Alkyl phosphate anti-valve seat recession additive

This fact sheet is a summary of the Priority Existing Chemical (PEC) report at the time it was assessed and published.

CAS number: Confidential

The alkyl phosphate additive is manufactured in and imported to Australia for use as a fuel additive. It is used for anti-valve seat recession protection in automotive engines. It is commonly blended into lead-replacement petrol (LRP) and is also available in aftermarket products that consumers add to automotive fuel.

In July 2003 NICNAS completed a full assessment of the alkyl phosphate additive [WORD 510 KB]. Here are the main findings of the report.

The alkyl phosphate additive can enter the body by being swallowed or through skin contact. Of these, skin contact is the most likely way for exposure to occur. There is no data for the alkyl phosphate additive itself because it is manufactured in kerosene.

The kerosene-based alkyl phosphate additive may cause skin irritation. This is most likely due or contributed to by the kerosene.

If swallowed, the kerosene-based alkyl phosphate additive has a low toxicity. Accidental ingestion by a child of the alkyl phosphate additive after-market formulation is not considered a significant health risk to children by virtue of the alkyl phosphate additive.

Ingestion of or contact with the kerosene and solvent naptha (which is contained in one of the consumer products) may represent, however, specific health effects such as irritancy and lung damage.

Gaps in the data identified during the assessment are not regarded as significant impediments to assessment of the risks associated with the current use of the alkyl phosphate additive in lead replacement petrol.


Based on limited data, the kerosene-based alkyl phosphate additive has a low toxicity to aquatic animals.

The assessment has not identified any significant risk to the environment due to the current use of the alkyl phosphate additive in lead replacement petrol.

There are insufficient data to classify the alkyl phosphate additive itself as a hazardous substance. The inclusion of additives in the various alkyl phosphate formulations may represent specific hazards.

More information on alkyl phosphate formulations can be found in the Material Safety Data Sheets available from the supplier.

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Last update 1 August 2013