Carcinogenicity of polynuclear hydrocarbons and benzene rings (1933) established that polynuclear aromatic hydrocarbons (PAHs) were
carcinogenic components of pitch. ... Although less is known about
their health effects than about those of PAHs, it is clear that some
nitro-PAHs are potent mutagens and carcinogens.(1)
Benzene and polynuclear hydrocarbons containing more than two benzene
rings fused together are toxic and said to possess cancer producing
(carcinogenic) property. Such polynuclear hydrocarbons are formed on
incomplete combustion of organic materials like tobacco, coal and
petroleum.(2)

From the two sources cited above, I keep seeing that polybenzenoid compounds like 1,2-benzanthracene, 3-methylcholanthrene and 1,2- benzpyrene are mentioned to be carcinogens.

In general, why are polynuclear compounds carcinogenic? I google searched on this topic and all I could find is their effects and concentrations in various substances.
My questions are:

Why are they carcinogenic

Is there a reason for a given organic compound to be carcinogenic?


References

Potential Carcinogenic Effects of Polynuclear Aromatic Hydrocarbons and Nitroaromatics in Mobile Source Emissions, STEPHEN S.HECHT(link)
pg403, NCERT Class XI part 2(pdf link)
1.Why are they carcinogenic:

From my point of view as a medicinal chemist, polycyclic aromatic hydrocarbons compounds tend to be metabolized by specific cytochrome P450 (CYP 450) isofroms to form highly electrophilic species, which are highly reactive and can react with the DNA of the cell and damage it. Specifically, they can react with the nucleophilic nitrogens in the DNA bases such as adenine.
To see more detailed mechanism of the formation of the electrophilic species from the compounds, check this article: https://socratic.org/questions/how-do-polycyclic-aromatic-hydrocarbons-cause-cancer

2.Is there a reason for a given organic compound to be carcinogenic?

Mechanism for carcinogenicity can vary, in general, any compound damaging or altering the DNA can be carcinogenic. For example, highly reactive electrophiles (such as formaldehyde).