SEGH Articles

Back to the Future: Brian E Davies (Past President)

08 April 2014
Should we reduce our emphasis on the toxic elements? Is it time to go back to the future?

 

 

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: ewartdavies@gmail.com


References

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).

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Fate and partitioning of heavy metals in soils from landfill sites in Cape Town, South Africa: a health risk approach to data interpretation 2019-06-14

    Abstract

    The fate and persistence of trace metals in soils and sludge from landfill sites are crucial in determining the hazard posed by landfill, techniques for their restoration and potential reuse purposes of landfill sites after closure and restoration. A modified European Community Bureau of Reference’s (BCR) sequential extraction procedure was applied for partitioning and evaluating the mobility and persistence of trace metals (As, Cd, Cr, Cu, Ni, Pb, Sb, Se, Zn) in soils from three landfill sites and sludge sample from Cape Town, South Africa. Inductively coupled plasma optical emission spectroscopy was used to analyze BCR extracts. The mobility sequence based on the BCR mobile fraction showed that Cu (74–87%), Pb (65–80%), Zn (59–82%) and Cd (55–66%) constituted the mobile metals in the soils from the three sites. The mobility of Cu, Zn and Ni (> 95%) was particularly high in the sludge sample, which showed significant enrichment compared to the soil samples. Geo-accumulation index (Igeo) and risk assessment code were used to further assess the environmental risk of the metals in the soils. Exposure to the soils and sludge did not pose any non-cancer risks to adult and children as the hazard quotient and hazard index values were all below the safe level of 1. The cancer risks from Cd, Cr and Ni require that remedial action be considered during closure and restoration of the landfill sites.

  • An investigation into the use of < 38 µm fraction as a proxy for < 10 µm road dust particles 2019-06-13

    Abstract

    It is well documented that a large portion of urban particulate matters is derived from road dust. Isolating particles of RD which are small enough to be inhaled, however, is a difficult process. In this study, it is shown for the first time that the < 38 µm fraction of road dust particles can be used as a proxy for road dust particles < 10 µm in bioaccessibility studies. This study probed similarities between the < 10 and < 38µm fractions of urban road dust to show that the larger of the two can be used for analysis for which larger sample masses are required, as is the case with in vitro analysis. Road dust, initially segregated to size < 38 µm using sieves, was again size segregated to < 10 µm using water deposition. Both the original < 38 µm and the separated < 10 µm fractions were then subject to single particle analysis by SEM–EDX and bulk analysis by ICP-OES for its elemental composition. Dissolution tests in artificial lysosomal fluid, representative of lung fluid, were carried out on both samples to determine % bioaccessibility of selected potentially harmful elements and thus probe similarities/differences in in vitro behaviour between the two fractions. The separation technique achieved 94.3% of particles < 10 µm in terms of number of particles (the original sample contained 90.4% as determined by SEM–EDX). Acid-soluble metal concentration results indicated differences between the samples. However, when manipulated to negate the input of Si, SEM–EDX data showed general similarities in metal concentrations. Dissolution testing results indicated similar behaviour between the two samples in a simulated biological fluid.

  • Degradation of petroleum hydrocarbons in unsaturated soil and effects on subsequent biodegradation by potassium permanganate 2019-06-13

    Abstract

    To date, the oxidation of petroleum hydrocarbons using permanganate has been investigated rarely. Only a few studies on the remediation of unsaturated soil using permanganate can be found in the literature. This is, to the best of our knowledge, the first study conducted using permanganate pretreatment to degrade petroleum hydrocarbons in unsaturated soil in combination with subsequent bioaugmentation. The pretreatment of diesel-contaminated unsaturated soil with 0.5-pore-volume (5%) potassium permanganate (PP) by solution pouring and foam spraying (with a surfactant) achieved the total petroleum hydrocarbon (TPH) removal efficiencies of 37% and 72.1%, respectively. The PP foam, when coupled with bioaugmentation foam, further degraded the TPH to a final concentration of 438 mg/kg (92.1% total reduction). The experiment was conducted without soil mixing or disturbance. The relatively high TPH removal efficiency achieved by the PP–bioaugmentation serial foam application may be attributed to an increase in soil pH caused by the PP and effective infiltration of the remediation agent by foaming. The applied PP foam increased the pH of the acidic soil, thus enhancing microbial activity. The first-order biodegradation rate after PP oxidation was calculated to be 0.068 d−1. Furthermore, 94% of the group of relatively persistent hydrocarbons (C18–C22) was removed by PP–bioaugmentation, as verified by chromatogram peaks. Some physicochemical parameters related to contaminant removal efficiency were also evaluated. The results reveal that PP can degrade soil TPH and significantly enhance the biodegradation rate in unsaturated diesel-contaminated soil when combined with bioaugmentation foam.