So, the fact the canned tuna in Australian cupboards is likely to contain smaller species is already a bonus when it comes to reducing mercury risk.īut let’s drill down to the details. Skipjack is the smallest of the major tuna species, while yellowfin are larger. Skipjack and yellowfin are the main tuna species listed as ingredients in canned tuna in brands sold at Australian supermarkets. So this concern has largely been associated with the use of tuna species such as albacore and larger tuna specimens. Mercury concentrations are higher in predatory fish such as tuna and generally increase with age and size. Over the years, some scientists have raised concerns about high concentrations of mercury in canned tuna. Shutterstock Tuna in Australian cupboards is likely a smaller species Tinned tuna is cheap, tasty and nutritious. But to make matters worse, a substantial proportion of mercury in fish is present as methylmercury - a potent neurotoxin formed by bacteria in waters and sediments.Īlthough mercury pollution has increased since industrialization, the accumulation of methylmercury in animals is a completely natural phenomenon.Įven fish caught in the middle of the ocean, far from any polluting sources, will contain methylmercury. Most forms of mercury are potentially very toxic to humans. So the bigger the fish, the higher the likely mercury content. In other words, it builds up as smaller fish get eaten by middle-sized fish, which get eaten by large fish, which get eaten by us. Mercury is naturally present in our environment but can biomagnify to relatively high concentrations in fish - particularly predatory fish.

That’s a level even the keenest tuna-lover would be hard-pressed to consume.

Lab tests we did for the ABC TV science program Catalyst in 2015 suggest - depending on your body weight and the exact brand of tuna you buy - you could eat anywhere between 25 and 35 small tins (95g or 3.3 ounces each) of tuna a week before you hit maximum mercury limits. Canned tuna generally has lower levels of mercury than tuna fillets because smaller tuna species are used and the tuna are generally younger when caught.” Sounds good, but how much can you eat before you need to worry about mercury?Īccording to Food Standards Australia New Zealand: “It is safe for everyone (including pregnant women) to consume canned tuna as part of their fish intake. A tin of tuna is significantly cheaper than many types of fresh meat or fish. For as little as AU$1 ($0.75) a tin, canned tuna is an excellent, affordable source of protein, polyunsaturated fats, and other nutrients.

Mercury poisoning tuna