Avobenzone is an unstable chemical that rapidly degrades when exposed to sunlight and water, producing toxic breakdown products that harm marine ecosystems. When it decomposes in seawater, especially in the presence of chlorine from pools or coastal water treatment, it forms highly reactive compounds that damage coral tissue and DNA. These degradation products have been shown to induce oxidative stress in corals, leading to bleaching and increased disease susceptibility. Avobenzone accumulates in marine sediments where it continues to release toxic byproducts, creating long-term contamination zones that inhibit coral larval settlement and reef regeneration.