The Proposition 65 regulations identify "no significant risk" levels for certain carcinogens. The most recent list of no significant risk levels can be found here:

Does Prop 65 have BPA?

Bisphenol A is on the Proposition 65 list because it can harm the female reproductive system, including effects on ovaries and eggs. ... Proposition 65 requires businesses to determine if they must provide a warning about exposures to listed chemicals.

Why is Prop 65 controversial?

It remains politically controversial even after more than 30 years (see Controversy and claimed abuse below), in large part because business objects to Proposition 65's burden of proof , which in effect requires businesses to know the scientific safety level for specific cancer- and birth defect-causing chemicals that ...