While preparing noodles, the seasoning plastic packet fell into boiling water without realizing and cooked for 7-8 minutes. i ate the food, i wonder how dangerous it was in terms of plastic leaching into food and potential health issues in future?

That incident happens more often than you thought and it does not cause any short or long term consequences.

You are highly unlikely to suffer any untoward consequences from this episode. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guideli