Estonian curative mud has been studied extensively in in the past. Latest research was conducted in 2013-2014 the Centre of Excellence in Health Promotion and Rehabilitation. Fieldwork was arranged as well in Käina Bay near Orjaku village, where most of the samples from Orjaku peloid were taken during the ice-free period from the area with active mud resources, but samples were also taken from areas with passive or predicted mud reserves and from outside the boundaries of the deposits for comparison.
The latest results confirm that Käina Bay contains the most mineral sediments out of all analyzed deposits in Estonia. On the lithological composition on average Orjaku peloid contains 91.4% of minerals, 6.5% of organic matter, and 3.7% of carbonates. Research data show in general that the lowest concentrations of heavy metals are in Käina Bay. The lowest lead (Pb) concentrations among all Estonian mud deposits were detected in Käina Bay, where values do not exceed 20 ppm, in all points the concentration of zinc (Zn) is within the norms – 80 ppm and the concentration of copper (Cu) is the lowest – 9 ppm on average. On the basis of a low concentration of heavy metals, the sediments in Käina Bay can be considered the ecologically cleanest in Estonia.