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Disturbance of cerebral function in people exposed to drinking water contaminated with aluminium sulphate: retrospective study of the Camelford water incident

BMJ 1999; 319 doi: http://dx.doi.org/10.1136/bmj.319.7213.807 (Published 25 September 1999) Cite this as: BMJ 1999;319:807

Camelford: prolonging the agony?

Altmann et al (1) conclude that poisoning with aluminium sulphate in
Camelford 10 years ago 'probably led to long term cerebral impairment', an
opinion which has predictably led to immediate media attention, including
speculation about damage to children and unborn foetuses at the time and
doubtless to some rekindling of psychological distress in this
population. There is a possibility that the paper by Altmann et al will
stimulate a further round of litigation (2). This should be carefully
considered because the evidence presented by Altmann et al was obtained
under instruction of plaintiffs' solicitors in the context of the earlier
round of litigation which ended in 1994, where the out of court
settlements were small (average £2,000) and despite the medias assertions,
the authors have not presented new evidence.

It is possible that some people exposed to polluted water in Cornwall
in July 1988 suffered brain damage (3). However the absence of
physiological measures of absorption of aluminium and other toxins at the
time of the accident has made it impossible for a definite conclusion to
be reached. With regard to persisting complaints attributed to the
accident, the paper by Altmann et al is unhelpful and their conclusion
unwarranted. Methodological flaws include use of a highly self-selected
group of litigants and sibling controls which is a source of bias, however
this and difficulties with interpretation of the evoked potential data
have been described already (4,5,6).

They also persist in using the
unrevised normative data for the National Adult Reading Test, a test which
is used to estimate premorbid ability. The revised norms for this test
were published in 1991 and are used throughout the UK; by using the
outdated version they overestimate IQ in the patient group increasing
the likelihood of finding a decrement in tests of current ability.

In
addition the authors must be criticised for failing to discuss in depth
the relatively few key papers in this area, such as the thorough review by
David and Wesseley, or implications from other disasters involving
pollution such as Braer (7,8). Perhaps it is because of this that they
rebutt possible psychological causation of symptoms oversimply on the
basis of 'anxiety' self-reporting and really fail to deal with this
complex issue.

Nor do they defend the use of evoked potentials given the
crticisms levelled specifically at their work in the second report of the
Clayton Committee in 1991 (9).

Finally, they do not acknowledge or explain
the absence of effect in the only study on the entire exposed population
(of children) who were compared to an age matched non-exposed group of
Cornish children on routinely administered psychometric tests of
educational attainment given before and after the accident. No evidence
for impairment in the exposed group was found-implying that severe brain
damage was unlikely to have occurred (10).

In accord with David (5) I think that it is regretable that
psychological wounds may be reopened in North Cornwall at such a late
stage and seemingly without good reason.However I do hope that plans have
been made for early systematic assessment of exposure, and any physical
and psychological sequelae in the event of future accidents.

1. Altmann P, Cunningham J, Dhanesha U et al BMJ 1999, 3, 807-811.

2. The Guardian, Friday September 24 1999, p 9 col 1-2.

3. McMillan TM, Freemont AJ, Herxheimer A et al Camelford water
Poisoning Accident: serial neuropsychological assessments and further
observation on bone aluminium. Human Exptal Toxicol 1993,12, 37-42.

4. Esmonde TFG Methodological errors BMJ letters 1999, 319,7213,807

5. David A Camelford: faulty data and faulty assumptions. BMJ
letters,1999, 319,7213,807.

6. Fahy T Competing interests and weak study design undermine
conclusions. BMJ letters 1999, 319,7213,807

7. David A, Wessely SC. The legend of Camelford: medical consequences
of pollution accident. J Psychosom Res 1995, 39, 1-9.

8. Campbell D, Cox D, Crum J et al. Later effects of the grounding of
the tanker Braer on health. BMJ, 309, 773-774.

9. Clayton B Water pollution at Lowermoor North Cornwall. HMSO,
London 1991 pp 22-23

10. McMillan TM, Dunn G, Colwill, S.J Psychological testing on
children before and after pollution of drinking water in North Cornwall.
J. Child, Adolescent Psychiatry, 1993, 34, 1449-1459.

Competing interests: No competing interests

08 October 1999
T M McMillan
rofessor of Clinical Neuropsychology
Department of Psychological Medicine, University of Glasgow
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