This article presents first a brief overview of cyanide and mercury use in gold extraction processes, impacts of these chemicals on health and the environments. The paper provides a concise comparison of toxicity, cellular targets and mechanisms of actions for selected metallic and cyanide pollutants released from mining plants. The last part of the paper discusses the “expert panel’s safety claims that was briefly mentioned by Mr. Motumma Maqasa, the Minister of the Ethiopian National Defense Force (ENDF). The paper suggests the way forward and also warns the public (stakeholders) never to let MIDROC, and its accomplice- the Ethiopian government, off the hook in the fight to bring lasting solutions to the problems.

Cyanide and mercury based gold extraction processes.

Gold is found in various concentration in ores, special type of naturally occurring rocks, containing a particular metal or valuable mineral in a large amount. Abundance is an important factor for the extraction to be profitable. To extract gold from the ore, first the ore needs to be excavated, and then crushed/ pulverized. The milled ore is then treated with either mercury or sodium cyanide, oxygen and lime solution to dissolve or leach gold and silver from the ore. The process is done in a reactor in vat leach technique. However, large mines now use heap leach techniques in which cyanide solution is run through a heap, to leach or dissolve gold but also silver. In fact, sodium cyanide efficiently and effectively pulls gold from the ore, dissolve it into solution (Fields, 2001). The gold bearing solution (gold-cyanide complex) is retrieved while the insoluble parts are sent to holding dams, waste reserve or tailings. Cyanide is then released into the environment through a waste reservoir or tailing dam while gold is precipitated out of the solution (Acheampong, Meulepas & Lens, 2009) and further refined for marketing.
Like cyanide, elemental mercury is used in gold extraction. Mercury is mixed with milled gold-containing materials, forming a mercury-gold amalgam. The mercury-gold amalgam is then heated to evaporate the mercury and to separate out the gold. This way, a large amount of mercury (Hg) is released to the environment contaminating air, soil and water bodies (Hidayati, Juhaeti & Syarif, 2009).

While there are other methods of extracting gold from ore, such as gravitational method, mercury is still in use particularly in artisanal and small scale mining in some countries because mercury is inexpensive, easy to access and easy to use despite its toxicity to the people and the environment. But what is cyanide? What is mercury? What are the dangers these chemicals pose to health and the environment?

Cyanide toxicity

Cyanide is a compound consisting of one atom of carbon connected to one atom of nitrogen by three molecular bonds (C≡N), or any compound containing the cyanide bond (ASTDR, 2006). Cyanide can exit as a gas, liquid, or crystals. Exposure occurs by inhalation, ingestion or transdermal absorption (Bishop, Fody & Schoeff, 2018).
Cyanide is a rapidly acting toxic compound. It binds with ferric iron and inhibits cytochrome oxidase. This inhibition causes impaired oxygen utilization and cellular energy production leading to progressive histotoxic tissue hypoxia and metabolic acidosis (Baskin, S. I et al, 2008). Cyanide ions also inhibit other enzymes such as glutamate decarboxylase, xanthine oxidase, superoxide dismutase, NO synthase and nitrite reductase (Cassel, 1993).

Cyanide toxicity varies by dose, duration, and route of exposure (ATSDR, 2006). Most sensitive tissues are those with the fastest metabolism of oxygen (Jaszczak, E et al., 2017). Thus, exposure to high levels of cyanide harms the brain and heart first, and may cause coma and death (ATSDR, 2006). Exposure to lower levels may result in breathing difficulties, heart pains, vomiting, blood changes, headaches, and enlargement of the thyroid gland (ATSDR, 2006), confusion, hallucination, abdominal pain, and slurred speech. Baskin, S. I et al, (2008) stated that chronic cyanide exposure may lead to a kinetic rigid syndrome, tremors, pathological reflexes, disorders of sensitivity, intellectual deficits, and significant neurological morbidity arising from the apoptotic demise of neurons of the basal ganglia and sensory-motor cortex.

However, cyanide is biodegradable and does not bio-accumulate (Akcil, 2010). It is removed from water bodies primarily by volatilization as well as by aerobic or anaerobic biodegradation, according to Akcil (2010). Cyanide is cleared from the body mainly by enzymatic conversion to thiocyanate, a non-toxic product that is exerted in urine (Bishop, Fody & Schoeff, 2018). Furthermore, children exposed to cyanide are likely to exhibit the same effects as adults (ATSDR, 2006) and no known cases of birth defects or congenital deformation has been linked to cyanide. However, cyanide is fairly mobile in soil and is able to passes through soil into underground water (ATSDR, 2006).

On the other hand, cyanide is highly reactive with many heavy metals. When milled ore is treated with cyanide solution, cyanide extracts or dissolves gold, silver, and other heavy metals. While gold and silver are retrieved, the rest of the heavy metals are released into the environment.
Cyanide also combines with sulfur and forms acid mine drainage (AMD)—an acidified runoff—that can contaminate streams, and underground water. Acid mine drainage (AMD), according to Fields (2001), is a process in which acidic water is produced from the combination of sulfide minerals, water, air, and highly specialized bacteria. Once those sulfide materials are exposed to a steady supply of water and air, they begin producing sulfuric acid, and that in turn provides a medium in which the microbes thrive and further oxidize the minerals, producing a self- perpetuating chain reaction. AMD seeps out of fields of tailings, waste damps, piles of displaced surface matter and rock being slowly processed for gold removal. If left unchecked, AMD can contaminate groundwater and entire watersheds, contributing not just acidity but heavy metals—such as arsenic, lead, cadmium, mercury, zinc, iron, copper, aluminum, manganese, and chromium—which it releases from the ore it passes through (Fields 2001). These heavy metals are of special concern due to their toxicity, bioaccumulation tendency and persistency in nature and for causing birth defects (Agrawal, 2012).

Mercury toxicity

Mercury exists in three forms: elemental (or metallic), inorganic, and organic mercury compounds. Metallic mercury is liquid at room temperature and is used, among others, in mining. Inorganic mercury is formed when mercury combines with other elements, such as sulfur or oxygen, to form salts. Through methylation by microorganisms, metallic and inorganic mercury can be converted to organic mercury compounds, such as methylmercury. Organic mercury tends to bio-accumulates in the food chain.

Exposure to mercury occurs from breathing contaminated air, ingesting contaminated water and food. Exposure to high levels of mercury can permanently damage the brain, kidneys, and developing fetus (ATSDR, 1999). Chronic exposure over a long time causes neurological disturbances, memory problems, skin rash, and kidney abnormalities and damage to the nervous system. Infants born to women who were poisoned with methylmercury had developmental abnormalities and cerebral palsy, according to (ATSDR, 1999). Very young children are more sensitive to mercury than adults. Mercury in the mother’s body passes to the fetus and may bio-accumulate, possibly causing damage to the developing nervous system. Mercury’s harmful effects that may affect the fetus include developmental abnormalities, brain damage, mental retardation, incoordination, blindness, seizures, and inability to speak (ATSDR, 1999). Furthermore, organic mercury tend to bio-accumulate in the food chain and at high levels has been linked to tremors, paralysis, anemia, bone deformities, and death (Fields, 2001).

Other heavy metals toxicity

As stated previously, use of cyanide in mining causes the release of mercury and other heavy metals into the environment. Like mercury, other heavy metals such as lead, cadmium, arsenic and chromium are well known for causing birth defects (Agrawal, 2012). The developing fetus, newborns and children are much more sensitive to the effects of heavy metals even at low levels of exposure mainly due to:

(a) less body weight,

(b) higher food consumption metabolic rate per kilogram of body weight,

(c) higher gastrointestinal absorption rate,

(d) less effective renal excretion, and (e) less effective blood-brain barrier.

Lead is unique in that it is tightly bound to red blood cells, thereby enhancing the transfer from maternal circulation through the placenta, according to Agrawal (2012).

This toxicity of heavy metals was well illustrated in Ismawati (2016) report that chronic exposure to mercury was linked various birth defects, such as infants born without fingers, without ears, only with one eye, with cleft lips and palates, with upper or lower limb reductions, with head shape anomalies (microcephaly and hydrocephaly), with imperforate anus, with intestines or other organs stick outside of the belly through the belly button, with weak arms and legs (muscular dystrophies), with lump on the forehead, and or with congenital cataracts. As the children grew up, Ismawati (2016) added, “some of them have delayed development and or neurodegenerative anomalies and becoming mute and deaf. Some survived only to the age of 15, while most could not make to 6 months”. Even more disturbing, according to Ismawati (2016), was the finding that more children born with birth defects years after the mining activities stopped.

MIDROC’s use of cyanide and mercury and the safety claims

Based on the available literature, congenital deformities are associated with exposure to mercury, lead other heavy metals (see Table 1, below). These metals are non-biodegradable and tend to bio-accumulation in the food chains. Exposure to cocktails of these heavy metals may exacerbate the problem even at lower concentration. Cyanide dissolves heavy metals from the ores and releases them into rivers and underground water bodies. Cyanide-sulfur-acid water seeps through underground and dissolves rocks and release these heavy metals to toxic levels.
The problem is tightly linked to the use of mercury and cyanide. The later, as stated above, further causes release into the environment of heavy metals. Also MIDROC stated it generated about 32 million tons of slurry or waste damps over the last 20 years. When this amount of mining waste is constantly exposed to acid forming agents: cyanide, water and air, the amount of acid mine draining it produce must be significant. The amount of waste generated seems even far more than the stated 32 million tons if the amount of water and various chemicals that must be added to the ore, as part of the gold-silver extraction process, is taken into account.

Citing expert opinion, Fields (2001) stated that “many old mines have acid mine drainage problems since they were built without any form of engineering design controls or environmental awareness about that problem”. Fields (2001) 1statement points to the fact that no mining license should be issued, at least in the present time, unless the licensee can attests to that the operation does not present risk to the public and the environment because, among other, of acid mine draining otherwise the licensee must first puts in place required safety measures as a precondition. In this connection, given the geological & hydrological features of the region, what measures were put in place when MIDROC was issued the license the first time? If not, what remedial measures have been taken by MIDROC to address the problems? What measures have been implemented to prevent formation of acid mine drainage? What measures have been implemented to treat or neutralize chemicals/ wastes released to the environment as a result of the extraction processes?

Expert panel’s report: revelations or cover ups?

In an effort to disarm the people’s vehement rejection of MIDROC dirty mining operations, Mr. Motumma Maqasa, the Minster of the Ethiopian Ministry of National Defense Force (ENDF), explicated that the health problems were not caused by cyanide and mercury contamination as claimed.

Mr. Motumma Maqasa, the Minster of the ENDF stated that an expert panel was charged to investigate into the claims that cyanide and mercury released from the mines caused birth defects, deaths, and related health problems, and widespread environmental pollution. Citing the expert panel’s report, Motumma Maqasa denied the claims stating that the health problems were not due to those chemicals. However, he acknowledged that both mercury and cyanide are used in commercial mining in Ethiopia. He also acknowledged the panel’s findings of improper storage, retention and disposal of chemicals used in the extraction processes.

I have not seen the report. But the statement by the Minister of the ENDF is disturbing, to say the least. If the statement and the said report of the expert panel corroborate each other, then in deed, it is the most disturbing and damaging for the following reasons:

  • Firstly, the report is disturbing in that mercury is still in use in commercial mining in Ethiopia and that it is in use with government approval.
  • Secondly, the report confirmed that both cyanide and mercury are still being used in gold extraction in Laga Dambi and elsewhere in Ethiopia, while no proper waste disposal and management strategies were put in place or enforced by the government.
  • Thirdly, here in 2018, there exists an “expert panel” that claims that cyanide and mercury were not the causes or contributory factors for the observed birth defects and related health problems. In so doing, the expert panel ratified the continued use of mercury and cyanide as safe and acceptable standard of practices.
  • Fourthly, the ENDF official seems oblivious to the nature and magnitude of the problem on the ground. There is serious disconnection here. Lack of political mandate and will to solve the problem is one thing. Covering up a crime of such magnitude is entirely a different thing. The latter is a crime that dwarfs all other crimes. Such an act not only erodes public trusts and tarnishes the image of the highest office in the land and the moral authority of the leadership at its helm, but also it sends a chilling signal to the affected communities and the public at large that the government is on MIDROC’s side, not the victims and the environment.
  • The expert panel’s safety claims were baseless. Therefore, MIDROC and, its accomplices, the Ethiopian government, should be hold accountable for the long term health and environmental devastation caused by MIDROC’s dirty mining operations. The health and water pollution we currently see are just the tip of the ice berg. Sadly much worse is to come. That is why we should hold MIDROC, and its accomplices, accountable not only for what have happened but also all future ramifications including compensations for loss of lives, cost of care, lost livelihoods and costs for environmental clean-up and revitalization of the affected communities, including downstream communities. To address the long term health, socio-economic and environmental damages in the making, legal framework representing stakeholders need to be put in place.
  • Also one of the stated objectives of MIDROC was to enter into business transaction in the selling and buying of the products, such as gold (emphasis, mine), both within the local and foreign markets. The question is whether MIDROC, to achieve its stated objective, engaged, facilitated or encouraged its local suppliers, within or outside its own plants, to use mercury in gold extraction and in doing so played a role in further release of mercury into the environment?
    Expert panel’s social and ethical responsibilities: a call for clean ups

First of all, thank you for taking this responsibility seriously and for engaging to serve your people, country and profession. Even more so, thank you for noting the deficiencies in MIDROC’s mining practices and for admitting that you needed to do further investigation in order to make sound judgement. However note that you have ratified MIDROC’s continued use of mercury and cyanide to cause further destruction of lives, livelihoods and the environment while it continues to loot the health and wealth of the nation. Whatever your opinions may be, and the nature of data that you have- I assume you do, your endorsement of the use of mercury and cyanide in mining and its release into the environment as safe and acceptable standard of practice violates all the international codes, standards, and scientific understandings (Baskin S, I et al, 2008, Cassel1993, ASTDR 1999 & 2006, Argrawal 2012), see also the Minamata convention on mercury (videos 1, 2, 3).
In a country were witness statements can be fabricated by those in power, to cut precious lives short, it is not far-fetched to think that this report too was fabricated. However, I am in no way to assume yours is fabricated. Contrary to that, I believe you have a case here to make. I am in no doubt, however, that money or power could buy or silence experts to blur the truth. If that is the case, it does so only for the briefest of the moment. Today, we are in that darkest moment. You, the expert panel could save us from all the waiting by answering these simple questions:

  1. What was the nature and magnitude of the investigation?
  2. Did the investigation involve document review only?
  3. Did the investigation include laboratory testing?
  4. If yes, what were the analytical methods and instruments used in the analysis?
  5. What were the samples tested?
  6. Were urine, blood or hair, as appropriate, samples from affected individuals and unaffected included for comparison?
  7. Were the results of the investigation published or made public in writing or website?

Finally, what were the scientific or clinical findings on which the expert panel rested its conclusions that mercury and cyanide discharged from the mining were not the cause of the widespread birth defects, deaths, and related health problems and environmental pollution? To clean its name off such blunder, the expert panel must address these, and related, questions by publishing and making the findings of the investigation available to the public.

Conclusions: the way forward

Qeerroo, the Oromo public and the people of Ethiopia at large, understand that willful release of toxic chemicals into the environment for the sake of enriching the few while jeopardizing the health and well-beings of defenseless segments of our society and the environment is a crime of the highest order. Those who facilitated or are facilitating this crime, by commission or omission, must be hold accountable. Given the denials, betrayals, and fabrications by those whom we entrust to protect our most cherished values: the life of the fetus and the future generations, simply our future and the future of our nation, we should act in unison to reject the dispossessions and dirty mining operations that are causing health, social and environmental disasters.
In this connection, I must state the obvious that renewing MIDROC’s mining license will not solve the problems. Neither is the shutting down of the Laga Dambi or banning of MIDROC, for that matter, will solve the problems or cure those precious lives devastated by MIDROC’s toxic wastes. The problem has festered for too long. Neither is a total ban on mining or MIDROC will solve the problems. In spite of this, the government should withhold the license until MIDROC. In order to engage in this type of business that puts the people and the environment at risk, MIDROC must first: (a) addresses the health, social and environmental problems it caused, (b) put in place long term preventive measures, (c) institute remedial actions in case the preventive measures fail, (e) ensures that the measures put in place meet international and industry standards, and (f) that the measures are verifiable or verified by an independent third party. The nation should hold the stockholders, both MIDROC and the government, accountable for the damages inflicted on the communities and the environment. We should never let MIDROC, and its accomplice, off the hook. The stockholders must meet the industry standards and, above all, respect the will of the people- the stakeholders.



  1. Acheampong, M. A., Meulepas, R. J & Lens, P. N. L. (2010). Removal of heavy metals and cyanide from gold mine wastewater. J ChemTechnol Biotechnol
  2. Agency for Toxic Substances and Disease Registry (ATSDR). (1999). Toxicological profile for mercury. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. https://www.atsdr.cdc.gov/toxfaqs/tfacts46.pdf
  3. Agency for Toxic Substances and Disease Registry (ATSDR). (2006). Toxicological profile for cyanide (update). https://www.atsdr.cdc.gov/toxguides/toxguide-8.pdf
  4. Akcil, A. (2010). A new global approach of cyanide management: International cyanide management code for the manufacturer, transport, and use of cyanide in the production of gold. Mineral Processing & Extractive Metall. Rev., 31: 135–149.
  5. Baskin, S.I et al. (2008). Cyanide poisoning: In: Medical Aspects of Chemical and Biological Warfare
  6. Bishop, M. L., Fody E. P & Schoeff, L. E. (2018). Clinical Chemistry: techniques, principles, and correlations. 8th ed. Wolters Kluwer.
  7. Cassel, G. (1993). Cyanide and central nervous system: a study with focus on brain dopamine. https://www.diva-portal.org/smash/get/diva2:798876/FULLTEXT01.pdf
  8. Fields, S. (2001). Tarnishing the earth: gold mining’s dirty secret. Environmental Health Perspectives.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1242089/pdf/ehp0109-a00474.pdf
  9. Ismawati, Y. (2016). Children’s exposure to environmental toxicants. UN Committee on the rights of the child 2016 Day of General Discussion “Children’s Rights and the Environment”
  10. Jaszczak, E, Polkowska, Z., Narkowicz, S & Namieśnik, J. (2017). Cyanides in the environment—analysis—problems and challenges. Environ Sci Pollut Res
  11. Hidayati, N., Juhaeti, T & Syarif, F. (2009). Mercury and cyanide contaminations in gold mine environment and possible solution of cleaning up by using phytoextraction.


Ibsa Abdi, MLS (ASCP)

Ibsa holds a MSc in Health Sciences from Augusta University, Augusta, Georgia. He is an academician and a doctoral candidate in Health Science. He reads on public health, community, environmental health, and health equity.
He could be reached at ibsaa2@gmail.com


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