What is Isopherone?

Isophorone is a chemical with the formula C₉H₁₄O. It is a clear liquid with a peppermint-like smell. It evaporates faster than water but slower than charcoal starter or paint thinner and does not mix completely with water. Although it is man-made, it can naturally occur in cranberries.

What is Isopherone used for?

Isophorone is primarily used as a solvent in:

• Coating systems for metal cans, metal paints, and nitrocellulose finishes.
• Printing inks for plastics.
• Herbicide and pesticide formulations.
• Adhesives for plastics, polyvinyl chloride (PVC), and polystyrene.

It is also an intermediate chemical in making 3,5-xylenol, 3,3,5-trimethylcyclohexanol, and plant growth retardants.

In the Environment

• Isophorone is released into the air from products like inks and paints.
• In the air, it breaks down quickly, with half disappearing in less than five hours.
• It can enter water from industrial sources, breaking down over days to about a month by bacteria.
• In soil, isophorone may break down, evaporate into the air, or filter into groundwater, but limited data is available.
• Isophorone does not accumulate in the food chain.

Sources & Routes of Exposure 

Source of Exposure

• Air: Major sources include the printing and metal coating industries. Coal-fired power plants may also release isophorone.
• Workplace: People working with inks, paints, lacquers, and adhesives are more likely to be exposed.
• Water: Isophorone has been found in low concentrations in drinking water.

Routes of Exposure

• Breathing air containing isophorone.
• Drinking contaminated water.
• Eating food with isophorone.
• Occupational exposure in industries using isophorone.

Health Effects

Acute Effects

In humans: Skin, eye, nose, and throat irritation; headaches; and dizziness.

In animals: High levels cause inactivity and coma. Tests show moderate toxicity through inhalation or ingestion.

Chronic Effects

Long-term exposure may cause dizziness, fatigue, and depression in humans.

In animals: Central nervous system effects, including narcosis, staggering, depression, ataxia, lethargy, prostration, and coma.

Safe exposure limits:

• Reference Dose (RfD): 0.2 mg/kg/day based on studies in dogs.
• Provisional Reference Concentration (RfC): 0.012 mg/m³ based on rat studies.
• California EPA Reference Exposure Level (REL): 2 mg/m³ for long-term exposure based on developmental effects in rats.

Reproductive/Developmental Effects

• No human studies are available.
• Limited animal studies suggest potential birth defects and growth retardation during pregnancy with inhalation exposure.

Cancer Risk

• No human studies exist.
• Animal studies show increased kidney and reproductive gland tumors in male rats. However, these findings may not be relevant to humans.
• EPA classifies isophorone as a possible human carcinogen (Group C).

Safety

First Aid Measures

• Inhalation: Move to fresh air. If not breathing, provide artificial respiration and consult a doctor.
• Skin Contact: Wash thoroughly with soap and water. Consult a doctor.
• Eye Contact: Rinse eyes with water for at least 15 minutes. Consult a doctor.
• Ingestion: Rinse mouth with water. Do not give anything by mouth to an unconscious person. Consult a doctor.
• Inhalation: Move to fresh air. If not breathing, provide artificial respiration and consult a doctor.
• Skin Contact: Wash thoroughly with soap and water. Consult a doctor.
• Eye Contact: Rinse eyes with water for at least 15 minutes. Consult a doctor.
• Ingestion: Rinse mouth with water. Do not give anything by mouth to an unconscious person. Consult a doctor.

Exposure Controls & Personal Protection

Engineering Controls

• Practice good hygiene and industrial safety practices. Wash hands during breaks and after work.

Personal Protective Equipment (PPE)

• Eye/Face Protection: Use a face shield and safety glasses that meet government standards (NIOSH or EN 166).
• Skin Protection: Wear gloves, inspect them before use, and dispose of them safely after use. Wash hands thoroughly. Gloves must meet EU standards EN 374.
• Body Protection: Wear a chemical-resistant suit appropriate to the substance concentration and amount.
• Respiratory Protection: Use a full-face respirator with multi-purpose cartridges (US NIOSH or EU EN 14387) or a supplied-air respirator if necessary. Ensure respirators meet government standards.

Regulation

United States

OSHA: The Occupational Safety & Health Administration has set the following Permissible Exposure Limits (PEL) for isophorone:

• General Industry: 29 CFR 1910.1000 Table Z-1 - 25 ppm, 140 mg/m3 TWA
•  Construction Industry: 29 CFR 1926.55 Appendix A - 25 ppm, 140 mg/m3 TWA 
• Maritime: 29 CFR 1915.1000 Table Z-Shipyards - 25 ppm, 140 mg/m3 TWA

ACGIH: The American Conference of Governmental Industrial Hygienists has set a Threshold Limit Value (TLV) for isophorone of 5 ppm, 28 mg/m3 Ceiling; Appendix A3 - Confirmed Animal Carcinogen with Unknown Relevance to Humans 

NIOSH: The National Institute for Occupational Safety and Health has set a Recommended Exposure Limit (REL) for isophorone of 4 ppm, 23 mg/m3 TWA

Australia

Safe Work Australia: Safe Work Australia has set a time weighted average concentration of 5 ppm, 28 mg/m3 Ceiling for isophorone for a 40-hour work week. It also has an advisory carcinogen category of carc.2 which is a suspected human carcinogen.