Substance fact sheet
The National Pollutant Inventory (NPI) provides information on the types and amounts of pollutants being emitted in the Australian community.
This page provides facts about total phosphorus. It describes how you might be exposed to this substance, how exposure might effect you and the environment, common uses, comparative data about total phosphorus and its physical and chemical properties.
For more information about some of the terms used in this page, see the NPI glossary.
The National Pollutant Inventory (NPI) holds data for all sources of total phosphorus emissions in Australia.
There are no specific health effects directly associated with total phosphorus as such. Phosphorus is, in fact, an essential nutrient for all forms of life - it is an integral constituent of nucleic acids (the building blocks of genetic material), many other essential biochemicals (for example, coenzymes and adenosine triphosphate), and bones.
It must be noted, nevertheless, that many industrial organophosphates are nerve toxins (for example, some pesticides) and exposure to these can lead to sub-lethal and lethal effects. Some of these compounds may be carcinogens or teratogens.
A more general concern of total phosphorus is its environmental effects, where elevated levels of phosphorus (and other nutrients such as nitrogen, organic carbon, and silica) often cause blue-green algal blooms, which can affect human health through contact or consumption (of the water or food, especially fish, taken from the water).
The main pathway of phosphate into the human body is through eating. Mishandling of toxicants, such as organophosphate pesticides, leads to exposure by either direct absorption through the skin or by breathing in the vapours.
The major 'normal' exposure is through eating food or by drinking water containing phosphates. Mishandling of toxicants, such as organophosphate pesticides, will lead to exposure to only small amounts of phosphorus, but potentially lethal amounts of the pesticide.
See Sources for more information.
The main pathway of phosphate into the human body is through eating. Mishandling of toxicants, such as organophosphate pesticides, leads to exposure by either direct absorption through the skin or by breathing in the vapours.
High total phosphorus levels together with high total nitrogen levels, in conjunction with other necessary nutrients and favourable physical characteristics of aquatic environments, can result in plant and algal blooms. After assimilation in plant and algal growth, microbial breakdown and other processes such as mineralisation may transform organic and complexed phosphate forms through various steps into the readily available inorganic phosphate form.
Most total phosphorus is transported by processes such as runoff and streamflow, and sometimes groundwater flow, although wind also transports components of total phosphorus around the landscape. See also Sources (above) for both natural and human-mediated transport mechanisms for total phosphorus.
Total phosphorus in rivers, lakes, and oceans occurs in many forms, but which have widely differing availability for biological growth. The free orthophosphate ion component is readily available for plant (including algae) growth. The polymeric and adsorbed inorganic and small molecular weight organic forms are available on short time scales (say hours to days), while higher molecular weight organic and inorganic forms are available on longer time scales, say days to weeks. Phosphorus contained within the crystalline structure of complex mineral forms is available through weathering, but on geologic time scales.
It is important to note, however, that the sources, dispersion, transport, and fate of phosphorus in the environment is extremely complex, in some ways even more so than for nitrogen, because of the complexity of its forms and interconversions in the solid form. Inorganic phosphate levels in ocean waters and aerobic inland waters are of the order of up to tens of micrograms of phosphorus per Litre, whereas in anaerobic waters in sediments (or anaerobic bottom waters in lakes) they can reach hundreds of micrograms of phosphorus per Litre.
Thus, the oxidation-reduction status (usually expressed as redox potential) of the environment plays a critical role in the forms, and hence availability, of phosphorus. Further, this status is critically dependant on microbial activity (which, if at a sufficient level, causes anaerobic conditions to develop), but which in turn is dependant on the amount of readily-assimilable organic matter present.
High total phosphorus levels together with high total nitrogen levels, in conjunction with other necessary nutrients and favourable physical characteristics of aquatic environments, can result in plant and algal blooms. After assimilation in plant and algal growth, microbial breakdown and other processes such as mineralisation may transform organic and complexed phosphate forms through various steps into the readily available inorganic phosphate form.
Various factors, such as flow, light, turbidity, temperature, nitrogen levels, zooplankton grazing, etc., can limit plant and algae growth. Thus, it is not possible to recommend absolute total phosphorus concentrations for aquatic environments that will prevent plant and algae blooms. Nevertheless the following environmental guidelines have been set for total phosphorus (ANZECC, 1992).
Australian Water Quality Guidelines for Fresh and Marine Waters: (ANZECC, 1992):
Rivers and steams:10-100 micrograms/L (0.00001 to 0.0001 g/L) (as total-phosphorus)
Lakes and reservoirs: 5-50 micrograms /L (0.000005 to 0.00005 g/L) (as total-phosphorus)
Estuaries and embayments: 5-15 micrograms /L (0.000005 to 0.000015 g/L) (as phosphate-phosphorus)
Coastal waters: 1-10 micrograms /L (0.000001 to 0.00001 g/L) (as phosphate-phosphorus).
In recognition that other factors can have a major influence on the effects of nutrient levels, the future ANZECC guidelines will adopt a risk-based approach. This will involve the use of a decision-tree with guideline levels for phosphorus (and nitrogen) largely determined by these other influencing factors.
The Australian NOHSC National Exposure Standards Database link is probably the most useful source of information.
The major use for phosphorus is as an essential nutrient for all plant and animal life, commonly as phosphate in inorganic fertiliser. At the same time, phosphates and organophosphates are widely used in such diverse applications as detergents, plasticisers, flame-retardants, corrosion inhibitors, pesticides, and scale inhibitors in water heaters and boilers, etc.
A wide variety of small molecular weight esters of phosphates (organophosphates) are made industrially, and vary from highly toxic pesticides to non-toxic plasticisers and surfactants.
Food processing industries, sewage treatment plants, leachate from garbage tips, and intensive livestock industries (for example: animal feedlots and large poultry operations).
Catchment runoff - The inorganic phosphate and organophosphate components of total phosphorus are typically derived from soil, plant, and animal materials associated with both undisturbed and agricultural land uses.
Arising from the use of fertilisers and manures, and to a lesser extent the use of phosphorus-containing pesticides, on agricultural lands. Urban runoff - From home fertiliser use, detergents, flame-retardants in many applications (including lubricants), corrosion inhibitors, and plasticisers.
Phosphorus is one of the 20 most abundant elements in the solar system, and the 11th most abundant element in the earth's crust. However, it forms only about 0.1% of the rocks that make up the bulk of the crust and is thus classed as a trace element. Even so, there are some rocks that are composed chiefly of phosphorus-bearing minerals, and these are the chief source of phosphorus for industrial and agricultural purposes.
The inorganic phosphate organophosphate components of total phosphorus are typically derived from soil, plant, and animal material. In nature, phosphorus has almost no gaseous forms and so the major transport mechanism is by water flow. Nevertheless, significant amounts are transported via the atmosphere as dust. Indeed, in an undisturbed catchment the amount of phosphorus deposited from the atmosphere is equal to the amount that leaves by runoff.
Nearly all of the phosphorus compounds found in nature or used in commerce are present in the form of phosphate salts and various organic and inorganic derivatives of them. Highly reduced forms of phosphorus (phosphines, for example) occur rarely in nature, and in very small quantities since they are highly reactive. Less reduced forms, for example, phosphonates, are produced and metabolised in nature.
An extremely important form of phosphates in nature is the nucleic acids, the store of genetic information. These very large molecular weight (up to 108) compounds are formed from quite small organic molecules joined together by the phosphate group to form very long chains. On the other hand, coenzymes, such as adenosine triphosphate, have relatively low molecular weights.
Lubricant emissions, from vehicle use, contain phosphates which will be transported by runoff from rain, and thereby enter streams, lakes, and other water bodies.
Most food products contain phosphorus in various organic and inorganic forms. Lawn and garden fertilisers contain phosphates. Various household cleaners and polishes; furniture, paint, fabrics, carpets; and various other products may contain phosphates as plasticisers, flame-retardants, corrosion inhibitors, etc.
Approximately 400 substances were considered for inclusion on the NPI reporting list. A ranking and total hazard score was given based on health and environmental hazards and human and environmental exposure to the substance.
Total phosphorus was ranked as 27 out of 400. The total hazard score taking into account both human health and environmental criteria is 3.0.
On a health hazard rating of 0 - 3 total phosphorus registers 0.5. A score of 3 represents a very high hazard to health, 2 represents a medium hazard and 1 is harmful to health.
On an environmental rating of 0 - 3 total phosphorus registers 2.5 A score of 3 represents a very high hazard to the environment and 0 a negligible hazard.
Factors taken into account to obtain this ranking and these scores include the extent of the material's toxic or poisonous nature and/or its lack of toxicity, and the measure of its ability to remain active in the environment and whether it accumulates in living organisms. It does not take into account exposure to the substance. Environmental exposure is reflected in the NPI rank for this substance (see comparative data below). A substance that scores highly as an environmental hazard is oxides of nitrogen at 3.0 and one of the lower scores is carbon monoxide at 0.8. A substance that scores highly as a health hazard is arsenic at 2.3 and one of the lowest scores is ammonia at 1.0.
| Substance name | Total phosphorus |
| CASR number | Not applicable |
| Molecular formula | The formula for the orthophosphate ion is (PO4)3- |
| Synonyms | Total phosphorus is defined for the NPI as compounds that give rise to phosphate ions. This is a very broad group including many natural and anthropogenic substances, either containing phosphate or decomposing into it. These compounds include salts such as trisodium phosphate and calcium hydroxyapatite, and polyphosphates and organophosphates.The vast number and variety of molecular structures making up organic chemistry (that is, compounds based on carbon atoms) is mirrored in the chemistry of compounds based on phosphorus. This variety is based on the orthophosphates and the long-chain polyphosphates, compounds in which phosphate groups are linked by oxygen. |
| Physical properties: Phosphates: Phosphate salts vary very widely in their solubility, from several percent for solutions of salts such as trisodium phosphate, to micrograms per Litre for calcium hydroxyapatite. In addition, their solubility is strongly affected by the pH of the solution.However, the solubility of phosphate in waters containing hydrated iron(III) oxides is reduced by orders of magnitude, since phosphate binds extremely strongly to the oxide surfaces. Polyphosphates and organophosphates: These also vary widely in their solubility generally decreasing as the molecular weight increases, and again is very dependent on pH. |
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| Chemical properties: Phosphates: Phosphate salts in solution are only partially dissociated at neutral pH. Nevertheless, the degree of dissociation is critically important to its reactivity in not only precipitation/dissolution reactions, but also to the formation of the various organophosphate esters. Reactivity: |
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There is more information that may be useful in understanding some of the issues surrounding the NPI.