Earring sensitivity can be an allergic reaction to nickel; to the base metals often used in sterling silver and 9ct gold. or even the adhesives used to fuse components.
EU directives limit the use of nickel, but are silent on many other allergens such as lead, cobalt and chromium.
All Ear Sense earrings are made in the USA using a proprietary titanium alloy, and contain no known allergens, surpassing every standard of metals purity worldwide.