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Molly Magid: Welcome to ҕl Science Radio, where we interview a range of postgrad students to tune into the fresh voices entering the world of science and learn what sparked their passion. I’m Molly Magid, a Master’s student in the School of Biological Sciences.
Today I’m talking with Sarah Guy, she’s a PhD student studying Environmental Science at ҕl. Her research focuses on emerging environmental contaminants that may affect human health. Specifically, she looks at exposure to radioactivity through ingestion of shellfish.
Kia ora Sarah, welcome to ҕl Science Radio.
Sarah Guy: Good afternoon Molly!
So, you're studying environmental science, but, more specifically, what is your research about?
SG: I'm doing environmental chemistry, and my research is focusing on radioactivity in food, so trying to investigate exposure of the New Zealand population to radionuclides by ingestion of food. And, specifically, Polonium-210 which is a natural radionuclide, through the ingestion of shellfish.
How did these radioactive elements actually get into our food? Are they there naturally?
SG: Yes so, the whole project started actually in 2011 after the accident at the nuclear power plant in Fukishima, so there was concern of radionuclides making their way into the Pacific and then accumulating in shellfish and then maybe exposing the New Zealand population to radionuclides. And so to support seafood safety, two projects were put in place and those projects decided to investigate, not just the radionuclides from Fukishima, but actually any kind of radioactivity you could find in all the food around New Zealand.
Because there is two types of radioactivity. So the first one is from human-made sources, for example Fukishima and testing in the Pacific in the 60s. But also, natural radioactivity, so the interaction because the upper layer of the atmosphere and some cosmic rays. Radionuclides, for example, Carbon-14 is one of those radionuclides. But also some primordial radioactive material that were incorporated into the Earth when it was created and these kind of nuclides, for example, Uranium-238 and then those nuclides decay to more nuclides and Polonium-210 is one of those secondary, natural radionuclides.
So it's something that comes out of the decay?
SG: Yeah so it comes from—Uranium will be in rocks and Uranium will decay. So a nuclide is an element that is unstable due to an excess of energy in the nucleus and by emission of this energy, the nuclide will decay to another nuclide and then all the way down the line, it's finally going to reach a stable element.
So that's the two possibilities of nuclides that you can have, and that first study identified that there is actually no contamination from human-made nuclides in New Zealand food, and most of the exposure comes from Polonium-210, which is a naturally-occurring radionuclide in shellfish. And those concentrations are still quite low, but there was, I think it was a factor of a hundred between the lowest and the highest concentration. So the question was: why do we have such a big difference? And that's where I came along to try to identify whether it was related to the type of spaces, to the season we did the sampling, to the location. And trying to understand why we are being exposed to different levels and that was my first year of PhD, which was actually a master's, and we actually realised we needed to do more. So here I am, still there, four years later
How does the seafood pick up the radioactivity?
SG: Shellfish pick up a lot of chemicals in the water. They're filter-feeders, so anything that is in the water, they will accumulate them in quite high levels. And I guess it's very related to the chemical properties of the contaminants, so polonium is very particle reactive. Polonium will bind very strongly to particles in the water, and then will be accumulated by the shellfish. And also polonium has a quite high affinity for protein, so meaning it will bind to protein in the shellfish body, so it's very difficult for them to detoxify, so once polonium goes in the shellfish, it stays there.
What should we be concerned about? If people are consuming shellfish, are we exposed to the radioactivity?
:The level of radioactivity we're talking about from shellfish are very low. And they are lower than the level you would receive from an x-ray, for example. But it's quite a good thing to keep an eye on it. We know the natural background and then if there is some issue of contamination, we can have a baseline, and then re-evaluate so we know what's the difference. But those levels are normal levels. It's the kind of level you will find anywhere coming from a natural radioactive chemical.
Ok, so we shouldn't just give up on shellfish entirely?
SG: No, no definitely not. I think, you know, regulation agencies around New Zealand do great work at making sure there is no contamination. But we always, in this case, try to keep concentrations as low as possible, that's the rule of thumb for radioactivity. And shellfish, it is good, as well.
And, for you, what's the most fun or exciting part of your research?
:Oh, I love all of them! I think that's the beauty of environmental science, is that there is a high diversity of tasks. There is quite a lot of lab work, obviously, to do all the analysis, develop the methods. I love the development of the project, so trying to find a method, and then testing, adjusting, oh this doesn’t work, what can we do to make it work?
But also, for example, I ended up doing a diet shellfish survey. So, putting questionnaires together, building up the survey, recovering all the data from the survey participants. So it's quite a lot of different tasks, and I think it's a very good balance between those different aspects, so you never get bored. You know, you don't spend your whole day just doing one thing, or your whole four years just doing one thing. That's one of the very attractive things of environmental science in general. You need to balance all those aspects, and that was my favourite bit probably, just developing everything.
So what was your path to doing this research?
SG: I've always liked biology and chemistry, and I always knew I wanted to do a job related to human health, but when I was 18, I left high school and didn't really know what exactly I was going to do. And I ended up doing a master's in Science, Technology, and Health, which sounded fun at the time, and ended up majoring in Health and Drug Engineering. And this led me to the pharmaceutical industry, and I realised that it actually wasn't for me, so I quit my job and decided to learn English and travel.
So I came to New Zealand and travelled around New Zealand, had a great time. And then I realised it was a good time for me to actually switch slowly from what I used to do to something I wanted to do. And I knew the environment has always been quite important in my life. I'm an outdoors person, I love being out there, so I think environmental chemistry was definitely a good match between those two aspects of my life. Food safety, in general, it is very important for human health. I mean, it’s what you drink, what you eat every day, you don't want to like intoxicate yourself with some chemical.
And I was in Christchurch at the time, and lucky for me, ҕl was proposing an environmental science course. So I ended up meeting with Sally Gaw, she is the director of environmental science, and we sat down. It was a very great chat, and I left her office thinking: "oh yeah, I want to do that. That's definitely a path that I could follow." So that's how I ended up doing one year of postgrad, that was the plan at the start. That slowly became a year of a research master's and then became a PhD. I had the chance to get a great opportunity following what I wanted to do. And I'm very glad I took that opportunity, I wasn't planning to do that project, but I’ve enjoyed every part of it.
So that leads me to my last question. If there was one big change that could come out of your research, what would that be?
SG: I think it would be a more general aspect on climate change and all those chemicals, all the change in contamination. Because there is a quite high chance that those changes we see in the ocean—the change in temperature and pH, and obviously change in algae concentration—will lead to a different pathway, like a different level of accumulation. And I'm hoping that people will be realising that the climate change issue is not just a matter of temperature, and a matter of there will be more rain/there will be less rain, it will warmer/it will colder, it's actually involving so much more, and that we're gonna have to rethink so many aspects of feeding people and ecosystem health, and all those parameters that are being impacted. And we can't really see it, but it's actually there. And I think that this kind of research, I hope will help people to realise that we actually need to do something, and it's now, even yesterday was even better. And I think that would be the idea.
Thank you so much for talking with me Sarah!
SG: Thank you Molly!
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