Well, any doctor familiar with alpha thal will tell you that favism (the condition we are talking about is often set off my eating fava beans) only occurs in the more serious forms of alpha thal. However, I have heard from many alpha carriers who are indeed sensitive to chemicals. Of course, with this website, I hear from far more thal minors than any doctor will ever encounter, and I also hear about everything, whereas patients learn how frustrating it is telling doctors details when the doctors just brush off their concerns and say it can't be, so perhaps my experience talking to thal carriers is much broader than any doctor's experience.
I see little point in pursuing this with your doctor. Thal carriers are given no respect. I recommend that alpha thal carriers follow the same advice given to patients with HbH disease. Take a high dose of folic acid daily, 2-5 mg, as this is the main thing you can do to help you produce red blood cells. Also, I suggest B complex, natural vitamin E and magnesium, to help red cell production and to also help build stronger red cells and protect them from early destruction.