Toxicology – Chromium

Core concept

Chromium toxicity depends critically on oxidation state.

The clinically important distinction is:

Hexavalent chromium [Cr(VI)] = highly toxic, corrosive, oxidizing, sensitizing, and carcinogenic

whereas:

Trivalent chromium [Cr(III)] = poorly absorbed and substantially less toxic

The characteristic acute severe syndrome after ingestion of a soluble Cr(VI) compound is:

Caustic gastroenteritis → GI hemorrhage/fluid loss → shock + acute kidney injury + hepatic injury ± coagulopathy/multiorgan failure

Chronic occupational Cr(VI) exposure primarily causes:

Nasal/airway irritation + septal ulceration/perforation + dermatitis/chrome ulcers + occupational asthma + increased lung-cancer risk

The most important modern management principle is:

Treat acute Cr(VI) ingestion as both a severe caustic exposure and a potentially systemic multiorgan poison.

There is no proven specific antidote.

Important Chromium Species

Chromium exists in several oxidation states, but the most relevant are:

Chromium(0)

Metallic chromium.

Used in:

• Stainless steel
• Alloys
• Metal production

It is much less biologically reactive than Cr(VI).

Chromium(III)

Examples include:

• Chromium chloride
• Chromium sulfate
• Chromium oxide

Cr(III):

• Crosses cell membranes poorly
• Is poorly absorbed from the GI tract
• Is much less systemically toxic than Cr(VI)

However:

“Less toxic” does not mean completely harmless.

Specific Cr(III) salts, dusts, or formulations may still cause:

• Local irritation
• Dermatitis
• Occupational exposure problems

The older statement that there is essentially no evidence of Cr(III) toxicity is therefore too broad.

Chromium(VI)

Important Cr(VI) compounds include:

• Chromic acid
• Chromium trioxide
• Potassium chromate
• Potassium dichromate
• Sodium chromate
• Sodium dichromate
• Ammonium dichromate
• Zinc chromate
• Strontium chromate

Cr(VI) is the principal toxicologic concern.

NIOSH lists chromic acid/chromates as capable of causing:

• Respiratory irritation
• Nasal septal perforation
• Kidney/liver injury
• Eye injury
• Skin ulceration
• Sensitization dermatitis
• Lung cancer.

Common Occupational Sources

Exposure occurs particularly during:

• Chrome electroplating
• Stainless-steel welding/cutting
• Chromate pigment manufacture/use
• Stainless-steel and alloy production
• Aerospace painting
• Metal finishing
• Leather tanning
• Wood preservation
• Textile/dye work
• Chromate chemical production
• Work with wet cement containing trace Cr(VI)

NIOSH specifically identifies welding, steel work, electroplating, chromate painting, wood preservation, textile dyeing, and cement work as important Cr(VI) exposure settings.

Why Cr(VI) Is So Much More Toxic

Cr(VI) resembles:

• Sulfate
• Phosphate

anions.

Therefore:

Cr(VI) → enters cells through nonspecific anion transporters

Once intracellular:

Cr(VI) → Cr(V) → Cr(IV) → Cr(III)

during reduction by substances such as:

• Ascorbate
• Glutathione
• Cysteine

This intracellular reduction generates:

• Reactive intermediates
• Reactive oxygen species
• DNA adducts
• DNA-protein cross-links
• Oxidative DNA injury

and contributes to both:

Acute cellular toxicity + carcinogenesis

EPA describes this cellular uptake/reduction mechanism as central to Cr(VI) genotoxicity.

Extracellular Reduction Can Be Protective

An important paradox is:

Cr(VI) reduced to Cr(III) before cellular uptake → generally less toxic

because Cr(III) crosses membranes much less readily.

But:

Cr(VI) reduced after entering the cell → reactive intermediates + cellular damage

This is important when considering proposed vitamin C therapy.

Toxic Dose

There is no sufficiently reliable single dose threshold to guide clinical management.

Historical estimates have placed severe or potentially lethal oral Cr(VI) exposure in approximately the:

50–70 mg/kg range

but major interindividual variation exists, and case reports include both death and survival across a wide range of doses. OSHA has historically cited lethal oral chromate exposures around this range.

Therefore:

Do not use a reported “0.5–1 g lethal dose” as a fixed rule.

Severity depends on:

• Specific Cr(VI) compound
• Concentration
• Solubility
• Dose
• Route
• Delay to treatment
• Degree of caustic GI injury

Acute Ingestion – Clinical Syndrome

Soluble Cr(VI) salts are powerful oxidizing corrosives.

The early syndrome often begins with:

Oral/GI chemical burn → nausea/vomiting → abdominal pain → profuse diarrhea ± GI bleeding

Severe systemic poisoning may then progress to:

Shock → AKI + hepatic injury + coagulopathy → multiorgan failure

Fatal dichromate poisonings have demonstrated rapid progression from gastrointestinal symptoms to hemorrhage, renal/hepatic injury and systemic collapse.

Gastrointestinal Effects

Possible findings include:

• Burning of mouth/throat
• Odynophagia
• Dysphagia
• Severe abdominal pain
• Nausea
• Vomiting
• Diarrhea
• Hematemesis
• Hematochezia
• GI mucosal necrosis

Severe exposures can cause:

• Massive GI hemorrhage
• Perforation
• Peritonitis
• Profound fluid loss
• Hemorrhagic shock

The clinical picture may resemble ingestion of a strong acidic corrosive.

Cardiovascular

Severe Cr(VI) poisoning can produce:

• Tachycardia
• Hypotension
• Circulatory collapse
• Shock

Mechanisms include:

• GI fluid loss
• Hemorrhage
• Capillary/tissue injury
• Metabolic derangement
• Multiorgan toxicity

Renal Toxicity

The kidneys are major systemic target organs.

Possible manifestations include:

• Proteinuria
• Hematuria
• Acute tubular injury
• Oliguria/anuria
• Acute kidney injury

Renal failure is a classic complication of major dichromate poisoning.

Hepatic Toxicity

Severe systemic poisoning may cause:

• Aminotransferase elevation
• Hepatocellular injury
• Acute hepatitis
• Severe hepatic dysfunction

Combined:

AKI + hepatic injury + GI hemorrhage

is particularly suggestive of major systemic dichromate poisoning when exposure history is compatible.

Hematologic Toxicity

Severe poisoning may cause:

• Anemia
• Thrombocytopenia
• Hemolysis
• Coagulopathy
• DIC-like abnormalities

Methemoglobinemia has also been reported in catastrophic dichromate poisoning, but it is not a universal or defining feature.

Neurologic Toxicity

Neurologic effects are usually secondary to severe systemic illness and may include:

• Confusion
• Lethargy
• Encephalopathy
• Coma

Possible contributors include:

• Shock
• Acidosis
• Renal failure
• Hepatic failure
• Hypoxemia

Respiratory Toxicity – Acute Inhalation

Cr(VI) dusts and mists can cause:

• Nasal irritation
• Sore throat
• Cough
• Dyspnea
• Bronchospasm
• Wheezing
• Chemical airway injury

High-level exposures may produce:

• Pulmonary inflammation
• Pulmonary edema

NIOSH recognizes the respiratory tract as a major target organ of chromic acid/chromates.

Occupational Asthma

Cr(VI) can function as a respiratory sensitizer.

Sensitized workers may develop:

• Wheezing
• Chest tightness
• Cough
• Occupational asthma

even after exposures lower than those producing obvious corrosive injury.

OSHA specifically identifies chromium-associated occupational asthma.

Nasal Septal Injury

A classic chronic occupational finding is:

Nasal irritation → ulceration → septal perforation

Symptoms may include:

• Epistaxis
• Nasal irritation
• Crusting
• Ulcers
• Septal perforation

This has historically been particularly associated with:

• Chrome plating
• Chromate production
• Welding

OSHA identifies repeated Cr(VI) exposure as capable of damaging nasal mucosa and causing septal perforation.

“Pneumoconiosis” – Important Correction

The old chapter emphasizes chromium-associated pneumoconiosis.

That is not the most useful modern description of chronic Cr(VI) respiratory disease.

The major recognized occupational pulmonary problems are:

• Chronic upper-airway irritation
• Nasal ulceration/perforation
• Occupational asthma
• Respiratory irritation
• Lung cancer

rather than a characteristic chromium-specific pneumoconiosis.

Skin Toxicity

Chrome ulcers

A classic Cr(VI) lesion is the:

“Chrome hole”

These are often:

• Painless
• Deep
• Punched-out ulcers

and occur particularly on:

• Fingers
• Hands
• Forearms

especially where skin is:

• Cut
• Abraded
• Chronically contaminated

Irritant Dermatitis

Direct exposure can cause:

• Erythema
• Burning
• Irritant contact dermatitis
• Chemical burns

Allergic Contact Dermatitis

Chromium is an important skin sensitizer.

After sensitization:

Very small subsequent exposures can provoke eczema.

OSHA recognizes both irritant and allergic chromium dermatitis, including disease associated with wet Portland cement.

Ocular Exposure

Cr(VI) solutions, dusts, or mists may cause:

• Conjunctivitis
• Severe irritation
• Corneal injury
• Chemical burns

Immediate irrigation is required.

Carcinogenicity

This is one of the most important chronic toxicology points.

Hexavalent chromium compounds are established human carcinogens.

IARC classifies:

• Cr(VI) compounds → Group 1, carcinogenic to humans
• Metallic chromium → Group 3
• Cr(III) compounds → Group 3

with sufficient human evidence particularly for occupationally associated lung cancer.

NIOSH similarly considers Cr(VI) compounds occupational carcinogens and recognizes increased lung-cancer risk in exposed workers.

Cancer Sites

The strongest human evidence is for:

Lung cancer

Occupational data also support concern for:

• Nasal cancer
• Sinonasal cancer

in heavily exposed populations.

Thus, the old statement that chromium “may” cause bronchogenic cancer understates the evidence specifically for Cr(VI).

Diagnosis

Diagnosis depends mainly on:

Exposure history + route + clinical syndrome

Important questions include:

• What chromium compound?
• Cr(VI) or Cr(III)?
• Chromate/dichromate?
• Concentration?
• Ingestion, inhalation, skin, or eye exposure?
• Occupational process?
• Duration/frequency?
• PPE?
• Other metals or chemicals present?

Obtaining the:

• Safety Data Sheet
• Product label
• Workplace exposure information

can be extremely helpful.

Acute Laboratory Evaluation

For significant Cr(VI) ingestion obtain:

• CBC
• Electrolytes
• Bicarbonate
• Glucose
• BUN
• Creatinine
• AST/ALT
• Bilirubin

For severe poisoning also obtain:

• Blood gas
• Lactate
• PT/INR
• aPTT
• Fibrinogen
• LDH
• Haptoglobin
• Reticulocyte count
• Urinalysis
• Type and crossmatch

Consider:

• Methemoglobin concentration

if cyanosis or unexplained hypoxia is present.

ECG

Obtain an ECG in significant systemic poisoning.

Continuous monitoring is appropriate with:

• Shock
• Major electrolyte abnormalities
• Severe acidosis
• Multiorgan failure

Chromium Measurements

Chromium concentrations may document exposure but have important limitations.

Blood / Serum

Chromium clears relatively rapidly from plasma.

Cr(VI) can enter erythrocytes and be reduced to Cr(III), becoming bound intracellularly.

Therefore:

• Serum chromium primarily reflects relatively recent exposure
• RBC chromium can support significant Cr(VI) exposure

ATSDR notes that Cr(VI), unlike Cr(III), enters red cells, so comparing erythrocyte and plasma/serum chromium may sometimes help characterize exposure.

Urinary Chromium

Urinary chromium largely reflects:

Recent absorption over roughly the preceding 1–2 days

and is used more often for occupational biomonitoring than for acute bedside decision-making.

Important

A chromium level is not a clinical severity score.

ATSDR notes that elevated chromium values have not been reliably correlated with specific physiologic effects.

Therefore:

Do not delay resuscitation or caustic-injury evaluation while waiting for chromium measurements.

Hair and Nail Testing

Hair or nail chromium testing is generally:

Not clinically useful

for diagnosing an individual exposure because external contamination cannot be reliably distinguished from incorporated chromium.

Acute GI Injury Assessment

A substantial Cr(VI) ingestion should be managed partly according to modern caustic-ingestion principles.

Consider:

• Gastroenterology
• Surgery
• Medical toxicology/poison center

early.

Endoscopy

For significant symptomatic or intentional Cr(VI) ingestion:

Early upper GI endoscopy is generally considered within approximately 12–24 hours, provided the patient is stable and perforation is not already apparent.

Endoscopy helps determine:

• Esophageal injury
• Gastric injury
• Burn severity
• Future stricture risk

Modern caustic literature generally recommends early endoscopic evaluation when clinically indicated.

CT

Contrast-enhanced CT of the:

• Neck
• Chest
• Abdomen

may be particularly useful in severe poisoning to assess:

• Transmural necrosis
• Perforation
• Mediastinal injury
• Peritoneal injury
• Adjacent structures

CT complements endoscopy rather than being replaced by routine broad CT/MRI scanning of the entire body.

Important Correction to the Old Imaging Advice

The older recommendation:

“CT or MRI from the nose to abdomen in the first few days because abscess develops late”

is not a standard contemporary chromium-poisoning protocol.

Imaging should be:

Targeted to the suspected complication.

Examples:

• CXR/CT chest → severe inhalational injury
• Contrast CT chest/abdomen → suspected deep GI necrosis/perforation
• ENT imaging/endoscopy → severe chronic nasal disease when clinically indicated

Treatment

1. Rescuer / Healthcare Worker Safety

For industrial contamination:

• Wear appropriate gloves
• Eye protection
• Protective clothing
• Respiratory protection if dust/mist remains airborne

Avoid secondary contamination from:

• Contaminated clothing
• Wet solutions
• Chromate dust

2. Airway and Breathing

For significant inhalation or major ingestion:

Assess:

• Airway edema
• Respiratory distress
• Oxygenation
• Ventilation

Provide:

• Oxygen for hypoxemia
• Bronchodilator for bronchospasm

Early intubation is appropriate for:

• Progressive airway edema
• Severe respiratory failure
• Coma
• Inability to manage secretions

3. Circulation

Severe dichromate poisoning may produce profound shock.

Treat with:

• IV isotonic crystalloid when clinically appropriate
• Blood products for major hemorrhage

If shock persists:

Norepinephrine is generally a reasonable contemporary first-line vasopressor.

Correct:

• Acidosis
• Electrolyte abnormalities
• Hypoglycemia

as clinically indicated.

Gastrointestinal Decontamination

Do not induce vomiting

Never induce emesis.

Cr(VI) salts can be intensely corrosive.

Vomiting:

• Re-exposes the esophagus
• Increases aspiration risk
• Can worsen hemorrhage

ATSDR specifically states that vomiting should not be induced because of Cr(VI)’s corrosive effects and risk of rapid clinical deterioration.

Routine Milk/Water Dilution

The older recommendation for routine milk/water dilution should not be carried forward.

Modern caustic-ingestion guidance finds little evidence for benefit, and dilution may produce:

• Vomiting
• Distention
• Aspiration

Thus:

Do not routinely force milk or water after significant Cr(VI) ingestion.

Do Not Neutralize

Do not attempt chemical neutralization with:

• Alkali
• Acid
• Household chemicals

Neutralization can cause an:

Exothermic reaction → additional thermal injury

Activated Charcoal

Routine activated charcoal is not established therapy for Cr(VI) ingestion.

Problems include:

• Caustic injury occurs rapidly
• Aspiration risk
• Vomiting
• Interference with endoscopic visualization
• Uncertain chromium adsorption benefit

Modern caustic guidance advises against routine charcoal for corrosives.

Gastric Lavage

Do not perform routine gastric lavage.

Potential harms include:

• Esophageal re-exposure
• Hemorrhage
• Perforation
• Aspiration

Modern corrosive-ingestion guidance considers lavage contraindicated.

Nasogastric Tubes

Avoid blind NG/OG placement through a severely injured esophagus.

If enteral access is required:

Use endoscopic/surgical guidance when feasible.

Dermal Decontamination

Immediately:

• Remove contaminated clothing
• Remove contaminated jewelry/PPE
• Wash exposed skin thoroughly with soap and water

NIOSH recommends immediate soap flushing after chromic acid/chromate skin contamination.

Do not aggressively scrub damaged skin.

Ascorbic Acid Skin Soaks – Historical Practice

Older toxicology references recommend:

10–20% ascorbic acid skin soaking

after Cr(VI) contamination.

Experimental and historical occupational evidence suggests extracellular reduction of Cr(VI) may reduce local toxicity, and ATSDR discusses older reports of 10% ascorbate reducing chromium dermatitis/ulceration.

However:

This is not a substitute for immediate copious decontamination and is not a routine modern emergency requirement.

Immediate:

• Clothing removal
• Soap/water washing

remains the priority.

Eye Exposure

Immediately:

Irrigate copiously

with:

• Water
• Saline

for at least 15–20 minutes and longer if needed.

Remove contact lenses when possible.

Persistent:

• Pain
• Photophobia
• Corneal injury
• Visual disturbance

requires urgent ophthalmologic evaluation.

NIOSH recommends immediate irrigation after eye exposure.

Ascorbic Acid as an “Antidote”

This is one of the biggest updates to the old chapter.

The theoretical reaction is:

Cr(VI) + reducing agent → Cr(III)

which should reduce membrane penetration if it occurs before cellular uptake.

This is the rationale for vitamin C.

However:

There is no established human clinical evidence supporting a standardized ascorbic-acid antidote regimen for acute Cr(VI) poisoning.

ATSDR specifically states that although extracellular reduction may theoretically protect, human efficacy of ascorbate or other reducing agents has not been established, and intracellular ascorbate can have complex effects on Cr(VI) toxicity.

Therefore the old formula:

“1 g vitamin C per 0.135 g elemental chromium”

should not be used as an established modern antidote protocol.

Practical approach

For a very recent major soluble Cr(VI) exposure:

Discuss any proposed ascorbate therapy with a medical toxicologist/poison center.

It must not delay:

• Resuscitation
• Airway management
• Caustic injury assessment
• Treatment of shock

Dimercaprol (BAL)

The old chapter states:

“Dimercaprol has been used successfully.”

Modern interpretation is different.

BAL is not an established effective antidote for chromium poisoning.

ATSDR states that chelating agents such as:

• Dimercaprol
• EDTA

have not been shown effective in human chromium poisoning.

Therefore:

Routine BAL should not be used.

EDTA and Other Chelators

Similarly:

• CaNa₂EDTA
• Other experimental chelators

do not have an established clinical role.

A toxicokinetic potassium-dichromate case found Ca-EDTA did not meaningfully alter serum, RBC, or urinary chromium kinetics.

Chelation should therefore not be routine therapy.

Hemodialysis

Toxin removal

Chromium rapidly enters cells and binds intracellularly.

Consequently:

Conventional hemodialysis does not reliably remove enough chromium to function as an effective antidotal therapy.

In one detailed case, combined urinary and dialysis elimination represented only about:

0.16% of the ingested chromium dose

despite prompt dialysis.

Other severe cases similarly found little clinically meaningful chromium removal by:

• Hemodialysis
• Hemoperfusion
• Exchange transfusion.

When Dialysis IS Appropriate

Hemodialysis remains appropriate for conventional renal indications such as:

• Refractory metabolic acidosis
• Severe hyperkalemia
• Volume overload
• Uremic complications
• Severe AKI

Thus:

Dialysis treats the renal/metabolic consequences—not reliably the chromium body burden.

ATSDR likewise states that hemodialysis has not been shown effective as a specific chromium-removal treatment.

Hemoperfusion / Exchange Transfusion

These are not routine therapies.

Historical reports failed to demonstrate reliable clinical benefit or meaningful removal of the largely intracellular chromium burden.

GI Hemorrhage

Treat severe bleeding with:

• Large-bore IV access
• Type/crossmatch
• Packed RBCs
• Appropriate plasma/platelets when indicated

Early:

• Gastroenterology
• Surgery

involvement is appropriate.

Perforation / Transmural Necrosis

Suspect perforation with:

• Severe worsening abdominal/chest pain
• Peritoneal signs
• Pneumomediastinum
• Free intraperitoneal air
• Sepsis
• Shock
• Rising lactate/acidosis

This requires:

Immediate surgical evaluation.

Nutrition

Significant Grade IIb/III caustic injury may require:

• Temporarily restricted oral intake
• Carefully planned enteral feeding
• Postpyloric feeding
• Occasionally parenteral nutrition

The old automatic recommendation for parenteral nutrition after severe injury is overly broad.

Modern practice favors:

Enteral nutrition whenever it can be delivered safely.

Antibiotics

Routine prophylactic antibiotics are not indicated merely because chromium was ingested.

Use antibiotics for:

• Perforation
• Mediastinitis
• Peritonitis
• Aspiration pneumonia
• Documented infection

Corticosteroids

There is no established role for corticosteroids to treat systemic chromium poisoning.

For caustic esophageal injury, routine systemic steroids are also not reliably proven to prevent strictures.

Their use should therefore not be automatic.

Inhalational Exposure – Treatment

Remove from exposure.

Provide:

• Fresh air
• Oxygen if hypoxemic
• Inhaled β₂ agonist for bronchospasm

Severe respiratory injury may require:

• Noninvasive support in selected cases
• Intubation
• Lung-protective ventilation

For sensitization/occupational asthma:

Removal from continued chromium exposure is critical.

Chronic Dermatitis / Chrome Ulcers

Management includes:

• Eliminate ongoing exposure
• Local wound care
• Treat secondary infection only when present
• Occupational-health evaluation

Allergic dermatitis may require:

• Topical anti-inflammatory therapy
• Dermatology/occupational medicine assessment
• Avoidance of further chromium exposure

Repeated exposure after sensitization may provoke dermatitis at very low concentrations.

Nasal Disease

Workers with:

• Recurrent epistaxis
• Nasal ulceration
• Persistent crusting
• Septal damage

need:

• Removal/reduction of exposure
• Occupational medicine evaluation
• ENT assessment when clinically indicated

The old recommendation to wash the nose daily and routinely apply zinc/barium ointment is not a modern standard treatment strategy.

Exposure control is far more important.

Occupational Cancer Prevention

Because Cr(VI) is a carcinogen:

Engineering controls and exposure prevention are the central long-term intervention.

Important measures include:

• Local exhaust ventilation
• Process enclosure
• Substitution when feasible
• Appropriate respiratory protection
• Skin protection
• Hygiene facilities
• Exposure monitoring
• Occupational medical surveillance

Current Workplace Standards – Cr(VI)

The workplace limits in the old chapter are substantially outdated.

OSHA

Current federal OSHA Cr(VI) standard:

PEL = 5 μg/m³ as an 8-hour TWA

and:

Action level = 2.5 μg/m³ as an 8-hour TWA

This equals:

0.005 mg/m³

not the old 0.25 mg/m³ value.

NIOSH

Current NIOSH recommended exposure limit:

0.2 μg/m³ = 0.0002 mg/m³ as Cr(VI), 8-hour TWA

NIOSH treats Cr(VI) as an occupational carcinogen.

This is 25-fold lower than the OSHA PEL.

ACGIH

Current OSHA chemical-data listings cite an ACGIH value of:

0.0002 mg/m³ inhalable particulate TWA

with:

0.0005 mg/m³ STEL

for Cr(VI).

NIOSH IDLH

For chromic acid/chromates:

IDLH = 15 mg/m³ as Cr(VI)

Do Not Apply Cr(VI) Limits to All Chromium

Occupational limits differ by oxidation state.

For example, NIOSH lists much higher limits for:

• Chromium metal
• Cr(II)
• Cr(III)

reflecting their markedly different toxicology.

Therefore:

Always specify the chromium species when discussing occupational exposure.

Occupational Biomonitoring

Urinary chromium can help assess recent occupational uptake.

However:

• It varies between individuals
• It reflects mainly recent exposure
• It does not directly predict disease
• It may normalize despite a clinically important past exposure

ATSDR emphasizes these limitations and notes that urinary chromium primarily represents absorption within the previous 1–2 days.

Occupational monitoring is best interpreted with:

• Air measurements
• Job/task assessment
• PPE evaluation
• Clinical findings

rather than in isolation.

Admission

ICU admission

ICU-level management is appropriate after significant Cr(VI) ingestion with:

• Severe GI burns
• GI hemorrhage
• Hypotension/shock
• Severe metabolic acidosis
• AKI
• Hepatic injury
• Coagulopathy
• Altered mental status
• Respiratory failure
• Multiorgan dysfunction

Hospital Admission

Admission is generally appropriate for:

• Any clearly significant soluble Cr(VI) ingestion
• Persistent vomiting/diarrhea
• Dysphagia/odynophagia
• Abdominal or chest pain
• Hematemesis
• Renal abnormalities
• Hepatic abnormalities
• Significant inhalational injury

A deliberate Cr(VI) ingestion should not be discharged merely because initial vital signs are normal.

Disposition After Minor Exposure

A truly trivial exposure to:

• Metallic chromium
• Low-risk Cr(III) material

may require only decontamination and assessment.

However:

Known ingestion of soluble Cr(VI) deserves a low threshold for prolonged medical evaluation

because systemic renal/hepatic injury can evolve after the initial corrosive symptoms.

Prognosis

Minor local exposure

Usually favorable after adequate decontamination.

Chronic occupational exposure

Can result in:

• Persistent sensitization
• Chronic dermatitis
• Nasal septal damage
• Occupational asthma
• Increased cancer risk

Severe Cr(VI) ingestion

Can produce:

• Massive GI hemorrhage
• AKI
• Hepatic failure
• Coagulopathy
• Shock
• Multiorgan failure
• Death

Case reports demonstrate that deterioration may be rapid despite aggressive therapy.

Long-Term GI Follow-Up

Patients with significant caustic esophageal injury are at risk for:

• Esophageal stricture
• Dysphagia
• Gastric outlet obstruction

Grade IIb/III caustic injuries require gastroenterology follow-up.

Later progressive dysphagia warrants:

• Contrast evaluation
• Endoscopy

as appropriate.

Pregnancy

There is no chromium-specific antidotal therapy that should supersede maternal resuscitation.

After severe exposure:

Maternal airway, oxygenation, circulation, renal function, and caustic injury management are priorities.

Occupational Cr(VI) exposure during pregnancy should be minimized according to exposure-control standards.

Important Pitfalls

1. Treating all chromium as equally toxic

This is the fundamental error.

Cr(VI) ≫ Cr(III) in toxicologic importance.

2. Calling Cr(VI) merely a “heavy-metal poisoning”

Acute soluble Cr(VI) ingestion is also:

A severe corrosive ingestion

with potentially catastrophic local GI injury.

3. Using the old fixed lethal dose

The old:

0.5–1 g = lethal

rule is unreliable.

Risk depends on compound, dose, concentration, and clinical findings.

4. Missing systemic toxicity after the initial GI burn

After vomiting/abdominal pain, monitor for:

AKI + hepatic injury + coagulopathy + shock

5. Calling chromium pneumoconiosis the dominant chronic lung disease

The major chronic Cr(VI) respiratory hazards are:

• Nasal injury
• Asthma
• Respiratory irritation
• Lung cancer

6. Underestimating cancer risk

Cr(VI) compounds are IARC Group 1 human carcinogens.

7. Assuming Cr(III) and metallic chromium have the same carcinogenic classification

IARC classification:

• Cr(VI) → Group 1
• Cr(III) → Group 3
• Metallic chromium → Group 3

8. Inducing vomiting

Cr(VI) salts are corrosive.

Do not induce emesis.

ATSDR specifically advises against it.

9. Routinely diluting with milk/water

Modern caustic management does not support forced dilution because clinical benefit is unproven.

10. Giving activated charcoal routinely

Chromium-associated caustic injury is not a standard charcoal indication.

Airway safety and endoscopic visualization matter more.

11. Performing gastric lavage

Routine lavage is contraindicated.

It can provoke:

• Hemorrhage
• Re-exposure
• Aspiration
• Perforation

12. Treating vitamin C as a proven antidote

Reduction of extracellular Cr(VI) to Cr(III) is mechanistically attractive.

But:

Human efficacy and dosing are not established.

13. Using the old fixed vitamin-C formula

The historical:

1 g vitamin C per 0.135 g chromium

regimen is not an evidence-based modern standard.

14. Routinely giving BAL

Dimercaprol has not been shown effective in human chromium poisoning.

15. Assuming EDTA works because chromium is a metal

CaNa₂EDTA does not have an established therapeutic role.

Chromium toxicity should not be managed by automatically applying lead-poisoning chelation protocols.

16. Using dialysis as a chromium antidote

Chromium rapidly becomes intracellular.

Hemodialysis may remove only a tiny fraction of a major dose.

Use dialysis for:

AKI/metabolic indications

rather than expecting reliable toxin clearance.

17. Relying on chromium blood/urine levels to grade severity

They can confirm recent exposure but correlate poorly with clinical effects.

Treat the patient, not the chromium number.

18. Using hair chromium analysis

Hair/nail testing is easily confounded by external contamination and is generally not clinically useful for individual diagnosis.

19. Using the old occupational PEL

Old chapter:

~0.25 mg/m³

Modern OSHA Cr(VI) PEL:

0.005 mg/m³ = 5 μg/m³

High-Yield Toxicology Pearls

Chromium toxicology = always ask which valence state

Think:

Cr(VI) = corrosive + systemic poison + occupational carcinogen

Key points:

• Important forms:
• Chromium metal
• Cr(III)
• Cr(VI)
• Cr(VI) is much more toxic than Cr(III)
• Important Cr(VI) compounds:
• Chromic acid
• Chromium trioxide
• Potassium dichromate
• Sodium dichromate
• Chromates
• Mechanism:
• Cr(VI) resembles sulfate/phosphate
• Enters cells via anion transporters
• Intracellular reduction → Cr(V)/Cr(IV)/Cr(III) + ROS
• DNA/protein injury
• Acute ingestion:
• Caustic GI burns
• Vomiting/diarrhea
• GI hemorrhage
• Shock
• AKI
• Hepatic injury
• Coagulopathy
• Multiorgan failure
• Skin:
• Chrome holes
• Irritant dermatitis
• Allergic contact dermatitis
• Respiratory:
• Nasal irritation
• Septal ulceration/perforation
• Occupational asthma
• Cancer:
• Cr(VI) = IARC Group 1
• Strong association with lung cancer
• Cr(III) and metallic chromium:
• IARC Group 3
• Diagnosis is primarily:
• Exposure history
• Clinical syndrome
• Blood/urine chromium:
• Can document recent exposure
• Do not reliably grade toxicity
• Urinary chromium mainly reflects exposure over the previous 1–2 days
• Significant Cr(VI) ingestion → evaluate as caustic ingestion
• Endoscopy generally within ~12–24 h when indicated
• Contrast CT helps evaluate deep/transmural injury
• Do not induce vomiting
• Do not neutralize
• Routine milk/water dilution is not recommended
• Routine activated charcoal is not established
• Gastric lavage is contraindicated/not routine
• Skin:
• Remove clothing
• Immediate soap-and-water decontamination
• Eyes:
• Immediate copious irrigation
• No proven antidote
• Vitamin C:
• Mechanistically reduces Cr(VI) → Cr(III)
• Human therapeutic benefit is unproven
• Old fixed-dose protocol should not be used routinely
• BAL:
• Not recommended routinely
• EDTA:
• No established role
• Hemodialysis:
• Poor chromium removal after intracellular uptake
• Use for standard AKI/metabolic indications
• Modern occupational Cr(VI) limits:
• OSHA PEL: 5 μg/m³ 8-h TWA
• OSHA action level: 2.5 μg/m³
• NIOSH REL: 0.2 μg/m³ 8-h TWA
• NIOSH IDLH: 15 mg/m³ as Cr(VI)
• Prevention and occupational exposure control are central because chronic Cr(VI) exposure is carcinogenic