Mmmm…Raw Cookie D’oh!

For several years now, the government has told Americans to put down the tube of raw cookie dough and step away. New warnings about the harrowing dangers of cookie dough were announced by the FDA last week, right before our 4^th of July holiday. Seriously? You’ve been eating the stuff ever since your BFF started dating your ex in high school. What’s the big deal?

Where did things start to go wrong for Barney? Could it have been the raw cookie dough?

In this crazy, hustle and bustle world, who has the time to wait for the cookies to be cooked? Raw cookie dough allows you to savor all of the yummy cookie goodness without the grueling task of popping them into the oven and waiting 10 minutes, which feels like an eternity when you need your sugar fix. And then there’s the mess to clean up…who needs that?

So you defiantly crack open that tube and bury your face in the heavenly Play-Doh-like substance – nom nom. A few hours later, as you rest in content satisfaction on the couch, you begin to feel a great disturbance in The Force. An abrupt gurgle begins to percolate in your gut. Your stomach makes a demonic growl. Visions of volcanic eruptions suddenly waft through your woozy head. The horrific bout of bloody diarrhea that follows might be enough to convince you to listen to those pesky scientists at the FDA from now on. The intestinal apocalypse you experience may even have you wishing for death, but don’t do so lightly. Raw cookie dough has been known to kill.

Linda Rivera died in 2013, a victim of eating a few spoonfuls of raw cookie dough. Over 70 other people were sickened during this outbreak, which started in 2009 and affected mostly teenage girls and children.

How could something that tastes so good be so bad for you? Your first instinct might be the raw eggs in the dough, which could be contaminated with a common food poisoning bacterium, Salmonella. While this is indeed possible, the latest round of scares stem from flour contaminated with a particularly nasty strain of the bacterium Escherichia coli (E. coli). Shiga toxin-producing E. coli O121 has been identified as the culprit behind a massive recall of contaminated flour made by General Mills. Most E. coli strains are harmless, but this one is so not harmless.

Now you might be wondering:  how does E. coli, a bacterial species that inhabits the gut, get into flour? Flour comes from grain grown in fields where animals may do their business - not the kind of "chocolate chips" you want in your cookie dough! But the grain is not normally sterilized because manufacturers assume that people would actually cook the items made from that flour, which kills the E. coli. However, some people just want the “goods” and not the “baked” part.

The Shiga toxin produced by this type of E. coli is the cause for the alarm – these are proteins made by the bacteria that can bind to receptors on our cells, particularly in the intestine and the kidney, which is why people experience bloody diarrhea and renal failure when infected. Once inside our cells, the Shiga toxin can bind to our ribosomes, which make our cellular proteins. When our cells can’t make proteins, they eventually die.

E. coli bacteria are kind of scruffy-looking, but those “hairs” are actually flagella the bacterium uses to get around. About 10,000 of these can fit on the head of a pin. It only takes 10 of the more virulent strains to make you seriously ill.

Over 40 people have been sickened from the recent outbreak, almost a baker's dozen requiring hospitalization. There have been no deaths to date, and deaths from cookie dough remain extremely rare…but it has happened and is a most unpleasant way to leave the world. So cook your cookies or risk tossing them later.

The FDA also warned that pizza dough, “play clay” made from dough, or “flour crafts” that kids sometimes play with, can also lead to food poisoning. Even if they don’t eat it, the E. coli can get onto their hands, which usually end up in their mouth before they get washed.

In light of these cookie dough poisonings, manufacturers have started to use only pasteurized eggs and, more recently, heat-treated flour to destroy the bacterial culprits. However, they still caution that consumers cook the product properly to be on the safe side.

What about those of us who enjoy our desserts within a dessert, namely cookie dough ice cream? You can breathe easy - cookie dough ice cream is okay to eat because it is typically made with heat-treated flour and pasteurized eggs.

To put things in perspective, E. coli contaminated spinach sickened nearly 200 people and killed 3 of them in 2006. The point is not to eat more cookie dough instead of spinach (sorry)…but to handle and prepare ALL food properly no matter what it is.

Putting it all together, if you are making cookie dough or cake batter from scratch, odds are the flour you're using has not been heat-treated to kill bacteria, so there is a chance it could be contaminated. Even if it is not under the recall, the flour should be treated as you would any other raw food. If you must play cookie dough roulette, some companies are stepping up to the (kitchen) plate and making some that lacks eggs and uses heat-treated flour.

Contributed by:  Bill Sullivan

Follow Bill on Twitter.

Thorpe, C. (2004). Shiga Toxin--Producing Escherichia coli Infection Clinical Infectious Diseases, 38 (9), 1298-1303 DOI: 10.1086/383473

Obrig, T. (2010). Escherichia coli Shiga Toxin Mechanisms of Action in Renal Disease Toxins, 2 (12), 2769-2794 DOI: 10.3390/toxins2122769

Lead: Breaking Down The Bridges Of Life For Centuries

In February of 2015, after months of seeing her children randomly lose hair and complain of stomachaches and other symptoms, LeeAnne Walters finally had the water in her house tested by city officials. As she feared, the results were not good. Lead levels showed a content of 104 parts per billion, nearly 7 times the EPA limit for lead in drinking water. In April she would go on to discover that all four of her children had lead in their blood, and that her son Gavin was actually poisoned by this heavy metal.

The Walters are one of the many families in Flint, Michigan suffering the consequences of the lead poisoning epidemic that resulted from city officials switching the source of city water from Lake Huron to the Flint River. We now know that the corrosive nature of Flint River water leached the lead from aging city pipes; what started as a cost saving measure resulted in nearly tripling the percentage of Flint children having elevated lead blood levels.

Repeated exposure to lead can cause diverse symptoms including abdominal pain, headaches, memory loss, weigh loss, and anemia. Children are particularly susceptible to the ill effects of lead toxicity, which can result in developmental delays and learning disabilities among other long-term, irreversible health issues. Thus, despite the change back to Lake Huron water in October, this man-made disaster will be affecting the residents of Flint for decades to come. Thanks to recent national press attention, the events that led to this water crisis as well as its health-related consequences are well known to most.

The weight equivalent of only ~1/16^th teaspoon of salt in lead in the bloodstream of an adult sets off alarms of concern - but what is it about lead that makes it so toxic? What does lead do at the cellular and molecular level that contributes to such widespread and profound effects in the human body?

Mark Nowlin / The Seattle Times

Lead typically enters the body through either ingestion or inhalation of lead particles that contaminate water, food, or the environment. In the United States, up to 20% of the half a million children living with lead poisoning were exposed through the drinking of contaminated water. Once ingested, lead is absorbed through the gastro-intestinal (GI) system, a process that is greatly influenced by age:  while only 10% of lead ingested by adults is absorbed, up to half of that ingested by young children will be absorbed. In addition, diet and nutritional health play a role on absorption levels. Low calorie intake, vitamin, and iron deficiency, as well as a high-fat diet, have all been correlated with enhanced absorption of lead, which contributes to the higher prevalence of lead poisoning among children from economically depressed regions such as Flint, Michigan.

After absorption, lead enters the blood, where it is mostly associated with red blood cells (RBCs). One of the effects of lead is to weaken the membrane of cells leading to their rupture. In the context of RBCs, this results in a process known as hemolysis and contributes to the anemia often associated with lead poisoning. Another key effect of lead that contributes to anemia is the inhibition of enzymes responsible for making heme, a critical component of many proteins including hemoglobin. Unregulated inhibition of enzymes, like that caused by lead, generates an excess of reactive oxygen species (ROS), which in turn can disrupt nearly all components and functions of any cell. Unfortunately, not only does lead produce this so-called “oxidative stress”, but it also inhibits the antioxidant proteins and other molecules our cells would normally use to protect themselves. The net result is a perfect storm of damage and lack of protective mechanisms that spells the ultimate demise of the cell.

Interestingly, while the blood lead level is what health professionals use to monitor exposure, only a small fraction of the total lead burden in the body is found in the blood. A significant amount of lead accumulates in soft tissue organs such as liver, lungs, kidneys, and importantly the brain. Indeed, one of the primary targets of lead toxicity, especially in children, is the central nervous system. The adverse effect of lead in neurons is again a combination of ROS production and inhibition of antioxidants, plus the disruption of proteins responsible for neural functions such as the release of neurotransmitters. Nonetheless, nearly 90% of lead retained by adults and 75% of that retained by children ultimately ends up in the bones and teeth. It actually takes up to 30 years to eliminate half of the lead that enters the bone, and bone-to-blood transfer of lead, which increases during pregnancy, menopause, and aging, can serve as a source of lead toxicity long after initial exposure.

Lead’s uncanny ability to inhibit such a broad range of enzymes is due to its high affinity for sulfhydryl (sulfur and hydrogen) groups, including those attached to carbon, which are known as thiols. A biologically important thiol is the side chain of the amino acid cysteine, one of the 21 building blocks that make up proteins. Because two thiol groups can react with each other to form disulfide bonds, cysteines in different parts of a protein - or even in different proteins altogether - can bind to one another. The ability to form these disulfide bridges makes cysteine a very special amino acid that contributes to a protein’s structure, stability, function, and ability to interact with other proteins.

Disrupting and remaking disulfide bridges between proteins is the basis of chemicals used by hairdressers to straighten and curl up hair.

By strongly interacting with thiols, lead can break disulfide bridges and ruin the structure and function of enzymes, sometimes permanently. The ubiquitous presence of thiols in proteins and their importance to function is what allows lead to affect such a broad range of cells, organs, and processes. Another chemical property of lead that contributes to its toxicity is its divalency (ability to make two bonds). Once inside of cells, lead can take the place of biologically important divalent ions such as calcium and magnesium with dire consequences. Calcium, in particular, plays an important role as a signaling molecule and therefore its level inside of the cell is tightly regulated. When lead levels are high, it can activate proteins and processes, such as neurotransmitter and hormonal release, which are normally controlled by calcium fluxes.

Lead has been intrinsically interconnected with human history. Ancient civilizations considered it the father of metals and the Romans laced their wine and aqueducts with it. Soft, highly malleable, and with a low melting point, lead is in many ways an ideal material. But its more pernicious character as a poison has also been recognized for centuries. There is no known safe level of lead and its effects are widespread, long lasting, and unpredictable. While the pharmacokinetics, mechanism of toxicity, and chemical properties of lead are fascinating, they are insignificant and almost irrelevant in the context of the human cost lead poisoning has inflicted throughout history and continues to inflict. LeeAnne Walters’ son Gavin and the many other afflicted children from Flint, Michigan are unfortunately the latest to pay the price.

Contributed by:  Gustavo Arrizabalaga, Ph.D.

Follow Gustavo on Twitter.

References and resources:

http://emedicine.medscape.com/article/2060369-overview

http://www.cdc.gov/nceh/lead/

http://michiganradio.org/post/timeline-heres-how-flint-water-crisis-unfolded#stream/0

Flora G, Gupta D, & Tiwari A (2012). Toxicity of lead: A review with recent updates. Interdisciplinary toxicology, 5 (2), 47-58 PMID: 23118587