Aqueous Chlorination of D-Limonene.

When limonene (a common citrus-scented ingredient in beauty products) meets chlorinated water—like in swimming pools or municipal water treatment—it breaks down into multiple chlorinated byproducts. The study found that at high chlorine ratios (above 1:10), these byproducts can form haloforms, some containing bromine. Interestingly, most of these breakdown products were actually less toxic than the original limonene in lab testing.