In the past 40 years, hexavalent chromium has been a major concern in the health of industrial workers as well as residents of towns impacted by groundwater contamination. In this blog, we will investigate the dangers of this chromium ion and how it has impacted safety regulations in industry.
What Is Hexavalent Chromium?
It’s tasteless, odorless, and naturally occurring. Hexavalent chromium, or chromium-6, is caused by the erosion of natural chromium deposits and can be created in industrial processes. The bigger problem is caused when it leaks into the environment thanks to poor storage or the improper disposal of industrial waste.
But hexavalent chromium is only one of two main forms of the element. Trivalent chromium, or chromium-3, is an element essential to the human diet. In volatile environments, however, such as at high temperatures in cement rotary kilns, chromium-3 may oxidize and form the toxin chromium-6.
What Does Hexavalent Chromium Do to the Body?
Chromium-6 is recognized by the Occupational Health and Safety Administration (OSHA) as carcinogenic, which means it has the potential to cause cancer in those exposed. This is especially true when the exposure occurs through inhalation. The chemical can irritate a person’s nose, throat, and lungs, and repeated exposure can cause occupational asthma, kidney and liver damage, tooth erosion, and respiratory cancer.
In fact, lung, nasal, and sinus cancers were found to be more common in workers exposed to the element through inhalation for prolonged periods.
Adverse health effects from hexavalent chromium exposure include:
- Nasal cancer, from inhalation
- Sinus cancer, from inhalation
- Stomach cancer, from ingestion
- Gastrointestinal cancer, from ingestion
- Kidney damage or failure
- Liver damage or failure
- Skin ulcers
- Eye irritation
- Skin irritation
While inhalation is one of the more common ways to be exposed to the toxic element, people can also come into contact with chromium-6 by ingesting it in food or water or with skin contact. Studies have shown that the toxic element is most dangerous to humans through inhalation, but tests involving rats and mice show that sodium dichromate dihydrate, which contains hexavalent chromium, has the potential to cause cancer in lab animals after oral ingestion. Rats developed malignant tumors in the oral cavity, while mice had a number of benign and malignant tumors in the small intestine.
Who Is at Risk of Being Exposed to Hexavalent Chromium?
Whether they handle compounds that contain the element or breathe it in regularly, industrial workers are among the most likely to be exposed to chromium-6. According to the National Institute of Environmental Health Sciences (NIEHS), the United States is one of the world’s leading producers of chromium compounds.
According to the CDC, industrial workers like those listed below may be exposed to chromium-6:
- Steel mill workers
- Workers handling wet cement
- Leather tanners
- Electroplating workers
- Wood preservationists
- Textile dyeing workers
But it’s not just industrial workers who may be exposed to hexavalent chromium. There have been several instances over the last 40 years alone in which unsuspecting residents have been exposed to the toxic chemical in their water supply.
Regulation of Chromium-6 in Portland Cement & E-Waste
An important component of the many types of concrete used worldwide, portland cement is primarily made up of lime and silica and, to a lesser degree, alumina and iron oxide. The average concentration of hexavalent chromium in cement ranges between 0.5 and 2.46 milligrams per kilogram.
Allergic contact dermatitis, or cement eczema, was first reported in 1908 amongst workers constructing the Paris Metro system. The presence of hexavalent chromium in the portland cement was found to be the cause. Wet portland cement has also been found to cause caustic burns, or cement burns.
In the United States, OSHA has regulated industrial workers’ chromium-6 exposure by mandating personal protective equipment (PPE), sanitation stations, and hazard communication in the workplace. Employers must abide by the permissible exposure limit (PEL) set by OSHA, which is 15 milligrams per cubic meter of air for total dust and 5 milligrams per cubic meter of air for respirable dust when handling dry portland cement.
Europe, on the other hand, has responded to the dangers of chromium-6 in portland cement by controlling the mixture’s creation. In January 2005, the European Union issued a directive that cement in the European market must not release more than 2 mg/kg of soluble hexavalent chromium when mixed with water. Since that directive was implemented, allergic contact dermatitis related to chromium-6 has significantly decreased in Europe.
Hexavalent chromium was also listed in the 2006 EU ban on hazardous substances in electrical and electronic products, in an attempt to lessen the negative effects that e-waste disposal had on human health and the environment.
Groundwater Contamination in Hinkley, CA
Between 1952 and 1966, Pacific Gas and Electric Company (PG&E) dumped approximately 370 million gallons of wastewater tainted with chromium near Hinkley, CA. The company’s natural gas Compressor Station used hexavalent chromium to fight corrosion in the cooling tower water; the wastewater was released into unlined ponds and contaminated the groundwater under the town. The contamination was discovered more than 20 years later, in 1987. The affected groundwater covers an area of at least eight miles by two miles.
In 1993, Erin Brockovich, a law clerk at a firm hired by one of the town’s residents, became an activist for clean water as she began to question PG&E’s actions. Residents of the town had long suffered chronic asthma, coughing, bronchitis, and nosebleeds. Brockovich played an important role in building a case against PG&E, which was finally settled in 1996. More than 600 people were affected by the toxic groundwater, and many will remain so for the rest of their lives.
In the year 2000, a major motion picture was released starring Julia Roberts around Brockovich’s story. Today, there is little left in the town of Hinkley, but the residents who remain are still suffering from the effects of the contamination.
The Green Ooze Leak on I-696
In 2019, a mysterious green ooze started leaking onto I-696 in Madison Heights, MI, near Detroit.
The toxic ooze had seeped from storage in the former Electroplating Services building through the soil and onto the road. It was also found to have contaminated the nearby groundwater, which the Michigan Department of Environment, Great Lakes, and Energy (EGLE) and the Environmental Protection Agency (EPA) worked together to mitigate and clean up in a multi-step process including sump pumps and a groundwater injection treatment. Within 7 months of the initial leak, more than 260,000 gallons of contaminated groundwater had been collected, treated, and disposed of.
The green ooze was found to contain hexavalent chromium, and many drivers have, over the years, reported discolored water on the road, especially after it rains.
After years of legal battles, the demolition of the building which was found to be the cause of the toxic chemical spill was finally authorized in April 2022.
Chromium Spill in Huron River
In early August 2022, the Michigan EGLE was notified that Tribar Manufacturing, an auto supplier responsible for chrome-finished parts, had released approximately 10,000 gallons of liquid containing 5% chromium into the Wixom Sewage Treatment Facility. Wastewater from the facility is released into the Huron River through Norton Creek.
It was later discovered that an employee at the plant had overridden the company’s waste treatment alarms 460 times over the course of three hours before the toxic release began. That was among the concerns addressed in violation notices issued to Tribar Manufacturing by EGLE.
The second dangerous release by Tribar in four years, the 2022 chemical release endangered more than 100,000 residents in Ann Arbor, MI, and beyond. In the wake of the spill, residents were directed to not swim in or use water from the river to water their lawns or gardens, and to not eat fish from the river system. After more than a week of investigation and rigorous testing, the no-contact recommendation was lifted.
How To Minimize Exposure to Hexavalent Chromium
The United States has taken an umbrella approach to drinking water safety when it comes to chromium-6 as a part of the Safe Drinking Water Act (SDWA). In 1991, the Environmental Protection Agency (EPA) mandated a drinking water standard of 0.1 milligrams per liter (or 100 parts per billion) of total chromium, which includes hexavalent chromium as well as its other forms, like the non-toxic trivalent chromium.
OSHA mandated a waste disposal provision to ensure the safe disposal of chromium-6, requiring that “waste, scrap, debris, and any other materials contaminated with chromium (VI) and consigned for disposal are collected and disposed of in sealed, impermeable bags or other closed, impermeable containers.”
Industrial employers must take care to protect workers from hexavalent chromium exposure by following all mandated safety rules, such as providing PPE and non-alkaline soap at sanitization stations.
How Families Can Reduce Hexavalent Chromium Exposure Risks
Families also have a potential line of defense against the dangers of chromium-6. The most effective way to remove chromium-6 from water is by using a reverse osmosis system, though distillation and anion exchange methods can also reduce levels of the chemical.
Chromium-3 has been established as a safe and essential nutrient, but excess use of dietary supplements containing chromium should be avoided. Chromium, too, is a component of tobacco smoke, which adds yet another reason to avoid smoking in enclosed spaces in order to limit a child’s exposure.
If you are concerned about your or your family’s exposure to chromium, including hexavalent chromium, a medical test may be able to identify higher-than-normal levels in hair, urine, or blood. However, these levels alone cannot predict any health effects.
Although there are things we can do to protect ourselves against the dangers of hexavalent chromium in the air and drinking water, it is the responsibility of industrial companies and government agencies to monitor levels of the toxic chemical through every step of manufacturing.