It's easy to think that, but there are better reasons that are more likely sources. -In the U.S., each generation is living longer, thus have a greater chance to get heart dz, cancer, or autoimmune conditions. -Population rates have markedly increased. We went from 200 mil to 300 mil people in the US from 1968-1996. That increases disease rates. The likelihood that any of us know someone with these conditions is much greater w/greater numbers of population. -Dual working parents are much more common, which then leads to more daycare, and cohorting of persons, and thus sharing of viruses at younger ages much more common. -Population growth is more concentrated in inner cities which results in sharing of acute viral illnesses. The more viral exposures we have, the more chances our immune systems will overreact to them, and lend to more autoimmune diseases (MS, diabetes, inflamm. bowel dz, etc). -Another significant factor is that we are much heavier population, and that lends itself to disease. Many disease rates go up with increased BMIs. These social transitions over the past 50 years are much more likely to be leading to shifts in disease states. Other variables are there, too. However, it's less likely to be "pollution" of air, water, and food. Food choices, yes, but food, water and air contamination, no.