The investigation will be conducted by the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT), which has something of a reputation for conservatism. A locally nominated representative will be included on the panel.

COT's terms of reference are to advise whether chemical exposures resulting from the incident have caused or are expected to cause harm to health, and whether existing health monitoring and research are adequate. It is expected to report next spring.

A major stimulus was a medical assessment published in 1999 which showed that many of those exposed during the incident had "suffered considerable damage to neurological function" (ENDS Report 297, pp 28-32).

Labour promised a public inquiry into the incident while in opposition, but the investigation falls short of fulfilling this, or of meeting local campaigners' demands for a wide-ranging inquiry. There will be no investigation into allegations of a cover-up intended to safeguard plans to privatise the water industry, then at a critical stage.

Only the day before the investigation was announced, Environment Minister Michael Meacher wrote to local Liberal Democrat MP Paul Tyler saying the investigation would cover the "adequacy and transparency" of how the affair was handled. The Department for Environment, Food and Rural Affairs (DEFRA) says that the letter represented "early thinking" and that the handling of the incident had already been investigated.

Although the Government claims that there is no doubt about the events at the time, uncertainty remains about the levels of aluminium and other metals to which people were exposed. The response of the then South West Water Authority was never independently investigated, and the apparently complacent response of the local health authorities at the time was never scrutinised.