Radioactivity in Fungi
By Michelle, Miriam & Saskia 31st October 1997
Introduction
The Chernobyl nuclear disaster in 1986 continues to effect
life in a variety of levels. Eleven years after the catastrophy more research
is being done into the long-range effects of radioactivity poisoning. Entire
eco-systems continue to display the effects of cesium 137 and 134 but certain
species serve as especially good indicators of chemical levels.
An example are the variety of fungi and lichens in affected
areas. This page will explore the reasons that fungi and lichens work as
good indicators. Different species will be compared as well as the effects
of human consumption of radioactivity contaminated species.
Why does radioactivity build up in fungi ?
The reason why fungi and lichens work as such good indicators
for radioactivity and pollution in general is connected to their structure.
Using absorption to obtain their nutrition fungi and lichens lack water-conducting
organs like stems and roots. They absorb moisture and nutrients from the
atmosphere through surface cells. Dissolved or airborn materials, which
include pollutants, move freely through the compartments of hyphae. What
is more, radiation released during nuclear testings or accidents is absorbed,
especially in areas where it rained heavily shortly after the incident.
What are the effects for humans ?
The two most important chemicals involved are cesium 137
and cesium 134, which both have the ability to affect the genetic structure.
An overconsumption of nutrition polluted by radiocesium thus might cause
spontaneous genetic mutations (eg: cancer and genetic mutations in embryos).
It has been suggested by various scientists that the annual
intake of cesium should not exceed 35 becquerel per kilogram of bodyweight
for adults. For children and pregnant women the risk is even higher: here
the annual intake should not exceed 10 becquerel per kilogram.
The two cesium isotopes involved though have different
halflives:
2 years for cesium 134 and 30 years for cesium 137 !!
Even ten years afterthe Chernobyl catastrophe, which took
place on April 26 in 1986, the fungi and lichen population in Russia and
other European countries, for example Germany, is severely affected by radiation.
Depending on the region and the species the rate of radiation might still
highly exceed the advised limit of 600 becquerel per kilogram. Some samples
collected in North-Eastern Poland, Southern Bavaria and Belorussia even
showed a rate of more than 2000 becquerel per kilogram.
Conclusion:
The only possible advice is to limit your consumption
of mushrooms in general and to preferably only buy artificially propagated
mushrooms and not to collect mushrooms yourself. Of course it has to be
said that radioactivity is not the only risk we are facing considering ourconsumption
of nutrition but ir certainly represents another argument against the use
of nuclear power.
Sources:
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