Naphthalene Toxicity - Symptoms, Causes, Treatment & Prevention

```html

Overview

Naphthalene toxicity occurs when a person inhales, swallows, or absorbs a harmful amount of naphthalene, a volatile aromatic hydrocarbon found in mothballs, certain industrial solvents, and some pesticides. Acute exposure can damage the blood, lungs, liver, and nervous system, while chronic exposure may lead to hemolytic anemia and long‑term organ injury.

Who it affects – Anyone can be exposed, but the highest‑risk groups are:

• Children who play with or ingest mothballs.
• Workers in shoe‑manufacturing, coal‑tar production, petroleum refining, or printing.
• People with glucose‑6‑phosphate dehydrogenase (G6PD) deficiency, who are especially prone to hemolysis.

Prevalence – In the United States, the American Association of Poison Control Centers recorded ~4,600 naphthalene exposures in 2022, with 75 % involving children <5 years old.<sup>1</sup> Worldwide, occupational exposure remains a concern in low‑ and middle‑income countries where safety regulations are less stringent.<sup>2</sup>

Symptoms

Symptoms vary by route (inhalation, ingestion, dermal) and by dose. They may appear within minutes to several days after exposure.

Acute (high‑dose) exposure

• Respiratory: Cough, wheezing, shortness of breath, chest tightness, pulmonary edema.
• Gastrointestinal: Nausea, vomiting, abdominal cramps, diarrhea.
• Neurologic: Headache, dizziness, confusion, seizures (rare).
• Hematologic: Sudden onset hemolytic anemia – fatigue, pallor, dark urine, jaundice.
• Dermatologic: Skin irritation, erythema, blistering if direct contact.

Chronic (low‑dose, repeated) exposure

• Fatigue and mild anemia.
• Recurrent respiratory infections or chronic bronchitis.
• Peripheral neuropathy – tingling or numbness in hands/feet.
• Kidney dysfunction – proteinuria, decreased creatinine clearance.
• Potential carcinogenic effect – long‑term animal data suggest increased risk of liver tumors (IARC classifies naphthalene as “possibly carcinogenic to humans”).<sup>3</sup>

Causes and Risk Factors

Primary sources of naphthalene include:

• Mothballs (solid naphthalene crystals) and some air fresheners.
• Industrial solvents, paints, and adhesives.
• Combustion products – coal tar, cigarette smoke, gasoline exhaust.

How exposure occurs

• Inhalation: Vapor released from mothballs stored in closed spaces, or fumes in poorly ventilated workplaces.
• Ingestion: Accidental swallowing of mothballs, especially by children.
• Dermal absorption: Direct skin contact with liquid naphthalene or contaminated clothing.

Risk factors that increase susceptibility

• Age < 5 years (higher respiratory rate, hand‑to‑mouth behavior).
• G6PD deficiency – up to 20 % of males of African, Mediterranean, or Asian descent.<sup>4</sup>
• Pre‑existing anemia, liver disease, or renal impairment.
• Prenatal exposure – animal studies show teratogenic effects; human data are limited but suggest possible developmental toxicity.

Diagnosis

Diagnosis is clinical but supported by laboratory and imaging studies.

History and Physical Examination

• Ask about recent use of mothballs, occupational exposure, or proximity to coal‑tar products.
• Look for signs of hemolysis (jaundice, scleral icterus), respiratory distress, or skin lesions.

Laboratory Tests

• Complete blood count (CBC): Decreased hemoglobin/hematocrit with reticulocytosis indicates hemolytic anemia.
• Peripheral smear: Bite cells, Heinz bodies (especially in G6PD‑deficient patients).
• Liver function tests (ALT, AST, bilirubin): May be elevated.
• Renal panel: BUN/creatinine for acute kidney injury.
• Urinalysis: Dark urine, hemoglobinuria.
• Plasma or urine naphthalene level: Not routinely available in most labs, but can confirm exposure in occupational cases.

Imaging

• Chest X‑ray – may show infiltrates or pulmonary edema in severe inhalation injury.
• CT scan – reserved for suspected severe pulmonary or neurologic involvement.

Special Tests

• G6PD enzyme assay – important before giving oxidative drugs.

Treatment Options

Treatment aims to stop further exposure, support the affected organ systems, and treat hemolysis.

Immediate Measures

• Remove the patient from the source of naphthalene (ventilate area, discard mothballs, change contaminated clothing).
• Administer 100 % oxygen for respiratory distress.

Pharmacologic Therapy

• Intravenous fluids: Aggressive hydration to maintain renal perfusion and aid clearance of hemoglobin.
• Blood transfusion: Packed red blood cells for severe anemia (Hb < 7 g/dL) or symptomatic patients.
• Folinic acid (Leucovorin): May reduce oxidative stress in hemolysis, especially in G6PD‑deficient patients (evidence limited but used in practice).
• Corticosteroids: Considered in severe pulmonary inflammation, but benefit is uncertain.
• Phenobarbital or diazepam: For seizure control if neurologic symptoms develop.

Procedures

• Exchange transfusion – rare, reserved for life‑threatening hemolysis unresponsive to simple transfusion.
• Hemodialysis – indicated when acute kidney injury with oliguria does not improve with fluids.

Supportive & Lifestyle Measures

• Discontinue any oxidative drugs (e.g., sulfonamides, quinine) that could worsen hemolysis.
• Educate caregivers on safe storage of naphthalene products.
• Monitor CBC and liver/kidney labs daily until stable.

Living with Naphthalene Toxicity

Even after the acute phase, patients may need ongoing care.

Follow‑up Monitoring

• Weekly CBC for 4 weeks, then monthly for 3 months.
• Liver enzymes and creatinine every 2–4 weeks for 3 months.
• Annual pulmonary function tests if there was significant inhalation injury.

Day‑to‑Day Management Tips

• Environmental control: Keep mothballs out of reach, use alternatives (cedar blocks, silica gel) for pest control.
• Hydration: Aim for >2 L of water daily to aid renal clearance.
• Nutrition: Adequate iron and folate intake to support erythropoiesis.
• Sun protection: Patients with G6PD deficiency should avoid excessive sunlight, as UV can trigger hemolysis.
• Medication review: Have a pharmacist check all prescriptions for oxidative agents.

Prevention

• Store mothballs in sealed containers, away from children and pets; label clearly.
• Use non‑chemical pest deterrents (candle, cedar, vacuum sealing).
• Employ proper ventilation and personal protective equipment (PPE) in workplaces that handle naphthalene.
• Employ occupational health surveillance programs – baseline CBC and periodic monitoring for exposed workers.
• Educate communities with high G6PD‑deficiency prevalence about the risks of naphthalene.

Complications

If untreated or inadequately managed, naphthalene toxicity can lead to:

• Severe hemolytic anemia: May cause heart failure or stroke due to hypoxia.
• Acute renal failure: Resulting from hemoglobin nephrotoxicity.
• Chronic lung disease: Fibrosis or bronchiectasis after severe inhalation injury.
• Neurologic deficits: Peripheral neuropathy or, rarely, permanent cognitive impairment.
• Secondary infections: Due to immunosuppression from anemia.
• Potential carcinogenesis: Long‑term data are limited, but IARC classification suggests a possible increased cancer risk with chronic high‑dose exposure.

When to Seek Emergency Care

References

1. American Association of Poison Control Centers. National Poison Data System Annual Report 2022. (2023).
2. World Health Organization. Occupational Health: Naphthalene. WHO Fact Sheet, 2021.
3. International Agency for Research on Cancer (IARC). Monographs on the Evaluation of Carcinogenic Risks to Humans – Volume 96: Naphthalene. (2016).
4. Kaplan, M., et al. “G6PD Deficiency and Oxidative Stress.” Blood Reviews 2020;34:100549.
5. Mayo Clinic. “Naphthalene poisoning.” Accessed May 2024. https://www.mayoclinic.org.
6. Cleveland Clinic. “Hemolytic anemia: causes, symptoms, treatment.” Updated 2023. https://my.clevelandclinic.org.
7. Centers for Disease Control and Prevention. “Naphthalene Toxicity – Occupational Safety.” 2022.

```