Dichloromethane toxicity

Background

• Methylene chloride or dichloromethane (DCM) is a chlorinated organic solvent. It is a colorless, volatile liquid with a chloroform-like, sweet odor.
• Used in a wide range of industrial and research settings.

Routes of Exposure

• Inhalation
  • Methylene chloride vapor is absorbed readily from the lungs.
  • The odor threshold is 250 ppm, which is 10 times higher than the OSHA PEL (25 ppm).
  • Olfactory fatigue may also occur at high concentrations.
  • Methylene chloride is heavier than air and may cause asphyxiation in enclosed, poorly ventilated, or low-lying areas.

• Skin/Eye Contact
  • Methylene chloride vapor can cause skin and eye irritation.
  • Prolonged dermal contact may produce chemical burns.
  • Methylene chloride is absorbed slowly through intact skin but not in quantities that cause acute systemic toxicity.

• Ingestion
  • Acute toxic effects, including death, can result from ingestion.

Clinical Features

• CNS
  • CNS depression, headache, drowsiness, lightheadedness, slurred speech, decreased alertness, slowed reaction times, irritability, impaired gait, and stupor
  • Rapid loss of consciousness, coma, seizures, and death have been reported.

• Metabolic
  • Methylene chloride is metabolized to carbon monoxide, causing elevated carboxyhemoglobin levels. Carboxyhemoglobin levels may continue to rise for several hours after exposure.
  • The fetus is particularly vulnerable to poisoning with carbon monoxide.

• Cardiovascular
  • ECG changes resembling those of carbon monoxide poisoning.
  • Angina, myocardial infarction, and cardiac arrest associated with methylene chloride inhalation was reported in one patient
    • No adverse cardiovascular effects from methylene chloride have been reported for occupationally exposed workers.

• Respiratory
  • Airway irritation, hydrocarbon pneumonitis, pulmonary edema.

• Gastrointestinal
  • Nausea, vomiting, gastrointestinal ulceration and bleeding.

• Dermal
  • Skin irritation and blistering.
  • Prolonged dermal contact may result in second- and third-degree chemical burns.

• Ocular
  • Eye irritation and tearing. When splashed in the eye, methylene chloride can cause burning pain, keratitis, and iritis.

Differential Diagnosis

Drugs of abuse

• 25C-NBOMe‎
• Alcohol
• Amphetamines
• Bath salts
• Cocaine
• Difluoroethane
• Ecstasy
• Gamma hydroxybutyrate (GHB)
• Heroin
• Inhalant abuse
  • Hydrocarbon toxicity
  • Difluoroethane (electronics duster)
• Marijuana
• Kratom
• Phencyclidine (PCP)
• Psilocybin ("magic mushrooms")
• Synthetic cannabinoids
• Chloral hydrate
• Body packing

Toxic gas exposure

• Carbon monoxide toxicity
• Chemical weapons
• Cyanide toxicity
• Dichloromethane toxicity
• Hydrocarbon toxicity
• Hydrogen sulfide toxicity
• Inhalant abuse
  • Difluoroethane toxicity
• Methane toxicity
• Smoke inhalation injury
• Ethylene dibromide toxicity

Evaluation

Workup

• CBC
• CMP
• ECG
• Carboxyhemoglobin levels
  • Carboxyhemoglobin levels of exposed patients rarely exceed 15% but may remain elevated for 1 to 2 days after exposure due to continual metabolic conversion of fat-stored methylene chloride.
• CXR: for significant inhalation exposures.

Diagnosis

• Clinical Diagnosis based on history of exposure and symptoms.
• Levels of methylene chloride in blood are not clinically useful; however, they may be used to qualitatively document exposure.

Management

• Oxygen therapy
  • May consider Hyperbaric oxygen, it's use for DCM toxicity has not been studied.
• Supportive Care

Disposition

• Admit for symptoms or significant exposures.

References

• https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx?mmgid=230&toxid=42
• https://en.wikipedia.org/wiki/Dichloromethane