Arsenic, Prawns and Energy
Seeking clarity amidst insidious uncertainty regarding what is "safe" when it comes to common Arsenic exposures
Recently a client sent is some dried prawns for analysis at our Australian Laboratory, Toxtest. He had some high levels of Arsenic detected in his blood and urine during a routine doctor’s visit and wanted to follow up as to the possible source. What we found was both shocking and surprising while at the same time useful to know.
This article adds to two detailed articles we have written on Arsenic previously - Sources of Arsenic Exposure and Health Impacts of even low-level Exposure to Arsenic. These articles show other common food and environmental sources of arsenic along with precautions, especially for children. Have a read when you can as they are very informative and relevant to family and individual human health.
Note that we are currently investigating Part 2 of this article that will provide further clarity around this important topic as mentioned at the end.
To ease into it, here a a short fictionalised story, connecting Arsenic, Prawns and Energy while leaning into my biochemistry background and complete with a glossary at the end.
The sun dipped below the horizon, painting the sky in hues of orange and purple, as Dr. Evelyn Reed, a leading expert in metabolic biochemistry, settled into her armchair, a plate of grilled prawns beside her. She admired their glistening pink shells, a testament to the bounty of the sea. Yet, her mind drifted not to their culinary appeal, but to a complex, invisible thread connecting these seemingly innocuous crustaceans to a profound vulnerability in human physiology: arsenic and its insidious assault on metabolic energy production.
Evelyn recalled the elegant, intricate dance of molecules within every cell of the human body, a dance orchestrated to generate ATP, the universal energy currency. This process, often romanticized as the "powerhouse of the cell," relies on a delicate balance of enzymes, cofactors, and precisely regulated pathways. Glucose, the body's preferred fuel, embarks on a multi-step journey, from glycolysis to the Krebs cycle, culminating in oxidative phosphorylation within the mitochondria. Each step is meticulously designed, a cascade of biochemical reactions dependent on specific molecular structures and precise chemical affinities.
Enter arsenic. Not the sensationalized poison of Agatha Christie novels, but the ubiquitous environmental contaminant that exists in various forms. In prawns, and indeed much seafood, arsenic is predominantly found in organic forms, such as arsenobetaine. For a long time, these organic forms were considered largely benign, readily excreted by the body without significant harm. However, recent research, Evelyn mused, was painting a more nuanced and concerning picture. The human gut microbiome, a bustling metropolis of bacteria within us, possesses the capacity to metabolize some of these organic arsenic compounds, transforming them into more toxic inorganic forms. This insidious conversion, a silent biochemical alchemy within our own bodies, suddenly elevates the humble prawn from a mere meal to a potential vector for a metabolic disruptor.
Once inorganic arsenic, particularly its trivalent form (arsenite), enters the bloodstream, its true malevolence begins to unfold. It's a master of biochemical mimicry and sabotage. One of its primary targets is the very heart of metabolic energy production: the enzymes involved in glucose metabolism and the mitochondrial electron transport chain.
Consider pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, crucial enzymes in the pathways that break down glucose and generate precursors for ATP synthesis. Arsenic, with its cunning ability to bind to sulfhydryl groups on proteins, effectively "handcuffs" these enzymes, rendering them inactive. Imagine a production line suddenly grinding to a halt because key machinery is jammed. The flow of metabolites slows, and the efficient extraction of energy from glucose falters.
But arsenic's treachery doesn't stop there. It also interferes with phosphate. Arsenate, the pentavalent form of inorganic arsenic, is a chemical analog of phosphate. In the grand ballet of energy production, phosphate is vital for phosphorylation reactions, the very essence of how ATP is formed. Arsenate can deceptively slip into these reactions, forming unstable arsenate-ADP compounds. These "false" ATP molecules quickly hydrolyze, releasing energy as heat rather than storing it as chemical potential. This is a classic "uncoupling" effect, where the energy that should be harnessed for cellular work is simply wasted, leading to a profound decrease in the body's ability to produce usable energy. It's like a car engine running, consuming fuel, but failing to move the vehicle forward.
The mitochondria, the very "powerhouses" Evelyn had conceptualized, become sites of cellular chaos. Arsenic's interference with the electron transport chain, specifically at complexes I and III, leads to an increased generation of reactive oxygen species (ROS) – free radicals that wreak havoc on cellular components, including mitochondrial DNA and membranes. This oxidative stress further impairs mitochondrial function, creating a vicious cycle of energy depletion and cellular damage.
So, while a plate of prawns offers valuable protein and healthy fats, Evelyn knew that the unseen presence of arsenic, potentially transformed by our own internal ecosystems, posed a subtle yet significant threat. It was a reminder that even the most natural of foods, when intertwined with environmental realities and the complexities of human biochemistry, can unveil surprising connections. The enjoyment of a simple meal, for an educated mind like Evelyn's, transformed into a contemplation of the delicate equilibrium that governs life itself, and the persistent vigilance required to protect it from unseen assailants.
Glossary for the story above -
ATP (Adenosine Triphosphate): Think of ATP as the "energy currency" of your body. Just like you use money to buy things, your cells use ATP to power all their activities – everything from moving muscles to thinking thoughts. When your body needs energy, it "spends" ATP.
Arsenic: A naturally occurring element found in the environment (like in soil and water). It can be harmful to living things. In the story, we talk about different forms of arsenic: * Organic Arsenic: Forms of arsenic that are naturally found in living things, like in seafood (e.g., prawns). For a long time, these were thought to be mostly harmless. * Inorganic Arsenic: Forms of arsenic that are generally more toxic to humans.
Arsenobetaine: A specific type of organic arsenic found in seafood like prawns. It's usually considered less harmful than inorganic arsenic.
Arsenite (Trivalent Inorganic Arsenic): A very harmful form of inorganic arsenic. "Trivalent" refers to its chemical structure, which makes it particularly good at interfering with your body's processes.
Arsenate (Pentavalent Inorganic Arsenic): Another harmful form of inorganic arsenic. "Pentavalent" also refers to its chemical structure. It acts like a trickster, pretending to be something else in your body.
Biochemistry: The study of the chemical processes that occur within living organisms. It's about understanding how the molecules in your body work together to keep you alive.
Cellular Chaos: A term used to describe a state where the normal, organized processes within a cell break down and become disorganized, leading to dysfunction and damage.
Co-factors: Helper molecules that assist enzymes (see below) in doing their jobs. Think of them as necessary tools that enzymes need to function properly.
Electron Transport Chain: A series of protein complexes located within the mitochondria (see below) that are crucial for creating most of the body's ATP. Imagine it as a series of steps where tiny particles (electrons) are passed along, releasing energy at each step, which is then captured to make ATP.
Enzymes: Special proteins in your body that act like biological catalysts. They speed up chemical reactions without being used up themselves. Think of them as tiny workers that perform specific tasks very efficiently.
Glycolysis: The very first step in breaking down glucose (sugar) to get energy. It happens in the main fluid part of the cell, outside of the mitochondria.
Glucose: A simple sugar that is the main source of energy for your body's cells. It's what your body breaks down to create ATP.
Gut Microbiome: The vast community of bacteria, viruses, and other microorganisms that live in your intestines. They play a huge role in your health, including helping with digestion and even influencing your immune system.
Hydrolyse: A chemical reaction where a molecule is broken down by reacting with water. In the story, it refers to unstable energy molecules breaking apart and releasing their energy as heat instead of storing it.
Inorganic Forms (of arsenic): Refers to arsenic compounds that don't contain carbon and hydrogen bonds in the same way organic compounds do. These are generally the more toxic forms of arsenic.
Krebs Cycle (also known as the Citric Acid Cycle): A central part of how your body gets energy from food. It's a series of chemical reactions that take place after glycolysis, further breaking down food molecules to produce compounds that will then go into the electron transport chain.
Metabolic Biochemistry: The study of the chemical processes (metabolism) that occur within living organisms to maintain life. It's about how your body creates and uses energy.
Metabolic Disruptor: Anything that interferes with the normal chemical processes (metabolism) in your body, potentially causing harm.
Metabolic Energy Production: The overall process by which your body converts food into usable energy (ATP).
Mitochondria: Often called the "powerhouses" of the cell. These are tiny structures within your cells where most of the body's energy (ATP) is produced, especially through the electron transport chain.
Oxidative Phosphorylation: The final and most efficient stage of metabolic energy production, where the vast majority of ATP is generated within the mitochondria. This process relies on oxygen.
Phosphate: A crucial molecule (specifically, a phosphorus atom bonded to oxygen atoms) that is essential for many biological processes, especially for forming ATP.
Phosphorylation Reactions: Chemical reactions where a phosphate group is added to another molecule. These reactions are vital for energy transfer and signaling within cells, particularly in the creation of ATP.
Proteins: Large, complex molecules made up of smaller units called amino acids. Proteins do most of the work in cells and are required for the structure, function, and regulation of the body's tissues and organs. Enzymes are a type of protein.
Pyruvate Dehydrogenase / Alpha-Ketoglutarate Dehydrogenase: These are specific enzymes (see above) that are critical steps in breaking down glucose and other fuel sources to produce energy. Arsenic can "handcuff" these enzymes, making them unable to work.
Reactive Oxygen Species (ROS): Also known as "free radicals." These are highly reactive molecules that contain oxygen and can cause damage to cells, DNA, and other important components within your body. They are a natural byproduct of some cellular processes but can become harmful in excess.
Sulfhydryl Groups: Specific chemical groups (containing sulfur and hydrogen atoms) that are often found on proteins. Arsenic is known to bind very strongly to these groups, which is how it interferes with the function of many enzymes.
Uncoupling Effect: A situation where the energy derived from the breakdown of food is released as heat instead of being captured to make ATP (usable energy). It's like your body is burning fuel but not getting any work done.
First, to be clear, this article is not designed to vilify prawns and other foods or suggest one should not eat them. It is simply a real world observation and as such is designed to inform and elicit caution when making choices.
Arsenic in Prawns
Here is the word for word note from the client mentioned above -
Thanks for the second As prawn meat test results as attached. The first test (March) was for supermarket retail prawns from the Gulf of Carpentaria which explained my extreme blood & urine Arsenic levels, so we switched to locally caught prawns off the Tweed Heads coast from local trawlers hoping for healthier product but these tested as even worse for Arsenic, Cadmium, Mercury and Uranium. Both tests essentially indicate that prawns caught in these two Australian waters are unsafe for consumption.
Would you have any recommendation for a Government food safety authority that I could forward these results for further investigation? Any advice would be appreciated.
Some uncertainties and assumptions.
At this stage we have not interviewed the client as to possible other sources of arsenic, although he has done his own significant research and is convinced the prawns are the source of his significant Arsenic exposure. We have not as yet done our own health work-up and symptom profile for him. The assumption is that the prawns came from Australia but this has not as yet been verified. Keep you posted.
Results of the food analysis of the Prawn Meat supplied by this client showing only the toxic elements tested.
For some context and explanation as to what these results mean -
We calculate an estimated Provisional tolerable DAILY intake from Provisional tolerable weekly intakes (PTWI) as reported in the Literature (see references at end). Results are then expressed as a % of this PTWI for several age groups and genders. It is important to note however, that these PTWI are only estimates based on our current knowledge of toxicology and no levels of Cadmium, Arsenic, Lead or Mercury or indeed some of the other heavy metals shown here in food, are healthy or necessary, especially for children.
PDE stands for Permitted Daily Exposures and helps provide context for results. These guidelines and standards are established through either the United States Pharmacopeia (USP) or the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH). Australia generally adopts these guidelines and standards.
Important Note:
The arsenic levels reflected in the results above reflect ALL or Total forms of Arsenic - organic and inorganic and trivalent Inorganic Arsenic and Pentavalent Inorganic Arsenic. Our Laboratory does do speciation analysis of arsenic so as to discern different forms of arsenic, however the cost is higher than a Total analysis of Arsenic.
Please comment on this article, especially if you are from Australia, with your own experiences or knowledge as to Arsenic or other toxic metal or chemical content in Prawns and other foods we eat.
This article will also be updated as more information comes to light. Thanks.
Hartmut Michael Günther, last updated 29th June, 2025.
Recent Research Update 30th June, 2025
Arsenic in Prawns: Levels and Speciation
The current prevailing message in Research and Media on the web is indicative of the following advice -
“Arsenobetaine in prawns is non-toxic and poses no health risk under normal consumption levels. Total arsenic in prawns is high (0.037-3.4 µg/g or ppm), but the vast majority is arsenobetaine, with inorganic arsenic at safe levels (<0.1 mg/kg). Recent studies confirm prawns are safe, with no significant health risks, though speciation analysis is crucial to distinguish non-toxic arsenobetaine from trace inorganic arsenic.”
Note that the gentleman’s Prawn results above are between 44-88 µg/g or mg/kg or ppm.
I am still cautious however
In part due to bias coming as a result of naturally wanting to protect financial aspects of the fishing industry and the need for more speciation analyses and many unknowns as to what can happen in some people’s metabolism (possible inter-conversion and body storage of harmless to harmful forms of Arsenic) along with new and emerging sources of arsenic and arsenic compounds.
A Sri Lankan study detected AsIII at 0.010-0.044 mg/kg and AsV at 0.193 mg/kg in marine prawns, but these levels were deemed safe?
Minor organic forms like dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) are sometimes detected in prawns at trace levels (e.g., DMA at 0.048 mg/kg in marine prawns). These are less toxic than inorganic arsenic but have raised some concerns due to potential cytotoxicity, though evidence is limited and not specific to prawns.
Wild prawns had significantly higher total arsenic (up to 10 times) than farmed prawns, primarily as arsenobetaine. Inorganic arsenic levels were low and compliant with regulatory limits, with no health risks. The study emphasised the need for speciation analysis to avoid misjudging prawns based on total arsenic - Brazilian Study (2022) below.
Maximum levels for arsenic in food
There are limits in the Code for inorganic arsenic in certain foods. Foods sold in Australia and new Zealand (including imported food) must comply with these limits.
A limit of 1mg/kg applies to seaweed and molluscs, and for fish and crustacea, inorganic arsenic is not allowed above a level of 2mg/kg.
There is also a limit in the Code for total arsenic of 1mg/kg for cereals (including rice) and 0.5 mg/kg for salt.
These limits, which are set at levels consistent with protecting public health and safety and reasonably achievable, cover the major foods that are likely to contribute to arsenic exposure. They also take into account the entire population which includes sub-groups such as infants, children and the elderly.
Maximum levels are one of a number of risk management strategies we use to keep our exposure to arsenic at safe levels.
Why are the maximum levels in the Code different to other countries?
It is common for regulatory limits to vary across international jurisdictions. The maximum levels set by countries take into account chemical concentration data unique to that jurisdiction and may also use different analytical methods to measure the contaminant.
For example, our limits are higher than those in the EU and reflect data and analysis unique to the Australian environment and food supply.
from - Arsenic, Food Standards Australia and NZ, 2020
In NSW and Queensland, Australia, Food Standards Australia New Zealand (FSANZ) is the primary body responsible for setting standards and monitoring arsenic levels in food, including seafood. These standards are enforced by state and territory governments, including the NSW Food Authority and Queensland Health.
Follow-up and Part 2 of this article will look at -
The above client’s urine and blood medical test results indicate well above (>200%) levels of recommended “occupational exposure” of Arsenic in the body. There are many uncertainties and un-answered questions around these results and we will dive deeper into this so as to get clarity on what can be defined as levels of arsenic exposure that are not harmful. Interestingly it is recommended NOT to eat seafood for 3 days before doing these tests. We will be speaking with the pathologist who issues these results.
Usefulness & benefits of hair testing for assessing long-term low-level exposure to “heavy metals” like Arsenic and Mercury
Has Arsenic in seafood actual increased over the years (like Mercury) and if so, what is causing it.
Please comment on this article, especially if you are from Australia, with your own experiences or knowledge as to Arsenic or other toxic metal or chemical content in Prawns and other foods we eat.
This article will also be updated as more information comes to light. Thanks.
Hartmut Michael Günther
Fascinating article, thanks Hartmut. I’ve had my own issues with arsenic in salmon, which as you mention, is supposed to be ‘non-toxic’ but made me very sick.
I very much appreciate the level of sensitivity ToxTest is able to achieve when testing arsenic in foods.