Chromium-6 In Your Water? Ask

Late last month the Environmental Working Group released a study it commissioned, reporting the detection of hexavalent chromium -- a carcinogen when inhaled -- in tap water from 31 of 35 American cities.

The findings set off a scramble among cities around the country to determine if the compound, also known as chromium-6, is in their tap water. For consumers, the only way to learn if your water source has hexavalent chromium is to check with your public water supplier and request a water quality report, said New Jersey Institute of Technology (NJIT) Professor Taha Marhaba, a civil/environmental engineer.

Most municipal or city engineers should be able to provide such a report upon request, he said. Additional information specifically about hexavalent chromium levels may also be available.

"In general, hexavalent chromium can be found in either surface or groundwater sources and its source can be either natural or man-made industrial operations that have used chromium," Marhaba said. "The best way to remove this and other known and un-known contaminants from the water supply to a residence is to install a five-stage reverse osmosis home unit. They cost about $300. If you have your own well, I would advise testing for hexavalent chromium."

Marhaba is a professor and chair of the department of civil and environmental engineering and director of the New Jersey Applied Water Research Center at NJIT. His expertise in water quality most notably has developed what is known as the spectral fluorescent signatures (SFS) technique, which is used to rapidly identify organics in water, organics that could be problematic.

Odorless and tasteless

Chromium is an inorganic metallic element that is odorless and tasteless. It is found naturally in rocks, plants, soil and volcanic dust, humans and animals. The most common forms of chromium in the environment are trivalent (chromium +3), which has relative low toxicity and occurs naturally in many vegetables, fruits, meats, grains and yeast, and hexavalent (chromium +6). Trivalent chromium can be oxidized and dissolved through natural processes, leading to hazardous levels of aqueous hexavalent chromium in surface and groundwater.

The latter, which is more toxic and poses potential health risks to people, has been shown to cause allergic dermatitis in people who over many years use water containing water with a total chromium level in excess of the recommended maximum contaminant level (MCL). It can be found in the compounds salt sodium dichromate, chromium trioxide and various salts of chromate and dichromate.

Hexavalent chromium is used for the production of stainless steel, wood preservation, textile dyes, leather tanning, and as anti-corrosion coatings.

Marhaba noted that the Environmental Protection Agency (EPA) set a Maximum Contaminant Level Goal (MCLG) for total chromium at 0.1 mg/L or 100 parts per billion (ppb). This level was set at a level below which there were no adverse health effects on humans.