CEPA Public Health Objectives for Five Haloacetic Acids

Public Health Goals (PHGs) have been adopted and published for the five haloacetic acids (HAAs) detected in drinking water because of disinfection procedures by the Office of Environmental Health Hazard Assessment (OEHHA) of the California Environmental Protection Agency. The five regulated haloacetic acids are namely,

1. Dibromoacetic Acid 2. Dichloroacetic Acid 3. Trichloroacetic Acid 4. Monochloroacetic Acid 5. Monobromoacetic Acid

One of the main types of disinfection byproducts (DBPs) produced during the chlorination disinfection process are the HAAs. The 5 Public Health Goals (PHGs) are that HAA concentrations in drinking water do not significantly increase the risk of cancer or cause any other serious health issues. According to the HAA chemical, the PHGs based on cancer or noncancer effects are listed below, along with health-protective concentrations for the noncancer effects of carcinogenic HAAs.

HPC- Health Protective Concentrations; PHG- Public Health Goals; ppb - parts per billion

PHGs are not mandated by regulations and are only intended to protect the public's health, without considering their financial implications or other considerations. Maximum Contaminant Levels (MCLs) for drinking water in California are based on PHGs and are set by the State Water Resources Control Board (SWRCB). Each MCL shall be set as closely as economically and technologically practicable to the matching PHG. The federal MCLs imposed by the US Environmental Protection Agency may be equal to or stricter than California's MCLs (US EPA).

HAA has been found in tap water, food, and the environment including air, water, soil, and plants. HAA can be produced from both anthropogenic and natural sources. Most of the human exposure to HAA is through disinfected water. In disinfection, gaseous chlorine or bleach reacts with water to produce hypochlorous acid (hypobromous acid in the presence of bromine), which interacts with organic matter present in water to produce various DBPs.

The PHG development process does not include a quantitative risk-benefit analysis comparing risks from exposure to DBPs to risks from exposure to microorganisms in water, as that type of analysis falls outside of the scope of this assessment. This task is conducted by SWRCB in its description of best practices for drinking water disinfection and development of California MCLs.