Petrol Additive MTBE Set to Win Import Approval

The petrol additive MTBE (Methyl Tertiary Butyl Ether) has again become the focus of attention for water suppliers, this time in Australia, where the importing of fuel containing the additive looks likely to be approved by the Federal Government.

In response the Technical Director of the Australian Water Association on 4 June circulated an alert to all interested parties highlighting the undesirability of such a move and seeking to raise public awareness and general opposition before the intention becomes fact.

The chemical is a relative newcomer to the water pollution scene, its production and use rising in the 1990s as a substitute for lead in petrol.

It has been most widely used in the United States and it was there, in Santa Monica, California, in 1995, that an alarming incident alerted authorities to the extent to which MTBE contamination could endanger public water supplies.

Towards the end of that year MTBE was detected in one of the city's drinking water wells. By the middle of the following year the contamination had spread to other wells, forcing their closure and eventually the loss of over 70 percent of local raw water. This subsequently forced the city to import about half of its potable supplies at an annual cost of some $3.5million.

Since then debate has increased in user countries over the risks and benefits attached to MTBE. Although originally used to replace lead as an 'anti-knock' agent in petrol it came to be seen as having wider benefit by reducing unburned hydrocarbons in vehicle exhaust emissions and cutting the content of dangerous benzene and other aromatics in fuel. Awareness of the ability to spread in ground and surface waters from spillages and tank leakages came later.

When a potable source is contaminated MTBE imparts strong and objectionable tastes and odours to the water but ingestion is not yet linked with serious adverse health effects.

In the EU that matter is currently under scrutiny in a Europe-wide study led by Finland, a country with a wealth of pure raw water but currently importing more MTBE- amended petrol than any other EU state. The results of that study will inform future European action.

In the meantime one EU state, Denmark, has announced its intention to phase out MTBE. No such action appears likely in the UK where the results of a national survey, published last year, are said to indicate 'minimal risks' to large potable sources. A scientist involved with the survey saw this as mainly due to the fact that most UK sources are in rural areas whereas most groundwater contamination arises from leakages and spillages at urban petrol stations and fuel depots. In contrast the 1995 Santa Monica event had derived from public supply wells within the urban area.

International Water Association