Phosphate for strong bones

Phosphorus (P) occurs in nature in compound forms called phosphates. The majority of phosphorus found in the human body is concentrated in the bones, although the P found elsewhere nonetheless fulfills important functions.

The first phosphate fertilizers were made from ground animal bones. Today, most phosphorus is derived from phosphate rock. Appropriate management is needed to minimize the potential for negative impacts from impurities contained in phosphate ores.

Phosphate rock contains heavy metals , most notably cadmium. Cadmium from industrial sources is known to pose health risks, but good agricultural practices are considered sufficient to manage the risk of cadmium and other heavy metals accumulating excessively in agricultural soils. Some countries limit the amount of cadmium that can be added to farmers’ fields as part of their risk management strategies. The only known case of cadmium poisoning in an agricultural setting was, in fact, the result of industrial pollution of irrigation water for rice consumed by subsistence farmers whose diet was dependent on rice as a staple crop.

Cadmium can be removed from processed phosphate used by the food and drink industry and for feed. However, for fertilizer use, this process is currently too costly compared to other, more economical ways to manage the risk. There is no method for removing heavy metal contaminants from directly applied phosphate rock, such as that approved for use in organic agriculture.

Phosphate rock frequently contains naturally occurring radioactive materials as well. When the rock is processed, these radionuclides are split between the fertilizer and the phosphogypsum co-product. The level of radioactivity in fertilizers that are marketed falls below safety thresholds, so these products do not require any special handling or regulation. We are surrounded by background radiation. Again, ground phosphate rock applied directly will contain all the radioactivity of the ore.