I certainly agree that we have more issues today with chemicals and additives. I'd also like to bring up plants and herbs. Some of us just can't tolerate certain, strong smelling, or tasting plants. For example, if I eat celery, I'm taking a chance that it might cause me to wheeze, have a runny nose and make my eyes start to water. My mom was that way too. Anything with a intense, resiny character, like fresh oregano, can also cause my asthma symptoms to kick up.
I think that it's a complex medical issue, that they still don't have all of the answers to.
~ C