The History of Chromium Contamination
By Saima Hedrick
Chromium is a naturally occurring element that is present in rocks, soil, volcanic dust, and in some animals and plants. In its trivalent form (chromium III) it is part of the balanced human diet and aids in glucose and lipid metabolism. Chromium III can be found in common foods such as broccoli, potatoes, garlic, beef, and apples.
Chromium VI, however, is a very powerful carcinogen and breathing or inhaling it can have devastating side effects. Inhalation can cause damage to the lungs, kidney, neurological function, immune system, and ulcerations of septum; it has also been proven to cause lung cancer. Ingestion can cause abdominal pain, vomiting, and hemorrhaging. Contact with the skin, which is typically an occupational occurrence, can cause ulcerations and burns.
Chromium is used in many different industries for electroplating, pigments, wood preservation, leather tanning, and production of strong alloys. Since the discovery of a large chromium deposit in Baltimore, MD in 1827, chromium has been used in American industry without regulation. In 1943, the USGS discovered chromium VI contaminated groundwater in Long Island, NY. This was the first recorded contamination but the measurement methods for chromium were not as sophisticated and no conclusive data had been presented to show the hazardous effects on humans. The culprit was an aircraft production plant that was using diffusion wells to dispose of plating waste.
For many years several different bodies of water were found to be contaminated with chromium VI. It was not until 1990 that scientists in Norway published a comprehensive epidemiological study of the occupational hazards of chromium and got the attention of the international community. Shortly thereafter, in 1991, the EPA created a regulation for all forms of chromium. At this time, the maximum contaminant level (MCL) for drinking water was 0.1 mg/L and it was recognized that chromium VI is a carcinogen when inhaled.
In 1993 a legal clerk named Erin Brokovich put together a case against the Pacific Gas and Electric Company in California. The case, made famous by the Hollywood movie released in March 2000, was based on the exposure of the townspeople of Hinkley, CA to hexavalent chromium via groundwater used for drinking. The case was settled in 1996 but a survey showed surprisingly low incidence rates for cancer.
In 2001, the EPA contacted the University of California to determine the carcinogenicity of ingested chromium and initiated several similar research endeavors around the nation. The University of California released its findings and California decided to establish its own chromium MCL at 50 µg/L. However, the EPA regulation remained the same.
In September 2010, the EPA released the findings of a toxicological review of chromium VI for the public and the scientific community. The report is a summary of the findings of four independent organizations: 1) U.S. EPA’s Office of Pesticide Programs (OPP); 2) the New Jersey Department of Environmental Protection (NJDEP); (3) the California Environmental Protection Agency (CalEPA); and (4) the Agency for Toxic Substances and Disease Registry (ATSDR). This report is not yet official as it needs the validation of the scientific community before it can be published. Comments were submitted online until December 29, 2010 and are currently being reviewed by the EPA. If the findings of the report are validated, then the EPA will use this new information to revise the MCL.
Meanwhile, in December of 2010, the Environmental Working Group released a report stating that 30 out of 35 cities in the US have chromium contamination in the drinking water. The report went on to compare the current MCL to the more stringent one set by California and recommended that the EPA do the same. This sparked a lot of media attention and public interest in the chromium VI contamination. Hopefully, this increase in public interest will incite the EPA to follow California’s example so that drinking water can be more strictly regulated.
Health Effects of Hexavalent Chromium Exposure
Due to the recent report by the Environmental Working Group, chromium has become a matter of public interest. However, many are still unaware of the health effects of short and long-term exposure, and how to detect and treat chromium poisoning.
Chromium compounds most commonly occur in trivalent (chromium-3) or hexavalent (chromium-6) forms. Chromium-3 is found in many different types of food and is a beneficial compound for the human metabolism. However, in the presence of oxygen, it is converted to Chromium-6, which is a known human carcinogen. The initial symptoms of inhalation of this chromium-6 are sinusitis, asthma, and allergic dermatitis; all routine respiratory ailments that are not commonly associated with chromium exposure. As such, it is difficult to identify an exposed patient unless the patient’s history is carefully examined for potential modes of exposure. Inhalation of chromium-6 can cause much more harm that ingestion or skin contact as chromium-6 persists in the lung tissue long after the body has cleared it from other parts of the body.
Chromium is easily detected in the blood and the urine. If the healthcare provider suspects chromium-6 exposure, these tests can help determine the extent of that exposure. Since the blood only retains chromium for the life of a blood cell (120 days), a positive blood test indicates that the individual was exposed within that period of time. The urine, on the other hand, only retains chromium for 1-2 days and therefore indicates more recent exposure. The concentration of chromium, in both blood and urine, indicates the dose of exposure.
Short-term exposure can cause vertigo, fever, nausea, vomiting, diarrhea, and ulcers. Long-term skin exposure can cause eye irritation, nasal ulcers, gingivitis, periodontitus, dermatitis with swelling. Long-term inhalation exposure can cause a myriad of respiratory diseases, and lung cancer. A high dose can result in renal failure, circulatory collapse, multisystem organ failure, coma, and death.
Pregnant women, infants, and children are the most vulnerable because of the undeveloped systems that are not able to excrete chromium-6 as efficiently as an adult. Those with less acidic stomachs are also at greater risk because they cannot efficiently convert chromium-6 to chromium-3.
There is no treatment for chromium poisoning. The effects of short-term, low-dose exposure can be treated with removal from the exposure source and medication for the specific symptom. Those with long-term and high-dose exposure cannot be treated and will most likely die. Therefore, it is important to be vigilant about your environment and the harmful chemicals you may be exposing your body to. Visit the EPA’s Basic Information about Chromium in Drinking Water Web site and learn more about how you can test your drinking water and see the results of tests done at your local water distribution facility.