Earlier today (February 7, 2020) the Office of Environmental Health Hazard Assessment (OEHHA) published the final Public Health Goals (PHGs) for the four individual trihalomethanes (THMs). The PHGs are as follows:
Chloroform – 0.4 parts per billion (ppb)
Bromodichloromethane – 0.06 ppb
Dibromochloromethane – 0.1 ppb
Bromoform – 0.5 ppb.
The PHGs are set based on carcinogenicity and are set at the 1 additional case in one million persons (1 x 10-6) cancer risk estimate.
Two documents were posted : (1) OEHHA’s technical support document for the THM PHGs (OEHHA THM PHGs_Tech Support Doc ), and (2) Response to Public Comments and External Peer review (OEHHA_Response to Comments THM PHGs ).