While the news too-often tells of dangerous radiation from human sources, it bears reminding that the Earth itself is naturally radioactive… some places much more than others. Five natural radioactive “hot spots” stand out from all others, not just for their frighteningly high levels of radiation but also for the relatively good health of people who have lived there obliviously from time immemorial.
Guarapari, Brazil
Brazilian beaches may be famous for solar radiation (among other things) but strollers on Guarapari‘s pristine white sand shores may want to apply sunscreen to their soles as well. According to The National Center for Biotechnology Information (NCBI), the sands of Atlantic coast beaches running from north of Rio de Janeiro down to south of Bahia (roughly 500 miles) are naturally radioactive. The source is sand eroded from Monazite, an ore of the naturally radioactive element thorium commonly found in mountains backing the shore.
Radiation levels are highest at Guarapari’s beaches, a popular seasonal tourist attraction, where readings of up to 175 mSv (millisieverts)) per year have been measured. Compare this figure with the current annual safe limit for nuclear workers: 20 mSv a year. Not coincidentally, Japanese government’s enforced 20 km exclusion zone around the stricken Fukushima Daiichi nuclear power plant is also rated at 20 mSv per year.
Ramsar, Iran
Think 175 mSv’s a walk in the park? We see your Guarapari and raise you a Ramsar – Ramsar, Iran to be exact. This city and county on the southern coast of the Caspian Sea is famous (or should we say, infamous) for having the highest levels of natural background radiation on Earth: 250 mSv per year! Background radiation levels up to 80 times the world average peak in the city’s Talesh Mahalleh district, where natural hot springs are abundant and limestone sourced from the area is used to make bricks and masonry used in area homes.
Studies on the approximately 2,000 people living in the highest NBR areas show slightly lower rates of lung cancer – an unexpected result considering the elevated levels of radioactive radon gas in their homes. In addition, the population exhibits a significantly higher expression of the CD69 gene responsible for the production of lymphocytes (white blood cells in vertebrate immune systems) and natural killer (NK) cells. Ramsar, by the way, has been known from ancient times as a popular seaside vacation resort featuring medicinal hot springs – folk chemotherapy at its finest!
Paralana Hot Springs, Arkaroola, Australia
You’ll find the Paralana hot springs inside the Arkaroola Wilderness Sanctuary located in the arid northern Flinders ranges of South Australia but if you’re planning a hike in the area, bring your lead boots… and we don’t mean Led Boots on your MP3 player though a little Jeff Beck goes down easy just about anywhere. Subterranean springs flowing through uranium-rich rocks over 1 billion years old bring radioactive radon and uranium to the surface; hikers are well advised to refill their canteens somewhere else.
Flickr user and photographer Liam.jon_d (Bill Doyle) has posted an exquisite set of images taken during a visit to the Paralana hot springs in April of 2011. That greenish glow you see isn’t what you might expect: it’s life, thriving between a rock and a hard (radiation) place! So-called “extremophile” blue-green algae flourish in the area’s hot springs, shrugging off water temperatures of up to 62 degrees centigrade heated not by geothermal energy but from radioactive decay.
