Dangerous Dyes

Although common sense tells us that natural dyes are better than synthetic dyes.

However there are several aspects of the product life cycle - production - use - disposal - to be known, to make a proper comparison with natural dyes.

Compare synthetic dyes versus natural dyes
Comparison divided into four phases:
The manufacture,
The dyeing process,
Use of products by consumers and
Eventual disposal or recycling.

At each stage we need to analyze incoming materials, water use, energy use and effluent gases, liquids and / or solids that are generated.

Manufacture of synthetic dyes
The raw material is oil. Nonrenewable fossil fuels. When a molecule absorbs certain wavelengths of visible light and transmits or reflects others, the molecule has a color.

The part that brings color into a molecule called a chromophore. The chromophore is an aromatic structure containing benzene, naphthalene, or anthracene. A group from a donor chromophore color and is represented by the radicals following: azo (- N = N-), carbonyl (= C = O), carbon (= C = C =), carbon-nitrogen (> C = NH - CH = N-), nitroso (- NO or N-OH), nitric (- NO2 or = NO-OH) and sulfide (> The C = S, carbon-sulfur).

The dyes are synthesized in a reactor, filtering, and mixed with other additives to produce the final product. The synthesis involves reactions such as sulfonation, halogenation, amination, diazotization, and coupling, followed by separation processes that may include distillation, precipitation, and crystallization.

Mostly organic compounds such as naphthalene reacts with an acid or alkali along with an intermediary (such as a nitrate or a sulfonated compound) and solvent mixture to form the dye. The dye is then separated from the mixture and is purified.
In making the dye and its precursors, large amounts of contaminated water, up to 8,000 liters per kilo of dye,

Use in textile dyeing
The color-index of German textile industry includes more than 800 colors and 600 auxiliaries and finishing agents. The "Azo-dyes" can be called acidic, basic, mordant, reactive, disperse, direct, solvents or food dyes.

Not all acid dyes are "Azo-dyes. As seen a study of each animal tests and long-term consequences to human health has not been done and hardly done in the future.

Rensselaer-Bayern Aniline 1900

Direct Dyes Chromiun Geigy

Epidemic of bladder cancer
But it was the "epidemic" of bladder cancer among workers in the textil dyeing industry, which confirmed the suspicion that some azo-dyes are extremely dangerous. Action by having a proven tumor (cancer). Contact with concentrated colors and frequently mentioned causes of the epidemic.

Impact on consumers
According to the limited depth studies on the subject of chemical dyes, this proved that several allergenic dyes, especially the black and darker. A scientific study notes:
"The textile contact dermatitis is probably underestimated because it is not always present in typical fashion because we lack a suitable marker in the standard." .. "The allergens most frequently implicated were textile dyes disperse type, especially those belonging to the azo group (Disperse Blue-124, Disperse Blue-106, Disperse Orange 1 and Disperse Yellow-3)"

Not established a causal relationship of dyed textiles directly with cancer. But if the action of certain dyes in laboratory animals.
There is currently no list of hazardous dyes, there is only a list of aromatic amine dyes which are prohibited.