In Vitro: The rank order of haloacetaldehyde (HAL) cytotoxicity is tribromoacetaldehyde (TBAL)≈chloroacetaldehyde (CAL)>dibromoacetaldehyde (DBAL)≈bromochloroacetaldehyde (BCAL)≈ dibromochloroacetaldehyde (DBCAL)>IAL>bromoacetaldehyde (BAL)≈ bromodichloroacetaldehyde (BDCAL)>dichloroacetaldehyde (DCAL)> trichloroacetaldehyde (TCAL). The HALs are highly cytotoxic compared to other DBP chemical classes. The rank order of HAL genotoxicity is DBAL>CAL≈DBCAL>TBAL≈BAL>BDCAL>BCAL≈DCAL>IAL.