Radiation-eating Fungi

SEWilco writes "Fungus growths have been found in many extreme environments, including the Chernobyl reactor walls. Some fungi have been found whose growth is enhanced by radiation. I wonder if someone saved samples of the MIR-eating fungi."

Comments

Radiation Hormesis

[dontthink]

First off, IAAMP (I am a medical physicsist). This is sort of radiation-induced growth stimulus was actually studied extensively in the first half of the 20th century. A great reference for this behavior is a paper published in Human & Experimental Toxicology called "Radiation hormesis: its historical foundations as a biological hypothesis" by Calbrese and Baldwin, which examines the dozens of studies examining the effects of low dose radiation on plants, fungi, and insects - fascinating stuff. Over 2/3 of the studies in this time period showed increased growth with radiation, while the other 1/3 used relatively high doses (which is known to have net detrimental effects). People were actually interested in putting radioactive isotopes in fertilizer to encourage crop growth, but results weren't great and the A-bomb happened... and we all know where the public's perception of radiation went after that. I've got a PDF of that paper if anyone is interested (the online version requires a subscription, I believe).

Re:Radiation Hormesis

[dontthink]

Yup, I sometimes feel like I missed out by being born after the golden age of radium enemas. On a more serious note, the concept that low doses of radiation can be beneficial has been a pretty hot topic of debate in the radiological science community lately. There was an incident in Taiwan where radioactive Co-60 (is there really any other kind?) was accidentally recycled into scrap steel that was used in over 200 buildings, giving the occupants low doses of radiation. The standardized incidence ratios (the ratio of observed cancers to expected cancers based on the entire population) in these occupants was on the order of ~0.8, or a 20% reduction in cancer incidence. Also look at studies of cancer incidence between regions of high and low background radiation - rates are lower in high background regions. There are all kinds of problems with these epidemiological studies (confounding factors like socioeconomic status and such), but not always. One study compared 100 years of cancer incidence and mortality data of British radiologists - their life expectancies and cancer rates were significantly than other British physicians (also by ~ 20%). If interested, the Nuclear Shipyard Worker Study also has some very interesting results in this vein. Good, controlled research on the topic of low-dose radiation with respect to humans is hard to come by, however, considering the major stigma attached to radiation. Other than worker and background radiation studies, you've pretty much got to wait until an accident happens.

Re:Radiation Hormesis

[dontthink]

Yep, Cameron was extremely gung-ho about radiation hormesis... and it really isn't a new debate - it has been ongoing for the past century. The linear no-threshold model of radiation dose-response (endorsed by most regulatory agencies) was essentially developed as a tool for risk assessment derived from an extrapolation of A-bomb survivors with basically no data to support it at low doses. It really only became prominent due to its conservative nature, the public's perception of radiation, and simplicity. Interestingly, Cameron often described low levels of radiation as "essential trace energy," similar to how small amounts of otherwise toxic elements (essential trace elements) can be beneficial. Unfortunately, my TLD is usually negligible too...

Re:Radiation Hormesis

[dontthink]

They do have ideas why low-dose radiation can be beneficial. One possible mechanism is damage prevention. After irradiation, there is an increase in levels of proteins and enzymes that scavenge reactive oxygen species (ROS) (As a point of reference, the natural level of ROS in the body is about 3 orders of magnitude greater than that caused by background radiation). This response subsequently increases the rate that natural ROS are removed, resulting in a net decrease in damaged DNA in the system. Damage repair also likely plays a role; in vitro studies of human fibroblasts have shown that the cellular repair rate is increased by doses in the range of 1 - 500 mGy. Low doses of radiation may also induce apoptosis in cells that have undergone an oncogenic transformation. Low doses may also initiate increased immune competence, which could be beneficial in terms of many other diseases. More detail can be found here: Feinendegen, LE; "Evidence for beneficial low level radiation effects and radiation hormesis," The British Journal of Radiology, 2005, Vol 78, p 3-7. The bulk of this paragraph was blatently copy-pasted from a term-paper of mine...

Re:I thought this was news

[4e617474]

I doubt it's possible to get living organisms to shorten the half-life of radioactive materials, but fungi that abosrb radioactive materials can be very useful. When radioactive waste contaminates the ground, fungi can extract and concentrate it. The mushrooms can then be harvested for disposal as radioactive waste, leaving the soil in the area less radioactive. Paul Stamets describes it in Mycelium Running (there're good facts in between the hippie/druggie/mystical stuff) describing this and other similar applications of fungi as "mycoremediation".