No, people can only be allergic to large molecules, like the peanut protein Ara h1, which weighs 150 kilodaltons, not tiny molecules like sodium metabisulfite, which weighs 190 daltons. Sensitivity is the correct term.
Ahem - maybe it depends on the reference and perhaps also on semantics (size here = mass ?!) -
When it comes to allergens triggering an allergic response via the oral route, several speciﬁc characteristics have been described in the scientiﬁc literature. Only few proteins account for most food allergies and many food allergens share some common characteristics, which nevertheless are not unique to them (Bannon, 2004; Breiteneder and Mills, 2005; Vickery et al., 2011). Food allergens are usually relatively abundant in the food source, which seems to enhance their chance to interact with the immune system (Bannon, 2004). Allergenic food proteins are generally relatively small with a molecular size below 70 kDa (Vickery et al., 2011) However, a molecular size of at least 3.5 kDa is necessary to induce an antibody response, ...........
The major allergens in peanuts are generally considered Ara h 1 and Ara h 3 that are members of the cupin superfamily of proteins, and Ara h 2 and Ara h 6 that are members of the prolamin superfamily. ... Ara h 1, a member of this superfamily, is a 65-kDa, 7S globulin or vicilin seed storage protein.
Regarding the OP's "Sensitivities", perhaps i should have written "allergenic" in Post 3 since semantics may again be involved (or not), eg consider this quote -
However, even though there is significant heterogeneity amongst patients with food allergy, in practice all individuals are considered to be equally sensitive to all foods, and strict avoidance is the standard of care.
Or perhaps in the context of the OP, this Canadian one -
Sulphites do not cause true allergic reactions, and are generally grouped with the priority food allergens because sulphite-sensitive individuals may react to sulphites with allergy-like symptoms.
(3) Or, probably less likely, the OP was referring to one of the Famous Three - Sensitivity, Allergenicity and Intolerance, as in -
(4) Or perhaps most likely in view of US location, the word "Sensitivities" was being used in a (very) general FARRP kind of way,eg -
Enlightenment awaits, particularly after your Post2.
all1 - Stability of allergens.pdf 750.49KB
all2 - pathophysiology of food allergy.pdf 77.95KB
all3 - molecular basis peanut allergy.pdf 1.37MB
all4 - Sulphites,Canada,2017.pdf 447.99KB
PS - I note that the 2013 review by Yang Zhou gave size of Ara h1 as 150kD. Best of 3 ?
PPS - If I read it correctly, this 2018 article uses a value of ca. 69kD (with xrefs) -
all5 - Peanut allergens,2018.pdf 520.22KB
(the values given for Ara h3 are also much smaller than in the 2013 review, (57-62) cf (360-380)kD). Not my area of knowledge at all so cannot analyse further.)