Do vegetables grown in the city absorb pollution and are these vegetables as healthy and safe as those grown in the country?

As you might expect, opinions on this issue differ among experts. Plants definitely do absorb all sorts of chemicals from the air (primarily carbon dioxide!), but the chemistry of the conduction channels within plant tissue acts as a filter, allowing in only some of the chemicals. This is why a tomato grown with manure compost on the soil doesn't taste like manure. A larger danger than pollutants being absorbed from the air into the tissue of the vegetable would seem to be the pollutants which settle on the outside of that vegetable: soot and grime in particular. Wash vegetables grown in the city thoroughly, and they should be about as safe as vegetables grown in the country. After all, there are chemical pollutants in the soils and air in the country as well. The benefits of eating the vegetables should far outweigh the risks from growing them in a polluted environment. Unless, of course, you live near Chernobyl.