Cerebral dysfunction after water pollution incident in Camelford

doi:10.1136/bmj.320.7245.1337

BMJ 2000;320:1337 ( 13 May )

Letters

Cerebral dysfunction after water pollution incident in Camelford

Results were biased by self selection of cases

Study has several methodological errors

Study may prolong the agony

Inappropriate study, inappropriate conclusions

Results were biased by self selection of cases

The first 150 words of the full text of this article appear below.

EDITOR $---$ Altmann et al's results on a group of litigants were published almost 10 years after the water pollution incident inCamelford.¹ Although they acknowledge competing interests,they overlook the main problem $---$ the bias inherent in self selectionofcases.

The cases may have already had unexplained symptoms and cognitive problems, the incident serving to focus attention on a possiblecause. The results show significant impairment in neuropsychologicaland neurophysiological tests among the cases, which the authorsargue must be the result of prolonged toxicity to acute exposureto aluminium in drinking water. Neuropsychological tests are assumedto be objective, automated, computerised, and quantitative, butthey do require the conscious effort of subjects. Those complainingof poor memory and concentration are given a test that requiresboth, so performance cannot be taken at face value. Subjects arenot carrying out a deliberate deception, but their performancelike everyone else's is . . . [Full text of this article]

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This article has been cited by other articles:

Altmann, P., Cunningham, J., Marsh, F., Dhanesha, U., Ballard, M., Thompson, J. (2000). Authors' reply to Camelford letters. BMJ 320: 1536-1536 [Full text]