After two years of limited study, local environmental officials have found amounts of fluoride in Hillsborough County pasture grass that “approach levels damaging to cattle” if animals graze on it for their lifetime.

The effect of cattle grazing on grass with too much fluoride is a bone-brittling and tooth-mottling disease called fluorosis. Plants also can be damaged by fluoride, as gladiolus were years ago near one fertilizer factory before pollution control devices were installed in the phosphate industry.

Based on a report given Tuesday by staff of the Hillsborough Environmental Protection Commission, the country commissioners told the EPC – and it agreed – to collect more information about how much fluoride schoolchildren would ingest from contact with it in playground dirt. Commissioners want to know the potential effects Progress Village School students might feel if Gardiner Inc.’s proposed gypsum pile is built next to their school.

From two years of sampling EPC found abnormal amounts of fluoride in pasture grass “quite predictably close to phosphate manufacturing” plants including one grass lot grazing one horse on 78th Street near Gardiner’s current and proposed gypsum piles, according to Debra K. Sanderson, the EPC chief air monitoring scientist who briefed the County Commission.

Sanderson was quick to stress that the amount of fluoride detected in air and grass anywhere in the county did not begin to approach the amount needed to harm humans – the level was about 1,000 times less than would cause health effects by federal standards.

Fluoride is found naturally in Florida phosphate rock. When the ore is processed into fertilizer, as much as 85 percent of the fluoride may end up in waste gypsum piles according to the Environmental Protection Agency. Those piles and other cooling ponds, ditches and smoke stacks are the major sources of the fluoride being detected in the grasses, according to Sanderson.

“Our basic concern is that east Hillsborough County is zoned agricultural and ought to be viable agricultural land,” said Roger Stewart, EPC’s director. It shouldn’t be a situation where cattle owners can’t continuously graze their herds, he said.

“We’re on the edge of a hot spot of fluorides,” said Sanderson in an interview. “In Lakeland, it gets higher as you move (toward it). Farmers know they have to route the animals.”

In the Hillsborough and Polk region, Sanderson said the land is “perfectly OK to graze for a couple of years…You can’t raise them (cattle) from babies all the way through.”

Don Moores, who collects fluoride data for the Florida Department of Environmental Regulation, concurred with Sanderson’s findings. He said DER has found elevated fluoride readings at the Polk and Hillsborough border and in northern Hardee County. The problem does not extend any further east, he said.

“There isn’t much question that fluoride in high levels causes fluorosis and that it is high enough in some places to do that,” said Moores in an interview Wednesday.

The fluoride pollution problem was first detected in the 1960s and subsequently reduced. But reports of fluorosis cropped up again in the 1970s when fertilizer plants dramatically increased production, according to Sanderson.

In 1976, DER attempted to establish a statewide fluoride standard but failed though, due to “lack of hard scientific data” and “intense lobbying efforts by the phosphate industry,” she said.

In 1981, enough east Hillsborough citizens complained about fluoride problems that one phosphate company bought up some of their land, said Sanderson. A mule breeder experienced high rates of abortions in mares and deformed young. A cattle rancher’s herd was diagnosed as having fluorosis.