While there isn't a single "dangerous" PSA level that applies to everyone, a consistently elevated or rapidly rising PSA (Prostate-Specific Antigen) can be a significant indicator of potential prostate issues, including cancer. Generally, a PSA level above 4.0 ng/mL is considered elevated, especially for men over 60, while for those under 60, a level above 2.5 ng/mL may warrant further investigation. Levels above 10.0 ng/mL are often associated with a higher likelihood of prostate cancer.