If a shopper has ever seen a small black-and-yellow warning label on a product or webpage – the one that mentions "chemicals known to the State of California to cause cancer" – they've encountered California Proposition 65. It shows up on everything from coffee shops to cookware to luggage, and it can feel alarming without context.

This guide explains what Prop 65 actually is, why it appears on so many products, where Monos stands, and clears up one of the most common consumer confusions in the materials world – the difference between urethane and polyurethane.

What is California Proposition 65?

California's Safe Drinking Water and Toxic Enforcement Act of 1986 – better known as Prop 65 – is a "right to know" law passed by California voters. Its purpose is to inform Californians about exposures to chemicals that the state has identified as causing cancer, birth defects, or other reproductive harm.

Under Prop 65, businesses are required to provide a "clear and reasonable" warning before knowingly exposing people in California to listed chemicals above certain levels. The state maintains an official list of these chemicals, which has grown to include approximately 900 substances since the law was first enacted.

The list is administered by the Office of Environmental Health Hazard Assessment (OEHHA), part of the California Environmental Protection Agency, and is updated regularly.

Why Prop 65 warnings show up on so many products

Prop 65 is one of the broadest consumer chemical disclosure laws in the United States. A few features make it especially visible:

  • Long chemical list. With around 900 listed chemicals, and listings ranging from industrial solvents to naturally occurring substances, many ordinary products contain trace amounts.
  • No concentration threshold for the warning trigger in many cases. Some chemicals require warnings even at low levels, which is why warnings can appear on products that pose minimal real-world exposure.
  • "Clear and reasonable" framing. Many companies choose to warn out of caution rather than risk litigation – meaning warnings often appear even when actual exposure may be well below safe-harbor levels.
  • California-specific. Only California requires these warnings, but products sold nationwide often carry them because re-labeling for one state isn't practical.

  • How Monos approaches Prop 65 and material safety

  • Monos designs and manufactures luggage with a focus on quality materials and rigorous testing. Suitcase shells use aerospace-grade polycarbonate (or aluminum, depending on the collection), and Monos has stated its products go through more than 40 durability tests during development.
  • Monos is also committed to material transparency. The brand is a Certified B Corporation, uses cruelty-free alternatives to animal-derived materials, and incorporates recycled materials where possible (including rPET in Metro bag linings).
  • For the most current information on Monos materials and any Prop 65 disclosures applicable to specific products, travellers should refer to the relevant product pages or contact Monos directly. Material specifications and disclosures can change as products evolve.
  • Explore collections:
  • Carry-On Luggage
  • Check-In Luggage
  • Aluminum Luggage
  • Expandables
  • Metro Bags

  • The urethane vs polyurethane confusion – cleared up

  • Few material terms cause more confusion than urethane and polyurethane. They sound similar, share part of a name, and are sometimes used interchangeably – but in a Prop 65 context, the distinction matters.
  • Urethane (also known as ethyl carbamate) is a specific organic compound. It appears on the Prop 65 list as a chemical known to the state to cause cancer. Historically, urethane has been found at trace levels in some fermented foods and beverages and was once used in certain industrial and medical applications.
  • Polyurethane is something different. It is a class of polymers – long-chain molecules made by reacting polyols with isocyanates. The result is a material used widely in foams, coatings, adhesives, footwear, automotive components, and certain bag and luggage components. Read more! https://monos.com/blogs/articles/prop-65-luggage-urethane-vs-polyurethane