Psychological testing on schoolchildren before and after pollution of drinking water in North Cornwall

The tap water supply in Camelford, North Cornwall and environs was contaminated by aluminium and other metals in 1988. Richmond tests were routinely given before and after the pollution and here scores are compared between 39 children from schools in the contaminated area and 64 children from Cornish schools outside the polluted area. The study was retrospective and it was not possible to determine whether or how much polluted water individuals had consumed. No differences were found between groups either before or after the pollution accident nor was there any evidence for any sub-group of the polluted group which had been affected. The limits of conclusions which can be drawn from data available are discussed.