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CAS 569-64-2

C.I. Basic Green 4 (Malachite green)

Malachite green is a bright green synthetic dye used for coloring textiles and sometimes as a laboratory stain. It matters because it can be toxic, its breakdown product lingers in fish and water, and it may increase cancer risk [1][2][3].

Where It Comes From

Textile, paper, and leather dyeing; historically (and illegally in some places) used to treat fish diseases. It turns into leucomalachite green (LMG), which persists in tissues and the environment [1][3].

How You Are Exposed

Eating fish/seafood with illegal residues; working with dyes or aquaculture treatments; contact with contaminated workplace dust or water [1][2][3].

Why It Matters

Can irritate skin and eyes; liver and thyroid effects seen in studies; causes cancer in lab animals. IARC classifies it as possibly carcinogenic to humans (Group 2B) [1][2].

Who Is at Risk

Aquaculture and dye workers; people who eat a lot of imported farmed fish from regions where MG use has occurred; pregnant people and children [1][3][4].

How to Lower Your Exposure

Buy fish from trusted sources that test for residues; follow fish advisories; don’t use malachite green in home aquariums; at work, use gloves/eye protection and ventilation; support proper wastewater controls [3][4].

References

  1. [1]IARC Monographs, Vol. 99 (2010): Malachite green and leucomalachite green.
  2. [2]NTP Technical Report 527 (2005): Toxicology and Carcinogenesis Studies of Leucomalachite Green.
  3. [3]WHO/FAO JECFA evaluations on malachite green residues in food.
  4. [4]U.S. FDA: Not approved for aquaculture; Import Alert 16-129 (malachite green residues in seafood).

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