An environmental group says laboratory tests show the presence of a toxic chemical in 31 of 35 cities, with Honolulu having the second-to-highest level.

The nonprofit Environmental Working Group said hexavalent chromium—the same chemical that led to a $333 million legal settlement described in the movie "Erin Brockovich"—is present in higher-than-recommended levels in the city’s water supply.

Drinking water from one location in the city tested had 2 parts per billion of hexavalent chromium. That compares with .06 ppb the California Environmental Protection Agency has proposed as a public health goal, the group said.

Water from Norman, Okla., ranked first in the tests with a concentration of 12.90 ppb for hexavalent chromium.

Rebecca Sutton, the Environmental Working Group’s lead investigator, said the Honolulu Board of Water Supply did not know the source of the hexavalent chromium. She said the chemical is a common industrial contaminant and can also originate from natural, geologic sources such as ground water.

"Regardless of the source of contamination, we need safe drinking water," she said.

The Board of Water Supply said it does not test for hexavalent chromium because the U.S. Environmental Protection Agency does not require it.

It does test for chromium but cannot tell how much of it is hexavalent chromium, spokesman Kurt Tsue said.

Tsue said he was "surprised" at the Environmental Working Group’s evaluation since it ranked the city as having the sixth-best drinking water in the nation earlier this year.

But as a result of the study, Tsue said, the board plans to hire a consultant to test for hexavalent chromium to find out whether it is widespread in the water system.

He said the board has met the federal guidelines for chromium, with a maximum contaminant level of 100 ppb.

Sutton said the single sample of city water tested was taken from a residence in the vicinity of Wilhelmina Rise in Kaimuki. She said taking more samples would have been better but her organization was constrained by the cost of testing.

She said she felt confident that sampling other residences would bear similar results.

As part of the procedure, Sutton said, water in pipes were flushed "full blast" for several minutes before the sample was taken.

Tsue said although the city’s water system is interconnected, wells in different regions of the island contribute to the supply and the trace levels of chemicals vary.

"It does vary across the island depending on where we pump from," he said.

Tsue and state Department of Health spokesman Janice Okubo said they would generally follow EPA guidelines and recommendations.

Federal officials have linked hexavalent chromium to lung cancer in the workplace, and Sutton’s group said federal tests show clear evidence of its cancer-causing activity in drinking water.

Federal labor safety standards restrict exposure of workers to hexavalent chromium, saying it can cause lung cancer in those who breath airborne particles, and damage the nose, throat, eyes and skin.

The EPA has set a maximum contaminant level of 100 ppb for chromium, including the combination of hexavalent chromium and the less toxic trivalent chromium. But it has set no maximum contaminant level for hexavalent chromium alone.

Neither has it set a maximum contaminant level for hexavalent chromium alone in the drinking water. The Environmental Working Group criticized the EPA for failing to set such a contaminant limit and to require utilities to test for its presence.

The agency yesterday said it is reviewing new science and has launched "rigorous and comprehensive" review of the health effects of hexavalent chromium.

"When this scientific assessment is finalized in 2011, EPA will carefully review the conclusions and consider all relevant information, including the Environmental Working Group’s study, to determine if a new standard needs to be set," it said.