Project Description

The Mercury Problem in Bolivia

Mercury contamination is a significant environmental and public health issue in Bolivia, particularly due to artisanal and small-scale gold mining (ASGM). In this process, mercury is used to amalgamate gold, releasing mercury into the environment and contaminating rivers, soil, and the atmosphere (UN Environment Programme, 2019). This contamination is especially severe in Bolivia's Amazonian regions. Mercury in water bodies transforms into methylmercury, a highly toxic form that bioaccumulates in the aquatic food chain. Tcis not only affects local biodiversity but also threatens the food security of communities that rely on fishing. Studies have shown that mercury levels in fish from affected areas exceed the safety limits established by the World Health Organization (WHO, 2021), posing a serious risk to human health. Mining communities and populations near ASGM areas are chronically exposed to mercury, which can cause neurological disorders, kidney damage, and cardiovascular problems. This issue is particularly concerning for pregnant women and children, who are more vulnerable to the neurotoxic effects of mercury (Grandjean et al., 1997). Economic dependence on artisanal mining in many regions exacerbates this problem, perpetuating the cycle of mercury contamination and exposure (Veiga, Maxson, & Hylander, 2006).

Furfural and benzoic acid

Figure.1 Mercury problem in Bolivia.

Indigenous communities in the lower Beni River basin, such as the Ese Ejjas, Tsimane’, Tacana, and Mosetene, are particularly affected. A recent study found that 74.5% of the evaluated individuals in these communities had mercury levels above the safety limit of 1 ppm. In general, the study conducted by the Central of Indigenous Peoples of La Paz (CPILAP, 2023) determined that the average mercury concentration in the evaluated individuals was 4 ppm, based on hair sample analysis from 302 people. The study revealed that 25.5% (77 people) had levels below the 1 ppm limit, while 74.5% (225 people) had higher levels, as shown in the figure.

Mercury concentrations by indigenous group

Furfural and benzoic acid

Figure 2.General composition of mercury levels in the sampled individuals.

This study included participants from six indigenous groups. The Ese Ejjas, with a sample of 72 people, showed the highest average mercury concentration at 6.9 ppm, followed by the Tsimane’ with a sample of 10 people at 6.87 ppm, and the Mosetene with 64 people at 4.01 ppm.

Furfural and benzoic acid

Figure 3.Proportion of mercury concentration according to indigenous population.

Current Solutions

Bolivian authorities are implementing regulations and programs to mitigate the impact of mercury, including the supervision of mining activities, environmental monitoring, and the promotion of less polluting gold extraction technologies (El País, 2023; Pan American Health Organization, 2024). However, conventional detection methods, though effective, require qualified personnel and expensive equipment, limiting their accessibility and efficiency.

Conventional Mercury Detection Methods and Their Challenges.

METHODS ADVANTAGES DISADVANTAGES
Cold Vapor Atomic
Fluorescence
Spectroscopy (CVAFS)
  • Extremely low detection limit down to 0.02 ppt.
  • Higher cost and complexity.
  • Requires careful preparation of reagents due to extreme sensitivity.
  • Sensitive to interferences from water vapor and other molecular species.
Direct Analysis by Thermal
Decomposition
  • No sample preparation required.
  • Less acidic waste generation.
  • Ideal for solid samples.
  • Lower sensitivity for liquid samples compared to CVAAS and CVAFS.
  • Limited capacity to process large volumes of liquid samples.
  • High equipment acquisition cost.
Inductively Coupled Plasma Mass
Spectrometry (ICP-MS)
  • High sensitivity and capability to detect trace amounts of mercury.
  • Multi-element capacity.
  • High equipment cost.
  • Special handling of samples and reagents.
  • Lower sensitivity for mercury compared to CVAFS.
Inductively Coupled Plasma Optical
Emission Spectrometry (ICP-OES)
  • Multi-element analysis.
  • Useful for samples with relatively high mercury concentrations.
  • Relatively low sensitivity for trace mercury.
  • Costly equipment.

Our Solution: Bacterial Biosensor

We propose the use of a bacterial biosensor as an innovative and effective solution for mercury detection in water. This biosensor will revolutionize how Amazonian communities, companies, and organizations measure water contamination, allowing for quick, precise, and continuous monitoring without the need to transport samples to distant laboratories. The iGEM Bolivia biosensor detects inorganic mercury (Hg2+) and organic mercury (CH3-Hg+) using synthetic biology, employing optimized genes and molecular logic gates. This technology offers specific and differentiated mercury detection, using transformed bacteria that can be lyophilized on paper and used with an electronic device to generate quantitative results.

Furfural and benzoic acid

Figure 4. Expected response of the mercury biosensor, both plasmids have the detection module using different merRs and a response module with different reporters.

Expected Impact

Public Health: The biosensor will enable authorities to design environmental and public health policies to reduce diseases related to mercury exposure, such as neurological and cardiovascular issues.

Empowerment: Communities will be able to independently monitor water quality, better managing their natural resources and protecting their health.

Biodiversity Preservation: Detecting mercury contamination will help implement policies to protect the fauna and flora of aquatic and terrestrial ecosystems in the Amazon, promoting biodiversity conservation.

Contribution to the Sustainable Development Goals (SDGs)

  • SDG 3: Good Health and Well-being

    Target 3.9: Reduce deaths and illnesses caused by hazardous chemicals and water pollution.

  • SDG 6: Clean Water and Sanitation

    Target 6.3: Improve water quality by reducing pollution and minimizing the release of hazardous chemicals.

  • SDG 15: Life on Land

    Target 15.1: Ensure the conservation and sustainable use of terrestrial and freshwater ecosystems.

The bacterial biosensor offers an innovative solution to address the mercury problem in Bolivia, providing an accessible and efficient tool for detecting and monitoring contamination, with a positive impact on public health and environmental conservation.

References

  • Central de Pueblos Indígenas de La Paz. (2023). Estudio: Contaminación por mercurio en comunidades indígenas asentadas en los ríos Madre de Dios y Beni. Nota técnica. https://bit.ly/4cqewtm
  • El País. (2023). Regulaciones y programas en Bolivia para mitigar el impacto del mercurio. El País.
  • García Moreno, M., Terrazas, O., Tarras-Wahlberg, H., Troche, C., & Méndez, R. (2023). Minería aurífera: El mercurio en cuestión. Friedrich-Ebert-Stiftung en Bolivia (fes Bolivia). https://library.fes.de/pdf-files/bueros/bolivien/20624.pdf
  • Grandjean, P., Weihe, P., White, R. F., Debes, F., Araki, S., Yokoyama, K., Murata, K., Sørensen, N., Dahl, D., & Jørgensen, P. J. (1997). Cognitive deficit in 7-year-old children with prenatal exposure to methylmercury. Neurotoxicology and Teratology, 19(6), pp. 417-428. https://doi.org/10.1016/S0892-0362(97)00097-4
  • Pan American Health Organization. (2024). Estrategias para la reducción del uso de mercurio en la minería artesanal. PAHO.
  • UN Environment Programme. (2019). Global Mercury Assessment 2018. UN Environment Programme, Chemicals and Health Branch.
  • Veiga, M. M., Maxson, P. A., & Hylander, L. D. (2006). Origin and consumption of mercury in small-scale gold mining. Journal of Cleaner Production, 14(3-4), pp. 436-447. https://doi.org/10.1016/j.jclepro.2004.08.010