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

• Published in: BMJ Vol. 319; no. 7213; pp. 807 - 811
• Main Authors: Altmann, Paul, Cunningham, John, Dhanesha, Usha, Ballard, Margaret, Thompson, James, Marsh, Frank
• Format: Journal Article
• Language: English
• Published: London British Medical Journal Publishing Group 25.09.1999; British Medical Association; BMJ Publishing Group Ltd; BMJ Publishing Group LTD; BMJ Publishing Group; British Medical Journal
• Edition: International edition
• Subjects: Adolescent; Adult; Adults; Age; Aged; Alum Compounds - adverse effects; Aluminum; Aluminum sulfate; Alzheimer's disease; Alzheimers disease; Analysis. Health state; Anxiety; Anxiety - etiology; Automation; Biological and medical sciences; Biopsy; Brain damage; Brain Damage, Chronic - chemically induced; Brain diseases; Causes of; Chemicals; Contaminated water; Contamination; Drinking water; England - epidemiology; Environmental pollutants toxicology; Epidemiology; Evoked potentials; Evoked Potentials, Visual; Female; General aspects; Hemodialysis; Hospitals; Humans; Intelligence quotient; Intelligence tests; Male; Measurement; Medical prognosis; Medical research; Medical sciences; Memory; Memory Disorders - chemically induced; Metabolism; Middle Aged; Physiological aspects; Potable water; Premorbid; Psychological Tests; Psychological trauma; Psychometrics; Psychomotor Disorders - chemically induced; Public health. Hygiene; Public health. Hygiene-occupational medicine; Reading; Research subjects; Retrospective Studies; Screening tests; Siblings; Stress, Psychological - chemically induced; Studies; Toxicology; Water; Water pollution; Water Pollution - adverse effects; Water Supply; United Kingdom; Europe; United Kingdom > UK; England; Camelford England; Camelford; Human; Drinking water; Health; Toxicity; Visual evoked potential; Epidemiology; Contamination; Pollution; Health and environment; Test Psychomotricité; Clinical investigation; Public health; Aluminium sulfate; Intelligence quotient
• ISSN: 0959-8138; 0959-8146; 1468-5833; 1756-1833
• DOI: 10.1136/bmj.319.7213.807

Abstract Objective: To establish whether people exposed to drinking water contaminated with 20 tonnes of aluminium sulphate in the Camelford area of Cornwall in the south west of England in July 1988 had suffered organic brain damage as opposed to psychological trauma only. Design: Retrospective study of affected people. Participants: 55 affected people and 15 siblings nearest in age to one of the group but who had not been exposed to the contaminated water were studied. Main outcome measures: Various clinical and psychological tests to determine medical condition and anxiety levels in affected people. Assessment of premorbid IQ (pFSIQ) with the national adult reading test, a computerised battery of psychomotor testing, and measurement of the difference in latencies between the flash and pattern visual evoked potentials in all participants. Results: The mean (SE) pFSIQ was above average at 114.4 (1.1). The most sensitive of the psychomotor tests for organic brain disease was the symbol digit coding (SDC) test (normal score 100, abnormal <85). Participants performed less well on this test (54.5 (6.0)) than expected from their pFSIQ (P<0.0001) and a little less poorly on the averaged less discriminating tests within the battery (86.1 (2.5), P<0.0001). In a comparison with the 15 sibling pairs (affected people's age 41.0 (3.3) years v sibling age of 42.7 (3.1) years (P=0.36) the exposed people had similar pFSIQ (114.7 (2.1)) to their siblings (116.3 (2.1), (P=0.59) but performed badly on the symbol digit coding test (51.8 (16.6)) v (87.5 (4.9) for siblings, P=0.03). The flash-pattern differences in exposed people were greater than in 42 unrelated control subjects of similar age (27.33 (1.64) ms v 18.57 (1.47) ms, P=0.0002). The 15 unexposed siblings had significantly better flash-pattern differences than their affected siblings (13.4 (2.4) ms v 29.6 (2.9) ms, P=0.0002). No effect of anxiety could be shown on these measurements from the analysis of the anxiety scores of exposed people. Conclusion: People who were exposed to the contaminated water at Camelford suffered considerable damage to cerebral function, which was not related to anxiety. Follow up studies would be required to determine the longer term prognosis for affected individuals. Key messages Aluminium is a well established neurotoxin Accidental contamination of drinking water in Camelford by aluminium sulphate led to symptoms of loss of concentration and short term memory that were initially attributed to anxiety In residents exposed to the contaminated water psychomotor performance was poorer than predicted from premorbid IQ and the difference between flash-pattern visual evoked potentials was greater than normal Anxiety did not influence either of these measures of cerebral function Aluminium sulphate poisoning probably led to long term cerebral impairment in some people in Camelford