Medical Hydrology and Balneology: Environmental Aspects

Psammotherapy in Porto Santo Island
(Madeira archipelago)
Gomes CSF (1) , Silva JBP (1)
(1) GeoBioTec, University of Aveiro, Aveiro, Portugal
cgomes@ua.pt
Psammotherapy is a practice that uses sand-baths for therapeutic purposes. Sandbaths
in the biogenic carbonate sand from Porto Santo Island, in the archipelago of
Madeira, constitutes a good example of the positive interaction of minerals on
human health. Recent studies provided much information on relevant physical and
chemical properties that could explain this sand’s 200-year-long use, although on a
much empirical manner, for the treatment of muscular-skeletal (rheumatic and
orthopedic) diseases, such as rheumatoid arthritis, gout, osteoporosis, and fibromyalgia.
The biogenic carbonate sand from Porto Santo Island consists mainly of bioclasts
of calcareous red algae (Rhodophyta), sand-bathing traditionally taking place
outdoors in the dry and warm sand of the transition zone beach/frontal dune, along
the southern coast of the island. However, since 10 years ago, sand-bathing can be
carried out indoors, as is the case of the Geomedicine Clinic of Hotel Porto Santo,
in conditions that try to replicate the outdoors sand-bathing conditions.
The biogenic carbonate sand is essentially composed of calcium carbonate in the
forms of calcite, Mg-calcite and aragonite. The amount of grains derived from
volcanic rocks, as a rule, is less than 10%.
Analysis of chemical data shows that Ca, Mg and Sr are the major elements of
the biogenic carbonate sand from Porto Santo, elements which are bio-essential for
human health. P, S, Si, Al, I, Br, F, B, V, Zn, Cu, Fe, and Se are the minor/trace
elements identified in the same sand.
The average grain size of this biogenic carbonate sand is estimated at 0.200mm,
all sand grain sizes ranging between 0.063mm and 0.500mm: > 0.250mm – 0.5%;
0.250mm-0.125mm – 85.5%; 0.125mm-0.063mm – 13% ;