Trace levels of the chemical bromacil were recently detected in water samples collected at one Waipahu I pump and one Mililani I pump, according to local health officials.
However, Hawaii Department of Health officials are advising consumers they should not be alarmed as levels were well below the Environmental Protection Agency Lifetime Health Advisory Level for drinking water, and bromacil is filtered out through the Honolulu Board of Water Supply's Granular Activated Carbon treatment facilities before being delivered to drinking water supplies.
In addition, trace levels of boron were detected in water from several Waipahu GAC treatment facilities and water from the Waialua GAC treatment facility. The levels of boron found were also well below the EPA Lifetime Health Advisory Level for drinking water.
The Honolulu Board of Water Supply tests for the presence of these chemicals as part of its regular monitoring schedule and reported these latest findings to the Hawaii DOH, as required by state law. The Hawaii DOH is providing the information to the public as is also required by state law.
"We are confident that these trace levels do not pose a public health threat," said Gary Gill, deputy director for Environmental Health. "These chemicals had not previously been detected at these sampling points. The Department of Health will continue to work with the Honolulu Board of Water Supply, so that tests for these chemicals continue as part of its regular monitoring schedule to ensure that public health is not compromised."
Bromacil is a broad-spectrum herbicide used for weed control for pineapple fields and citrus plants. Boron naturally occurs in rocks and soils and enters the environment mainly from the weathering of boron-containing rocks.
The trace levels of bromacil found at the sources were well below the EPA Lifetime Health Advisory Level for drinking water. EPA defines the Lifetime Health Advisory Level as the concentration in drinking water that is not expected to cause any adverse, non-carcinogenic effects for a lifetime of exposure.
The EPA Lifetime Health Advisory Level for bromacil is 70 parts per billion, which is measured in micrograms per liter. By contrast, the bromacil level detected at a Waipahu I pump was 0.46 parts per billion and at a Mililani I pump was 0.66 parts per billion.
The Honolulu Board of Water Supply also reported very low levels of boron at three Waipahu GAC treatment facilities and at the Waialua Wells GAC treatment facility, ranging from 0.092 to 0.15 milligrams per liter or parts per million. These levels were also well below the EPA Lifetime Health Advisory Level for boron in drinking water of 6 parts per million and do not represent a health threat.
The Honolulu Board of Water Supply conducts tests at sources and treatment facilities as mandated by federal and state drinking water regulations.