Radiation Levels and Hagfish

• News reports about the nuclear accident in Japan try to convey to the public something about the amount of radiation released. One term commonly used in these reports is “milliSevert” (mSv). In one year the average person is exposed to normal background radiation of 2-3 mSv. This very small amount of radiation is produced by cosmic rays, decay of uranium in rocks and minerals, breakdown of radon gas in rock, and other non-manmade sources. A person exposed to a brief 100 mSv exposure of radiation would be okay over the short term, but when exposed to 400 mSv and higher the immune system is compromised. Perhaps it’s best understood this way: “Radiation is always harmful – it breaks DNA and can produce free radicals that damage cells” (Dr. P.Z. Meyers, University of Minnesota). “There is no safe level or threshold of ionizing radiation exposure.” (Nuclear Information and Resource Service, June 30, 2005, http://www.nirs.org)

• The good news is that cells can respond to minimal doses of radiation by increasing the production of protective (e.g., antioxidants) and restorative enzymes that help repair broken DNA. There’s certainly no escaping radiation exposure. A CT scan of the chest delivers 7 mSv and a CT scan of the pelvis exposes the patient to 10 mSv. In contrast, the dose from a chest x-ray is only 0.1 mSv and from a dental x-ray, 0.005 mSv. Over the past couple of years, I have had two CT scans of the chest (15 mSv) and one of the pelvis (10 mSV). Including background radiation dosage, all this adds up to about 25 mSv. I can only hope that my DNA repair mechanisms and immune system do their job. (Scientific American, May, 2011)

• Two researchers at the University of Milan in Italy compared the carbon dioxide output of four men walking, jogging, and biking, with that produced by a hybrid automobile traveling the same distance. The walking and biking men produced much less carbon dioxide than the car, but the four joggers produced more of it than the hybrid. (Scientific American, May, 2011)

• The lamprey eel, to many, is a very ugly fish, but there’s another kind of “fish,” the hagfish, that makes the lamprey look attractive. The hagfish is eel-like but there its similarities to the lamprey end. A full-size hagfish is 18 inches long, lives in saltwater, has tentacles around its side-biting mouth, and poorly developed eyes. It burrows into the ocean floor, leaving only its head sticking out, and may form dense groups of up to 15,000 individuals in a given area. The most unique feature of the hagfish is its ability to exude slime (mucous), which it uses as a defense mechanism, and in many parts of the world they are called “slime fish.” A single hagfish placed in a two-gallon bucket of seawater can produce enough slime to fill the bucket and then some. In nature, when attacked by a predator, the hagfish becomes encased in its own fiber-reinforced slime. When the predator gives up, the hagfish ties itself into a knot and frees itself of slime by passing the knot down the body. It can also “sneeze” to blow slime out of its nostrils. In South Korea hagfish are eaten. They are said to be delicious, having the consistency of slightly overdone scallops. (www.aquaticcommunity.com; http://www.nhptv.net/wild/agnatha.asp; Google “hagfish slime” to see a video of hagfishes sliming)

• The U.S. subsidized corn ethanol $16.8 billion from 2002 to 2008. During the same period, traditional fossil fuels were subsidized $70.2 billion. (Sierra, May/June, 2011)