Charcoal grills are considered bad for you and your health.
Grilling foods over charcoal can result in the formation of carcinogens, especially when you grill the meat or foods at high temperatures over the charcoal.
Grilling the foods and meats at high temperatures and charring when cooking or grilling with charcoal can create heterocyclic amines and polycyclic aromatic hydrocarbons which are chemicals that have been linked to an increase in risk of developing certain cancers.
And charcoal grilling often also produces more smoke than gas grills do and the smoke from charcoal grills can also contain PAHs, which are also carcinogens.
And foods that are in direct contact with the heat charcoal coals can also lead to formation of HCAs in meat.
Grilling of meat at excessively high temperatures over charcoal or until the meat has been charred can also exacerbate the formation of carcinogens in foods.
To minimize the health risks of grilling over charcoal, grill the foods at a lower temperature if possible to reduce the formation of HCAs.
Ensure the charcoal grill is clean to avoid re burning of any charred bits and creating more carcinogens and trim excess fat from eat which also reduces flare ups and the potential for smoke.
Marinating meat can also help to reduce formation of HCA on the meats and monitor the temperature of your charcoal grill to avoid overheating and avoid overcooking of the meat to the point of charring and choose leaner cuts of meat to reduce fat drips and smoke and use a grill cover to reduce smoke and maintain lower temperatures when cooking with charcoal.
In general it's often very safe to eat foods grilled over charcoal as many people including myself do and have still remained healthy.