Barium Exposure Routes and Health Effects in Australia
Barium is not as nasty as Arsenic, Mercury or Lead, but it's not a nutrient either.
Recently a client expressed concern about possible exposure to Barium. She wanted to know how dangerous it was and what are the main ways she could be exposed, particularly as she lived close to a railway line and the Whyalla Steelworks smelter in South Australia.
A quick google search revealed -
Iron Smelting and Barium:
The Whyalla Steelworks utilises iron ore mined in the Middleback Range. This ore contains various elements, including trace amounts of barium. During the iron smelting process, some of the barium may be released into the surrounding environment as dust.
Railways and Barium:
Railway lines, particularly those transporting materials like iron ore or coal, can generate dust containing barium. The wear and tear on tracks, wheels, and braking systems contributes to the release of dust particles into the air.
Whyalla's Context:
The Whyalla Steelworks is a significant industrial site, and the dust generated from its operations, including the railway lines used to transport materials, can be a source of barium exposure.
Trace Element:
It's important to note that barium is not a major component of iron ore or steel production. It's typically present as a trace element. However, even trace amounts can contribute to dust pollution in industrial areas.
Dust Sources:
Dust from steelworks can come from various sources, including the ore handling, smelting processes, and the transport of materials to and from the site.
However, the client also wanted to know other possible sources and related health effects from various levels of Barium exposure. Additionally, Barium is one of the 32 metals we routinely conduct an analysis for across a range of mediums that include food, water, soil, dust and hair at Toxtest. I thought it was time to update our current knowledge as other clients also ask about Barium exposure routes. So here we go…
Executive Summary
We have included a Glossary at the end as there are technical terms used throughout.
Barium is a naturally occurring element with various industrial and medical applications. For the general population, oral intake through drinking water and food represents the most prevalent route of exposure. The average daily barium intake is estimated to be approximately 1.33 mg/day, primarily from food (1.24 mg) and water (0.086 mg), with a very small contribution from air (0.001 mg). While most environmental barium levels pose minimal health risk, the critical health endpoints associated with barium exposure appear to be hypertension and kidney function. Medical procedures utilising barium sulfate are generally considered safe due to the compound's insolubility and negligible absorption.
Acutely, high doses of soluble barium salts can trigger vomiting, muscle weakness, and potentially fatal heart-rhythm disturbances. Chronic low-level intakes are most consistently linked with small rises in blood pressure and subtle kidney changes. While "chemtrail" claims remain unsupported by atmospheric measurements, industrial chemical uses, such as in hydraulic fracturing wastewater, are emerging areas of concern regarding environmental contamination.
Barium Exposure Routes: A Comprehensive Overview
Sources offer slightly different rankings of exposure routes based on estimated average daily absorbed dose for a healthy adult, but there is general agreement that ingestion through food and water constitutes the most significant pathway.
1. Oral Intake: Food and Water (Highest Exposure) Ingestion is the primary exposure route for the general population.
Food Sources: The average dietary intake is approximately 1.24 mg/day or around 1 mg/day. Barium is naturally present in many foods, with certain items showing significantly higher concentrations:
Brazil nuts: 1,500-3,000 mg/kg. One source states up to 1,000 mg/kg.
Herbs and spices: 20,750-38,172 μg/kg.
Seaweed and kelp: Variable, naturally high accumulators.
Nuts (general): 1,755-5,033 μg/kg.
Tea (dry bags): up to 27 mg/kg.
Wheat products: 19-5,403 μg/kg in grain-based products.
Vegetables: 3-4,023 μg/kg, with tomatoes and soybeans showing bioconcentration factors of 2-20. Leafy greens and root crops can range from 50 µg to 2 mg per kilogram fresh weight.
Fruits: 15-3,169 μg/kg.
Meat products: less than 0.2 mg/kg.
Infants and children can also be exposed through infant formulas (16-216 μg/L) and breast milk (average 3.61 μg/L).
Drinking Water: The estimated daily exposure from water is approximately 0.086 mg/day.
Typical concentrations in Australian town supplies range from <0.002 mg/L to 1.1 mg/L or 0.01–0.2 mg/L. Surface water and public supplies average 0.030 ppm or less, but can reach 0.30 ppm in some US regions.
Private wells in some areas can exceed limits, with highest measured levels reaching 10 ppm. Bores tapping barite-rich strata in inland Queensland and the Northern Territory have reached 2.4 mg/L.
Australian Drinking Water Guidelines: There is a notable difference in the reported guideline value among sources. One source states the Australian guideline as 2.0 mg/L (2.0 ppm), while another provides a health-based guideline value of 0.7 mg/L. This discrepancy highlights the importance of checking the most current regulatory information.
2. Medical Procedures (Intermittent High Exposure) Barium sulfate is extensively used in medical imaging, such as barium swallows and enemas for X-ray imaging of the gastrointestinal tract, and very low-density suspensions for CT contrast studies.
Single Procedure Exposure: Can range from 50-500g of barium sulfate.
Safety: Medical exposure is generally considered safe because barium sulfate is highly insoluble in water, meaning very little of the toxic barium metal is absorbed into the body. Systemic exposure is functionally zero unless aspiration or gut perforation occurs.
3. Cosmetic and Personal Care Products (Low but Chronic Exposure) Barium compounds are found in various personal care items.
Barium Sulfate: Used as an opacifying agent or filler in products like face powders and dusting powders (up to 15.8% or 37% in leave-on products), and certain foundations and sunscreens (<1% w/w). It is considered safe when formulated to be non-irritating, with extensive clinical experience showing no sensitisation potential.
Barium Peroxide: Used as an oxidising agent in henna-based hair dye formulations. This is considered more problematic, with one source noting a 2022 EU recall of an imported hair-dye cream with 18% banned barium peroxide, enough to cause chemical burns if undiluted. Experts have called heavy metals in hair dyes "slow poison" due to their tendency to be absorbed into the bloodstream. Some cosmetics may also contain "Lakes D&C Red 6 Barium" as a colourant.
4. Household Dust (Continuous Low-Level Exposure) Household dust acts as a collector for various contaminants and provides a continuous source of exposure, especially for children who spend more time on floors.
Estimated Daily Exposure: Very low.
Concentrations: Sydney homes show a median of 120 mg/kg in settled dust. Studies in the USA reported 20 mg/g in house dust and 137 mg/g in dust fall.
Risk Classification: Dutch studies classify barium among compounds in household dust "without potential human health risk". However, older housing stock, mining towns, and unsealed roads can elevate indoor levels.
5. Occupational Exposure (Highly Variable) Workers in specific industries face higher exposure risks, primarily through inhalation of dust or fumes.
Workplace Sources: Drilling mud operations (oil and gas industry), manufacturing (paint, ceramics, glass, rubber), and pyrotechnics (barium compounds emit green light when burned). Welding-rod flux production is also a source.
Exposure Levels: UK industry data suggests exposures can be controlled to less than 10 mg/m³ for an 8-hour time-weighted average. Predicted exposure levels can range from 0.1–1 mg/m³ for airborne barium sulfate or 0.02 to 6.1 mg/m³.
Take-home Exposure: Dust on work clothes can be a main pathway for family members.
6. Air Inhalation (Lowest Exposure) This is generally the lowest exposure route, with an estimated daily exposure of 0.001 mg/day.
Concentration Ranges: Background air typically contains about 0.0015 ppb or less than 0.05 µg/m³. Near factories, levels can reach about 0.33 ppb or less.
Intermittent Spikes: Short-lived bursts, such as from fireworks, flares, and sparklers, can push local air concentrations to 400 µg/m³ PM₂.₅.
7. Environmental Soil Contact (Minimal Direct Absorption) Barium is a natural component of soil, with concentrations varying depending on local geology.
General Soil Range: 15 to 3,500 ppm barium or 100-3,000 mg/kg in the earth's crust, with an average crustal abundance of 628 mg/kg.
Contaminated Sites: Higher levels are possible near industrial activities. In Australia, a study near Melbourne found soil barium levels up to 910 mg/kg due to natural geological sources. The National Environment Protection Measure (NEPM) has set an ecological investigation level (EIL) of 300 mg/kg for barium in soil.
Recent Australian Environmental Incidents (2020-2025)
There is a disagreement among sources regarding identified recent barium contamination incidents in Australia since 2020.
Some sources state that specific barium contamination incidents in Australia since 2020 were not identified in current literature or in their available data.
Conversely, another source documents three specific mining-related incidents that produced local spikes above guideline values:
Mount Morgan, QLD (2023): Heavy rain mobilised acid mine drainage, pushing Dee River barium to 1.6 mg/L.
Hunter Valley, NSW (2024): Low-flow conditions near coal and barite deposits produced grab-sample peaks of 0.32 mg/L.
Barrow Creek, NT (2022): A drill-mud spill left soils at 480 mg/kg within 30 m of the rig; the site has since been capped. While specific incidents may not be broadly identified, barium compounds are recognised as critical raw materials with potential for increased environmental release, and Australia faces ongoing challenges with toxic releases from mining and industrial activities.
Controversial and Emerging Exposure Sources
"Chemtrails" Theory: A persistent conspiracy theory alleges that aircraft condensation trails are composed of deliberately sprayed chemical or biological agents, including barium. However, there is no credible scientific evidence to support this claim. Numerous studies of aircraft contrails have shown they are composed primarily of water ice and do not contain elevated levels of barium or other unusual substances.
Industrial Chemical Use: Barium has been detected in hydraulic fracturing wastewater, raising concerns about environmental contamination from oil and gas operations. NASA's high-altitude barium-cloud rockets (e.g., KiNET-X mission 2023) pose negligible ground-level risk due to high altitude release and dispersion.
Health Effects of Barium Exposure
The health effects of barium depend significantly on the form of the element and the level of exposure. Soluble barium compounds (e.g., barium chloride, nitrate) are readily absorbed and are toxic, while insoluble compounds (like barium sulfate) are generally not harmful as they pass through the gut with minimal absorption.
1. Acute Effects (Short-Term, High-Dose Exposure) Symptoms may manifest within minutes to days of exposure to high doses of soluble barium salts. These can include:
Vomiting, abdominal cramps, and diarrhoea.
Difficulties in breathing.
Increased or decreased blood pressure.
Numbness or tingling around the face and extremities.
Muscle weakness and paralysis.
Changes in heart rhythm (cardiac arrhythmias).
In severe cases, death, typically from cardiac arrest or gastrointestinal haemorrhage.
Mechanism: Barium acts as a competitive potassium channel antagonist, blocking the passive efflux of intracellular potassium. This can lead to decreased resting membrane potential, making muscle fibres electrically unexcitable and causing paralysis. High doses can also cause profound hypokalemia (abnormally low serum potassium levels), which contributes to dangerous arrhythmias.
2. Chronic Effects (Long-Term, Low-Dose Exposure) Long-term exposure to elevated barium levels is primarily associated with effects on the cardiovascular system and kidney function.
Cardiovascular System: Hypertension (high blood pressure) is a critical endpoint, with a higher incidence observed after occupational exposure. Human epidemiology links water containing ≥0.7 mg/L to small but significant rises in systolic and diastolic blood pressure. Effects on blood pressure and cardiac malfunction have also been reported in animals.
Kidney Function: The kidney appears to be the most sensitive target organ in repeated exposure studies, with renal intoxication reported in experimental animals at doses of ≥0.4 mg/kg/day.
Other Systems: Association with body mass index and waist circumference has been noted in population studies, and hearing loss has been reported in experimental animals. Occupational exposure to barium dust can lead to baritosis, a usually benign lung opacity that typically reverses after exposure stops and rarely impairs lung function.
3. Dose-Response Relationships and Safety Thresholds
Human NOAEL (No-Observed-Adverse-Effect Level): 0.21 mg barium/kg body weight per day.
Tolerable Daily Intake: 0.02 mg/kg body weight per day.
LOAEL (Lowest-Observed-Adverse-Effect Level):
For acute effects of soluble salts, high doses above 1 mg/kg are cited. One source specifies an oral LOAEL of 0.2 mg kg⁻¹ day⁻¹ for acute symptoms.
For chronic effects, an oral LOAEL of 0.21 mg/kg/day has been identified for cardiovascular effects in humans, based on epidemiological studies, or 0.2 mg kg⁻¹ day⁻¹ based on increased blood pressure in controlled studies in Illinois communities.
Animal studies report a LOAEL of 0.51 mg barium/kg/day based on increased blood pressure in chronic oral rat studies, and renal tubular changes at ≥0.4 mg/kg/day.
An inhalation LOAEL of 3.6 mg/m³ for pulmonary and cardiovascular effects in animals is also noted.
It is important to recognise that the concept of a single LOAEL can be an oversimplification, as the effects of barium can be influenced by individual factors like age, diet, and overall health status. A more nuanced approach, considering a range of factors, is often needed for a comprehensive risk assessment.
Carcinogenicity: Barium is not classified as carcinogenic by the International Agency for Research on Cancer, and the US EPA concluded that barium is not likely to be carcinogenic to humans from ingestion exposure.
Biochemical Role and Bioaccumulation
Unlike essential trace metals, barium has no confirmed biochemical function in humans. It is not considered an essential nutrient for humans or plants; in fact, it can interfere with the function of essential minerals like potassium and calcium, which explains some of its toxic effects. The element is best viewed as environmentally ubiquitous but biologically expendable.
Humans eliminate approximately 90% of barium in faeces and 2% in urine at normal intake levels. Very little administered barium is absorbed, with the majority eliminated in faeces. Barium is principally found in bone, with small amounts in muscle, adipose tissue, skin, and connective tissue.
Vulnerable Populations
Certain populations may be more susceptible to the effects of barium:
Children and Infants: Face a higher exposure risk due to hand-to-mouth behaviour and time spent on floors where dust settles. Developing organs may also be more sensitive to toxic effects, and they have immature renal clearance.
Occupational Workers: Particularly those in oil/gas drilling, ceramics, glass, and paint manufacturing, with a higher incidence of hypertension observed in occupationally exposed populations.
Pregnant People: High maternal doses have been shown in animal data to reduce placental potassium and could affect foetal cardiac conduction.
Individuals with Kidney Disease: Clear barium more slowly, which can lead to an increased internal dose and potentially higher risk.
Risk Mitigation Strategies
Effective risk mitigation involves strategies at household, regulatory, and occupational levels:
Household Level:
Frequent damp-dusting and cleaning to reduce toxic dust accumulation.
Use high-rated HVAC (heating, ventilation, and air conditioning) filters and replace them regularly.
Awareness of chemical content in personal care products, avoiding those listing "barium peroxide" or "barium chloride".
Frequent hand-washing, especially for children, to lower dust ingestion.
Regulatory Level:
Water quality monitoring and treatment to ensure drinking water adheres to guidelines.
Avoiding hair dyes containing lead or soluble barium compounds.
Enforcement of cosmetic regulations (e.g., Australian Industrial Chemicals Introduction Scheme, AICIS rules) where soluble barium salts are prohibited, but inert barium sulfate is allowed.
Occupational Level:
Workplace exposure controls, including fit-tested P2 respirators when cutting barite or mixing drilling muds.
Laundering work gear separately to prevent "take-home" exposures for family members.
Adherence to workplace air exposure standards, such as 0.5 mg/m³ for soluble barium (8-hour time-weighted average) and 10 mg/m³ for inert barium sulfate dust.
Standing upwind of large fireworks displays and limiting exposure for asthma patients.
Glossary
Acute Effects: These are health effects that occur shortly after exposure to a substance. For barium, acute symptoms can include vomiting, abdominal cramps, diarrhoea, breathing difficulties, changes in blood pressure, numbness, and muscle weakness. In severe cases, high levels of soluble barium can lead to changes in heart rhythm, paralysis, and even death.
AICIS (Australian Industrial Chemicals Introduction Scheme): This is the regulator for cosmetic ingredients in Australia.
Arrhythmias: This term refers to changes in the heart's rhythm. In the context of barium exposure, high levels of soluble barium can cause dangerous arrhythmias.
BaSO₄ (Barium Sulfate): This is an insoluble compound of barium widely used in medical imaging (such as barium swallows and enemas) and some cosmetics. It is generally considered safe because it is insoluble in water, meaning very little of the toxic barium metal is absorbed into the body, with less than 0.01% crossing the gut wall. It typically passes through the digestive system without causing systemic exposure unless a perforation occurs.
Barite Seams: These are natural geological formations (rock layers) rich in the mineral barite, which is primarily barium sulfate. These seams can be a source of barium dissolved into groundwater and surface water.
Baritosis: This is a benign lung condition resulting from the chronic inhalation of barium dust, particularly in occupational settings. It typically presents as lung opacities on imaging and is generally reversible, often fading after exposure stops. It is described as a type of pneumoconiosis.
Benchmark Dose (BMD): This is a statistical lower confidence limit on a dose that causes a specified response. This definition is provided by the sources and is a technical term used in toxicology to estimate safe exposure levels.
Bioconcentration Factors: These factors indicate the ratio of a chemical's concentration in an organism to its concentration in the surrounding environment. For example, tomatoes and soybeans show bioconcentration factors of 2-20 for barium, meaning they can accumulate barium to levels 2 to 20 times higher than in the soil they grow in. The general definition of bioconcentration factors is inferred from the sources' context and is a standard ecological term.
Biomarkers: These are measurable indicators of a biological state or condition. In toxicology, biomarkers can be used for the early detection of health effects related to chemical exposure. The general definition of biomarkers is inferred from the sources' context and is a standard scientific term.
"Chemtrails": This refers to a discredited conspiracy theory that alleges aircraft condensation trails are composed of deliberately sprayed chemical agents, including barium. Scientific surveys of atmospheric scientists have found no evidence to support these claims, indicating that observed trails are consistent with ordinary water-ice contrails.
Chronic Effects: These are health effects that develop over a long period of exposure to a substance. For barium, chronic low-level intake is most consistently linked with small rises in blood pressure (hypertension) and subtle kidney changes.
Cumulative Exposure Assessment: This involves considering the total lifetime exposure to a substance from all sources combined. This term is mentioned in the sources as a suggested improvement for research prompts and its definition is based on common scientific understanding.
Ecological Investigation Level (EIL): This is a guideline value for concentrations of contaminants in soil below which there is not expected to be an adverse effect on terrestrial ecosystems. For barium in soil, the National Environment Protection Measure (NEPM) has set an EIL of 300 mg/kg.
Geological Sources: These refer to naturally occurring formations in the Earth's crust, such as rock, soil, and mineral deposits (like barite seams), from which elements like barium can leach into water or be present in soil.
HEPA-Filter Vacuums: These are vacuum cleaners equipped with High-Efficiency Particulate Air (HEPA) filters, which are designed to capture a very high percentage of airborne particles, including fine dust and contaminants like barium, as part of risk mitigation strategies for household dust. The general definition of HEPA filters and their function is widely understood and not explicitly defined in the sources.
Hypertension: This is the medical term for high blood pressure, which is a critical health endpoint identified for long-term, low-dose barium exposure, particularly after occupational exposure.
Hypokalaemia: This is a medical condition characterised by low levels of potassium in the blood serum, which can be a symptom of acute, high-dose exposure to soluble barium compounds. Normal serum potassium levels are typically 3.5–5 mEq/L, while severe hypokalaemia from barium exposure can result in levels as low as 0.8–2.7 mEq/L.
Insoluble Salts: These are forms of barium, such as barium sulfate (BaSO₄), that do not dissolve readily in water or bodily fluids. They are generally considered safe for medical or cosmetic use because they are poorly absorbed by the body and pass through the digestive system largely intact.
Inward-rectifier K⁺ Channels: These are specific types of potassium ion channels found in cell membranes that play a crucial role in maintaining the resting membrane potential of cells, particularly in muscle fibres. Barium acts as a competitive antagonist, blocking these channels and preventing the passive efflux of intracellular potassium, which can lead to decreased resting membrane potential and muscle unexcitability, causing paralysis. This is a highly technical biochemical term; the sources provide its function in barium toxicity.
Lake Pigments: These are a type of pigment created by precipitating a dye with an inert binder or "mordant." They are used as colourants in various cosmetic products.
LOAEL (Lowest-Observed-Adverse-Effect Level): This is the lowest dose or concentration of a substance at which an adverse effect is observed in a study or population. For barium, the human oral LOAEL for cardiovascular effects (specifically increased blood pressure) is estimated to be 0.21 mg barium/kg body weight per day or 0.2 mg kg⁻¹ day⁻¹.
mg/kg (Milligrams per Kilogram): This is a unit of concentration often used to measure the amount of a substance present in a solid material, such as soil or food.
mg/L (Milligrams per Liter): This is a unit of concentration often used to measure the amount of a substance dissolved in a liquid, such as water.
Nanomaterials: These are materials engineered at the nanoscale (typically 1 to 100 nanometres). Their unique properties at this size can lead to new industrial uses and potentially different exposure pathways or health impacts. This term is mentioned in the sources as an "emerging source" and its definition is based on general scientific understanding.
Nephropathy: This is a general term referring to kidney damage or disease. Animal studies have reported renal intoxication or kidney damage as a potential chronic effect of barium exposure.
Neuromuscular Signalling: This refers to the communication processes between nerve cells (neurons) and muscle cells, which are essential for muscle movement and function. Barium's toxicity mechanism involves disturbing this signalling by blocking potassium channels. The general definition of neuromuscular signalling is inferred from the sources' context.
NOAEL (No Observed Adverse Effect Level): This is a safety threshold, representing the highest dose of a substance at which no adverse effects are observed. For humans, the established NOAEL for barium is 0.21 mg barium/kg body weight per day.
P2 Respirators: These are a type of respiratory protective device designed to filter out airborne particulate matter, including fine dust. They are recommended for workers in high-exposure environments, such as those cutting barite or mixing drilling muds, as a risk mitigation strategy. The general definition of P2 respirators is widely understood and not explicitly defined in the sources.
PM₂.₅: This refers to Particulate Matter with a diameter of 2.5 micrometres or less. These fine airborne particles are small enough to be inhaled deep into the lungs and can carry various contaminants, including barium, such as from fireworks smoke.
Pneumoconiosis: This is a class of lung diseases caused by the habitual inhalation of dust, leading to inflammation, coughing, and fibrosis. Baritosis, a condition resulting from barium dust inhalation, is a type of pneumoconiosis.
ppb (Parts per Billion): This is a unit of concentration used to describe very small amounts of a substance, typically in air or water, where one part per billion means one unit of substance per billion units of solution or mixture.
ppm (Parts per Million): This is a unit of concentration, where one part per million means one unit of substance per million units of solution or mixture. It is commonly used for measuring concentrations in water.
Probabilistic Exposure Models: These are computer models used to estimate exposure levels across a population, taking into account the variability and uncertainty in exposure factors and activity patterns. They can provide a more realistic picture of exposure distribution than single-point estimates. This term is mentioned in the sources as a suggested improvement for research prompts and its definition is based on common scientific understanding.
Pyrotechnics: This term refers to the art or science of designing, making, and displaying fireworks and other explosive devices. Barium compounds are used in pyrotechnics to produce a vivid green light when burned. The general definition of pyrotechnics is widely understood and not explicitly defined in the sources.
Remediation Technologies: These are methods and techniques used to clean up or mitigate contamination in the environment, such as for barium contamination in soil or water. This term is mentioned in the sources as a suggested improvement for research prompts and its definition is based on common scientific understanding.
Soluble Salts: These are forms of barium, such as barium chloride or barium nitrate, that dissolve readily in water. Unlike insoluble barium sulfate, soluble barium compounds are toxic because they release the Ba²⁺ ion, which can be absorbed into the bloodstream and cause adverse health effects, particularly at high doses.
Time-Weighted Average (TWA): This is an average concentration of a substance in the air over a specific period, typically an 8-hour workday. It is often used to establish occupational exposure limits to ensure worker safety. The general definition of time-weighted average is implied by the sources' context and is a standard occupational health term.
Tolerable Daily Intake: This is an estimate of the amount of a substance that can be ingested daily over a lifetime without appreciable health risk. For barium, the tolerable daily intake is 0.02 mg/kg body weight per day.