Retention of fluoride from diets containing materials produced during aluminium smelting.

1. Using male rats, the availability of fluoride from five by products of the aluminium smelting industry was tested. This was done by considering the balance between fluoride administered in controlled diets and the total fluoride content of waste products eliminated over an experimental period of 1 week. 2. Results indicated that yields of available fluoride expressed as percentage weight of original material were cryolite (Na3ALF6), 45.9%; sodium fluoride (NaF), 41.7%; aluminium fluoride (AFL3.H20), 9.1%; mist eliminator grid solids (with CaF2), 9.4%; reclaimed alumina with adsorbed F, 0.27%. 3. Of the various tissues analysed for fluoride content, only the kidney and femur showed any significant correlation with the amounts of fluoride absorbed or retained.