Zinc Pyrithione (ZPT)CAS 13463-41-7
Anti-dandruff active ingredient also used in exterior paint, deck stains, and antimicrobial shower curtains.
Toxic Chemical Databases
Substance-specific listings — these flags are for Zinc Pyrithione alone, not for the broader family.
Chemical Type
Heavy-Metal Pyridine Biocide
Chemical Description
ZPT is best known as the active ingredient in anti-dandruff shampoo, but in building materials it is a major commercial biocide for exterior paint, marine antifoulants, deck stains, and antimicrobial textile and shower-curtain treatments. EU REACH classified ZPT as a Category 1B reproductive toxicant in 2020 based on developmental-toxicity findings in rodent studies. Aquatic toxicity is severe — ZPT was a co-named culprit in marine sediment contamination near boat-storage facilities. Persistent on exterior surfaces; bioaccumulates in marine sediments.
Biological Activity
Severity scores specific to this substance, NOT the parent family average. Differences between siblings are real and meaningful.
Top Health Consequences
- REACH Category 1B reproductive toxicant
- Developmental toxicity in animal studies
- Severe aquatic toxicity in stormwater runoff
- Bioaccumulation in marine sediments
Pathways of Exposure
- Inhalation during exterior paint and stain application
- Dermal contact with treated shower curtains and bath products
- Skin contact with treated outdoor textiles
Building Materials with Zinc Pyrithione
Listed alphabetically — product categories where this specific substance appears.
Antimicrobial Textile Treatments
Deck & Outdoor Stain Additive
Exterior Antimicrobial Paint
Marine Antifouling Coatings
Treated Shower Curtains & Bath Mats
How We Keep Zinc Pyrithione Out of a House
Zinc Pyrithione is on our avoid list, which means it is specified out of the project before bidding — not caught on site. Keeping chemistry like this out of the house is the practical difference between a healthy home and an ordinary one.
If you want a house specified this way from the start, or an existing house assessed for what is already in it, that is the work we do. Earth Bound Homes builds in Menlo Park, Redwood City, San Mateo County and across the San Francisco Bay Area.