BY DR. JOSE PALU-AY DACUDAO
THE WORST nuclear power plant accident in history was the Chernobyl disaster.
In 1986, Chernobyl’s reactor No. 4 underwent an explosion and meltdown. The Soviet Union government then established an area that became the Chernobyl Exclusion Zone, a radioactive area prohibited to humans not on official business endorsed by the state.
This restricted zone and the defunct reactor are now administered by the State Agency of Ukraine on Exclusion Zone Management. (When the Soviet Union disintegrated, its component states, called republics, attained independence, including Ukraine.)
The Exclusion Zone extends approximately 2,600 square kilometers (or about 1,000 square miles).
Yet this same dangerously radioactive zone now hosts a variety of large mammals, most of which were locally extinct before Chernobyl’s the catastrophic explosion and meltdown.
Examples are Eurasian beaver (Castor fiber), elk (Alces alces), roe deer (Capreolus capreolus), red deer (Cervus elaphus), wild pig (Sus scrofa), European badger (Meles meles), brown bear (Ursus arctos), grey wolf (Canis lupus), raccoon dog (Nyctereutes procyonoides), Eurasian lynx (Lynx lynx), red fox (Vulpes vulpes).
Of particular interest to fans of biodiversity such as myself is the successful introduction of the endangered mammals, the European bison (Bison bonasus) and Przewalski’s horse (Equus przewalskii).
Why is it relatively safe for mammals other than humans to repopulate a radioactive area?
As a matter of fact, Chernobyl’s radionuclides are dangerous.
Iodine-131 is a radioisotope of iodine that a radioactive decay half-life of about eight days before transmuting into stable xenon-131, and in the process emits lots of beta (electron) and gamma (photon) rays, I a short span of time, which can damage and destroy living tissues.
Unfortunately, mammals (unique to vertebrates) have thyroid glands that avidly take up iodine, and can’t distinguish between stable and radioactive isotopes of iodine. When Chernobyl exploded, almost all mammals died within two weeks, notably of hypothyroidism. Radioactive iodine got into their thyroids and cooked these glands.
Since the thyroid gland secretes iodine-containing thyroid hormones essential to life, once a mammal’s thyroid gland is destroyed, it will die. (Thus patients are recommended to take potassium iodide pills in order to saturate the thyroid with stable iodine and exclude radioactive iodine from getting in.)
However, after the initial termination of Chernobyl’s mammals, wildlife from adjacent areas immigrated in, or got introduced. These and their offspring have thrived, transforming the exclusion zone into a haven of mammalian diversity.
In so doing, these mammalian populations had to overcome the effects of two medium-lived fission products. (To be continued)/PN
