In 1970, when SEGH began, we talked about many ideas: is aluminium involved in dementia?; is arsenic an essential element?; is chromium involved in Type 2 diabetes?; can the incidence of gastric cancer be related to copper and zinc in the environment? By 1982, when I organised SEGH, and its first conference, in Britain, priorities had changed to environmental metals and sometimes we now appear to be a pollution society.
Have we reached the end of the metals era? For example, lead. The danger to child mental development has been recognised and quantified: the role of hand dirt is understood, paint and petrol are lead free, government regulations are in place, the environmental chemistry of lead is broadly understood. New ideas are now more likely to come from the clinical rather than the earth sciences. Or, cadmium. Little epidemiological evidence has emerged that environmental cadmium is a significant health problem. The special problems in Asia are probably because of poor iron nutrition (Simmons et al., 2003).
Death from all causes in 2012 (England and Wales) was 489,274. Accidental poisoning by ‘noxious substances’ accounted for 1,416 (0.3%) in contrast with 8,367 (1.7%) alcohol related deaths. Malignant neoplasms and diseases of the circulatory system each represented 28.8% total deaths. Morbidity data are broadly similar.
For cardiovascular diseases magnesium is a cofactor for over 300 enzyme systems and is required for energy generation and glycolysis. Magnesium is involved in nerve conduction, muscle contraction, potassium transport, and calcium channels. An environmental geochemistry link is seen in reports that deaths from heart attacks are greater where drinking water is soft. We all drink some tap water if only in tea, coffee or diluted ‘squash’.
In the next SEGH conference I plan to present a paper giving results from a desk study to establish the plausibility of a hard/soft water effect. The daily Reference Nutrient Intake (RNI) for Mg is men = 12 mmol. Nationally, solid food, pus bottled water plus alcoholic drinks for men provide (mean) 10.62 mmol Mg or 89% RNI. Adding in tap water: reservoir water contributes little Mg (total Mg intake 88.9% RNI); (mean) aquifer water Mg raises total intake to 11.85 mmol (96.5% RNI); a very hard water (North Downs chalk) raises total intake to 50.3 mmol (419% RNI). A beneficial role for Mg in hard drinking water seems plausible.
A recent paper (McKinley et al., 2013) reported a relationship between environmental exposure to trace elements in soil and cancer across Northern Ireland. Copper is an integral part of the antioxidant enzyme, copper-zinc superoxide dismutase. Copper deficiencies in animals and crops in Britain are a well attested problem. Yet we know little about any link from soil to humans.
Much reliable health data can now be accessed over the internet. Perhaps it is time to return to some of the older unanswered questions in environmental geochemistry and health. Should we reduce our emphasis on the toxic elements? Is it time to go back to the future?
By Professor Brian E Davies: email@example.com
McKinley, J. M., Ofterdinger, U., Young, M., Barsby, A., & Gavin, A. (2013). Investigating local relationships between trace elements in soils and cancer data. Spatial Statistics, 5, 25–41.
Simmons, R. W., Pongsakul, P., Chaney, R. L., Saiyasitpanich, D., Klinphoklap, S., & Nobuntou, W. (2003). The relative exclusion of zinc and iron from rice grain in relation to rice grain cadmium as compared to soybean: Implications for human health. Plant and Soil, 257(1).