SEGH Articles

Putting the Health in SEGH

18 November 2015
Dr Alex Stewart, recently retired from Public Health England, has been an active member of the SEGH International board over many years and a major driving force in bringing the health community together with environmental scientists to promote inter-disciplinary research.

Dr Alex Stewart retired at the end of June as a Consultant in Health Protection for Public Health England, for which his responsibilities included the recognition, characterisation and response to the health effects of environmental issues, including the geochemical components.  Dr Stewart has been involved in SEGH activities for about 20 years, having gained experience and an interest in linking environmental geochemistry and its influence on human health through his interest in iodine deficiency in his years as a GP in the Karakoram mountains of northern Pakistan.

We take the opportunity to ask a few questions of Alex to gain an insight into his extensive experience to the benefit of other scientists at any stage of their career.  In addition, Alex gives us some idea of his plans for the future and his continued engagement with SEGH.

When you started out on your career, what were your fears, hopes, and the reality?  Were there any surprises along the way? 

As a young medical doctor I wanted to work in the wilder parts of the world, but wondered if I was up to it. I was able to join an experienced doctor in starting the General Practice in Baltistan, northern Pakistan, where the health services were thin, stretched and of limited ability. When my colleague retired a few years later, I took over with confidence and developed the work. Perhaps the biggest surprise was my ability to adapt good medical practice in a situation where resources were limited (we ran an outpatient clinic without nearby hospital or laboratory support) and the villagers did not always return quickly for review. It was sometimes hard to know if patients had died, got better or decided my treatments were not worth having! This made learning about what worked and what did not a lot slower but eventually earned me local respect because I was able to ground the medical work in a deep knowledge of the local community.

How were the environmental and health sciences considered early in your career and was there much collaboration between disciplines at the time?

We in health had little understanding of the impact of environmental issues on health, particularly when I was a student and young doctor. Doctors still largely concentrate on the person sitting in our consulting room and ignore wider issues, including, sadly, family and social aspects. The natural environment hardly came into my early understanding of health and disease.

Was there any one event that stood out for yourself personally that influenced your career or the perception of geochemical and health research?

The sharpest event that affected my perception of geochemistry and health was an evening in our house in Baltistan with two passing geologists from Oxford. They were studying the Main Karakoram Thrust, often by binoculars from their jeep in the valley, covering a lot of ground quickly: Baltistan is dry, with very little soil cover on the rocks, so the basic geology can be quite clear in many places. I had become interested in the locally perceived differences in the prevalence of goitre (thyroid swelling in the neck due, in this area, to iodine deficiency) between our side of the river (“1/100”, I was told) and the inhabitants of the villages across the river (“1/10” was the local comment). I had looked and asked about differences between the two sides of the valley and could find nothing that made sense until these passing geologists showed me the Main Karakoram Thrust and indicated its importance as the boundary between Asia (the far side) and the Island Arc north of India (our side). As I began to look into this it was clear that plate tectonics played some part in the distribution of the iodine deficiency disorders across northern Pakistan and perhaps further afield (Stewart AG. Drifting continents and endemic goitre in northern Pakistan. British Medical Journal, 1990; 300: 1507-1512). Following this through led eventually to my appointment as a Consultant in Health Protection with interest in and responsibility for environmental issues (e.g. Mahoney G, Stewart AG, Kennedy N, Whitely B, Turner L, Wilkinson E. Achieving attainable outcomes from good science in an untidy world: Case studies in land and air pollution. Environmental Geochemistry & Health. 2015; 37: 689-706.).

How has your involvement in SEGH helped in your career and enjoyment of your work?

SEGH has been of enormous support, stimulation and help in my career over the past 20-odd years. I first encountered it at a halogen meeting in Kingston-upon-Thames while home on leave in 1994. I went to hear Ron Fuge, the iodine guru from Aberystwyth. Although Ron was unable to attend the meeting at the last minute, I found some of the other presentations fascinating and Joy Carter (former SEGH President), at Reading in those days, enrolled me into SEGH. This encouraged me (particularly after our sudden and unexpected return to the UK in 1996 after the Pakistani Government asked us to leave, reasons unstated) to build friendships, read the journal, and attend meetings. Through the SEGH meetings, in particular, I met a lot of fascinating people and learned a lot more than I could have imagined about the environment, geochemistry and possible influences on health. I also gave presentations or posters which were probed in the SEGH gentle but knowledgeable manner, helping develop my thinking on a number of issues. I have been delighted to serve on the SEGH board; SEGH has been a constant during periods of diminished support for environmental public health issues in the health protection arena (Stewart AG, Worsley A, Holden V, Hursthouse AS. Evaluating the impact of interdisciplinary networking in Environmental Geochemistry and Health: Reviewing SEGH conferences and workshops. Environmental Geochemistry and Health, Special edition. 2012; 34(6): 653-664).

Do you have any advice for young scientists setting out on their careers in environmental geochemistry or health sciences?

Don’t be afraid of cross-boundary work: that’s where exciting challenges and discoveries are to be made in any subject. Develop friendships and relationships with people outside your speciality, learn their scientific language and ways of thinking and undertake joint work. You never know where that will lead.

What do you consider to be the important topics for environmental-geochemistry-health related research in the future?

We need to continue our interest in elemental chemistry, but move beyond metals into organics, into volatiles, building relationships with air-scientists to look at the unseen pollution and health effects of fine and ultra-fine particles. I think linking the genetic fingerprint of cancers with specific toxins will enable us to identify, control and reduce/prevent specific diseases. However, this cannot be done by either geochemists or health professionals alone, but only in collaboration. Collaboration means both sides actively being involved in each other’s research proposals and activities, not just bolting two different approaches together.

What are some of your hopes for the future?

I would dearly like to see more health professionals involved with SEGH, but have run out of ideas how to involve them. I hope the younger generation of scientists can succeed where I have been unsuccessful.

Now that I am retired I hope to have some time to examine some of the environmental-health questions that have sat on my desk for 10+ years, such as: Does environmental iodine deficiency exist? What is the explanation for the global distribution of iodine deficiency disorders? What is the environmental input, if any, into lung cancer in North West England? Could some of the ill-health of deprived communities in industrialised countries be due to historical pollution, perhaps through trans-generational mechanisms?


On a personal note, Alex has made an important contribution to SEGH's encouragement of cross disciplinary work across geochemistry and health sciences, both in the UK and through European meetings.  Alex's tireless enthusiasm has helped to provide a platform from which the following generation of cross disciplinary scientists are less inhibited by the artificial boundaries.  Fortunately, Alex will continue to be engaged with SEGH, clearly with some exciting issues to pursue in retirement.

by Dr Michael Watts

British Geological Survey (SEGH webmaster)

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


    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


    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


    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.