A field study of the validity of static paper sampling in fluoride pollution surveys.

A field study of fluoride pollution and of its consequences was made over a period of five years in the vicinity of an alumina reduction plant. This study, based upon the use of a static soda impregnated paper sampler, shows that the results obtained are in good agreement with the atmospheric fluoride concentrations obtained with dynamic samplers, especially when fluoride is present in gaseous form (HF). The results suggest that vertically mounted paper samplers are less sensitive to the collection of particulate fluorides. Collection rate is strongly influenced and increases with speed. If this parameter is known, an accurate estimation of the absolute atmospheric concentration is possible; the values shown by this technique are in good correlation with the value (annual mean) of pasture fluoride content. As a correlation exists between pasture fluoride content and the symptoms shown by cattle, the static filter samplers can predict disease in the case of slow chronic fluorosis. The field study agrees with earlier laboratory experiments and shows the validity of these simple and inexpensive types of exposure methods.