in the absence of a satisfactory explanation being found in the previous literature , it is hypothesized , on the basis of data gathered in 1748 children , that the occurrence of the rings is negatively correlated with the level of the regions ' general health conditions as well as with an unfavourable individual case history , and positively with a genetically determined pigment proneness and the individual 's age .
C0008059
children
C0027361
individual 's