Banned Azo Dyes Testing

1. Introduction to Banned Azo Dyes

Certain azo dyes used in the dyeing of workwear garments. Carcinogenic aromatic amine-decomposable dyes refer to dyes that, under certain conditions, decompose to release carcinogenic aromatic amines through reduction reactions. These dyes belong to the azo dye category, containing an azo group (—N=N—) in their molecular structure. Not all azo dyes are hazardous; only those that produce carcinogenic aromatic amines pose risks to human health. Currently, there are 24 recognized carcinogenic aromatic amines globally, involving approximately over 200 azo dyes. It is important to note that azo dyes constitute the largest category of synthetic dyes, characterized by a wide color spectrum, comprehensive color range, good color fastness, and high durability, making them widely used in dyeing various fibers. Banned azo dyes account for only about 5% of all azo dyes, meaning not all azo dyes are prohibited.

With the release of the EU regulations on banned azo dyes and the implementation of China's mandatory national standard GB 18401—2003 "National General Safety Technical Code for Textile Products," carcinogenic aromatic amine-decomposable dyes have become one of the most critical monitoring indicators in both international and domestic production and trade of textiles and apparel.

2. Hazards

Banned azo dyes are a small subset of azo dyes, which are widely used in the market for dyeing textiles, apparel, leather products, and more. Textiles, apparel, or other consumer goods dyed with carcinogenic aromatic amine-decomposable dyes, after prolonged contact with human skin, may undergo reduction reactions under biochemical conditions of normal human metabolism, decomposing to generate carcinogenic aromatic amines. These can alter the DNA structure of human cells through a series of activation processes, leading to diseases and potentially inducing cancer.

3. Testing Standards

Unlike formaldehyde, which is easily identifiable and soluble in water, carcinogenic aromatic amine-decomposable dyes in textiles are insoluble in water, colorless, and odorless, making them impossible to detect by appearance alone. They can only be identified through technical testing.

Currently, gas chromatography and liquid chromatography are primarily used to detect banned azo dyes. Relevant domestic testing standards include GB/T 17592-2011 "Textiles—Determination of Banned Azo Dyes" and GB/T 23344-2009 "Textiles—Determination of 4-Aminoazobenzene." Generally, testing is first conducted according to GB/T 17592. If aniline and/or 1,4-phenylenediamine are detected, further testing is performed according to GB/T 23344.

Additionally, China's mandatory national standard GB 18401-2010 "National General Safety Technical Code for Textile Products" prohibits the use of carcinogenic aromatic amine-decomposable dyes in textile products, with a limit of ≤20 mg/kg for carcinogenic aromatic amines.

4. Related Standards

GB/T 17592—2006 "Textiles—Determination of Banned Azo Dyes"

ISO/TS 17234:2003 "Leather—Chemical Tests—Determination of Certain Azo Dyes in Leather"

EN 14362—1:2003 "Textiles—Methods for Determination of Certain Aromatic Amines Derived from Azo Colorants—Part 1: Detection of the Use of Certain Azo Colorants Accessible Without Extraction"

EN 14362—2:2003 "Textiles—Methods for Determination of Certain Aromatic Amines Derived from Azo Colorants—Part 2: Detection of the Use of Certain Azo Colorants Accessible by Extraction"

German Standard §35LMBG82.02—2 "Analysis of Consumer Goods—Testing of Textile Consumer Goods for the Use of Certain Azo Dyes"

German Standard §35LMBG82.02—3 "Testing of Consumer Goods—Detection of Banned Azo Dyes in Leather"

German Standard §35LMBG82.02—4 "Analysis of Consumer Goods—Testing of Polyester Fibers for the Use of Certain Azo Dyes"

German Standard DIN 53316:1997 "Testing of Leather—Determination of Certain Azo Dyes in Leather"

GB/19601-2004 "Limit and Detection Method of 23 Banned Azo Dyes in Dye Products"

GB/T 23344—2009 "Textiles—Determination of 4-Aminoazobenzene"

GB/T 24101—2009 "Limit and Determination of 4-Aminoazobenzene in Dye Products"