WHY DO PENGUINS NOT DEVELOP SKELETAL FLUOROSIS?

Despite having an exceptionally high fluorine (F) concentration in their bones (up to 9000 mu g/g in the present study), radiographs of mature Adelie penguins (Pygoscelis adeliae) do not show any symptoms of skeletal fluorosis. In this research, a series of chemical fractionation and speciation analyses for F gave a tentative explanation for this seemingly abnormal fact. The results showed that the inorganic fraction of F in penguin bones represented only about one-third of the total F with the rest bound organically, mostly in the form of fluorinated chitin or its derivatives. A laboratory experiment with rats on a high F intake indicated that chitin might prevent skeletal fluorosis by effectively combining with F and inhibiting abnormal mineralization, thereby decreasing the expected increase in bone mineral density.