B.V. Apparao

SUMMARY: Fluoride contents of water and food, collected from the subjects of five selected areas of Tamil Nadu in South India, were determined. Surveys were conducted to ascertain dental fluorosis prevalences among children of the areas, and dental and skeletal fluorosis prevalences in the adult populations. Dean's Community Fluorosis Index (CFI) for dental fluorosis was calculated, from the children's survey, and was found to be correlated with the prevalence and severity of fluorosis in the areas. A direct correlation was also confirmed between the mean fluoride level in drinking water and the percentage incidence of dental fluorosis. The dominant role of fluoride from drinking water, when compared with that from food, was established.

The corrosion rates of mild steel in a neutral aqueous environment containing 60 ppm C1 ‐ in the absence and presence of the sodium salt of amino (trimethylene phosphonic acid) (ATMP), polyacrylamide (PAA) and Zn 2+ have been evaluated by the classical weight‐loss method. The formulation consisting of 50 ppm PAA and 50 ppm Zn 2+ and also the ATMP (300 ppm) ‐ZN 2+ (50 ppm) system shows synergistic effect while the formulation consisting of 300 ppm ATMP and 50 ppm PAA shows antagonistic effect. The formulation consisting of 300 ppm ATMP, 50 ppm Zn 2+ and 50 ppm PAA has 98 per cent corrosion inhibition efficiency and 99.9 per cent biocidal efficiency. The mechanistic aspects of corrosion inhibition are based, in a holistic way, on the results obtained from potentiostatic polarization study, X‐ray diffraction technique, UV‐visible, FTIR and luminescence spectra. Found that the protective film consists of FE 2+ ‐ATMP complex, Fe 2+ ‐PAA complex and Zn(OH) 2 .