Exposure Science: What Toxicants Are We Consuming, Are They Dangerous, and How Do We Cope?

     In the early 1500s, the famed alchemist Paracelsus supposedly coined a phrase that has remained an enduring principle in toxicology: “The dose makes the poison.” The next thing to consider is, “What makes the dose?” The answer is, of course, the level of exposure. In 1983 the National Research Council (NRC) devised a four-step process to assess risk: hazard identification, dose-response assessment, exposure assessment, and risk characterization. Two of those, dose-response assessment and exposure assessment, are key to exposure science. Exposure science is a companion field to environmental epidemiology and toxicology. The NRC defines dose-response assessment as:

“The determination of the relationship between the magnitude of exposure and the probability of occurrence of the health effects in question.”

They further defined exposure assessment as:

“The determination of the extent of human exposure before or after application of regulatory controls.”

     We know we are being exposed to many different chemicals in the environment, from the water we drink, the food we eat, and the air we breathe. We know we are accumulating microplastics and other chemicals that bioaccumulate in our bodies. One of the main determinations from exposure science is to know what a threshold dose is for causing harm. That varies considerably for different chemicals from completely safe at all levels to completely unsafe at any level. Some chemicals accumulate in the body or bioaccumulate, and so the dose may increase over time.

     According to Wikipedia via the NRC and others:

“Exposure science is the study of the contact between humans (and other organisms) and harmful agents within their environment – whether it be chemical, physical, biological, behavioural or mental stressors – with the aim of identifying the causes and preventions of the adverse health effects they result in.”

     Below are two exposure science frameworks. The first is a general framework. The second incorporates technologies that aid exposure assessment. 

     In order to evaluate risk, we need to know what we are being exposed to and at what levels. In our modern world of tens of thousands of different chemicals, both natural and synthetic, that is no easy task. Exposure avenues such as occupational exposures, lifestyle exposures, and relative position to sources of contamination, ie. downwind or downstream, can be paired with epidemiological data about exposure times and susceptibility in the population. This susceptibility may be genetic susceptibility or predisposition to get cancer and also includes the addition of other factors, including lifestyle factors that can increase both total toxin exposure and susceptibility. We know very well that airborne toxins can sicken and kill. Some act fast, others slower. Chemical warfare is waged with poisonous gases that can kill fast. Industry produces and manages poisonous gases as well, with the goal of preventing exposure. Exposure to fine particulate silica dust and coal dust leads to the debilitating incurable fatal lung diseases silicosis and black lung disease. These diseases develop over time to a point where they can’t be stopped. Controlling and reducing exposure is what prevents them.

     Teasing meaningful trends from fields like cancer epidemiology and finding things like genetic biomarkers and exposure biomarkers remains a challenge and a focus. Biomarkers are defined as “measurable indicators of biological processes or conditions.” They are how we can tag specific exposures to specific responses in better detail. Isolating the effects of one chemical when we are exposed to thousands of chemicals seems a daunting task. Sometimes there are obvious relationships. We know that mismanaged lead-acid battery recycling facilities have released large amounts of lead dust that have sickened and killed children and sickened adults. We know that workers at plants that make coking coal and those who live very nearby develop diseases and often die from them. There are numerous examples of high-exposure events that harm human and environmental health. A lot of what we know about exposure science has come from studying accidental or unintentional events where people or another biota were poisoned. Unfortunately, there are also numerous attempts to try and tie questionable exposure levels to real effects by those who advocate for stronger regulations. There may also be attempts to dissociate possible relationships between contaminants and effects. Thus, we need to be careful to follow science rather than manipulative policy spin.

 

 

The Exposome

     People or other biota with higher susceptibilities would require less exposure to cause harm than people without those susceptibilities. Designing studies to determine relationships between susceptibility and exposure levels was seen as a need when Christopher Paul Wild coined the term ‘exposome’ in 2005 to refer to the external, internal, and biological response factors of exposure. It is seen as complementary to the genome used to describe genetic factors, or transcriptome, proteome, and metabolome to describe those respective factors. Biological response factors may include inflammation, infection, lipid peroxidation, and oxidative stress. His goal was to study exposure in a more systematic way. His argument was that genetic fingerprinting through biomarkers was much further along than exposure fingerprinting through exposure biomarkers. Just as metabolic fingerprinting through the detection and measurement of specific metabolites yields meaningful knowledge so should exposure fingerprinting through some expression of the exposome. He calls these fields ‘omics technologies.’ In his own words:

“The concept of an exposome may serve to highlight this requirement {to develop reliable exposure assessment tools} and to balance the effort going towards characterization of the genome. An extension of the current generation of biomarkers, together with an evaluation of the new generation of “omics” technologies, has a crucial role to play in this regard. However, advances will require increasing collaboration between epidemiologists, biostatisticians, experts in bioinformatics, and laboratory and environmental scientists.”

The exposome describes environmental exposures encountered throughout life, and how these exposures impact biology and health. It is a way to explore and refine exposure assessment, step 2 of the NRC’s risk assessment process. We often need to know not just whether an environmental exposure is causing a specific response but whether or not it is simply a contributing factor among many to a response and at what magnitude.

     Some exposure science graphics and flow charts are shown below.

     In a paper published in November 2013 in Toxicology Science authors Gary W. Miller and Dean P. Jones set out to explore the exposome and its relationship to the biological framework. The paper was titled: ‘The Nature of Nurture: Refining the Definition of the Exposome.’ The authors echoed Wild when they argued that our knowledge of nature as the genetic side of the picture was much farther along than our knowledge of nurture, the environmental side of the picture. The human genome is well-mapped but hopes that it would lead to widespread disease reduction have been tempered by the gradual realization that the majority of disease factors are not genetic. They acknowledged the need to better quantify the environmental contributions to disease. They also noted that biology and environment, nature and nurture, often overlap and grade into one another.

“The simple distinction between genes and environment is blurred by knowledge that environmental exposures cause permanent genetic changes via mutagenesis and also have long-term impact on gene expression through epigenetic mechanisms. Importantly, epigenetic mechanisms are central to differentiation and development, impacting genome function before birth and throughout life.”

“The epigenome is highly reliant on nurture, ie, the nature and timing of environmental exposures and external forces.”

Miller and Jones expanded the Wild’s exposome concept to arrive at a more comprehensive definition:

Exposome: The cumulative measure of environmental influences and associated biological responses throughout the lifespan, including exposures from the environment, diet, behavior, and endogenous processes

     They explain the need for a new science of nurture to improve our understanding of environmental contributions to disease through mechanisms such as epigenetics and balance it with our understanding of predisposed susceptibility to disease through genetics.

“…exposome research can begin to provide the tangible and quantifiable entities that medicine and public health desperately need. The success of the Human Genome Project exposed an imbalance in the nature-nurture interaction. Elucidating the exposome, ie, developing an integrated science of nurture, will help fulfill the promises of the Human Genome Project.”

As a cumulative exposure idea, the exposome also encompasses other factors such as the metabolome. The metabolome refers to the complete set of small-molecule chemicals found within a biological sample. The end products of metabolic reactions are known as metabolites. Metabolite chemicals may be endogenous, produced internally naturally, or exogenous, produced by consumption typically via water, food, or air.

     According to Lindzi Wessel in a September 2019 article in Knowable Magazine, what is needed to be known in exposomic toxicology, is:

“…which environmental exposures are the most worrying and if there are windows of vulnerability — times of life when exposures may be especially harmful.”

Wessel highlights the growing presence of environmental monitoring technology with costs coming down and coverage growing. She mentions silicon bracelets that measure exposure to various airborne contaminants. The growing presence of satellite air monitoring can help to determine exposure levels by comparing that data to one’s cellphone location data. Better data acquisition very often leads to different outcomes than expected as she recounts in a few examples, such as determining the correct allergen among different possibilities or the risk level of an asthmatic entering a room before it was vacuumed or just after (studies have shown that just after is worse).

     Exposure scientists want to know:

“…if certain substances are dangerous in particular combinations, during particular times — such as during pregnancy — or to particular groups of people.”

Our ability to collect data about both our environment and our real-time health via sensors on our smartphones can also greatly aid our ability to assess both exposure occurrences and exposure responses. Wessel notes:

“Signatures left over in blood, urine, teeth and even toenails can hint at previous exposures. Blood in particular holds clues that can let researchers work backwards to match biological changes to triggering exposures, says Dean Jones, a biochemist at Emory University in Atlanta and coauthor of a 2019 article about the promise of the exposome paradigm in the Annual Review of Pharmacology and Toxicology.”

“With tens of thousands of detectable components that hint at what the body is doing chemically, metabolites may be one possible alphabet scientists could use to read back what’s happened internally following various exposures.”

     Another way to link internal responses to external exposures with blood metabolites is through examining human serum albumin, a protein that captures and removes harmful compounds circulating in blood. The graphic below shows how this information may be used to uncover such links.

 

     Even if we can link blood metabolites to toxicant exposures it remains challenging to determine which chemical led to the specific metabolites. We have metabolite data for tens of thousands of chemicals but there are even more for which we have no data. Thus, there is a big data problem that needs to be solved. One method of studying the genetic factors of disease is the genome-wide association study or GWAS. It is a method that determines which genes vary in conjunction with a particular disease or symptom. Wessel notes:

“In 2010, Harvard bioinformatician Chirag Patel adapted the GWAS into an environment-wide association study {EWAS} to see how 266 environmental factors varied in step with the risk of developing type II diabetes.”

This led to a better understanding of the combination effects of different exposures. Wessel also notes that the GWAS methodology, still considered imperfect, is more contained in that in the human genome about 20,000 genes code for proteins. However, we are exposed to hundreds of thousands of different chemical compounds, both natural and synthetic, from the environment. Thus, EWAS remains more challenging than GWAS, but it is gaining traction.

          Metabolic diseases like obesity and diabetes are serious problems in most places in the modern world.  A January 2022 paper in Environment International highlights how biomarkers can integrate exposomics and metabolomics. Classes of environmental toxicants such as endocrine-disrupting chemicals (EDCs) and metabolism-disrupting chemicals (MDCs) lead to disruption in signaling and metabolic pathways. The authors note:

“Contaminants including heavy metals and organohalogen compounds, especially EDCs, have been repetitively associated with metabolic disorders, whereas emerging contaminants such as perfluoroalkyl substances and microplastics have also been found to disrupt metabolism. In addition, we found major limitations in the effective identification of metabolic biomarkers especially in human studies, toxicological research on the mixed effect of environmental exposure has also been insufficient compared to the research on single chemicals. Thus, it is timely to call for research efforts dedicated to the study of combined effect and metabolic alterations for the better assessment of exposomic toxicology and health risks.”

     Computational exposure science is an emerging field. According to a 2015 paper in Environmental Health Perspectives, computational exposure science is the:

“…integration of advances in chemistry, computer science, mathematics, statistics, and social and behavioral sciences with new and efficient models and data collection methods to reliably and effectively forecast real-world exposures to natural and anthropogenic chemicals in the environment.”

It seems to me that now in the age of big data, machine learning, and AI we could be on the cusp of a much better understanding of biological responses to specific exposures. When I read and later reviewed Sandra Steingraber’s book ‘Living Downstream: An Ecologist’s Personal Investigation of Cancer and the Environment’ I noted her frustration regarding the difficulty of teasing out data about the biological effects of exposure to environmental toxicants. Hers was a very personal story of trying to track her own development of bladder cancer, which has been associated with environmental exposures, early in life. She suspects her condition was caused by or influenced by exposure to the pesticide atrazine which was commonly used where she grew up in the farm region of Illinois. She may never know if this is true but if we can refine our knowledge through the advancement of exposure science perhaps people in the future in a similar situation can know. More importantly, we may be able to predict what people will be most susceptible to with better knowledge of not only genetics but of the sciences of the other “omes,” or “omics” as they are sometimes referred to. Exposomics, bioinformatics, and better and more environmental monitoring can help acquire that knowledge, and machine learning and AI can probably help to find hidden patterns in the data.

     Computational exposure science was given a framework and modeled in the 2015 study mentioned above. The framework is shown below.

     Another important thing noted in that paper is that there has been a dramatic increase in the number of chemicals for which probabilistic exposure assessments have been completed. 

This new data can also be integrated and processed via machine learning. The problem remains the obtaining of accurate quantification of human exposures to individual chemicals, accumulated chemicals, chemical combinations, and toxic byproducts. One potential result is developing a model for each person in terms of susceptibilities that includes assessment of genetic factors, lifestyle exposures, occupational exposures, and internal data like blood metabolites.   

 

References:

 

The next omics? Tracking a lifetime of exposures to better understand disease. Lindzi Wessel. Knowable Magazine. September 19, 2019. The next omics? Tracking a lifetime of exposures to better understand disease | Knowable Magazine

Exposure science. Wikipedia. Exposure science - Wikipedia

National Research Council (US) Committee on the Institutional Means for Assessment of Risks to Public Health. Wahington (DC): National Academies Press (US); 1983. Risk Assessment in the Federal Government: Managing the Process. Front Matter | Risk Assessment in the Federal Government: Managing the Process | The National Academies Press

A Discussion of Exposure Science in the 21st Century: A Vision and a Strategy. Paul J. Lioy and Kirk R. Smith. Environmental Health Perspectives. Volume 121, Issue 4. Pages 405 – 409. January 31, 2013. A Discussion of Exposure Science in the 21st Century: A Vision and a Strategy | Environmental Health Perspectives | Vol. 121, No. 4

Computational Exposure Science: An Emerging Discipline to Support 21st-Century Risk Assessment. Peter P. Egeghy, Linda S. Sheldon, Kristin K. Isaacs, Halûk Özkaynak, Michael-Rock Goldsmith, John F. Wambaugh, Richard S. Judson, and Timothy J. Buckley. Environmental Health Perspectives. Volume 124, Issue 6. Pages 697 – 702. November 6, 2015. Computational Exposure Science: An Emerging Discipline to Support 21st-Century Risk Assessment | Environmental Health Perspectives | Vol. 124, No. 6

Complementing the Genome with an “Exposome”: The Outstanding Challenge of Environmental Exposure Measurement in Molecular Epidemiology. Christopher Paul Wild. Cancer Epidemiol Biomarkers Prev (2005) 14 (8): 1847–1850. Complementing the Genome with an “Exposome”: The Outstanding Challenge of Environmental Exposure Measurement in Molecular Epidemiology | Cancer Epidemiology, Biomarkers & Prevention | American Association for Cancer Research

Exposome. Wikipedia. Exposome - Wikipedia

A review of environmental metabolism disrupting chemicals and effect biomarkers associating disease risks: Where exposomics meets metabolomics. Jiachen Sun, Runcheng Fang, Hua Wang, De-Xiang Xu, Jing Yang, Xiaochen Huang, Daniel Cozzolino, Mingliang Fang, and Yichao Huang. Environment International Volume 158, January 2022, 106941. A review of environmental metabolism disrupting chemicals and effect biomarkers associating disease risks: Where exposomics meets metabolomics - ScienceDirect

The Nature of Nurture: Refining the Definition of the Exposome. Gary W. Miller and Dean P. Jones. Toxicol Sci. 2013 Nov 9;137(1):1–2. The Nature of Nurture: Refining the Definition of the Exposome - PMC

Metabolome. Wikipedia. Metabolome - Wikipedia

Assessing the Exposome with External Measures: Commentary on the State of the Science and Research Recommendations. Michelle C. Turner, Mark Nieuwenhuijsen, Kim Anderson, David Balshaw, Yuxia Cui, Genevieve Dunton, Jane A. Hoppin, Petros Koutrakis, and Michael Jerrett. Annual Review of Public Health Volume 38, 2017. Assessing the Exposome with External Measures: Commentary on the State of the Science and Research Recommendations | Annual Reviews

The Exposome: Molecules to Populations. Megan M. Niedzwiecki, Douglas I. Walker, Roel Vermeulen, Marc Chadeau-Hyam, Dean P. Jones, and Gary W. Miller. Annual Review of Pharmacology and Toxicology. Volume 59, 2019. The Exposome: Molecules to Populations | Annual Reviews

 

EPA Air Quality: National Summary for 2023: Analysis

     The annual EPA Air Quality National Summary includes air quality trends, emissions trends, and weather influence. The data clearly shows improvements in nearly all ambient air pollutants in the most recent trend from 2010-2023. EPA notes:

“These estimates are based on actual monitored readings or engineering calculations of the amounts and types of pollutants emitted by vehicles, factories, and other sources. Emission estimates are based on many factors, including levels of industrial activity, technological developments, fuel consumption, vehicle miles traveled, and other activities that cause air pollution.”

Input from state and local air quality agencies, tribes, and industry is used to get the data. Percent changes in air quality are shown below. I made two graphs from the data to show the same information graphically, one for 2010-2023 and one for 2000-2023.

     The next table shows the percent changes in emissions. Similarly, I made two graphs from the data, one for 2010-2023 and the other for 2000-2023. The emissions data shows changes in VOC emissions as well as the six criteria pollutants.

“Emissions of air pollutants continue to play an important role in a number of air quality issues. In 2023, about 66 million tons of pollution were emitted into the atmosphere in the United States. These emissions mostly contribute to the formation of ozone and particles, the deposition of acids, and visibility impairment.”

     The graph below shows some interesting, important, and optimistic trends. It is clear that the aggregate emissions from the six criteria pollutants (lead, carbon monoxide, nitrogen oxides, sulfur dioxide, PM 2.5, and ozone) have thoroughly decoupled from GDP, vehicle miles traveled, and population. Energy consumption and CO2 emissions have also decoupled from GDP, vehicle miles traveled, and population, but not as much as the air pollutants. There are several reasons for the reductions in air pollutants including the retiring of more coal-fired power plants which reduced sulfur dioxide, PM, and NOx, and some of the other criteria pollutants. This increase in the retiring of these plants was made possible in large part due to the wide low-cost availability of less-emitting natural gas to replace coal. That availability was enabled by advances in the upstream oil & gas industry such as high-volume hydraulic fracturing, horizontal drilling, and other associated technological and efficiency improvements in the industry. Tighter regulations also contributed to the decrease. It is a success story that should be told more often.

     The final graph below shows that there is still more work to be done to decrease air pollution since millions of people still live where air pollutants are present at high levels, particularly ozone and particulate matter.

     Finally, the EPA notes that the weather has a strong influence, particularly on the ozone and particulate matter that make up most of the air pollution problems faced today.

“Weather conditions influence emissions and air quality.  EPA has developed statistical approaches to account for weather’s influence on ozone and fine particles.  While these approaches do not change the quality of air we breathe, they do help us understand how well emission reduction programs are working.”

 

References:

 

Air Quality – National Summary. U.S. EPA. 2024. Air Quality - National Summary | US EPA

Earth’s Carbonate-Silicate Cycle: Will the Brightening Sun Disrupt It Enough Over the Next Billion Years to Destroy Life on Earth? Maybe or Maybe it Will Take Longer

     The earth undergoes several different geochemical cycles such as a carbon cycle and a nitrogen cycle. In geology, one of the most important cycles is the carbonate-silicate cycle. It is a long-term cycle that takes millions of years to complete. Wikipedia describes it as follows:

‘The carbonate–silicate geochemical cycle, also known as the inorganic carbon cycle, describes the long-term transformation of silicate rocks to carbonate rocks by weathering and sedimentation, and the transformation of carbonate rocks back into silicate rocks by metamorphism and volcanism.”

When weathered rocks are buried the CO2 in them is removed from the atmosphere. It returns to the atmosphere via volcanism. Thus, this cycle is a long-term CO2 regulator, often referred to as the Earth’s thermostat or buffering system. The carbonate-silicate cycle can be considered a branch of the carbon cycle, the inorganic branch as distinguished from the organic carbon branch of the cycle. It cycles over a much longer time period than organic carbon does.

     Carbonic acid (H2CO3) is a weak acid that occurs in rainwater and over time dissolves both carbonate rocks and silicate rocks. The main reactions of the carbonate-silicate cycle are shown below:

“99.6% of all carbon on Earth (equating to roughly 108 billion tons of carbon) is sequestered in the longterm rock reservoir. And essentially all carbon has spent time in the form of carbonate. By contrast, only 0.002% of carbon exists in the biosphere.”

Both biology and tectonics affect weathering rates and atmospheric CO2. The carbonate-silicate cycle is considered to be insensitive since it allows for large temperature swings in the Earth’s history. All planets with water may all have some sort of carbonate-silicate cycle.

     A 2019 article about the cycle by James Kasting at Chicago University notes:

“Most silicate weathering is thought to occur on the continents today, but seafloor weathering (and reverse weathering) may have been equally important earlier in Earth’s history.”

He also explains the carbonate-silicate  cycle as follows:

“The by-products of silicate weathering include calcium and magnesium ions (Ca2+ and Mg2+), bicarbonate ions (HCO3−), and dissolved silica (SiO2). These dissolved products are carried by streams and rivers down to the ocean where various organisms use them to make shells of calcium carbonate (CaCO3) or silica. Today, much of this carbonate precipitation is carried out by organisms that live in the surface ocean, such as the planktonic foraminifera. During the Precambrian, this function was performed primarily by benthic, mat-forming organisms, creating stromatolites. But carbonate would precipitate anyway, even on an abiotic planet, as the products of weathering—specifically, alkalinity ≅ [HCO3−] + 2[CO32−]—accumulated in the ocean. When organisms such as foraminifera die, they sink into the deep ocean. The deep ocean is slightly more acidic than the surface ocean, and so most of the carbonate redissolves. A portion of it is preserved, however, and forms carbonate sediments that coat parts of the seafloor. When this seafloor is subducted, some of the carbonate is scraped off, but some of it is carried down to great depths. There, the heat and pressure cause calcium and magnesium to recombine with silica (which by this time is the mineral quartz), reforming Ca/Mg silicates and releasing gaseous CO2. This CO2 is restored to the atmosphere by volcanism. Ignoring Mg, the entire cycle can be represented by the reaction

 CaSiO3 + CO2 ↔ CaCO3 + SiO2

     New research suggests that life may have more than 1 billion years left on Earth, perhaps 1.6 billion years or more. A September 2024 paper described by Phys.org notes that other feedbacks could take place, extending life on Earth. It is a strange prediction, I suppose, since it is difficult to predict what will happen the next day, let alone the 365 billion days into the future it would take to make up 1 billion years. According to phys.org:

But if Earth's biosphere has a much longer lifespan than thought, that affects the hard steps model.

"A longer future lifespan for the complex biosphere may also provide weak statistical evidence that there were fewer 'hard steps' in the evolution of intelligent life than previously estimated and that the origin of life was not one of those hard steps," the authors conclude.

If that's the case, then exoplanet habitability could be less rare than thought.

     I’m not sure what I wanted to accomplish with this post. Perhaps I just wanted to introduce the carbonate-silicate cycle, associated feedback cycles, and some possible (far-off) future implications.  

 

References:

Life might thrive on the surface of Earth for an extra billion years. Evan Gough. Phys.org. September 20, 2024. Life might thrive on the surface of Earth for an extra billion years (msn.com)

Carbonate-silicate cycle. Wikipedia. Carbonate–silicate cycle - Wikipedia

The Goldilocks Planet? How Silicate Weathering Maintains Earth “Just Right.” James F. Kasting. Elements. Volume 15, Number 4, August 2019. Geoscience World. Kasting_2019.pdf (uchicago.edu)

The Value of Oil in South Sudan, a Fledgling Country Trying to Recover from Conflict

 

     South Sudan gained independence as a country in 2011. They are the youngest country in the world. Sudan’s second major civil war ended in 2005 with the Comprehensive Peace Agreement (CPA). The southern part of the country voted overwhelmingly to secede, and South Sudan became an independent country in 2011. The CPA established guidelines for oil revenue sharing based on where the oil originated. South Sudan gained 75% of the country’s oil production to Sudan’s 25%. Oil from South Sudan flows through Sudan to ports for export. Sudan collects fees for transporting the oil. According to an EIA analysis of energy in Sudan and South Sudan:

“Since the split, oil production growth in Sudan and South Sudan has stagnated because of insufficient upstream investment and continued domestic political instability in both countries.”

     Unfortunately, a civil war broke out in South Sudan in 2013 with a peace agreement reached in 2018 that remains a bit tenuous. There are also long-standing disputes between Sudan and South Sudan on borders, oil-sharing issues, and other matters. In April 2023, a war broke out in Khartoum, the Sudanese capital city, between the Sudanese Armed Forces (SAF) and the rebel group known as the Rapid Support Forces (RSF). Recently the RSF has been credibly accused of genocide by the U.S. government.

     South Sudan is heavily dependent on oil revenue. Oil accounts for almost all its exports and 90% of government revenue, according to the IMF. 80% of South Sudanese people survive on agriculture and the country is also heavily dependent on humanitarian aid. It is quite clear that oil revenues can really help both of these countries, especially if oil production could increase with more exploration and infrastructure buildouts. Unfortunately, that is not likely in the near term due mainly to ongoing conflict risks. The main pipeline transporting oil from South Sudan and Southern Sudan through Sudan to Port Sudan on the Red Sea where it is exported was damaged in February 2024 and has been shut-in since. It is expected to come back online with partial volumes as early as January 8, 2025. South Sudan was producing about 150,000 barrels of oil per day (BPD) before the pipeline was damaged and is expected to produce 90,000 BPD when it initially comes back on (about 60% of the country’s total oil production). It is unknown whether or when it can return to full production. Some oil still flows for export through other pipelines. South Sudan gets 40% of the revenue while the oil companies that developed it get 60%. The country of 12 million citizens are in dire need as the loss of oil revenue has resulted in many people, mostly government workers, not being paid and has increased the level of poverty in the country. Many are facing starvation in both South Sudan and Sudan. South Sudan is an example where domestic oil development and the revenue it creates can be a key source of revenue for the entire country, especially the government. It is an example showing the value of fossil fuel development and production in warding off poverty and starvation. The loss of that revenue has been catastrophic thus far. However, as in most African countries, there is also corruption. South Sudan’s GDP dropped from about $8 billion in 2022 to a little over $5 billion in 2024 (Elon Musk’s net worth could cover about 82 years of South Sudan’s GDP or one year of 82 countries’ GDPs of a similar amount).

 

SOUTH SUDAN GDP IN CURRENT PRICES (2019-2029) (in billions U.S. dollars)

Source: Statista

 

South Sudan Petroleum Geology

     The Central African Rift System (CARS) bounded on the north by the Central African Shear Zone (CASZ) provides the main geological structure that controls oil accumulation. Oil is sourced from cretaceous-aged shales and produced from Cretaceous-aged sandstones as shown below. Lacustrine shales, claystones, sandstones, and conglomerates fill these very deep basins, some with over 45,000 feet of sediment. The southern part of South Sudan does not have basins for the most part and the surface is Precambrian igneous and metamorphic rocks. Rifting occurred during early deposition so there are syndepositional features and several different trap types. Chevron began exploring these basins in 1975.

 

     A series of north-south oriented rift basins with thick sedimentary sequences host the oil. The most productive basin is the Muglad Basin followed by the Melut Basin. These basins are part of the extensive East Africa Rift System.

     According to a July 2023 study of the Muglad Basin by Mohammed Ahmed Gumaa Mohammed:

“{There were} three major phases of extension with intervening periods when uplift and erosion or non-deposition have taken place. The depositional environment is nonmarine ranging from fluvial to lacustrine. The basin has probably undergone periods of transtensional deformation indicated by the rhomb fault geometry. Changes in plate motions have been recorded in great detail by the stratigraphy and fault geometries within the basin and the contiguous basins. The rift basin has commercial reserve of petroleum, with both Cretaceous and Tertiary petroleum systems active. The major exploration risk is the lateral seal and locally the effect of the tectonic rejuvenation as well as tectonic inversion. In some oilfields, the volcanic rocks constitute a major challenge to seismic imaging and interpretation.”

     A 2012 study in AGES Extracts made the following conclusions about the geology of the Muglad Basin which are similar to those in the more recent analysis by Mohammed:

“Although there are uncertainties in the age of oceanic crust and basinal unconformities, this study has shown at a macro tectonic scale the importance of unconformities as a tectonic correlation tool.  These unconformities are common to all basins in the WCARS, mark changes in the African stress field and can be directly linked to changes in the relative opening of the ocean floor.  The Muglad basin has undergone a polyphase development which has resulted in three major phases of extension with intervening periods (unconformities) when uplift, erosion, non-deposition have taken place.  Evidence from other rift basins within the WCARS infers that the Muglad basin has also undergone periods of shear deformation.  Thus the WCARS can be shown to be intimately connected to regional plate tectonic processes which are recorded in the stratigraphy and fault geometries of the basins.  How the sequence of plate tectonics events links with the stratigraphy and changes in plate motions is complex and is still poorly understood and is a research area that is worthy of further investigation.”

     A July 2023 study in the International Journal of Innovative Science and Research Technology explored the production performance and petroleum resources of the Dar Petroleum Operating Company. Some data from the study report is given below.

     The U.S. Energy Information Administration maintains oil and gas data and analysis  for all countries. Some data for South Sudan are given below:

      A petrophysical and petrographical study of the Muglad Basin was published in March 2021 in Environmental Earth Sciences. Some slides from that study are shown below.

 

References:

 

The promise of oil and gas in South Sudan. Alex Irwin-Hunt and Munyaradzi Makoni FDI Intelligence. October 31, 2022. The promise of oil and gas in South Sudan | fDi Intelligence – Your source for foreign direct investment information - fDiIntelligence.com

South Sudan says will resume oil production from Jan 8. AFP. January 7, 2025. South Sudan says will resume oil production from Jan 8

South Sudan on the brink after oil exports derailed by Sudan’s civil war. Mat Nashed. March 26, 2024. South Sudan on the brink after oil exports derailed by Sudan’s civil war | Salva Kiir News | Al Jazeera

Country Analysis Brief: Sudan and South Sudan. Last Updated: March 20, 2024. Next Update: March 2026. EIA.  Country Analysis Brief: Sudan and South Sudan

As South Sudan’s oil revenues dwindle, even the security forces haven’t been paid in months. Deng Machol. AP World News. August 9, 2024. As South Sudan's oil revenues dwindle, even the security forces haven't been paid in months | AP News

Geology of South Sudan. Wikipedia. Geology of South Sudan - Wikipedia

Rift Basins of Interior Sudan: Petroleum Exploration and Discovery. Thomas J. Schull. AAPG Bulletin. Volume: 72 (1988). Issue: 10. (October). AAPG Datapages/Archives: Rift Basins of Interior Sudan: Petroleum Exploration and Discovery

Petroleum Industry in South Sudan: Evaluation of Production Performance & Petroleum Resources in Dar Petroleum Operating Company. Awow Daniel Chuang. Ministry of Petroleum- Republic of South Sudan. International Journal of Innovative Science and Research Technology. Volume 8, Issue 7, July 2023. IJISRT23JUL699.pdf

Integrated petrophysical and petrographical studies for characterization of reservoirs: a case study of Muglad Basin, North Sudan. Abeer A. Abuhagaza, Marwa Z. El Sawy, and Bassem S. Nabawy.  February 2021. Environmental Earth Sciences. (2021) 80:171. IntegratedpetrophysicalandpetrographicalstudiesforcharacterizationofreservoirsacasestudyofMugladBasinNorthSudan.pdf

Muglad Basin. Wikipedia. Muglad Basin - Wikipedia

Melut Basin. Wikipedia.  Melut Basin - Wikipedia

Regional tectonic controls on basement architecture and oil accumulation within the Muglad basin, Sudan. J. Derek Fairhead, Stanislaw Mazur, Christopher M Green, and Mohamed Elamin Yousif. ASEG Extended Abstracts · December 2012. 22nd International Geophysical Conference and Exhibition, 26-29 February 2012 - Brisbane, Australia. Fairhead_etal_2012.pdf

Discovery of Early Mesozoic Magmatism in the Northern Muglad Basin (Sudan): Assessment of Its Impacts on Basement Reservoir. Jian Zhao, Jian Zhao, and Lirong Dou. Front. Earth Sci., 04 May 2022. Sec. Economic Geology. Volume 10 - 2022 | https://doi.org/10.3389/feart.2022.853082.

 

Integrating AI into the Power Grid: Challenges and Opportunities

 

     With power-hungry AI technology growing immensely, there has been much chatter about powering it. Nuclear, including deep underground nuclear and the possible re-opening of the Three Mile Island nuclear plant, natural gas, and renewables are set to power more and more AI as time goes on. Realistically, natural gas will likely be the main power source since it can be built and integrated faster than nuclear and will be more reliable than renewables.

     The simple fact is that while AI can be a great technology for human benefit, it is not so great for the climate due to its very high energy use. It is a far more useful technology than the other main power-hungry ‘processing power’ technology, cryptocurrencies, which have very few societal benefits and some societal detriments.

     Manav Mittal, a senior project manager at Consumers Energy, wrote an opinion piece for Utility Dive about optimizing AI integration into the grid. Power demand from AI data centers is already growing fast and that pace will continue for at least several years. He acknowledges that there will be environmental and infrastructure costs to integrating AI, but these can be minimized with foresight. Mittal offers four areas where AI integration can be optimized for sustainability: energy efficiency, renewable energy, modernizing the grid, and demand response.

     Improvements in AI data center energy efficiency are very possible. The first area where this is so is in the process of cooling data centers. Older inefficient HVAC-based air-cooling systems can be replaced by liquid cooling and immersion cooling. Another area where efficiency improvements are possible is hardware, especially in developing more energy-efficient processors and GPUs. Mittal thinks data centers should be incentivized to adopt these newer and more efficient technologies.

     The use of renewable energy to power data centers is a long-established practice of tech companies like Meta who want to power up to 100% of their data centers with renewable energy. Collaboration with renewable energy developers and utilities is required. The power purchase agreement (PPA) for long-term renewable energy supply is key to these deals. Onsite renewables and storage can help these facilities be more self-sufficient and less grid-dependent.

     Modernizing the grid is essential to integrating AI and is easier said than done. The use of real-time data and sensors can better manage energy distribution. The ability to adjust power flow based on demand on smaller scales can help integrate AI. Oddly perhaps, AI itself can help to integrate AI data centers by utilizing machine learning to optimize power flows.

“By integrating AI into grid management, utilities can anticipate and respond to shifts in energy demand caused by data centers, ensuring a more stable grid overall.”

He also advocates for more energy storage systems, including large-scale batteries.

     Demand response programs, where businesses and consumers are incentivized to reduce their power usage during power demand peaks, is another tool that can help integrate AI data centers.

“Data centers are prime candidates for demand response because they can adjust their operations — such as shifting workloads to off-peak hours — without negatively impacting performance.”

He also thinks that deeper and smarter collaboration between technology companies, utilities, policymakers and local communities can help. Government incentives can be helpful.

     Stresses on power grids are now coming from many different sources including EVs, electrification of processes, heat pumps, and AI-based tech like smart cities, autonomous vehicles, AI-capable PCs and laptops, and Internet of Things (IoT) devices. Kathryn Ackerman wrote a July 2024 article for Sourceability that addresses some of these concerns. She emphasizes the need for smart grids and upgraded transmission:

Over 70% of U.S. transmission lines are over 25 years old and approaching the end of their 50-80-year lifecycle. According to the U.S. Department of Energy, “This has major consequences on our communities: power outages, susceptibility to cyber-attacks, or community emergencies caused by faulty grid infrastructure.”

In late mid-October 2023, the Department of Energy (DOE) tackled this problem with investments in the Grid Resilience and Innovation Partnerships (GRIP) Program to strengthen grid resilience and reliability. However, the power industry is still stuck between a rock and a hard place: costly upgrades and an unclean energy grid due to the lack of renewable energy located within a close distance.

“Demand for electricity in 2030 will be 14% to 19% higher than 2021 levels,” according to an analysis from REPEAT (Rapid Energy Policy Evaluation and Analysis Toolkit), an energy policy project led by Princeton professor Jesse Jenkins, states.

“A 21st-century grid has to accommodate steadily rising electricity demand to power electric vehicles, heat pumps, industrial electrification, and hydrogen electrolysis, and it needs to extend to new parts of the country to harness the best wind and solar resources. Both factors mean we simply need a bigger grid with more long-distance transmission,” Jenkins told CNBC.

     Ackerman proposes five power components that can reduce the strain on a grid from AI power demand: high-efficiency power converters, uninterruptible power supplies (UPSs), energy storage systems, smart grid technologies, and advanced cooling solutions.

     Power converters are devices that convert AC into DC and vice versa. High-efficiency power converters can minimize energy loss leading to greater efficiency.

“New technologies such as silicon carbide (SiC) and gallium nitride (GaN) are becoming popular in power electronics due to their superior efficiency and thermal performance compared to traditional silicon-based components.”

Many original component manufacturers (OCMs) are utilizing SIC components.

     Uninterruptible power supplies (UPSs) are required for many AI applications, especially training models. Typical UPS systems can last 8-15 years.

     Energy storage systems, when discharged, can help power grids during demand peaks and can prevent power fluctuations.

     Smart grid technologies can integrate AI into grid management, thereby helping to optimize the integration of AI data centers. These AI-based technologies can also help with demand response management and improve grid reliability.

“Innovative grid technologies that leverage AI can enhance grid reliability by offering predictive maintenance, load forecasting, and real-time grid monitoring. These systems can dynamically adjust power distribution based on demand patterns, optimizing energy usage and reducing the risk of blackouts.”

     Advanced cooling solutions include liquid cooling systems and advanced air-cooling technologies. She mentions some other cooling solutions without explanation, including solar, geothermal-driven, and free cooling. 

     Integrating AI has the same challenges as integrating other forms of electrification, namely how to make the grid and its processes more efficient, cleaner, and more responsive to changes in demand.

 

 

 

References:

 

Opinion. From code to current: How to keep AI data centers in check for a sustainable grid. Manav Mittal. Utility Dive. January 3, 2025. From code to current: How to keep AI data centers in check for a sustainable grid | Utility Dive

The Need for a Strong Power Grid Infrastructure in the Age of AI. Kathryn Ackerman. July 16, 2024. Sourceability. The Need for a Strong Power Grid Infrastructure in the Age of AI