That's a classic example of dangerous vs harmful; driving too fast is dangerous to your health but not harmful to it; smoking vice-versa. Let's not get "smart" about exhaust fumes or burning down your house smoking in bed
Exposure to heavy metals is bad for you. Getting in a pit is harmless, unless it collapses; ;then often deadly. Living in Houston, a low-lying swampy area with mushy unstable seeming soil, I am amazed and disturbed when I often see workers in unsupported pits.