Complex sentence: Although the water contained higer levels of radon, the health risk from radiation was low, but the water also contained arsenic, lead, vanadium, and uranium Epstein, M.S. et al, Appl. Spectrosc.
Split into simpler sentences: Although the water contained higher levels of radon, the health risk from radiation was low. But the water also contained arsenic, lead, vanadium, and uranium Epstein, M.S. et al, Appl. Spectrosc.