Does talcum powder came in contact with private part cause cancer? i was blowing balloons it was an old balloon there was white powdery thing stuck maybe it's talc. my hands have become powdery and i didn't washed it and i put my finger inside anus?

What you described is highly unlikely to have any harmful effect, other than the mechanical trauma to anus. You can reduce your risk of cancer by adopting healthy habits: Eat a mostly vegetarian diet, no alcohol, tobacco and street drugs, avoid excessive exposure to sun, maintain healthy weight, get HPV vaccine, exercise 30 minutes each day, drink enough water so your urine is mostly colorless.