What are carcinogens? Mention any two groups of carcinogens with an example for each.

Explanation

These include physical , chemical and biological agents , which transform normal cells by directly causing changes in the DNA of this cells .
1. physical agents: They include various form of ionizing . UV radiation is a powerful mutagen for skin cancer . The exposure of the thyroid gland to x- rays has shown to increasethe incidence of thyroid cancer .
2 chemical agents : The chemical carcinogens that have been found to be carcinogenic in humans include :
a) chemical mixtures like soot ( black carbon ) , tars , cigerette smoke , etc,
b) Industrial chemical : Arsenic , nickel coumpound , benzidine , etc .
c) Drugs: Mustard gas , phenacetina .