Some claims are made that thalassotherapy was developed in seaside towns in Brittany, France during the 19th century.[3] A particularly prominent practitioner from this era was Dr Richard Russell,[4][5][6] whose efforts have been credited with playing a role in the populist "sea side mania of the second half of the eighteenth century",[7] although broader social movements were also at play.[8] In Póvoa de Varzim, Portugal, an area believed to have high concentrations of iodine due to kelp forests, and subject to sea fog, the practice is in historical records since 1725 and was started by Benedictine monks; it expanded to farmers shortly after. In the 19th century, heated saltwater public baths opened and became especially popular with higher classes.[9]Others claim that the practice of thalassotherapy is older: "The origins of thermal baths and related treatments can be traced back to remote antiquity. Romans were firm believers in the virtues of thermalism and thalassotherapy.[8]