Toxic turkeys?

Now that the Thanksgiving feasting is winding down, now would be a great time to tell you that that succulent turkey you’ve been scarfing down for the last couple of days contains measurable amounts of carcinogens. That’s right: your turkey has toxic chemicals that cause cancer. No this isn’t some conspiracy – Big Turkey hasn’t been pumping cancer causing chemicals into the birds. It’s a natural product found in turkeys (in all cooked products, actually), and while the risks are real, they’re actually really low (so go on and continue eating).

Surprisingly, people don’t really like it when I bring this up at mealtimes. And I’ve brought it up enough times to know that you’re probably still concerned and have some questions, so let’s just nip those in the bud while we are here.

turkey-pick

Turkey meat contains measurable amounts of heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs), which have been shown to cause cancer in laboratory studies.

Q: How do turkeys naturally have cancer causing chemicals in them?

A: Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are classes of compounds that occur naturally throughout the world (including your turkey). These are diverse groups of chemicals that are all large and perfectly flat, which means they easily insert themselves into your DNA, disrupting the structure and causing DNA damage. This is the first step to cancer (and only the first step).

Q: Is there a way to avoid eating HCAs and PAHs?

A: HCAs and PAHs are natural byproducts formed by incomplete combustion of organic material. If you remember your middle school chemistry class – fires start when a fuel (organic matter) and oxygen combine and rearrange their chemical bonds to form water vapor, carbon dioxide (CO2), which releases a lot of heat. If organic matter is not fully combusted, in addition to CO2 you get things like HCAs and PAHs. Some marinades help reduce HCA and PAH formation and avoiding direct contact to flame (like grilling and barbecue) can also reduce their formation. But since meat is organic matter, and cooking is essentially very inefficient burning, it’s pretty much unavoidable in your plate.

Q: So why doesn’t everyone who has ever eaten a turkey in their life have cancer?

A: Well, part of it is that DNA damage is only the first step to cancer. There are a lot more required before you need to get worried. As it turns out, your DNA gets damaged pretty frequently – UV light damages DNA (hence all the hubbub about sunscreen), and a lot of times DNA gets damaged when your cells are dividing, just by chance. So your cells, in turn, have evolved quite a few ways of repairing your DNA all the time.

Q: But what about those studies that show increased risk of cancer with meat consumption?

A: You mean like those released by the World Health Organization about bacon causing cancer? Okay, yes, like I said before, the risk is low, but it’s still a risk. While your body is capable of defending itself from HCAs and PAHs at any given time, the more meat you eat, the more your body will have to defend itself, meaning eventually your cells may not catch the damaged DNA in time, resulting in cancer. Think of sun exposure as an example – if you go out into the sun more, you’re more likely to get skin cancer because you’re exposing yourself to UV light more than someone who likes to stay inside. So if you eat more meat, you’re exposing yourself more to HCAs and PAHs, then you’re increasing your risk for cancer.

Q: Do I have to stop eating this turkey?

A: Probably not. I certainly haven’t stopped. Like everything else in toxicology, it’s the dose that makes the poison. Too much of anything, even something that’s good for you, eventually becomes bad for you (again, think of sun exposure and skin cancer). But to put things in perspective – the Global Burden of Disease Project estimates 34,000 deaths per year result from diets high in processed meats. In contrast, about 600,000 people die each year from alcohol consumption, 200,000 people die every year from air pollution, and about 1 million people die each year from cancer resulting from smoking. Thanksgiving turkey isn’t really the top of my list of toxic worries.

The early bird gets the quantum dots

Earthworms are kind of a big deal for environmental scientists. As it turns out, they’re not just food for those early birds – earthworms are detritivores, meaning they feed on dead organic matter and help decompose it, releasing nutrients that were sealed up back into the environment for plants and microbes to use. They’re a key player in the circle of life. However, sediment and soils have a tendency to accumulate a lot of pollutants, making it tough living for soil dwelling animals. Luckily, earthworms are masters at detoxifying pollutants through their unique physiology. Heavy metals, like lead or cadmium, are easily captured and stored away using specialized proteins called metallothioneins. These proteins have a remarkable capacity for binding onto free metals and transporting them away where they can’t cause any harm to sensitive tissues, sequestering them for long periods of time. Metallothioneins are common proteins – even we, humans, have them. What makes the earthworm system special is that the metallothioneins transport the bound metals to the liver (or the earthworm version of the liver, the chloragogen) where it covers the protein-bound metals with layers of amino acids and proteins, most likely to help eventually excrete them later. Earthworms are so good at this that oftentimes entire populations of worms that live in highly contaminated areas become almost completely resistant to the metals. This makes earthworms ideal candidates for cleaning up major chemical spills, remediating and cleaning the environment.

Inside the lowly earthworm lies a metal processing facility like no other. And as it turns out, a nanotechnology factory as well.

Inside the lowly earthworm lies an impressive metal processing facility (and nanomaterial factory). These little guys chomp down on soil, heavy metals and all, and processes them using a series of detoxification proteins called metallothioneins to capture and store toxic metals for safe keeping.

What’s even more interesting, however, is that this same metal detoxification pathway makes them an efficient (and more importantly, cheap) semiconductor factory. Researchers have found that the choragogen provides just the right conditions that allow metals like cadmium and tellurium to react and create tiny (high quality) nanoparticles called quantum dots. These miniscule particles, ranging from 2 to 10 microns across (that’s about 10 to 50 atoms!), are incredibly useful in the tech industry. When quantum dots are hit with a beam of light or have an electric current passed through them, they emit colored light, which happens to be sharper, brighter, and more vibrant than traditional LED lights. If you’ve recently bought a high definition TV then it’s very likely that the display you use to watch your favorite TV shows uses quantum dot display technology. But that’s not all, quantum dots can potentially revolutionize much of the tech industry, changing the way we approach anything from solar panels to lights, inks, and even biomedical technology.

Quantum dots are tiny (2-10 micrometers across!) particles that emit sharp, bright, and vibrant light when hit with light or an electric current. They have diverse uses and are currently used in high definition electronic displays.

Quantum dots are tiny (2-10 micrometers across!) particles that emit sharp, bright, and vibrant light when hit with light or an electric current. They have diverse uses (from solar panels to TV displays) and are a major milestone for the technology industry.

What makes earthworm quantum dots so intriguing (aside from the fact that they come from worms) are the potential biological uses. Remember that layer of amino acids and proteins that the worms use to cover the metallothionein-metal complex? That is what chemists call a passivating layer, which means it helps protect the interior complex but also helps them dissolve and distribute in water. Nanomaterials are notoriously hard to dissolve in water as they tend to clump (much like when you mix oil and water), and as they say, the human body is mostly just water (roughly 60% or so). So any biomedical use needs to find a way to make quantum dots behave in watery bodies. So far all solutions people have come up with either make the quantum dots toxic to living organisms (which kind of defeats the purpose) or alters the quantum dots so much that we see a loss in performance. The humble earthworm seems to have found a way around all of that. Laboratory experiments show that quantum dots made by earthworms are easily dissolved and taken up by mammalian cells in petri dishes, with no signs of any toxic effects.

Rat macrophage-like cells (right) are stained green with quantum dots made by earthworms. On the right are cancer cells green with quantum dots made by earthworms (and nuclei stained blue with a chemical stain). Quantum dots made by earthworms are easily dissolved and distributed into living cells and are not toxic to cells, unlike quantum dots made artificially in a lab, making earthworm quantum dots a potentially important tool in biomedical fields.

Rat macrophage-like cells (left)  and cancer cells (and nuclei stained blue with a chemical stain; right) are stained green with quantum dots made by earthworms. These particles are easily taken into living cells and are not as toxic as man-made quantum dots. Sturzenbaum et al., 2013. Nature Nanotechnology.

To be sure, there’s still a lot of quirks that need to be worked out and much to be learned still about the system before we’ll be seeing earthworm biotechnology farms cropping up (though wouldn’t that be something fun to imagine…). So for now, just bask in the mysterious glow of natural selection and ponder the series of serendipitous events that led to the evolution of a tiny nanotechnology factory within the humble earthworm. That’s certainly enough to keep me busy for a while.

Read more about earthworms and quantum dots doi:10.1038/nnano.2012.232

Just be yourself

This blog is first, and foremost, a platform for me to communicate my science and to share my world with you all. With that being said, it’s important to consider the impacts that current events have on society as a whole, since our science only exists because the world around us does too.

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Unless you’ve been living underneath some very large, fortunate rock, you’re aware that Donald Trump is the president elect of the United States of America. I (and many, many others) are quite alarmed by this at many different levels: as a person of color, as a member of the LGBTQ community, as a scientist. As impartial and objective science supposedly is, scientists can, are, and should be partisan (there’s definitely going to be more on this in the future). It’s no secret which candidate most scientists backed in this last election: the one that believes that climate change is a real and human driven phenomenon, the one that doesn’t believe that vaccines cause autism, the one that does not want to slash scientific funding. And unfortunately that was the candidate who lost.

Not 24 hours after the election, word of Trump’s plan to appoint Myron Ebell as head of the EPA was announced, solidifying many environmentalists’ worst fears. Mr. Ebell is a notable climate change skeptic and has been a vocal opponent to the Clean Power Plan, a bill introduced during President Obama’s administration to drastically reduce emissions from electricity generation (which greatly curtails the coal industry). That was just the first of many announcements of key members of Trump’s cabinet and staff – most recently including Steve Bannon as chief strategist, a noted anti-Semitic white nationalist. Considering that it’s been less than a week since the election and so much has already been stirred up, it’s no wonder we all feel worried about the future of science in America. And that’s not to say the other looming implications of Trump’s presidency aren’t terrifying as well: a step back in human rights for ethnic and religious minorities (particularly Muslim people), transgendered people, the disabled, and women, just to name some of the groups at stake.

While the wound may still be fresh, there’s already been an outpouring of the community around the world and online. People are reaching out to each other with affirmations: you are valued, you are safe, and we will get through this together. Dr. Josh Drew at Columbia University wrote an open letter to his students on the importance of continuing their work in environmental science. Dr. Meghan Duffy of the University of Michigan wrote a beautiful piece reminding all of us to say ‘Yes’ to meaningful goals beyond our own research, which may have larger impacts in the long run. Dr. Terry McGlynn from Cal State Dominguez Hills, wrote a fantastic call to protecting those who are most vulnerable in this time. Dr. Andrew Thaler, editor in chief at Southern Fried Science, wrote a Mandate for Ocean Outreach, a call to arms for all scientists to critically think about how to fix our shortcomings in bridging science to stakeholders. I highly recommend reading these pieces, and any others that you can find.

While I am not nearly as established, knowledgeable, or eloquent as these writers, I do want to throw my own voice into the mix, particularly as one vulnerable person to another. To my brothers and sisters worried about the future: the bravest thing to do right now is to be yourself, your truest self, and then double down on it. It’s a scary time to be gay, or Muslim, or Black, or a woman, to be yourself, but now is the most important time to be all those things and more. Be everything it is that racist, homophobic, white nationalists hate most.

It’s petty of me, but I fully believe in spiteful pleasure, finding happiness in defiance to those that hate you. Take heed in the fact that the powers that will be are so threatened by the mere thought of you that they felt it necessary to take the White House, the House, and the Senate, in order to address your existence. That’s how much power you hold over them. By simply existing, by continuing to live your life despite whatever it is they try, you are partaking in the biggest act of rebellion possible. So live your life as a person of color, as a woman, as a member of the LGBTQ community, as a Muslim, as yourself, with twice the commitment: once for you, and once more for them. Know that I’m right there with you, along with 61 million other people.

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Many thanks to Kevin Kohl for use of his graphic, which was inspired by a tweet from Fryda Wolff.

A Primer: Behavior as a toxicology research tool

Oftentimes when we think about an organism’s health, we don’t really think about including behavior. Maybe it’s just me, but behavior was something associated with the brain, and that thing is just too complicated to think about that they really should just get their own category (which, to be fair, many research groups do separate neurobiology and behavior into their own group, which might contribute to this way of thinking). But, ever since I’ve started my dissertation work, I’ve definitely come around and seen the light – behavior is an incredibly important aspect of physiology and we should all care about it!

Sure, behavior is extremely important part of social interactions; it doesn’t take a scientist to know that. But it’s not always as obvious how behavior is related to your health. Your body comes equipped with many amazing strategies to deal with stress, but it’s your behavior that determines how much stress your body experiences. Changes in behavior are really easy ways for animals to quickly avoid stress. Think about what you’d do if you were stuck outside on a hot summer afternoon. Sure, your body can deal with that stress through all sorts of neat ways like sweating, changing your breathing and heart rate, making new, more heat-sturdy proteins, etc. Or, you could just go find some shade or go inside where it’s air conditioned. Maybe grab an ice cream cone. Your body is capable of some amazing coping mechanisms, but does that mean you have to always use them? A simple change in how you behave can save you a lot in time and energy when dealing with a stressful environment.

More than that though, lots of behaviors may seem really simple on the surface actually involve a lot more than we realize. Let’s use another example – this time imagine yourself as a small fish trying to remain uneaten (a pretty important behavior, if you ask me). The obvious thing to do when a fish senses a predator is to quickly swim away and find somewhere safe to hide out in. Not exactly rocket science. But let’s break that down into the various steps it takes to complete that action. First, you need to realize that the predator is there to begin with. You might see the predator, hear it, or maybe even smell its presence. That requires a fully functional sensory system. Your eyes, ears, nose, and touch receptors need to be on point and they need to transmit that message to your brain. Well, that’s a huge complex system right there so you better be sure your brain is working properly as well. But that’s not all, your brain has to tell your muscles which way to move, and how much to move, so your nervous system needs to be in tip top shape. Your body is also going to help you prepare for this escape by changing its hormone balance. It’s fight or flight, is not a great time to be thinking about making babies or putting on fat reserves, so your endocrine system is going to temporarily turn the dial down on things like sex hormones, growth and fat storage, and instead mobilize stored energy to make sure you have enough fuel to get away. So right there, in this little fish swimming away from a predator, you need a fully functioning sensory organ system, nervous system, endocrine system, and who knows what else – all to tell your body to just keep swimming. Those systems are some key places that a pollutant can muck it all up and cause real problems for a fish (or any animal, really). So as a toxicologist, when I see a fish that’s behaving abnormally, that is a clue that at least one of these systems is off in some way, as well as potentially which areas might have been affected.

Behavior can be complex but with that complexity comes with a wealth of potential for researchers to study. It takes a lot of work, for sure, but behavior is such an important part of an animal’s life that we really shouldn’t be leaving it out anymore. There’s not doubt, studying behavior has many challenges (and the more complex the behavior, the more challenging it becomes), but that just means we have to get creative. In future posts, I’ll be introducing you to the different ways I, and other scientists, study animal behavior and show you some really creative solutions people have come up with to tackle these complex behaviors.