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14 February 2017

Aquaculture America 2017 Presenter: Dr. Ralston on Ocean Fish and Selenium

Written by Dr. Nick Ralston, Posted in Preview, Fish Net Blog

As a Biomedical Research Scientist, how and when did you first become interested in looking at seafood?

I was working with the Human Nutrition Research Center which studies selenium physiology and became aware of how important selenium is in brain studies. Along the way I found out that Mercury had a very high binding affinity for selenium. And pretty much the way mercury toxicity causes its problems and the things we'd expect to see if they were interfering with selenium, all lined up pretty much immediately. This was back in about 2001.

Please tell us about your work developing the “Health Benefit Value” index of risks or benefits associated with maternal consumption of fish during pregnancy.

The interesting thing about this health benefit value is that we developed it for the EPA and we've established it on fourteen thousand ocean and freshwater fish samples. The reason why the health benefit value is better than previous criteria is that it actually is based on the biochemistry of how mercury interferes with selenium physiology. What's important to know is not just how much mercury is present in the ocean fish sample, but how much there is in relation to the selenium. The thing we found out is that selenium is vastly more abundant in ocean fish than Mercury is. So most types of ocean fish prevent instead of contribute to causing mercury toxicity. But there are a couple of types of Seafood’s that have been associated with causing harm and those have negative health benefits values. And the best way to prevent harm from eating those types of Seafood’s is eating seafood that have positive health benefits values.

Will you cite specific examples?

The studies that were done in the Faroe Islands were some of the original ones that caused us concern about mercury exposures. We knew that Mercury was very toxic especially during fetal development studies in Minamata Bay in Japan had shown that. So in the Faros, which is an island group between Scotland and Iceland they eat a tremendous amount of pilot whales. Pilot whales are the top predator of their part of the ocean. And so they have really high mercury levels. Whales in general, their meats can be extremely high in mercury if it's predacious type whale and their selenium doesn't keep up. That's really unusual among fish and really among the fish the only species that we see that happen in commonly are the really top predatory types like sharks and swordfish. So the negative health benefit values of shark and swordfish line up completely with what FDA and EPA have been saying all along. Women should not eat those types of fish. But now we know it's because they have negative health values. 

You will be a presenter at Aquaculture America 2017 in San Antonio, Texas this February, what will be the subject and your area of focus?

There I'll be talking about studies that we did for NOAA (National Oceans and Atmospheric Administration). These studies were specifically designed to task whether mercury from ocean fish would contribute to causing mercury toxicity or if the selenium from the ocean fish would prevent it. We'd done several studies of this nature before but this was the first time that we'd used ocean fish as the source of selenium to prevent mercury toxicity. And we found that just like all of our previous studies, and studies by other laboratories around the world, ocean fish is a great source of selenium and the more selenium you get the better protected from Mercury you are. We found that animals that were being provided huge amounts of mercury, were given them poisonous amounts of mercury, and of course they were poisoned. They have bad neurological effects and all kinds of consequences that we know from the mercury poisoning. But if we replace the protein that were being fed to these rats with that poisonous amounts of mercury, naturally the amount of mercury they were getting was actually increased. So the assumption might be that while we should be even more poisoned because now they're getting more mercury. But contrary to that what we found was that the more ocean fish they consumed the more consequences of mercury toxicity went away. And so we saw no consequences associated with mercury toxicity in these rats that were getting lethal amounts of mercury. So the ocean fish selenium was very effective in preventing the consequences normally associated with exposures to terrifically high levels of mercury.

What can you tell us about the studies your company Sage Green NRG does looking at mercury and other heavy metal toxicants?

What we want to do is start working on the freshwater fish issue because unlike ocean fish, which tend to be really selenium rich. Selenium has been washing into the ocean from rivers for millions of years; the ocean is very rich in selenium. But in River communities some of them have very little selenium. And the thing that we found in our EPA study was that if there is very little selenium present in a watershed, the fish in that watershed are going to bio-accumulate tremendous amounts of mercury. And this explains why some locations have very high levels of mercury in the freshwater fish. Now these fish are potentially even more dangerous than eating whale or shark meat because whale shark meat have some selenium in them but some freshwater fish have extremely low levels of selenium. And like I said the less selenium they have the more mercury they accumulate. So eating those fish for Native American or First Nations communities that eat a lot of fish or even more particularly people in Asia, Africa, South America, some of them are at high risk.

Can you cite some specific examples?

Ocean fish generally have very positive selenium health benefit values. The commonly consumed commercial types are generally between 10 and 20, which is a good positive health benefit value. But shark meat and pilot whale meat are around minus 100. So you have to eat a good amount of ocean fish to counteract the risks of harm from eating shark or whale meat.

Please detail some of the approaches you have developed to remediate these toxicants.

Well in freshwater community, what we would intend to do is if they are consuming fish that are very high in mercury. I'm working to develop some studies in Columbia where gold mining activity has put tremendous amounts of mercury into some of the rivers. And unfortunately Columbia has some of the lowest selenium blood levels that I have ever seen. So they're particularly vulnerable to Mercury. What we would probably want to do there is augment their diet with selenium rich foods. Oddly enough (and perhaps ironic) one of the best ways we could do it is probably by giving them canned tuna. Because tuna is rich in selenium. 

You are working with the UND Aerospace 2020 Vision for a Sustainable World team. Thus far are you looking at any promising solutions to plastic waste?

Oh that's sort of a separate thing but another one I'm very excited about. I work together with an engineering group that has actually finally overcome the issue that has kept gasification from being able to convert trash and other forms of biomass into fuel. The group that patented this technology, the guy is a rocket scientist (a good friend of mine actually) but he applies more or less the interior of a rocket, it’s a lot more complex than most people know. He kind of applied technology from that in order to be able to more effectively convert everything that gives part of municipal solid waste (trash, garbage etc.) and he’s able to convert it into the starting materials for making liquid fuels. That is the part we've always known how to do, how start with the basic materials and turn them into liquid fuels. His magic though is being able to take the trash and municipal solid waste and turn that into the starting materials. His approach is just superior and excellent. It's the most encouraging thing I've come across. You know I'm very happy with my work but I’m even more thrilled with some of his! And definitely it will change how we deal with an awful lot of things worldwide. If people started being paid to turn in their bags of trash, I think we’d have a lot less going out into the rivers and into the oceans and contaminating the seas. So this is going to be very big it's one of the few world-changing things that I'm aware of. 

Roughly how far out from release is this technology?

Well we've already got truck mounted systems that can be taken to somebody that wants to test out the system and turn trash into fuel. So we're kind of there. It has to be scaled up, the technology is ready it just has to be expanded to municipal scale.

Between your works at the environmental health research program at UND’s Energy & Environmental Research Center, what does the problem of plastics in the oceans mean to you, personally?

Well I'm a scuba diver so I'm always just astonished when I see trash that shows up. We're all aware of the Pacific gyre and how much trash you know must be in the ocean for it to turn up on any beach anywhere. It's a bigger problem than most people realize. Most people think it's just oh I see that on the beach it's kind of ugly. The bigger issue is how this might be harming the health of not just the fish, but also all of the biota below the fish. Because consuming something like plastic is terrible. Plastic is not dissolvable and going through the digestive tracts of small creatures, it just doesn't work. So there is a danger from all of his plastic exposure that we could hurt the entire food chain that supports life in the ocean. And really that's part of the reason why I think something like my friend's ability to turn trash into fuel is going to be so important. It will not only help a global warming type issues, but I'm really thrilled about the possibilities of it keeping plastic from continuing to be thrown into the oceans just freely. If it is something that you can actually get money for, people will not consider it trash they'll consider a resource that they can make money for. And that's the sort of thing we need to make a sustainable change in how we deal with things like municipal solid wastes.


About the Author

Dr. Nick Ralston

Dr. Nick Ralston

Nick received his Ph.D. in Biomedical Research from Mayo Graduate School in Rochester, MN where he studied biochemical mechanisms of disease. At Bowman Gray Medical School in Winston-Salem North Carolina, he studied stereochemistry specific reactions of omega-3 and omega-6 fatty acids in relation to inflammation and the physiology of lipids that are unique to lysosomes. At the Human Nutrition Research Center in Grand Forks ND, he studied boron and selenium biochemistry and physiology.

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