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Proceedings of the Phosphogypsum Fact-Finding Forum, December 7, 1995, Tallahassee, Florida


The Florida Institute of Phosphate Research and The Florida Center for Public Management at Florida State University co-sponsored this Fact-Finding Forum on December 7, 1995 in Tallahassee, Florida. The purpose of the Forum was to expose the audience and a select panel of Florida state and local government decision makers to a scientific discussion of the effects and uses of phosphogypsum.

In assembling the best national and international scientific talent for presentations, the Florida Institute of Phosphate Research staff made a determined effort to include scientists with opposing views on the effects of using phosphogypsum. However, it was very difficult to find scientifically-trained speakers, or groups who could recommend such experts, on the negative impacts of phosphogypsum usage. This factor understandably gave the panel and audience the perception that the presentations were unbalanced. We very much regret that, but it should not detract from the quality and value of the information presented at the Forum.


Environmental Effects of Phosphogypsum (PG)

1. There is no significant risk to human health for those individuals working with or around PG; for example, those building a road or spreading it agriculturally.
2. Whereas shielding materials placed over PG are able to protect people rather completely from the impacts of radon, they are less effective in attenuating gamma radiation, so that the gamma factor must always be considered.
3. There appears to be no significant risk to someone traveling over a phosphogypsum-based road, but only to someone who might build a house on it and occupy that house for 70 years (EPA scenario).
4. The marine studies at Louisiana State University employing PG/cement structures as oyster clutch substrates or artificial reefs have shown no bioaccumulation of toxic materials to date, but these studies need to be extended over longer periods to give confidence in the results.
5. The use of PG as a cover material in municipal waste landfills accelerates the decomposition of a ”standard garbage” and has the promise of providing additional landfill space, but it also increases the evolution of hydrogen sulfide. There is technology available to recover economically the sulfur values of the hydrogen sulfide.

Uses of Phosphogypsum

1. Much structural and environmental data have been accumulated by various researchers in the use of PG in county and secondary roads, but its use in federal and state heavy-duty roads needs additional research.
2. Compelling economic benefits have been calculated for constructing county roads using PG mixtures.
3. Realistic agricultural PG application rates of from 250 to 500 lbs/acre/year constitutes an acceptable risk, even using the USEPA’s conservative limits.
4. Preliminary economics show a distinct cost advantage to farmers or cattle ranchers in using PG to supply soil calcium or sulfur, and in improving the soil structure.
5. The economics of using PG in marine structures, as well as the environmental risks involved, need confirmation before this proposed use can be taken seriously.

Miscellaneous Interesting Points Made by the Speakers

1. The Canadian level of concern (action level) on radon is more liberal than USEPA’s (roughly 5 times our 4 pCi limit).
2. The USEPA has set very low limits on acceptable radiation levels – of the order of 70 mrem/year – very close to the average USA background level.
3. Although the USEPA has stated that they are going to relax the present limit of 700 lbs of PG they allow to be used for research purposes, it is probable that any demonstration-scale experiment will still require a variance.

The policy panel and the audience showed great interest in the uses and the effects of using PG. Discussion was often lively about what could be done to liberalize present USEPA rules so as to allow larger, demonstration-type projects using PG.

The panel proposed that FIPR and USEPA adopt a cooperative approach to resolving differences about the effects, uses and policies governing PG.