Although the risks of allergies or irritation are highest for those who are most consistently in contact with paints over a prolonged period, such as painters, people with more acute exposures such as residence dwellers in a newly painted home may also be at higher risk. Even public places where painting is being done could potentially be a health hazard both for the workers and the general public. Water-based paints require important additives (e.g., preservatives) which are often the cause of an irritant or allergic reaction. Minute amounts of an additive may induce a potent allergic reaction. Volatile paint ingredients, including preservatives of the isothiazolinone class and synthetic resins such as epoxy resins and isocyanates, may cause respiratory and other nondirect contact symptoms of allergic dermatitis. As allergens, the most problematic isothiazolinone continues to be methylisothiazolinone (MI), however, due to increased awareness and focus on MI, stricter controls are in place (for products such as leave-on cosmetics) and some countries are reporting a decrease in MI sensitization after peaking between 2012 and 2017. Other isothiazolinone allergens include methylchloroisothiazolinone (MCI), octylisothiazolinone (OIT), benzisothiazolinone (BIT), and butylbenzisothiazolinone (BBIT), with an increase in BIT. There is increasing awareness of titanium dioxide nanoparticles used in water-based paints and sprays as being a health hazard, including a potential carcinogenic risk. The most problematic recent epoxy resin is diglycidyl ether of bisphenol A resin (DGEBA-R); diglycidyl ether of bisphenol F (DGEBA-F) is also a significant allergen. Both aromatic and aliphatic isocyanates may be volatile, causing asthma, airway irritation, and hypersensitivity pneumonitis; although polyisocyanates based on hexamethylene-1,6-diisocyanate (HDI) are less volatile. Allergic reactions may take repeated exposures over months to years before symptom manifestation. Allergens are also found in other products (e.g., MI is still commonly used as a preservative in cosmetics). Cross-sensitization between products within the same class can occur, but co-existing reactions may be due to co-exposure and not cross-sensitization.