SEGH Articles

Exposure to Arsenic And Other Toxic Elements Through Eating Earth

01 February 2012
The practice of deliberately eating earth, known as geophagy has been common in many cultures across the world. Unfortunately, very little scientific research is being conducted in this area and its impact on human health.



The work decribed below has been published and can be accessed from the following link:

The practice of deliberately eating earth, known as geophagy has been common in many cultures across the world.  It continues to be practiced today in many parts of the world including amongst certain groups within the United Kingdom.  The reason behind this practice remains unknown, although it has been suggested it is consumed for nutritional and medicinal purposes. Since geophagy is more prevalent during pregnancy, it has been suggested that eating earth may remedy deficiencies that results in anaemia in women.  However, others argue that eating earth may cause anaemia.   Unfortunately, very little scientific research is being conducted in this area and little is known about the composition of earth that is consumed in different parts of the world and their impact on human health.   The mineral content of the earth will naturally vary from region to region and the potential of exposure to toxic elements is likely.   This is a cause for concern especially in certain parts of the world where there are environmental problems resulting in the presence of elevated levels of toxic elements such as arsenic in water and the food chain.  Arsenic is a toxic element that is present at high levels in drinking water in Bangladesh and India.  Although many studies have focused on arsenic exposure in India (West Bengal) and Bangladesh through drinking water, very little work has been done to consider other sources of exposure.  Exposure to arsenic through consumption of rice and vegetables has been highlighted (Cascio et al. 2011 and references therein).  It was reported that the Bangladeshi's residing in the United Kingdom are exposed to a higher level of arsenic compared to white Caucasians (Cascio et al. 2011) due to their high intake of rice. 

Shaban Al-Rmalli is a PhD student (PhD supervisors:  Parvez Haris & Richard Jenkins, De Montfort University; Collaborator:  Michael Watts, British Geological Survey) at De Montfort and his research project was to identify the different sources of arsenic exposure in the Bangladeshi community not just from rice and vegetables.   The aim of the project is to identify sources of exposure to toxic elements that may explain the reasons underlying the disproportionately higher prevalence of different disease including diabetes, cardiovascular disease and some types of cancer amongst UK Bangladeshis (Cascio et al.  2010 & references therein).   Information obtained could be used to help modify the diet of the Bangladeshis (both in the UK and in Bangladesh) so that they avoid certain types of foods/non-foods that may contain high levels of toxic elements.  As part of his PhD project, Shaban analysed over 1,000 Bangladeshi food and non-food samples.  Amongst the samples he purchased from ethnic Bangladeshi shops in the United Kingdom was baked clay (imported from Bangladesh) that are called Sikor in Bengali (see Figure).   Discussions with the members of the Bangladeshi community and shop keepers revealed that these clay tablets are purchased mainly by Bangladeshi and African women and especially by pregnant women from these communities.  This revelation was rather alarming and further investigation into this issue revealed that in Bangladesh some women can consume as much as 500g of these clay tablets per day.   The average weight of the sikor tablets shown in the Figure is approximately 15g and most women consume between 3-4 tablets per day.  This is particularly worrying as intake of high levels of toxic elements could not only harm the health of the pregnant women but that of the unborn baby since many toxic elements including lead and arsenic can transfer from the mother to the baby through the placenta.  What was a cause for further worry is that women in Bangladesh are already being exposed to high levels of arsenic and manganese etc through drinking water and consumption of sikor may potentially lead to a further increase in exposure to these elements.   It was therefore vital that such samples are analysed to evaluate their content of arsenic as no previous studies have considered this issue.   

Sikor samples, originating from Bangladesh,  were purchased and analysed for their As, Pb, Cd, Mn, Fe and Zn levels using ICP-MS. Furthermore, detailed As speciation analysis was performed using HPLC-ICP-MS (   The levels of As (3.8-13.1 mg kg-1), Cd (0.09-0.4 mg kg-1) and Pb (21-26.7 mg kg-1) present in the sikor samples were of concern and could have detrimental effect on the health of the consumer. Speciation analysis revealed that sikor samples contained mainly the toxic inorganic As. It was calculated that modest consumption of 50 g of sikor is equivalent to ingesting 370 μg of As and 1235 μg of Pb per day, based on median concentration values. Just consuming 50g sikor per day exceeds the permitted maximum tolerable daily intake (PMTDI) of inorganic As by almost 2-fold (   The study concluded that sikor consumption can be a source of exposure to As, Cd and Pb in some Bangladeshis and in some other populations where this is consumed such as in India & Africa.   In the future, it is important to evaluate the bioavailability of As and other elements from sikor and their impact on human health.

The authors of the study recommend that those responsible for public health, act to create awareness about the potential dangers of consuming baked clay in populations where this practice is prevalent.  As a result, the United Kingdom Food Standards Agency has advised pregnant women not to eat baked clay ( ).  However, public health officials in other parts of the world including Bangladesh, India, Africa and other parts of the world where geophagy is more prevalent need to also act urgently to advise women about the potential dangers of eating clay.

For further details, please contact Dr P.I. Haris, E-Mail:


Al-Rmalli, S.W.,  Jenkins, R.O., Watts, M.J., and Haris, P.I. Risk of human exposure to arsenic and other toxic elements from geophagy: trace element analysis of baked clay using inductively coupled plasma mass spectrometry.  Environmental Health 2010, 9:79 (23 December 2010).

Cascio, C., Raab, A.,  Jenkins, R.O., Feldmann, J. Meharg, A.A. and Haris, P.I. (2011)  The impact of a rice based diet on urinary arsenic.  J. Environ. Monit., 2011, 13, 257-265.

Related reports 

Food Standards Agency issues warning about eating clay.

Keep up to date

SEGH Events

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

  • Characteristics of PM 2.5 , CO 2 and particle-number concentration in mass transit railway carriages in Hong Kong 2017-08-01


    Fine particulate matter (PM2.5) levels, carbon dioxide (CO2) levels and particle-number concentrations (PNC) were monitored in train carriages on seven routes of the mass transit railway in Hong Kong between March and May 2014, using real-time monitoring instruments. The 8-h average PM2.5 levels in carriages on the seven routes ranged from 24.1 to 49.8 µg/m3, higher than levels in Finland and similar to those in New York, and in most cases exceeding the standard set by the World Health Organisation (25 µg/m3). The CO2 concentration ranged from 714 to 1801 ppm on four of the routes, generally exceeding indoor air quality guidelines (1000 ppm over 8 h) and reaching levels as high as those in Beijing. PNC ranged from 1506 to 11,570 particles/cm3, lower than readings in Sydney and higher than readings in Taipei. Correlation analysis indicated that the number of passengers in a given carriage did not affect the PM2.5 concentration or PNC in the carriage. However, a significant positive correlation (p < 0.001, R 2 = 0.834) was observed between passenger numbers and CO2 levels, with each passenger contributing approximately 7.7–9.8 ppm of CO2. The real-time measurements of PM2.5 and PNC varied considerably, rising when carriage doors opened on arrival at a station and when passengers inside the carriage were more active. This suggests that air pollutants outside the train and passenger movements may contribute to PM2.5 levels and PNC. Assessment of the risk associated with PM2.5 exposure revealed that children are most severely affected by PM2.5 pollution, followed in order by juveniles, adults and the elderly. In addition, females were found to be more vulnerable to PM2.5 pollution than males (p < 0.001), and different subway lines were associated with different levels of risk.

  • Comparison of chemical compositions in air particulate matter during summer and winter in Beijing, China 2017-08-01


    The development of industry in Beijing, the capital of China, particularly in last decades, has caused severe environmental pollution including particulate matter (PM), dust–haze, and photochemical smog, which has already caused considerable harm to local ecological environment. Thus, in this study, air particle samples were continuously collected in August and December, 2014. And elements (Si, Al, V, Cr, Mn, Fe, Ni, Cu, Zn, Mo, Cd, Ba, Pb and Ti) and ions ( \({\text{NO}}_{3}^{-}\) , \({\text{SO}}_{4}^{2-}\) , F, Cl, Na+, K+, Mg2+, Ca2+ and \({\text{NH}}_{4}^{+}\) ) were analyzed by inductively coupled plasma mass spectrometer and ion chromatography. According to seasonal changes, discuss the various pollution situations in order to find possible particulate matter sources and then propose appropriate control strategies to local government. The results indicated serious PM and metallic pollution in some sampling days, especially in December. Chemical Mass Balance model revealed central heating activities, road dust and vehicles contribute as main sources, account for 5.84–32.05 % differently to the summer and winter air pollution in 2014.

  • Annual ambient atmospheric mercury speciation measurement from Longjing, a rural site in Taiwan 2017-08-01


    The main purpose of this study was to monitor ambient air particulates and mercury species [RGM, Hg(p), GEM and total mercury] concentrations and dry depositions over rural area at Longjing in central Taiwan during October 2014 to September 2015. In addition, passive air sampler and knife-edge surrogate surface samplers were used to collect the ambient air mercury species concentrations and dry depositions, respectively, in this study. Moreover, direct mercury analyzer was directly used to detect the mercury Hg(p) and RGM concentrations. The result indicated that: (1) The average highest RGM, Hg(p), GEM and total mercury concentrations, and dry depositions were observed in January, prevailing dust storm occurred in winter season was the possible major reason responsible for the above findings. (2) The highest average RGM, Hg(p), GEM and total mercury concentrations, dry depositions and velocities were occurred in winter. This is because that China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. (3) The results indicated that the total mercury ratios of Kaohsiung to that of this study were 5.61. This is because that Kaohsiung has the largest industry density (~60 %) in Taiwan. (4) the USA showed average lower mercury species concentrations when compared to those of the other world countries. The average ratios of China/USA values were 89, 76 and 160 for total mercury, RGM and Hg(p), respectively, during the years of 2000–2012.