THE DISTRIBUTION OF LEUKEMIA IN ASSOCIATION WITH DOMESTIC WATER-QUALITY IN SOUTH-WEST ENGLAND

This study assessed whether there is any variation in the incidence of haematological malignancies between geographical areas of differing w ater supplies in the South West peninsula of the United Kingdom (1984 to 1988 inclusive), The possibility of correlations existing between v ariation in water quality and variation in the incidence of haematolog ical malignancies was examined, Haematological incidence data, taken f rom the Leukaemia Research Fund's Data Collection Study, were mapped i nto 46 geographical areas of differing water supply, The distribution of the mapped cases was then tested for homogeneity using the Potthoff and Whittinghill (1966) test score, The age-adjusted incidence ratios calculated during the heterogeneity testing were examined for correla tions with water quality indicators using correlation and stepwise reg ression, Significant heterogeneity in the incidence rates among water supply areas was observed for two groups of disease - acute leukaemias and myeloproliferative disorders. Three water quality indicators - pH , nitrate concentration and aluminium concentration - varied considera bly over the study period, Significant correlations were observed betw een the standardized incidence ratios of five disease categories and s ome water quality indicators, especially aluminium and trihalomethane concentrations, The standardized incidence ratios of some haematologic al malignancies differed between geographical areas of water supply in South West England, and the evidence suggests that this variation may be associated with variation in water quality indicators, Although th is lends support to similar findings in the United States of America, the pattern of correlations are affected by disease latency and statis tical methodology.