Is Anguilla’s fish safe?
You only have to read magazines and surf the net to see worrying stories of fish from all around the world being contaminated with mercury. The most common contaminant is methyl mercury, which also happens to be the most toxic form.
So where does it come from? The use of coal in industry or for domestic heating releases large amounts of mercury into the atmosphere; the dumping of fluorescent light tubes releases mercury into the soil and groundwater; and the uncontrolled use of mercury in illegal mines, to help extract gold from the ore, pollutes rivers and oceans with mercury.
Most mercury initially gets into the food chain as the free metal, its vapour or one of its inorganic salts, like mercuric chloride. Mercury gets into the food chain by being taken up by microscopic organisms called dinoflagellates. Once taken up most mercury is converted to methyl mercury and stored by those organisms. The problem is the story doesn’t stop there. Those dinoflagellates are the food for other, larger, organisms, which then also get eaten by small fish. Those small fish get eaten by bigger fish and so on all the way up to the top predators, the large fish like tuna and mahi mahi. Unfortunately, at each stage of the process the methyl mercury becomes more concentrated, so by the time you reach the top there can be quite high levels of the stuff. And that’s why health authorities in many countries are concerned about fish mercury levels.
Fish from south east Asia show high levels of methyl mercury, as do those from many areas around the USA, so fish products coming from these regions should be considered suspect. However, those are a couple of the known, reported, contaminated coastlines; many others may be just as bad, but no one knows it, or is admitting to it.
But what is a safe level? The World Health Organisation (WHO) and the Food and Drug Administration in the USA (FDA) have both come out with the same sort of numbers – 1ppm (part per million) as the top end of the safe range. This is the same as 1 milligram per kilogram of fish, or 1/10th of an ounce in every 1700 lbs of fish. That may not sound much at all but, in terms of mercury, it’s a lot – so it shows just how nasty this stuff is. And once you’ve eaten it you only get rid of it incredibly slowly, so if you keep on eating it, even if only sporadically, it will slowly build up in your body and may get to damaging levels. This is especially serious for children, both the born and the unborn, so pregnant women need to very careful to avoid food contaminated with mercury.
So what about our fish? Two groups of students at Saint James School of Medicine, over two semesters, have worked with local fishermen to get samples of several of the more commonly caught fish and test them for their mercury levels. The students – Caitlin Rogers, Marissa DiGregorio, Jordan Borash, Gagandeep Singh, Atish Patel and Neha Jain – analysed six different species of fish, from both the top and middle of the food chain, for their mercury levels and found that none of them had mercury at even a tenth of the WHO/FDA safety cut off. The fish checked were tuna, mahi mahi, hind, red snapper, blue tang and longjaw squirrelfish – all of which are safe to eat from a mercury contamination perspective.
Of course, mercury is only one of many toxic things that you can get from fish, including some very common types of food poisoning from eating unclean or decaying fish. But we currently only have the ability to test for mercury and we intend to continue this investigation with more samples from other species. But since such a wide range has already proved to be safe, the likelihood is that all of Anguilla’s fish are safe to eat from the point of view of mercury, even for kids and pregnant women.
