a Benzene ring is a common chemical structure, some Benzene compounds are safe (like in perfumes) and some are extremely carcinogenic (causes cancer).. it depends on the chemical composition that we are talking about, how long and how much were you exposed to..
in some countries (such as the middle east), Benzene refers to Gasoline and yes even Gasoline can be carcinogenic when exposed at high amounts for extended amount of time..
sudden unexplainable decline in health, loss of appetite and/or significant loss of weight; along with cough, constant running nose, malaise and/or rashes..
seek a doctor if you have serious health issues.. and if you work in a factory, you should inform them about any sudden changes in your health..
all the best..