What is Acrylic Acid?

Acrylic acid (IUPAC name: prop-2-enoic acid) is an organic compound with the formula CH₂=CHCO₂H. It is the simplest unsaturated carboxylic acid, made of a vinyl group attached to a carboxylic acid. This colourless liquid has a sharp, tart smell. Acrylic acid mixes well with water, alcohol, ether, benzene, chloroform, and acetone.

It polymerises easily in the presence of oxygen. At room temperature, this process can release heat and may become explosive if confined. It is sensitive to heat and sunlight and is a fire hazard when exposed to heat or flames. Acrylic acid is incompatible with strong oxidisers, bases, and alkalies. It can polymerise explosively when it contacts amines, ammonia, oleum, chlorosulfonic acid, iron salts, or peroxides. It can also corrode iron and steel.

What is Acrylic Acid used for?

Acrylic acid is mainly used to make acrylic esters and resins used in coatings and adhesives. It is also used in:

• Oil treatment chemicals.
• Detergent intermediates.
• Water treatment chemicals.
• Water-absorbing polyacrylic acid polymers.

Acrylic acid is widely used for polymerisation to create products like polyacrylates and as a monomer for polyacrylic and polymethacrylic acids. It is used in manufacturing plastics, tackifiers, and flocculants. Other uses include water-soluble resins, moulding powders, paper coatings, polishes, adhesives, leather finishes, paint formulations, and general finishes and binders.

Sources & Routes of Exposure 

Source of Exposure

Industry Sources: Acrylic acid may be released in wastewater and emissions during its production and use. It is emitted from facilities making acrylic acid or acrylate, including guided missiles, space vehicles, and electronic components.

Diffuse Sources: Acrylic acid emissions can come from polishes, paints, coatings, adhesives, plastics, textiles, and paper finishes. It has also been used as a pesticide.

Natural Sources: Some algae produce acrylic acid naturally, and it is found in sheep’s rumen fluid.

Transport Sources: None reported.

Consumer Products: Products containing acrylic acid include polishes, paints, coatings, adhesives, plastics, textiles, and paper.

Routes of Exposure

People can be exposed to acrylic acid through:

• Inhaling air contaminated by nearby production plants or consumer products.
• Direct contact with products containing acrylic acid.
• Drinking contaminated water.
  Exposure mainly happens in workplaces where acrylic acid is manufactured or used. Consumers can also be exposed through products like paints, coatings, adhesives, and textiles.

Health Effects

Acute Effects

• Acrylic acid strongly irritates the skin, eyes, and mucous membranes. Contact with the liquid can cause blindness if it gets into the eyes.
• Inhalation by rats caused nose and eye irritation, lung bleeding, and liver and kidney damage.
• Acute exposure in animals shows moderate toxicity from inhalation or ingestion and high toxicity from skin contact.

Chronic Effects

Long-term effects in humans are unknown.

In animals, inhaling acrylic acid caused nasal damage, and oral exposure reduced body weight and affected organ weights.

Safe exposure limits:

• Reference Concentration (RfC): 0.001 mg/m³ based on nasal damage in mice.
• Reference Dose (RfD): 0.5 mg/kg/day based on reduced pup weights in rats.

Reproductive/Developmental Effects

• No human studies are available.
• In animals, acrylic acid exposure reduced weight gain and fertility, although the fertility decrease wasn’t statistically significant. It caused birth defects when injected into rats.

Cancer Risk

• No human studies are available.
• In mice, topical exposure caused skin cancer, but other studies didn’t find carcinogenic effects.
• The EPA has not classified acrylic acid for its cancer-causing potential.

Safety

First Aid Measures

• Eye Contact: Remove contact lenses and flush eyes with water for at least 15 minutes. Seek immediate medical attention.
• Skin Contact: Rinse skin with water for at least 15 minutes while removing contaminated clothing and shoes. Wash clothing and clean shoes before reuse. Seek immediate medical attention.
• Serious Skin Contact: Wash with disinfectant soap, apply antibacterial cream, and get immediate medical help.
• Inhalation: Move to fresh air. If breathing is difficult, provide oxygen. If not breathing, give artificial respiration and seek medical help immediately.
• Serious Inhalation: Evacuate to a safe area. Loosen tight clothing and administer oxygen if needed. Avoid mouth-to-mouth resuscitation if the material is toxic. Seek immediate medical help.
• Ingestion: Do not induce vomiting unless directed by medical personnel. Never give anything by mouth to an unconscious person. Loosen tight clothing and get medical help if symptoms appear.

Handling & Storage

• Keep locked up and away from heat and ignition sources.
• Store in a cool, dry, well-ventilated area.
• Keep containers tightly closed and avoid incompatible materials like oxidisers, acids, alkalis, and moisture.
• Ground all equipment and never add water to acrylic acid.

Exposure Controls & Personal Protection

Engineering Controls

• Use ventilation systems to keep vapours below safe limits.
• Ensure eyewash stations and safety showers are nearby.

Personal Protective Equipment (PPE)

• Use a face shield, full suit, gloves, boots, and a vapour respirator. Ensure respirators are approved by safety standards.
• For large spills: Use splash goggles, a full suit, gloves, boots, and a self-contained breathing apparatus to avoid inhaling the product. Consult a safety specialist before handling acrylic acid.

Regulation

United States

ACGIH: The American Conference of Governmental Industrial Hygienists has set a Threshold Limit Value (TLV) for acrylic acid of 2 ppm, 5.9 mg/m³ TWA ; Skin; Appendix A4, Not Classifiable as a Human Carcinogen

NIOSH: The National Institute for Occupational Safety and Health has set a Recommended Exposure Limit (REL) for acrylic acid of 2 ppm, 6 mg/m³ TWA; Skin

Australia

Safe Work Australia: Safe Work Australia recommends an 8-hour time-weighted average (TWA) exposure limit for acrylic acid of 2 ppm (5.9 mg/m³)