ACMT Toxicology Visual Pearl: Sink or Swim

Answer:

1 – Camphor

Background

Mothballs are most often used inside the home to repel insects, particularly moths, from damaging clothing but are also used in the garden to repel pests and other animals. Mothballs are typically composed of camphor, naphthalene, or paradichlorobenzene (PDB), with camphor being the least commonly available. These active ingredients are fumigant insecticides meaning they exist as solids that release toxic gases to kill and control pests [1,2].

How can you tell mothballs apart from each other?

The active ingredient of mothballs is not distinguishable through physical appearance or odor, however, the float test can help distinguish between them.

• Float Test (Table 1)
  • Place the mothball in water, and in saturated salt solution
  • To prepare the solution, stir in table salt to room temperature or warm water until no more salt dissolves and begins to deposit on the bottom of the container.
  • 50% Dextrose solution may be used in place of saturated salt solution with equivalent accuracy [3]
  • Camphor floats in both solutions
  • Naphthalene sinks in water but floats in saturated salt solution
  • Paradichlorobenzene sinks in both solutions

Table 1: Distinguishing the Various Types of Mothballs

What is the toxicity of the different types of mothballs?

1. Camphor

• Camphor, originally derived from the bark of the fragrant Cinnamomum camphora tree, is found in a variety of over-the-counter topical products including Vicks Vaporub™, Tiger Balm™, Bengay™, IcyHot™, Biofreeze™, and cold sore ointments.
• The mechanism of action of camphor has not been fully identified, though it has been demonstrated to have bacteriostatic and fungistatic activity in vitro [1,4].
• Toxicity can occur following dermal exposure, oral ingestion, or intranasal instillation with oral ingestion resulting in the highest systemic toxicity. [5,6].
• Clinical signs include [7]
  • Nausea, vomiting, abdominal pain
  • Salivation
  • Hypotension, and tachycardia
  • Seizures, most commonly in children [8]

2. Naphthalene

• Naphthalene is a component of petroleum and coal tar.
• Exposure to naphthalene has occurred through the manufacturing of synthetic resins, solvents, fuels, and dyes in addition to mothballs [1].
• Clinical features of toxicity include [2,9,10]
  • Skin irritation
  • Headache
  • Diaphoresis
  • Nausea, vomiting, and abdominal pain
  • Seizures
  • Hemolytic anemia
  • Methemoglobinemia
  • Hemolysis and methemoglobinemia are thought to arise from the metabolites, naphthol, and naphthoquinone, and patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency are most susceptible [2,11].

3. Paradichlorobenzene

• Paradichlorobenzene (PDB) is an organic compound in the form of colorless or white crystals.
• It is widely used in the manufacturing of dyes, pigments, insecticides, fungicides, disinfectants, repellents, and solvents [1].
• Minor unintentional exposures to PDB typically do not cause any toxicity.
• Acute PDB ingestion most often causes mild symptoms such as nausea, vomiting, and mucous membrane irritation, however, there have been rare reports of hepatotoxicity and pulmonary edema as well as methemoglobinemia [1,2].

Management

• Treatment of mothball ingestion is supportive care regardless of the type of mothball consumed.
• Gastric decontamination with activated charcoal might be an option early after a large ingestion
• Seizure activity is possible, most often seen with camphor, and can be controlled with benzodiazepines.
• In cases of severe naphthalene or PDB poisoning, evaluate renal and hepatic function along with evaluating for hemolysis and methemoglobinemia [1,9]
• Naphthalene ingestion and rarely PDB ingestion can result in delayed hemolysis and/or methemoglobinemia; consider 24-48 hour outpatient laboratory evaluation in higher-risk patients such as those with larger ingestions or G6PD deficiency.
• Patients who are discharged from the ED should be instructed to seek care if they develop delayed symptoms [1].

Bedside Pearls

• Most mothballs sold in the United States are composed of paradichlorobenzene (PDB) or naphthalene.
• Camphor containing mothballs may cause altered mental status and seizures, particularly in children.
• Naphthalene and rarely PDB containing mothballs may cause hemolysis and methemoglobinemia which may be delayed in onset.
• Bedside testing such as the float test may be helpful in identification of mothballs acutely in the ED.