Which of the following is NOT a common cause of contact dermatitis?

Contact dermatitis is a skin condition that results from the skin's reaction to substances that irritate it or cause an allergic reaction. Among the options listed, the factors that most commonly lead to contact dermatitis typically include fragrances, metals, and environmental triggers, as they directly interact with the skin upon contact.

Fragrances are commonly found in personal care products and can easily provoke irritation or allergic responses, making them a frequent cause of contact dermatitis. Metals, such as nickel, are also well-documented triggers, particularly in jewelry or clothing fasteners, leading to sensitization in many individuals. Environmental factors, such as plants (e.g., poison ivy), can cause allergic contact dermatitis as well.

In contrast, food allergens typically cause reactions in different ways, primarily through ingestion rather than direct skin contact. While some individuals may experience skin reactions as a secondary response to food allergies, such as hives or eczema, these are not classified as contact dermatitis. Thus, food allergens are not a root cause of contact dermatitis, setting them apart from the more usual triggers like fragrances, metals, and environmental factors.