Hexavalent chromium, or chromium-6, has been recognized as a known carcinogen that can lead to adverse health effects if ingested in even trace amounts. If you have ever heard of the Erin Brockovich film, it is all about how the Hinkley, California community was poisoned by the chemical.
Now, before you get alarmed, let’s explore hexavalent chromium in water. In this article, we will uncover what it is, why it matters, and what we can do to ensure the safety of our water supply. Let’s dive in.
- Hexavalent chromium (chromium-6) is a cancer-causing chemical found in the tap water of 251 million people throughout the United States.
- The EPA maximum contaminant level for total chromium in water is 100 PPB, while the California Office of Health Hazard Assessment has set a public health goal strictly for chromium-6 in tap water of 0.02 PPB.
- Chromium-6 enters the water supply from the erosion of natural deposits and from ant-corrosive metal coatings, textile dyes, wood preservation products, and industrial discharge.
- The best way to detect chromium in drinking water is to use a certified lab test kit that scans for chromium based on EPA method 200.8 to ensure precise measurement.
- The most effective treatment method to remove chromium from tap is reverse osmosis filtration.
What Exactly Is Chromium?
Chromium is a naturally occurring element in rocks, soil, plants, and animals. It exists mainly in two valence forms, including trivalent chromium (chromium III) and hexavalent chromium (chromium VI).
Trivalent chromium is an essential nutrient for the human body and plays a role in various biological processes. On the other hand, hexavalent chromium, particularly chromium 6, is of concern due to its potential health risks.
Chromium 6 is utilized in various industrial and manufacturing processes, including electroplating, tanning, and pulp processing. Moreover, it can be present in consumer goods like spray paints, tanned leather, and stainless steel products.
Why Is Chromium In The Water?
Chromium can find its way into water sources through various pathways. While natural chromium deposits in rocks and soils can contribute to the presence of trivalent chromium, the focus of concern primarily lies on hexavalent chromium, specifically chromium 6.
Chromium can leach into drinking water through different mechanisms:
- Industrial discharges. Industrial activities can release chromium compounds into water bodies, leading to contamination of nearby water sources. Wastewater from industries involved in metal plating, stainless steel production, and other processes may contain hexavalent chromium that can find its way into drinking water supplies.
- Soil and groundwater contamination. Natural chromium deposits in soil can contribute to the presence of chromium in groundwater. Over time, rainfall or irrigation can cause the leaching of chromium compounds from the soil into underground aquifers, which may serve as sources of drinking water.
- Corrosion of plumbing systems. Chromium can leach into tap water from corroded pipes, fittings, or fixtures. Older plumbing systems, particularly those with chrome-plated components, may release small amounts of hexavalent chromium into the water as these materials degrade.
What Level Of Chromium Is Safe In Drinking Water?
The enforceable standard for chromium in drinking water is the maximum contaminant level (MCL). It represents the highest allowable concentration of a contaminant in water delivered to public water system users.
Chromium in drinking water is regulated under the term “total chromium,” which includes hexavalent (chromium 6) and trivalent chromium. The Safe Drinking Water Act sets the current regulatory standard for total chromium in drinking water.
The Environmental Protection Agency (EPA) has set a maximum contaminant level of 100 ppb for total chromium, including hexavalent chromium and the less harmful trivalent chromium.
Additionally, California scientists from the Office of Environmental Health Hazard Assessment recently adjusted its proposed limit for hexavalent chromium in drinking water to 0.02 ppb.
This revision was prompted by new research findings highlighting the heightened vulnerability of young children and sensitive populations to chromium-6 exposure. The significance of this update lies in recognizing the specific health risks associated with hexavalent chromium and the need to implement suitable measures to safeguard these vulnerable groups.
What Are The Effects Of Chromium On Drinking Water?
Exposure to elevated levels of chromium 6 in drinking water has been associated with several health risks. Public health researchers have identified particular risks, including:
- Carcinogenicity. Chromium 6 is a known human carcinogen, with studies linking long-term exposure to an increased risk of lung, nasal, and sinus cancers.
- Allergic reactions. Some individuals may develop allergic dermatitis upon contact with chromium-contaminated water, leading to skin irritation, redness, and itching.
- Gastrointestinal issues. Ingesting high levels of chromium 6 can cause gastrointestinal problems such as stomach ulcers, abdominal pain, and diarrhea.
- Respiratory effects. Inhalation of chromium 6 in drinking water vapor during activities like showering or cooking can lead to respiratory issues, including nose, throat, and lung irritation.
How To Test For Hexavalent Chromium In Water
There are no DIY methods to test for chromium-6 at home. However, the two primary methods to test for hexavalent chromium in water are a certified lab test or checking the local water quality database with your zip code.
Certified Lab Test
The most accurate and reliable way to test for hexavalent chromium is by sending a water sample to a certified laboratory. These labs have specialized equipment and expertise to conduct precise analyses.
I recommend using the Freshnss Labs water test kit that scans for chromium based on EPA method 200.8 to ensure precise measurement. The kit comes with everything you need to properly collect a water sample and send it to a certified lab to be analyzed. Within 3 business days, you will receive a detailed report including all contaminants detected, any health or plumbing alerts, and the best treatment methods based on your data.
Check Water Quality Reports
Another approach is to review water quality reports provided by your local water utility or regulatory agency. These reports often include information about the levels of various contaminants, including hexavalent chromium.
Water quality reports are made available to the public and may be accessed online or by request. Look for the section that addresses explicitly chromium or heavy metals to see if hexavalent chromium levels are within acceptable limits.
Alternatively, you can also search the EWG database by zipcode for chromium contamination in your area.
What Cities Have The Highest Chromium 6 Levels In Tap Water?
According to a recent study by the Environmental Working Group, chromium-6 was present in tap water of 31 out of 35 cities in the U.S. that were tested. Here are the cities that tested positive for the highest levels of hexavalent chromium:
Norman Oklahoma Drinking Water
The highest concentrations of chromium-6 in the United States were found in Norman, OK with an average concentration in Norman’s drinking water is 12.9 parts per billion (PPB). This alarmingly high level of Chromium 6, a toxic form of chromium, is nearly 1,965 times higher than the concentration with negligible cancer risk.
Honolulu Hawaii Water
Tap water in Honolulu has been found to have the second-highest concentration of hexavalent chromium, also known as chromium 6, among 35 American cities with a concentration of 2.00 PPB.
Houston Texas Drinking Water
Houston’s tap water has garnered attention for its remarkably high levels of chromium 6, securing the city’s unenviable distinction of being the third-highest among major US cities, trailing only behind Phoenix and St. Louis. The three-year average of chromium 6 concentration in Houston’s drinking water hovers just below 750 parts per trillion, with occasional peaks reaching a staggering 6500 parts per trillion.
To put these figures into perspective, they exceed the widely acknowledged threshold of 20 parts per trillion—cited by numerous scientists and medical professionals as posing negligible risk—by a substantial margin of approximately 35 to 300 times.
Riverside California Drinking Water
Riverside tap water has recently recorded an average concentration of chromium 6 at a significant level of 1.69 PPB.
To put it into perspective, these levels are approximately 110 times higher than the concentration considered to have a minimal effect on the risk of developing cancer.
How To Treat Chromium In Water
When it comes to treating chromium in water, a few effective methods are available. Two popular options for removing chromium 6 and hexavalent chromium from drinking water are reverse osmosis and activated carbon filtration.
Reverse osmosis systems utilize a semipermeable membrane to reject harmful contaminants and is able to remove over 99% of chromium-6 from drinking water. Water is forced through the membrane, which traps impurities, ensuring clean and safe drinking water. Reverse osmosis systems are known for their high efficiency in removing various contaminants, making them an effective choice for chromium removal.
The steps in reverse osmosis (RO) involve:
- Pre-filtration.The water passes through a pre-filter to remove larger particles and sediments that could clog the RO membrane.
- Membrane filtration. The water is then forced through a semipermeable membrane with extremely tiny pores. These pores are small enough to block the passage of chromium 6 molecules and other contaminants.
- Rejecting contaminants. The chromium 6 and other impurities like dissolved solids, heavy metals, and bacteria are trapped by the membrane and separated from the purified water.
- Disposal of rejected water. The concentrated solution containing the trapped contaminants, including chromium 6, is flushed away, while the purified water is collected for use.
Granular Activated Carbon
Activated carbon filters are designed to adsorb contaminants and chemicals, including chromium 6, from water. These filters contain activated carbon with a large surface area, which attracts and traps the chromium 6 particles as water passes through. Activated carbon media is commonly used in whole house water filtration systems, point-of-use system, and water filter pitchers, making them an affordable and efficient option for chromium removal.
The steps in granular activated carbon filtration include:
- Adsorption. Water flows through a filter housing containing activated carbon, a highly porous material. As the water passes through the carbon, the large surface area of the activated carbon attracts and adsorbs chromium 6 particles onto its surface.
- Chemical bonding. The activated carbon has chemical properties that allow it to form bonds with chromium 6. These bonds effectively trap chromium 6 within the carbon pores.
- Contaminant removal. As water continues to flow through the carbon filter, the trapped chromium 6 and other impurities remain adsorbed onto the activated carbon, ensuring they are not released back into the water.
Regular maintenance. Over time, the activated carbon becomes saturated with contaminants, including chromium 6. Periodic replacement or regeneration of the carbon filter is necessary to maintain its effectiveness in removing chromium 6 from the water.
Both reverse osmosis and activated carbon filtration methods work by physically and chemically capturing chromium 6 particles, preventing them from passing through and providing clean and safe drinking water.
It’s essential to follow manufacturer guidelines and recommended maintenance schedules to ensure optimal performance and efficiency of the filtration systems.
Frequently Asked Questions
How much chromium is in tap water?
Although the current EPA maximum contaminant level for total chromium is 0.1 mg/l, tap water can contain higher amounts of chromium depending on your location and water utility provider.
Do water filters remove chromium?
Yes, water filters can remove chromium 6 in drinking water. The most effective treatment is reverse osmosis or activated carbon filtration.
How does chromium-6 get into drinking water?
The primary sources of hexavalent chromium in drinking water are the erosion of natural deposits of chromium which become oxidized or runoff from industrial operations, pulp mills, and metal plating factories.