It’s being called “the new asbestos” and it threatens our drinking water sources: chromium has been found in water, from underground reservoirs to our taps. Read on to learn about how chromium affects your health, and how you can remove it from your tap water.
Do you remember Erin Brockovich? She was the lawyer who helped residents of the town of Hinckley, California, obtain millions in compensation after a chemical plant polluted their groundwater with chromium (VI), causing widespread disease, particularly cancer. Unfortunately, this is far from being an isolated incident.
Chromium is a hard metal that is highly resistant to oxidation. It is heavily used in metallurgical, chemical and building industries.
The three most common forms of chromium are chromium (0) (the elemental metal in its natural state), chromium (III) (also called trivalent chromium) and chromium (VI) (also called hexavalent chromium). Chromium (III) and chromium (VI) both occur because of natural chromium erosion but more commonly as a result of industrial pollution.
Chromium (III) and chromium (VI) are used for chrome plating, making steel, leather tanning, paint, dyes and plastic pigments, wood treatments, anti-corrosion products and more. Industrial waste from these processes ends up contaminating our drinking water.
Chromium’s toxicity depends on its form. Chromium (0) and chromium (III) are not toxic in small quantities; chromium (III) can even be beneficial; whereas chromium (VI) is highly toxic. We’ll take a closer look at the health impacts of chromium (III) and chromium (VI) later in this article.
There are several ways chromium ends up in drinking water. The principal sources are industrial waste and sludge from waste-water treatment plants. In many cases, chromium industrial waste ends up in the aquatic environment, in other words: our drinking water sources.
What’s more, some water treatment processes increase the quantity of chromium (VI) in the water. Chlorine, for example, causes a chemical reaction that transforms chromium (III) into chromium (VI). Ozonation can also transform chromium (III) into chromium (VI). [ref: https://www.anses.fr/en/system/files/EAUX2011sa0127EN.pdf] Chromium can also be present in the metals used in the production, treatment and distribution of drinking water.
Chromium is on the list of chemical substances controlled by the European REACH regulation (Registration, Evaluation, Authorisation and Restriction of Chemicals). The aim of this legislation is to provide a high level of protection of human health and the environment from the use of chemicals. According to an article published by the International Journal of Environmental Research and Public Health, 512 facilities in Europe are on the European pollutant release and transfer register as releasing chromium compounds into air and water.
Chromium (VI) is present in our environment and drinking water, and therefore still presents a danger to our health.
Let’s start with chromium (III), which is considered a beneficial nutrient. Chromium (III) is present in many foods and is also available as a dietary supplement. It helps the body make use of carbohydrates, fats and proteins. It also has an antioxidant effect, which means it protects cells from free radical damage. According to the National Institutes of Health, the adequate intake of chromium (III) for adults between 19 and 50 years old is 35 micrograms (μg) for men and 25 μg for women.
On the other hand, chromium (VI) is known to be toxic to human health, wildlife, and the environment. It impairs the growth of aquatic plants and fish, as well as the fertility and longevity of some invertebrate animals. It is a carcinogen (causes cancer), mutagen (causes DNA mutations), and reprotoxic (toxic to the reproductive system).
Studies have shown that chromium (VI) in drinking water can cause cancer of the mouth and small intestine, as well as stomach ulcers and liver problems. The IARC (International Agency for Research on Cancer) classifies chromium (VI) as Group 1: carcinogenic to humans.
A report by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) on the health risks of chromium in drinking water concluded that in order to avoid negative effects, the intake of chromium (VI) should be no more than 1 microgram per kilogram of bodyweight per day (μg/kg bw/d). An intake of more than 5 milligrams per kilogram of bodyweight per day (mg/kg bw/d) would trigger carcinogenic effects. Based on these results, the report concluded that the maximum amount of chromium (VI) in drinking water should be 6 micrograms per litre (μg/L).
Unfortunately, the legal limits of chromium in water are much higher than that.
In its latest Guidelines for Drinking Water Quality, the World Health Organisation fails to mention chromium (VI). Instead, it gives a provisional guideline value 50 μg/L for total chromium.
This fails to address the significant differences between chromium (III) and chromium (VI).
The European Union’s Drinking Water Directive states: “For chromium, the value remains under WHO review and a transitional period of 15 years should therefore apply before the value becomes more stringent.”
The limit given in the Directive for chromium is 25 μg/L. However, this value “shall be met, at the latest, by 12 January 2036.” Until that date, the limit is 50 μg/L. [ref: https://eur-lex.europa.eu/eli/dir/2020/2184/oj]
It is worrying to note that this maximum value is for total chromium. It does not differentiate between chromium (III) and chromium (VI). Given that chromium (III) is a nutrient and chromium (VI) is a carcinogen, the current and future limits specified by the Drinking Water Directive seem to fall short of offering real protection.
The Dutch Drinking Water Decree follows the WHO and European guidelines and sets the limit of chromium in drinking water to 50 μg/L. Here too, there is no mention of different types of chromium.
While the Dutch National Institute for Public Health and the Environment (RIVM) says on its website that dutch drinking water contains little or no chromium (VI), there has recently been an incident concerning chromium in the environment.
In July 2022, inspectors found chromium (VI) in the groundwater around the Tata Steel factory following a fire. While the GGD health service stated there was no risk of exposure to residents, the RIVM has found that residents living around the factory are prescribed medicines for cardiovascular disease, diabetes, high blood pressure, and respiratory problems 5-16% more than residents outside the region. They are also 25% more likely to get lung cancer.
France’s drinking water legislation follows the EU’s guidelines and limits total chromium content to 50 μg/L.
In France, around 94% of industrial emissions containing chromium (VI) end up in the aquatic environment: in other words, in surface water and groundwater where drinking water is extracted.
There have been several incidents involving this chemical.
2020: Nine thousand households in Marseille had been drinking polluted water for six years. In 2014, the company responsible for a chromium (VI) leak was condemned. But the council didn’t inform residents until 2020. Analyses revealed that levels of chromium (VI) in nearby groundwater were 500 times the authorised amount. In one sample, the amount of chromium (VI) was 127 mg/L, 1200 times higher than the legal limit.
2016: The chemical laboratory in Clermont-Ferrand sampled 71 samples of emissions from cement factories and found that 51% were over the 50μg/L limit.
2016: The national hydrology laboratory in Nancy analysed 469 samples of drinking water taken over 175 sites and found that 50% contained measurable traces of chromium (VI) (at least 0,2 μg/L), 10% of the samples measured above 6 μg/L, with some samples going up to 25 μg/L.
In 2021, the Italian Minister of Health modified the legislation on drinking water to change the maximum chromium content to 25 μg/L. This will come into effect on 12 January 2026. Until that time, the limit is 50 μg/L. Here too, the legislation mentions only total chromium, without mentioning chromium (VI).
However, a 2016 decree amending the Italian directive on drinking water advises that as a precautionary measure, a provisional parametric value for chromium (VI) of 10 μg/L is recommended.
The town of Spinetta Marengo was the centre of a chromium (VI) scandal back in 2008. At an ageing chemical factory owned by a chemical company, workers noticed leaks that contained high levels of chromium (VI). Despite the company promising to repair broken infrastructure, environmental inspectors found chromium (VI) at more than 40 times the legal limit in water wells near the plant. Criminal charges were brought against the plant’s owners for intentionally poisoning the ground water and failing to clean up the site. Over ten years later, a study by local health authorities found that people living within four kilometres of the factory were 30% more likely to develop leukaemia, parkinson’s disease, and stomach or kidney cancer than people living elsewhere.
Given that the water is managed at a regional level in Italy, there is currently no detailed data showing chromium (VI) levels in drinking water.
The United Kingdom’s legislation on drinking water quality sets the limit for total chromium to 50μg/L. There is no mention of chromium (VI).
DEFRA’s latest report on drinking water finds that 100% of the samples tested meet the legal requirements, but given that the legislation leaves such a wide margin, and fails to differentiate between toxic and non-toxic types of chromium, a question mark remains over the safety of tap water, not just in the UK but everywhere.
Ireland follows the European Union’s Drinking Water Directive that sets the limit of total chromium at 50 μg/L.
In its latest report on the quality of drinking water, the Irish Environmental Protection Agency found that all the samples tested met the standard.
That said, there have been scandals around chromium (VI) pollution in Ireland. In 2008, Erin Brockovich gave her support to residents of Cork Harbour when the Department of the Environment was accused of covering up the extent of toxic waste. An estimated 500,000 tons of waste containing chromium (VI) were thought to be buried at the former Irish Steel site.
The United States Environmental Protection Agency’s (EPA) drinking water standard for chromium is 0,1 milligrams per litre (100 μg/L) – twice the European limit.
The EPA’s website states: “In order to ensure that the greatest potential risk is addressed, EPA’s regulation assumes that a measurement of total chromium is 100 percent chromium-6, the more toxic form. If tap water from a public water system exceeds this federal standard, consumers will be notified.”
An analysis of 3834 tap water samples in representative cities of the United States showed a chromium concentration ranging from 0.4 to 8 μg/L.
In another study, 31 of the 35 American cities tested had detectable levels of chromium (VI) in their drinking water.
Curious about what’s in your water? Take a look at the Environmental Working Group’s tap water database: https://www.ewg.org/tapwater/
Both ion exchange filters and reverse osmosis remove chromium (VI). The 5-stage ZeroWater filter has also been designed to remove this substance from tap water. In tests, it has been found to remove 99.6% of hexavalent chromium. You can check the filter’s performance data sheet here: https://cdn.shopify.com/s/files/1/0311/5499/5336/files/Performance_Data_Sheet_for_all_certified_devices_10-12-20.pdf?v=1605213179
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