What is Diethyl Sulfate?

Diethyl sulfate is a highly toxic and likely carcinogenic chemical compound with the molecular formula (C₂H₅)₂SO₄. It is the diethyl ester of sulfuric acid and exists at room temperature as a colourless, oily liquid with a faint peppermint odour. It is slightly soluble in water but miscible with alcohol, diethyl ether, and most polar solvents. In hot water, diethyl sulfate readily decomposes into ethyl hydrogen sulfate and ethanol.

What is Diethyl Sulfate used for?

Diethyl sulfate is primarily used as a chemical intermediate and ethylating agent in the synthesis of ethyl derivatives of phenols, amines, and thiols. It also serves as an accelerator in the sulfation of ethylene and certain sulfonation processes. Key applications include:

• Manufacturing dyes, pigments, carbonless paper, and textiles
• Serving as an intermediate in synthetic ethanol production from ethylene via indirect hydration (strong acid) processes
• Use in household products, cosmetics, agricultural chemicals, pharmaceuticals, and laboratory reagents
• Application as a mutagen, as in 1966, when it was used to develop the Luther variety of barley

In the Environment

Diethyl sulfate can enter the environment through its production and use in the synthesis of various chemicals. Once released:

• Air: Exists as a vapour, with a half-life of 9 days via reaction with photochemically produced hydroxyl radicals and less than 1 day by hydrolysis.
• Soil & Water: Hydrolyses rapidly, with a half-life of 1.7 hours in water. Due to its rapid hydrolysis, volatilisation, adsorption to soil, sediment accumulation, biodegradation, and bioaccumulation are minimal.
• Breakdown Products: Hydrolysis produces monoethyl sulfate and ethanol.

Sources & Routes of Exposure

Sources of Exposure

The most probable routes of exposure to diethyl sulfate include:

• Occupational exposure during production or use, primarily through inhalation or dermal contact.
• Environmental exposure from fugitive emissions near manufacturing sites.

Routes of Exposure

Potential human exposure occurs through:

• Inhalation of vapours
• Dermal contact with liquid diethyl sulfate
• Ingestion, though this is less common

Health Effects

Acute Effects

There is no human data on acute effects. However, animal studies indicate:

• Moderate acute toxicity from ingestion in rats, mice, and rabbits
• High acute toxicity from dermal exposure

Chronic Effects

There is limited human data on long-term exposure. However, animal tests have demonstrated:

• Toxicity upon repeated exposure
• Potential for long-term systemic effects

Reproductive/Developmental Effects

There is no human data on reproductive or developmental effects. However, in animal studies, pregnant rats given a single subcutaneous dose of diethyl sulfate had offspring with malignant tumours of the nervous system

Cancer Risk

• Epidemiological studies indicate an increased mortality rate from laryngeal cancer in workers exposed to high concentrations of diethyl sulfate.
• In animal studies, diethyl sulfate has caused:
  • Tumours in the forestomach of rats exposed via gavage (direct stomach administration)
  • Local tumours and lung metastases in rats exposed via subcutaneous injection
• The EPA has not classified diethyl sulfate for its carcinogenic potential.

Safety Measures

First Aid Measures

• General Advice: Seek immediate medical attention and present the safety data sheet to medical personnel.
• Inhalation: Move the person to fresh air. If breathing has stopped, provide artificial respiration. Seek medical attention immediately.
• Skin Contact:
  • Remove contaminated clothing and shoes.
  • Wash affected skin with soap and water.
  • Seek immediate medical attention.
• Eye Contact: Rinse thoroughly with water for at least 15 minutes and consult a physician.
• Ingestion:
  • Do not induce vomiting.
  • Never give anything by mouth to an unconscious person.
  • Rinse the mouth with water and seek medical attention immediately.

Exposure Controls & Personal Protection

Engineering Controls

• Minimise contact with skin, eyes, and clothing.
• Ensure proper hand hygiene before breaks and after handling.

Personal Protective Equipment (PPE)

• Eye/Face Protection:
  • Tightly fitted safety goggles
  • Face shield (8-inch minimum)
  • Equipment must meet NIOSH (US) or EN 166 (EU) standards.
• Skin Protection:
  • Use chemical-resistant gloves.
  • Inspect gloves before use and dispose of contaminated gloves properly.
  • Follow correct glove removal techniques to avoid skin exposure.
  • Gloves must comply with EU Directive 89/686/EEC and standard EN 374.
• Body Protection:
  • Complete chemical protective suit based on concentration levels.
• Respiratory Protection:
  • Air-purifying respirators (full-face) with multi-purpose combination cartridges (US) or ABEK cartridges (EN 14387).
  • If ventilation is inadequate, use a full-face supplied-air respirator.
  • Respirators must meet NIOSH (US) or CEN (EU) standards.

Regulation

United States

No workplace exposure standards established.

Australia

No workplace exposure standards established.

International

IARC has classified diethyl sulfate as a Group 2A, probably carcinogenic to humans, based on limited evidence in humans and sufficient evidence in animals.