About 50 km south of Vitória, the state capital of Espírito Santo, in southeastern Brazil, lies the coastal town of Guarapari, a popular tourist destination. Know for its sandy white beaches, Guarapari is a popular holiday escape for holiday makers from the landlocked Minas Gerais state as well as people from Vitória and Vila Velha. While Brazil has a long coastline and hundreds of miles of beaches, Guarapari is one of very few places where the sand is naturally radioactive.
Praia dos Padres, Guarapari. Photo: FABIAN KRONENBERGER/Flickr
Guarapari’s sand contains monazite, a primarily reddish-brown phosphate mineral that contains several rare-earth elements, including radioactive uranium and thorium. The background radiation level on Guarapari beach is about 20μSv per hour. In some spots it can be as high as 131 μSv per hour. To place that in context, a single chest X-ray can deliver 100 μSv.
Monazite in the sand from Brazil was first noticed in sand carried in ship's ballast by the Austrian scientist Carl Auer von Welsbach in the 1880s. Von Welsbach was looking for thorium for his newly invented incandescent mantles. Monazite sand was quickly adopted as the thorium source and became the foundation of the rare-earth industry. Monazite mines in southern India and Brazil dominated the industry before World War II, after which major mining activity transferred to South Africa and Australia.
Harvesting sand from the beaches in 1910. Photo: bionerd23/Flickr
Workers packing monazite sand in sacks. Photo: bionerd23/Flickr
Workers processing monazite sand. Photo: bionerd23/Flickr
The association of Guarapari’s radioactive sand with medicinal therapy was made by physician Silva Mello in 1972, who advocated laying on the sand to cure oneself of arthritis and cancer. In his book Guarapari: Miracle of Nature, Mello exposited the virtues of natural radiation, and as a result thousands of tourists began to visit the region around the city of Guarapari. Many people completely cover themselves with the monazitic sand supposing that this is healthy and may cure their diseases. The state’s tourism industry has definitely profited from this fact. Guarapari’s sand’s supposed therapeutic properties are extolled in advertisements by the Brazilian media.
A vintage photograph showing a full beach in Guarapari. Photo: bionerd23/Flickr
The Brazilian Nuclear Agency does not recommend staying on the beach for long periods, because the gamma radiation field is quite intense on the beach. High energy gamma radiation can penetrate the body and cause skin cancer and damage the tissue. If inhaled, the alpha radiation from the sand can cause lung cancer.
The Agency proposed that the black sand, which contains high concentration of monazite, should be removed for the benefit of the tourists. The expense incurred in this operation could be easily recovered by extracting monazite from the sand and selling the minerals. As a matter of fact, the entire Brazilian coast from north of Rio de Janeiro up to the region south of Bahia, a distance of about 500 miles, is rich in monazite and there are quite a few heavy mineral production industries in the region for this purpose.
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