M. Morton

Trace elements in water and congenital malformations of the central nervous system in South Wales.

The concentrations of 20 trace elements were determined by atomic absorption spectrophotometry on representative samples of tap-water collected from 48 local authority areas in South Wales. The associations between twelve trace elements and central nervous system (CNS) malformation rates for the 48 areas were examined. Significant correlations for four trace elements were observed. Of these, Al was positively correlated while for the remaining three-Ca, Ba, and Cu-negative associations were found. Regression analysis of the data suggested that the relationships between Ba and Cu with CNS malformation rates were improtant than those of Al and Ca.

Mortality in adults and trace elements in water.

Representative samples of tap water were collected in 48 local-authority areas in South Wales. The associations between twelve trace elements and both total and ischaemic-heart-disease (I.H.D.) mortality were examined. Interrelationships between the trace elements were found to be strong and complex, but only calcium (Ca) seemed to make an important contribution to mortality. The addition of other elements improved regression only marginally. The association between Ca and total mortality was found to be closer than that with I.H.D. mortality. This is inconsistent with a specific effect of Ca, and hence water hardness, on I.H.D.

Neural tube malformations and trace elements in water.

A retrospective case-control study was conducted to test the hypothesis that there is an association between the trace element content of domestic tap water and neural tube malformations in infants. Of 11 elements examined a notable difference was found only for zinc, this being lower in the cases than in the controls. This difference, however, was small and when allowance is made for the total number of statistical comparisons it is compatible with chance fluctuation. From the results of this study, together with the inconsistency of the literature as a whole, it is concluded that trace elements in tap water are unlikely to be of relevance to congenital malformations.

Mortality and the concentration of elements in tap water in county boroughs in England and Wales.

To explain the associations of water hardness and air temperature with area differences in ischaemic heart disease mortality, samples of tap water were obtained from homes in 61 county boroughs in England and Wales, and the concentration of calcium and 12 other elements was estimated. Multiple regressions were calculated with the death rates from various causes as dependent variables and with the concentration of the elements in the tap water, mean annual temperature, mean annual rainfall, and a socioeconomic index as independent variables. The well known negative association between water hardness and ischaemic heart disease was shown to be due to calcium, and none of 12 other elements examined appeared to contribute significantly to the association. Area differences in other causes of death also showed an association with calcium. There was little association between temperature and ischaemic heart disease.