chemistry Literacy for $1,000. . ." "The answer is, 'Absolutely nothing.'" Ding! Contestant: What things on Planet Earth are "chemical-free"? Ding! Ding! Ding! Ding! Ding! Ding! Ding! Tonight in the United States (and maybe even in Canada), the legendary game show, Jeopardy!, will be dedicated to questions on chemistry in celebration of 2011 as the International Year of Chemistry. Here are the details from the IYC website: Jeopardy!, one of North America’s leading syndicated game shows, will feature questions related to chemistry and IYC in an episode airing in the United States and Canada on June 21, 2011. With its 9 million daily viewers, Jeopardy! provides the perfect venue for publicizing the IYC’s message – to celebrate chemistry and the contributions that it makes to society, and to increase the interest and public appreciation of chemistry. Watch Jeopardy! on June 21 and play along with the contestants to test your knowledge of chemistry. The show can be viewed in the United States on ABC-TV (check local listings for air times in your area). And for those of you playing along at home, @CASChatter will be live-tweeting beginning at 7:30 pm EDT. Perhaps I shall as...

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Arsenic-permissive bacteria – implications for arsenical cancer chemotherapy
Dec04

Arsenic-permissive bacteria – implications for arsenical cancer chemotherapy

Like many of you, I waited this week for details on the NASA press conference and Science paper on a major discovery - painted as an "alien lifeform" by some news outlets. The truth did not live up to the hype but it was an impressive biological finding: a group led by Felisa Wolfe-Simon discovered a bacterium in California's Mono Lake that could still grow when phosphorous was completely replaced with arsenic. The bacterium, strain GFAJ-1 of the Halomonadaceae family of Gammaproteobacteria, appears to use arsenic in place of phosphorus in molecules where phosphate is used - shown most conclusively here for DNA. The story is perhaps best told by science writer extraordinaire, Ed Yong, at Not Exactly Rocket Science, and biologist PZ Myers is to be commended for representing us well to our chemistry colleagues by actually breaking out the periodic table in his excellent teaching post. Addendum (4 Dec, 2:46 pm): An excellent chemistry-flavored post at The Curious Wavefunction also came to my attention - he/she cited this great 1987 Science paper, "Why Nature Chose Phosphates (PDF)," from the late Harvard chemist Frank Westheimer which discusses, among other things, the difficulties in overcoming the lability of arsenate esters in biomolecules. The bacterium doesn't exactly thrive on arsenic, to be sure. It's home, Mono Lake, contains arsenic in the form of arsenate at a concentration of about 200 μM. The research team isolated and propagated the bacterial strain from lake sediment and observed that when grown in a defined culture medium, it normally incorporated a small amount of arsenic into biomolecules (as determined by ICP-MS from dry weight calculations) relative to phosphorus at a ratio of 0.002 to 1. But to truly allow significant arsenic incorporation, the bacterial culture had to be grown stepwise in arsenate (AsO43-) at concentrations from 100 μM to 5 mM. Then, a single colony was isolated and grown and maintained at 40 mM arsenate in growth medium. Under these conditions, the bacteria didn't seem particularly happy as they grew more slowly with an oblong morphology and large vacuoles inside the cells, but they did multiply by 20-fold after six days in the highest concentration. Here, the bacteria preferentially incorporated arsenic at a ratio of 7.3 to phosphorus in dry weight. So, the bacteria are still able to use some phosphate from the trace amount in the medium (about 3.1 μM). But the remarkable feat is that the bacteria can be maintained on 40 mM arsenate. That is the impressive discovery. I began to think about this in the context of arsenic chemotherapy. Although arsenic is toxic to most cells, Paul Ehrlich's group had...

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