GM rice 'could reduce reliance on phosphate fertiliser' - SciDev.Net:

Fluoride chemicals, silicofluorides, used by over 91% of US fluoridating communities are waste products of phosphate fertilizer manufacture:

"Phosphate fertilisers, which often contain the toxins fluoride and arsenic, are among the most environmentally damaging of all fertilisers. Their manufacture can cause atmospheric pollution, and the fertilisers themselves can pollute soil and rivers."