Radioactive Tuna arrive!

Discussion in 'Food & Cooking' started by duckfat, May 29, 2012.

  1. duckfat

    duckfat

    Messages:
    1,354
    Likes Received:
    24
    Exp:
    Retired Chef
    Here's an article I found this morning about radioactive Bluefin arrive in CA athat had been impacted by the Fukushima run off.

    Any thoughts on how this might impact the Sushi/fish industry in North America?

    LOS ANGELES — Across the vast Pacific, the mighty bluefin tuna carried radioactive contamination that leaked from Japan's crippled nuclear plant to the shores of the United States 6,000 miles away — the first time a huge migrating fish has been shown to carry radioactivity such a distance.

    "We were frankly kind of startled," said Nicholas Fisher, one of the researchers reporting the findings online Monday in the Proceedings of the National Academy of Sciences.

    The levels of radioactive cesium were 10 times higher than the amount measured in tuna off the California coast in previous years. But even so, that's still far below safe-to-eat limits set by the U.S. and Japanese governments.

    Previously, smaller fish and plankton were found with elevated levels of radiation in Japanese waters after a magnitude-9 earthquake in March 2011 triggered a tsunami that badly damaged the Fukushima Dai-ichi reactors.

    But scientists did not expect the nuclear fallout to linger in huge fish that sail the world because such fish can metabolize and shed radioactive substances.

    One of the largest and speediest fish, Pacific bluefin tuna can grow to 10 feet and weigh more than 1,000 pounds. They spawn off the Japan coast and swim east at breakneck speed to school in waters off California and the tip of Baja California, Mexico.

    Five months after the Fukushima disaster, Fisher of Stony Brook University in New York and a team decided to test Pacific bluefin that were caught off the coast of San Diego. To their surprise, tissue samples from all 15 tuna captured contained levels of two radioactive substances — ceisum-134 and cesium-137 — that were higher than in previous catches.

    To rule out the possibility that the radiation was carried by ocean currents or deposited in the sea through the atmosphere, the team also analyzed yellowfin tuna, found in the eastern Pacific, and bluefin that migrated to Southern California before the nuclear crisis. They found no trace of cesium-134 and only background levels of cesium-137 left over from nuclear weapons testing in the 1960s.

    The results "are unequivocal. Fukushima was the source," said Ken Buesseler of the Woods Hole Oceanographic Institution, who had no role in the research.

    Bluefin tuna absorbed radioactive cesium from swimming in contaminated waters and feeding on contaminated prey such as krill and squid, the scientists said. As the predators made the journey east, they shed some of the radiation through metabolism and as they grew larger. Even so, they weren't able to completely flush out all the contamination from their system.

    "That's a big ocean. To swim across it and still retain these radionuclides is pretty amazing," Fisher said.

    Pacific bluefin tuna are prized in Japan where a thin slice of the tender red meat prepared as sushi can fetch $24 per piece at top Tokyo restaurants. Japanese consume 80 percent of the world's Pacific and Atlantic bluefin tuna.

    The real test of how radioactivity affects tuna populations comes this summer when researchers planned to repeat the study with a larger number of samples. Bluefin tuna that journeyed last year were exposed to radiation for about a month. The upcoming travelers have been swimming in radioactive waters for a longer period. How this will affect concentrations of contamination remains to be seen.

    Now that scientists know that bluefin tuna can transport radiation, they also want to track the movements of other migratory species including sea turtles, sharks and seabirds.
     
  2. durangojo

    durangojo

    Messages:
    2,171
    Likes Received:
    89
    Exp:
    Professional Chef
    i was just reading about that myself. the so called 'experts' are quick to state that the radiation in the tuna is below the 'harmful' level. hmmm...how do they know what that is?  if it's cummulative like mercury, how much tuna will it take to kill you, or at least make you null and void? or maybe it's like escolar....maybe you're safe if you only eat a little bit!

    joey

    the real concern should be that this is just the tip of the iceberg......it's global now
     
    Last edited: May 29, 2012
  3. zoebisch

    zoebisch

    Messages:
    178
    Likes Received:
    11
    Exp:
    Other
    Hey look at the bright side.  Now they won't have to tag and track them, they can just check the radioactive signature.  Maybe they can label it as "irradiated" tuna...safe for raw consumption.  :D
     
  4. duckfat

    duckfat

    Messages:
    1,354
    Likes Received:
    24
    Exp:
    Retired Chef
    LOL now that's funny!  /img/vbsmilies/smilies/lol.gif

    Dave
     
  5. ordo

    ordo

    Messages:
    2,462
    Likes Received:
    251
    Exp:
    Home Cook
  6. chefedb

    chefedb

    Messages:
    5,516
    Likes Received:
    177
    Exp:
    Retired Chef
    Yes I read that and now it will be easy to find all the people that ate it.. They will glow in the dark.
     
  7. allanm

    allanm

    Messages:
    38
    Likes Received:
    10
    Exp:
    Home Cook
    Durangojo,

    They found 4 Bq/kg  of cesium-134 and 6.3 Bq/kg of cesium-137.

    The normal limits vary by country but seem to be around 500 - 600 Bq/kg.

    A normal banana averages 100 - 120 Bq/kg mainly from potasium-40.

    A 70kg human being contains about 8,000 Bq of naturally occurring radioactive material, 4,400 Bq of potasium-40.

    A single dose of 140,000,000 Bq/kg will kill a dog in three weeks, this translates to 980,000,000 kg of tuna for a 70 kg person.

    Cesium is chemically similar to potassium and will pass out of your system through sweat and urine fairly quickly.

    Cesium does tend to accumulate in plants, particularly mushrooms.

    During the 50s and 60s the US conducted something like 383 open air nuclear bomb tests add in the others by Russia, France, England, etc. This significantly increased the amount of radio-cesium in the environment.  So the scientist actually do have significant data to work with.

    Second hand cigarette smoke contains more and nastier radioactive material. It also permanently attaches itself to the surface of your lungs.

    I would be way more worried about the mercury in the tuna.
     
  8. durangojo

    durangojo

    Messages:
    2,171
    Likes Received:
    89
    Exp:
    Professional Chef
    thank you alanm for taking the time to explain. seems to me the u.s. govt. will have to be on top of testing regularly though. the tuna tested was the first catch and only in the water for a short time.  the longer the tuna stays in the water growing bigger and swimming in radioactive contaminated water, they will no doubt carry more on them. of course the tuna caught off japan will be off the scale i would think. the good news if you can call it that, is that americans don't really have a demand or palate for bluefin tuna but apparently its a treasured delicacy in japan, so most of it gets shipped back to the motherland and sold at hefty prices...

    joey
     
    Last edited: Jun 4, 2012