James Randerson is right to argue for the importance of experimentation and the gathering of empirical data in order to take forward scientific discovery (Don't punish the scientists, April 25). But, as the researcher who dug out the National Archives papers - dating from the early 50s to mid 60s - on the scientific experiments on human "volunteers", on which your sister paper the Observer based its story on April 22, I am not as sanguine as Randerson in believing these experiments were purely conducted for the benign purpose of future protection of the health of the workforce handling radioactive materials.

Although the ethics of the experiments were carefully evaluated by government lawyers of the time, one letter I uncovered, dated February 12 1965, from the then UK Atomic Energy Authority's chief medical officer, KP Duncan, to Dr Geoff Schofield, then senior medical officer at the Sellafield/Windscale works, commented: "I was a little surprised to find that you had already started [the proposed experiments] and trust that you get all these points documented."

Randerson dismissively comments that the radiation experiments are "conspiracy theorists' dreams". Sadly, in this case, the conspiracy explanation may be the most accurate one. In the 50s and 60s Sellafield was run by the UKAEA, which had a dual mission: research and development for the civilian nuclear programme; and to create the fissile materials, such as plutonium and enriched uranium, and to design and build the warheads for the British atomic bomb programme. The experiments discussed by Randerson were developed in the wake of the major accident in October 1957 at the so-called atomic piles at Windscale, operated to make plutonium for weapons, the result of which ended in the uncontrolled distribution of large quantities of radioactive fallout across the north-west of England, Ireland and further afield.

Papers presented to the United Nations' first international conference on atomic energy in Geneva in 1958 revealed that the Sellafield operators had taken advantage of the plant's coastal location to dispose of liquid radioactive wastes to sea. Such a cavalier approach to deliberately releasing huge quantities of radioactive toxic poisons into an uncontrolled maritime environment is evidently unethical - and was known to be so at the time. No informed consent was sought from the public who used the local beaches for pleasure, or the fishermen who made their living in the Irish Sea - or indeed the north-east Atlantic and North Sea.

So Randerson may be right in stating that two of Sellafield's chief medical officers in the 80s "were building up a store of information about plutonium levels in the bodies of workers that they could compare with levels measured in urine samples taken routinely from the deceased workers when they were alive". But what remains unexplained is the real reason behind why they were doing so.

Michael Redfern QC - the lawyer appointed to head the inquiry into the irradiated body parts issue - should examine all of the National Archives files on radiation exposure experiments, including those presently withdrawn from public access by the UKAEA, to find out why.

· Dr David Lowry is a researcher specialising in nuclear, security and environmental policy
drdavidlowry@hotmail.com

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