EUROPE: Rates of allergy to hair dye have jumped in several countries as younger people color their tresses, according to European researchers. Dermatologists cite reports that suggest the incidence of allergy is rising. Para-phenylenediamine (PPD) and its chemical cousins—called aromatice amines—trigger the allergic reactions. Eczema may show up on the face or around the hairline, and in severe cases, a patient’s face swells up leading to painful bruising that requires treatment. More th...