I do a lot of grilling (various vegetables and meats), but was recently told this will have similar effects to smoking. Is there much merit to the concerns over grilled foods containing carcinogens?
Short answer: yes. Long answer: depends on what you're cooking.
Grilling some popular food items can produce cancer-causing compounds called heterocyclic amines (HCAs)
HCAs, a family of mutagenic and cancer-causing compounds, are produced during the cooking of many animal products, including chicken, beef, pork, and fish. In January of 2005, the federal government officially added HCAs to its list of known carcinogens.
Cancer Project nutritionists determined that many commonly grilled foods contain alarmingly high levels of HCAs. This table lists the five foods containing the highest levels.
The risks are low and mainly come from burning animal fat. There's little risk associated with grilling vegetables. Leaner meats are better. It applies to fatty fish also. I've also read that natural lump charcoal is better than treated briquettes. You can google this stuff and find tons of references and articles talking about polycyclic aromatic hydrocarbons (PAHs), but there's not a lot of science saying specifically how much of it will hurt you. And people have been doing it for thousands of years, though evolutionarily it was probably less meat, most of which was lean meat from game and more vegetables in the diet.
Here in South Africa we are grill, or barbecue (we call it "braai") nuts. We grill anything from vegetables to red and white meat to fish and shellfish, using charcoal, wood and gas. I've been eating grilled-food by the bucket loads since I can remember. The average South African braai's at least once a week.
Unfortunately I don't have a scientific source or cite-able reference for you, but to my knowledge South Africa doesn't have a specifically higher percentage of cancer cases than the rest of the world as caused by eating grilled food. So my answer would be a definite no. At least no more than cooking your food in any other method or anything else you do in your day-to-day life, in any case.