American Chemical Society (ACS) Laboratory Safety Test 2025 – 400 Free Practice Questions to Pass the Exam

Repeated exposure to allergens, regardless of the route—whether through skin absorption, inhalation, or even injection—can trigger allergic reactions in sensitive individuals. Allergic reactions are part of the immune system's response to foreign substances, known as allergens, which the body mistakenly identifies as harmful.

Each of the mentioned routes of exposure can potentially introduce allergens into the body. For instance, inhalation might occur with airborne allergens such as pollen or chemical vapors, while skin contact with certain substances can lead to localized allergic reactions or dermatitis. Meanwhile, injection could expose an individual to allergens through vaccines or medications.

Importantly, it's the cumulative effect of these exposures that often heightens the individual's sensitivity and could lead to an allergic reaction. This makes repeated exposure critical to understanding how allergies develop and persists among individuals in laboratory settings or environments with potential allergens.