Cancer-causing chemical found in Houston's drinking water

Hexavalent chromium made infamous in movie 'Erin Brockovich'

HOUSTON – We need it to cook and clean and we need it to survive. But Houston's Channel 2 Investigates has discovered tap water in many Houston area communities has a chemical that could make residents dangerously sick.

A cancer-causing chemical made infamous by Erin Brockovich, has been found at high levels in Houston's tap water. The chemical is called hexavalent chromium or chromium 6.


"The city of Houston's water ranks about third in the country in terms of high level of chromium 6," said Bill Walker, managing editor at the nonprofit Environmental Working Group.

But just how high is the chromium 6 in Houston's tap water? In California-- the Office of Environmental Health Hazard Assessment, indicates cancer rates start to rise at a concentration of 0.02 parts per billion (ppb)

"To put that in perspective, a part per billion is roughly one drop of water in an Olympic-sized swimming pool," Walker said.

According to EWG's data from the city of Houston, Houston's average is 0.75 ppb.

Why is chromium 6 so dangerous? "It could increase your chance or your risk to get cancer," said Dr. Qilin Li, with Rice University, adding, "It could also cause damage to liver and kidney."

Chromium is found naturally in rocks, plants, soils, volcanic dust and animals. Chromium 6 occurs naturally in the environment from the erosion of natural chromium deposits. It can also be produced by industrial processes.


"Chromium 6 ... can come from industrial pollution, such as electroplating industry and could come from mining," Li said.

Houston's Channel 2 Investigates looked even closer at the numbers across Harris County and found the nine highest samples, from 2013-2015, all came back to the exact zip code, 77099.

In some cases the rates were over 6.0. That's 300 times the recommended health level set in California of 0.02 ppb.

"The level that you're talking about in Houston would mean an additional 330 cases of cancer over a lifetime," Walker said. 

KPRC went to Houston Public Works for answers. 

"I would like you to know that the water is safe," Yvonne Forrest, a Senior Assistant Director for Public Works, said. "The city of Houston provides safe drinking water that meets or exceeds all the established levels for the state or federal government." But the federal government nor the state of Texas has set a standard for chromium 6 levels.

The EPA has set the standard for total chromium levels in drinking water to 100 ppb. 

Only one state has set a standard for chromium-6 in drinking water.

California's drinking water standard for chromium 6 took effect on July 1, 2014. It established a maximum contaminant level of 10 ppb for chromium 6 in drinking water. But California's health goal is 0.02 ppb.

The U.S. Environmental Protection Agency told us they are working to assess chromium 6 and have to have a proposal ready for public comment in 2017.

The EPA sent Channel 2 Investigates this statement:

The EPA has a drinking water standard of 100 parts per billion (ppb) for total chromium, including hexavalent chromium. EPA and states are responsible for ensuring that public water systems are in compliance with the current standard.   The agency has also collected nationally representative data on the occurrence of both total chromium and hexavalent chromium through the third unregulated contaminant monitoring rule (UCMR3). Only one of the almost 5,000 public water systems that monitored total chromium under the UCMR3 reported results that exceeded EPA's standard.  The EPA is actively working on the development of the Integrated Risk Information System (IRIS) assessment of hexavalent chromium, which will include a comprehensive evaluation of potential health effects associated with hexavalent chromium, and EPA expects that the draft IRIS assessment will be released for public comment in 2017.

So it comes down to your personal choice. We asked Li if her drinking water had chromium 6 levels of 6.7 ppb, would she have a water filtration system at her home? "If I lived in this area and I find high concentrations, I probably would," Li said.

Follow-up questions between Channel 2 Investigates and Houston Department of Public Works:

Again, the city of Houston’s Drinking Water Operations Branch conducts over 15,000 tests on drinking water samples each month to ensure the city’s drinking water meets or exceeds all federal and state standards. Chromium 6 is not regulated by the U.S. Environmental Protection Agency (EPA) or the Texas Commission on Environmental Quality (TCEQ) separately from total chromium. The City of Houston is currently meeting the requirements established for total chromium, which includes chromium 6.

Channel 2 Investigates: Can you explain why the nine highest samples, anything over 4.0 were in the exact same ZIP code 77099?

Public Works: These addresses represent four ground water facilities and a location within that service area.  The results indicate that this is a naturally occurring chemical in the groundwater.

Channel 2 Investigates: Do you know why more chromium 6 can be found in the samples taken in that one particular zip code?

Public Works: This could be associated with a groundwater aquifer since all of the wells are in close proximity.

Channel 2 Investigates: Is there one root cause?

Public Works: The four locations are ground water plants and could be associated with the aquifer that supplies water to those wells.

Channel 2 Investigates: Is there more naturally occurring chromium 6 in this area?

Public Works: Based on current data from samples taken at the Texas Commission on Environmental Quality’s approved locations, there seems to be more naturally occurring chromium 6 in that area.

Channel 2 Investigates: Is there more industrial polluting of chromium 6 in this area?

Public Works: Unknown.