Cities scramble to test water for chromium-6

By Marie Rohde

Milwaukee's Linnwood Water Treatment Plant operates Wednesday off Lincoln Memorial Drive. Chromium-6, a cancer-causing chemical, was found in water samples tested in both Milwaukee and Madison. (Staff photo by Kevin Harnack)

Spending $1,500 on a test that probably won‘t detect a cancer-causing chemical isn’t ideal, but Madison is one of many cities nationwide facing limited options in the race to detect contaminated water supplies in the wake of a concerning study.

Washington D.C.-based Environmental Working Group provoked a national controversy recently when it released a study that found levels of hexavalent chromium, commonly referred to as chromium-6, in 25 cities that was higher than the health goal proposed last year by the state of California.

Madison was ranked as the city with the fourth-highest concentration of the chemical found in its water. Milwaukee tied with Chicago at 15th highest.

Chromium, a metallic element, is odorless and tasteless. When combined with oxygen an atomic reaction can transform it into chromium-3, a substance needed by humans in trace amounts for sugar and lipid metabolism. It also can oxidize into chromium 6, said Abigail Canto, a chemical engineer with Madison-based Process Research Solutions LLC.

While chromium-6 can occur naturally, it often is a manufacturing byproduct, said Paul Biedrzycki, the director of disease control and environmental health for the City of Milwaukee Health Department.

A map shows the level of chromium-6 in water samples collected throughout the U.S. (Map courtesy of the Environmental Working Group, click on map to enlarge)

While the methodology used by the environmentalists was questionable — in each of 35 cities, one member of the group turned on the kitchen tap to collect a single sample of water — it got the attention of the national media, a number of Congressmen and the Environmental Protection Agency.

Now Joe Grande, the water quality manager with Madison Water Works, will spend $1,500 to test samples taken from each of the city’s 22 wells, though he has little confidence the results will be helpful in determining the presence of the cancer-causing chemical.

“We’re not sure that the results will give us much useful information,” Grande said. “If the tests determine it is present, the challenge will be to determine the significance of the results.”

The good news is it’s relatively easy and cheap to remove the chemical from water, said Biedrzycki. The bad news is that no one knows how much chromium-6 is dangerous.

Cantor said much more rigorous testing needs to be done before conclusions can be drawn.

“Obviously one sample in one city is not enough to base conclusions on,” Cantor said. “Also, does the chromium-6 come from the source water, interactions with the piping or the type of faucet the sampler happened to use?”

The EPA announced last week it is on a fast track to give guidance to water providers on how to sample for chromium-6 and said formal standards are in the works.

Carrie Lewis, superintendent of the Milwaukee Water Works, said the EPA has long required water utilities to test for total chromium content in water. The standard has been .1 micrograms per liter, a level that no water plant in the country has ever violated, according to the EPA.

The environmental group’s sampling showed Madison had 1.58 micrograms of chromium-6 per liter of water, while Milwaukee’s logged in at .18 micrograms per liter.

“We sent samples to a lab in Indiana and to State Hygiene Lab,” Lewis said. “We took six samples and it’s costing about $100 per sample.”

Grande said Madison is sending samples to California for testing. While the Milwaukee system is far larger, Madison’s testing will cost more because it has more sources to test.

Grande said he does not believe that chromium-6 detected in Madison is the result of environmental contamination. He said he is also concerned that the unstable nature of chromium could nullify test results.

“It’s unstable,” Grande said of chromium. “It can be changed by air, chlorine and other factors that may influence the results. We need more guidance on what we are looking for and how to do the testing.”