Hesperian Health Guides


Dyes give color to fabric. Dyes consist of many groups of chemicals and each group has many individual chemicals. Azo is the largest group of dyes. Twenty-two of the hundreds of azo dyes are banned because there is no doubt that they severely harm people’s health.

Solvents, acids, bases, metals, and other toxic chemicals are often added to dyes to help fabric take in the coloring. Some dyes come in powder form and must be mixed with a solvent before dyeing the cloth.

There are two ways dyes can be classified and identified: based on their application or based on their chemical structure. Application-based dyes are acid, basic, direct, disperse, mordant, reactive, pigment, and vat dyes. Different dyes are used for different fabrics and dye processes. Structure-based dyes include nitro, azo, carotenoid, triarylmethane, xanthene, acridine, quinoline, indamine, sulphur, amino- and hydroxyl- ketones, anthraquinone, indigoid, phthalocyanine, inorganic pigment, and others. Most dyes are identified with a "color index" (CI) name and number.

Dyes create dust and fumes that are easily inhaled and that can harm your mouth, throat, and lungs.

The charts include only some of the dyes that exist. See Chapter 8 "Learn about chemicals used in your factory" and how to find information about other dyes. See the Index of chemical names to find alternative names for dyes.

Prevent or reduce exposure:

  • Use ventilation systems that extract fumes and replace or dilute dirty air with clean air (see Chapter 17: Ventilation).
  • Enclose operations where possible.
  • Do not mix or pour dyes by hand.
  • Wear gloves. Wear correct respirators that fit you. All protective clothing should be clean, available each day, put on before work, and never taken home with you (see Chapter 18: Personal protective equipment).
  • Have an emergency plan that includes first aid treatment and protective equipment for spills, splashes, and accidental exposures. Keep necessary emergency supplies at the work site, stocked, and accessible to workers.
  • Work areas where dyes are used, stored, and mixed need to be controlled for heat and monitored for concentration of fumes and vapors. The areas should also have alarms, fire extinguishers, and a fire emergency plan (see Chapter 11: Fire).
  • Wash hands only with soap and water. Do not use solvents on skin to remove dye stains.

Note: These are groups of dyes, not individual dyes. Only individual chemicals have CAS numbers.


Anthraquinone dyes

might cause cancer

Azo dyes

fire or explosive

Might harm reproductive health

Known to cause cancer

Indigoid dyes

Sulfur dyes

fire or explosive

Triarylmethane dyes

might cause cancer

Dyes are liquid or solid chemicals that come in different colors. Solid dyes usually come as sand-like powders or crystals. Some dyes have a strong smell, but others have no smell at all. Some azo dyes release toxic aromatic amine chemicals that have an unpleasant, fishy smell.
Dyes are used in the garment and shoe industries to dye cloth, fur, and leather. Anthraquinone dyes are most commonly used for violet, blue, and green colors. Azo dyes are used on cotton, wool, silk, and nylon to make them red, orange, and yellow. Indigoid dyes are used for dark colors and are often used to dye jeans. Sulfur dyes are used on cotton and rayon. They are commonly used for dark colors such as black, brown, dark blue, and violet. Triarylmethane dyes make very bright colors.

They irritate and dye your skin. You may develop a skin rash, redness, and dryness. Your skin might start peeling, itching, and cracking. Most often, a rash appears between your fingers or on the back of hands and wrists. See First Aid.


They irritate and burn your eyes. They can cause itching, watery eyes, and swelling of the eyelids. See First Aid.


The dust and fumes can irritate your nose, throat, and lungs, causing congestion, coughing, wheezing, shortness of breath, and chest tightness. The longer you are exposed the more sensitive your nose and lungs become, which can lead to severe asthma attacks. Inhaling high amounts of pigment and dye dust and fumes can create buildup of fluid in the lungs, called lung edema. See First Aid.


They cause nausea, vomiting, and diarrhea. See First Aid and seek medical attention.


Dyes harm your immune system, liver, kidneys, and urinary tract. They can make your nose and lungs very sensitive and cause chronic asthma. Dyes damage your red blood cells so they can no longer deliver oxygen to your organs. This is called methemoglobinemia. Signs of methemoglobinemia are blue skin and lips, headache, weakness, difficulty breathing, and lack of energy. If it’s not treated, you may go into a coma and your heart may stop.

Azo dyes may affect fertility. They can cause liver cancer and especially bladder cancer.

Anthraquinone dyes may cause liver, colon, kidney, and bladder cancer.

Triarylmethane dyes may cause cancer.

Use elbow-length, butyl rubber gloves and eye/face protection (see Chapter 18: Personal protective equipment).

Use a supplied-air respirator. 
Dyes that do not create dust are safer, such as granular or liquid-form dyes. Natural dyes are usually safer than synthetic dyes.