Medical Geology in India

Medical Geology: Arsenic Poisoning

            There is often a perceived disconnect between subjects such as geology and others such as health or disease. One might not take the time to understand the underlying connection between the two, or even deem that connection to be important. However, geology, and more generally the environment in which one lives, directly affects the status of one’s health. Potential causes, such as arsenic in groundwater, can cause diseases or even mortality when that water is ingested. In a country such as India, where a vast majority of the population lives in close contact with their environment, geological factors have a greatly magnified effect on the health of the residents.

            Arsenic poisoning in western India and Bangladesh, classified as one of the world’s worst environmental disasters, is due to the leaching of arsenic from rocks such as those found in the Himalayas. After arsenic is separated from its original source, it “is transported either in solution or in suspension along with detrital sediment particles, by the rivers originating in the Himalayan mountains, Shillong Plateau and Bihar Plateau and flowing into the Ganga–Brahmaputra deltaic region” (Dissanyake 2010). After being deposited as sediment in the delta, where most coastal cities are located, the arsenic is then accidentally tapped into by the millions of people who own wells, dipping into the groundwater supply every day. They are then more susceptible to develop cancer, cardiovascular diseases, skin disorders, and many other issues. Such is the close relationship between the geological environment of India and the health problems of its citizens.

            Though geological origin is well understood in relation to arsenic poisoning, scientists in some regions are still trying to understand exactly how the arsenic is being leached. The two leading theories are that “oxygen might be desorbed and dissolved from iron oxide minerals by anaerobic groundwater or it might be derived from the dissolution of arsenic bearing sulfide minerals such as pyrite by oxygenated waters” (Bunnell 2007).  It is possible that the “shallow water table aquifers and degradation of organic matter contained in the sediments caused the reduction of adsorbed arsenic associated with it,” thus releasing toxic arsenic into the groundwater. When more organic material accumulates, it only takes a few weeks for more arsenic to enter the water supply (Dissanyake 2010).

Other countries, such as China, Taiwan, Vietnam, and Mexico also have high rates of arsenic poisoning, though Bangladesh appears to have one of the most severe cases. The Bengal basin is one of the largest in the world, created by the water and sediments carried by the Ganges, Brahmaputra and Meghna river systems. Arsenic is often found in such fine sediment as that of the Bengal basin, thus contributing to the estimation that 95% of the population of Bangladesh is susceptible to arsenic poisoning, primarily through use of their wells (Dissanyake 2010).  Though there may not be huge concentrations of arsenic in the sediment, it is “the vast amount of sediments involved in this process [that] makes even low levels of arsenic quite important” (Dissanyake 2010). Also, because certain crops such as rice utilize large amounts of contaminated water, the rice plant soaks up arsenic along with the other nutrients found within the soil. Therefore, when the crop is harvested, the population is also ingesting arsenic in their primary food source, as well as their primary water source.

Possible solutions vary and can be divided into short and long term remedies. Ideas include treating surface water sources, relying more on rain water harvesting, replacing contaminated water sources, and installing arsenic filters into the groundwater pumps. These measures are potentially costly and inconvenient, especially for the poorer areas in which contaminated areas might be located. Other measures, geared more toward long term solutions, are to create deeper tube wells to bypass the arsenic laden groundwater, include arsenic removal systems, or to have surface water treatment plants. Long term solutions, though more efficient and useful than the short term solutions, may allow hundreds of people to be exposed to the arsenic before they even take effect or are built. In cases where lives are at risk, especially in impoverished societies, the balance between efficient solutions and cost can be difficult to maintain.

Though arsenic poisoning is just one of many problems found in countries such as India, medical geology has applications in all countries and regions. Never having thought of the field before, I was incredibly intrigued by the complex relationship between the mineral composition of our environment and the food and water that we consume. In a situation like India’s, where so many live so close to their environment, the theoretical intrigue I experienced while reading the article is subdued by the realization that these case studies represent only a few of the struggles that thousands are experiencing every day. For those of us living in the United States, fear of being poisoned by our groundwater certainly exists, but not nearly at such dramatic levels. All this to show that the study of the environment is not just for those who want to “save the whales,” or hug trees or live on organic farms (though the latter option sounds lovely) –it’s also about studying the complex relationship between humans and the environment in which we live. In some cases, such as medical geology, being aware of the environment will even provide you with the knowledge to find solutions and save lives.

Bunnell, J.E., Finkelman, R. B., Centeno, J.A., Selinus, O., (2007). Medical Geology: A globally emerging discipline. Geologica Acta (5) 3, 273-381.

Dissanyake, C. B., Rao, C. R. M., and Chandrajith, R., (2010). Some Aspects of the Medical Geology of the Indian Subcontinent and Neighboring Regions. In Selinus, O., Finkelman, R. B., and Centeno J. A., (Eds.). Medical Geology: A Regional Synthesis. Springer.