OUTBREAK OF ACUTE FLUORIDE POISONING CAUSED BY A FLUORIDE OVERFEED, MISSISSIPPI, 1993

Objective. To determine the extent and confirm the cause of an August 1993 outbreak of acute fluoride poisoning in a small Mississippi commu nity, thought to result from excess fluoride in the public water suppl y. Methods. State health department Investigators interviewed patrons of a restaurant where the outbreak first became manifest and obtained blood and urine samples for measurement of fluoride levels. Stale heal th department staff conducted a random sample telephone survey of comm unity households. Public health environmentalists obtained water and i ce samples from the restaurant and tap water samples from a household close to one of the town's water treatment plants for analysis. Health department investigator; and town water department officials inspecte d the fluoridation system at the town's main water treatment plant.Res ults. Thirty-four of 62 restaurant patrons reported acute gastrointest inal illness over a 24-hour period. Twenty of 61 households that used the community water supply reported one or more residents with acute g astrointestinal illness over a four-day period, compared with 3 of 13 households that did not use the community water supply. Restaurant wat er and ice samples contained more than 40 milligrams of fluoride per l iter (mg/L), more than 20 times the recommended limit, and a tap water sample from a house located near the main treatment plant contained 2 00 mg/L of fluoride. An investigation determined that a faulty feed pu mp at one of the town's two treatment plants had allowed saturated flu oride solution to siphon from the saturator tank into the ground reser voir and that a large bolus of this overfluoridated water had been pum ped accidentally into the town system. Conclusions. Correct installati on and regular Inspection and maintenance of fluoridation systems are needed-to prevent such incidents.