← All chemicals

CAS 20325-40-0

3,3'-Dimethoxybenzidine dihydrochloride

3,3'-Dimethoxybenzidine dihydrochloride (also called o‑dianisidine dihydrochloride) is a chemical used to make certain dyes and pigments and as a color‑forming lab reagent. It is toxic and may cause cancer, so major health agencies flag it for concern and regulate some uses [1][2][3].

Where It Comes From

Made for azo dyes/pigments; can be released when some dyes break down; industrial waste streams [1][3].

How You Are Exposed

Breathing dust or getting it on skin at work; handling old lab test kits/reagents; contaminated air, dust, or water near production or waste sites [2][3].

Why It Matters

Classified as possibly/anticipated to be carcinogenic; causes tumors in animals; can irritate skin/eyes and be absorbed through skin [1][2].

Who Is at Risk

Dye/pigment workers; lab or clinical staff using legacy peroxidase color reagents; maintenance/cleanup crews; people near dye/pigment facilities or hazardous waste sites [2][3].

How to Lower Your Exposure

At work, use closed systems, local exhaust, chemical‑resistant gloves/clothing, and good hygiene; substitute safer reagents; review your SDS. In communities, avoid old reagents, follow disposal guidance, and test private wells if near facilities [2][3].

References

  1. [1]IARC Monographs. o‑Dianisidine and o‑Dianisidine‑based dyes. WHO/IARC (e.g., Vol. 100F).
  2. [2]NTP, Report on Carcinogens. o‑Dianisidine and dyes metabolized to o‑dianisidine (15th ed.).
  3. [3]U.S. EPA. Action Plan for Benzidine Dyes and o‑Dianisidine Dyes (TSCA).

Track your exposure to 3,3'-Dimethoxybenzidine dihydrochloride

Pollution Profile maps your lifetime exposure history to EPA-tracked chemicals.

Get early access

We use cookies and analytics to understand how people use Pollution Profile and improve the experience. We never sell your data. Learn more.