Fractionated algal organic materials as precursors of disinfection by-products and mutagens upon chlorination

► DBP formation and mutagenicity were analyzed in chlorinated size-fractionated algal materials. ► Fractionated algal cells were more reactive than proteins as the precursors of DBPs such as HAAs. ► Large algal fractions (>100 kDa) were major precursors of stable DBPs and showed low mutagenicity. ► Small algal fractions (3-10 kDa) were major precursors of HANs and HKs and showed high mutagenicity.