PREVENTION OF INDUSTRIALLY-INDUCED CATTLE AND SHEEP FLUOROSIS

Two industrial plants emitting fluorides were built in an industrial a rea at Vlissingen. The Netherlands; one produced phosphorus from natur al phosphates and the other produced aluminium through electrolyse. Co ntrol systems were installed to reduce emissions. An agreement was mad e between the farmers, manufacturers and provincial authorities of Zee land to examine possible claims and develop measures for prevention A 2 to 3 km area around the plants, was designated unsuitable for agricu lture and cattle-rearing. Beyond that area, contamination of pasture w as measured even 15 days. About thirty, differently contaminated herds were visited at regular intervals to evaluate fluoride intake and to initiate prevention hy distribution of rations containing 6 p. cent al uminium sulfate to reduce fluoride bioavailability and replacing conta minated feed with fluoride-free feed. Pasture contamination was much h igher in winter than in spring and summer; at the highest contaminated site, the average for autumn-winter was up to 100 ppm in the period 1 970-1980, whereas it generally remained below 50 ppm in spring and sum mer. The levels recently decreased to half those values. Prevention of fluorosis has proven entirely successful : no damage compensation has been granted since 1985.