Cr(VI)
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Hexavalent chromium (chromium(VI), Cr(VI), chromium 6) is
chromium Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. Chromium metal is valued for its high corrosion resistance and hard ...
in any
chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
that contains the element in the +6
oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
(thus hexavalent). Virtually all chromium ore is processed via hexavalent chromium, specifically the
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
sodium dichromate Sodium dichromate is the inorganic compound with the formula Na2 Cr2 O7. However, the salt is usually handled as its dihydrate Na2Cr2O7·2 H2O. Virtually all chromium ore is processed via conversion to sodium dichromate and virtually all compound ...
. Hexavalent chromium is key to all materials made from chromium. Approximately of hexavalent chromium were produced in 1985. Additional hexavalent chromium compounds include
chromium trioxide Chromium trioxide (also known as chromium(VI) oxide or chromic anhydride) is an inorganic compound with the formula CrO3. It is the acidic anhydride of chromic acid, and is sometimes marketed under the same name. This compound is a dark-purple s ...
and various salts of
chromate and dichromate Chromate salts contain the chromate anion, . Dichromate salts contain the dichromate anion, . They are oxyanions of chromium in the +6 oxidation state and are moderately strong oxidizing agents. In an aqueous solution, chromate and dichromat ...
, among others. Hexavalent chromium is used in textile dyes,
wood preservation Wood easily degrades without sufficient preservation. Apart from structural wood preservation measures, there are a number of different chemical preservatives and processes (also known as "timber treatment", "lumber treatment" or "pressure treat ...
,
anti-corrosion In chemistry, a corrosion inhibitor or anti-corrosive is a chemical compound that, when added to a liquid or gas, decreases the corrosion rate of a material, typically a metal or an alloy, that comes into contact with the fluid. The effectiveness ...
products,
chromate conversion coating Chromate conversion coating or alodine coating is a type of conversion coating used to passivate steel, aluminium, zinc, cadmium, copper, silver, titanium, magnesium, and tin alloys. The coating serves as a corrosion inhibitor, as a p ...
s, and a variety of niche uses. Industrial uses of hexavalent chromium compounds include chromate pigments in dyes, paints, inks, and plastics; chromates added as anticorrosive agents to paints, primers, and other surface coatings; and
chromic acid The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixtu ...
electroplated onto metal parts to provide a decorative or protective coating. Hexavalent chromium can be formed when performing "hot work" such as welding on
stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's r ...
or melting chromium metal. In these situations the chromium is not originally hexavalent, but the high temperatures involved in the process result in oxidation that converts the chromium to a hexavalent state.29 CFR OSHA General Industry 1910 Hexavalent chromium can also be found in drinking water and public water systems. All hexavalent chromium compounds are
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a sub ...
(due to their oxidizing power) as well as
carcinogenic A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...
(
IARC Group 1 Substances, mixtures, and exposure circumstances in this list have been classified as group 1 by the International Agency for Research on Cancer (IARC): The agent (mixture) is carcinogenic to humans. The exposure circumstance entails exposures tha ...
), especially if airborne and inhaled where they cause
lung cancer Lung cancer, also known as lung carcinoma (since about 98–99% of all lung cancers are carcinomas), is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung. Lung carcinomas derive from transformed, mali ...
. Positive associations have also been observed between exposure to chromium (VI) compounds and
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
of the
nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passe ...
and
nasal sinuses Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity. The maxillary sinuses are located under the eyes; the frontal sinuses are above the eyes; the ethmoidal sinuses are between the eyes and the spheno ...
. Workers in many occupations are exposed to hexavalent chromium. Problematic exposure is known to occur among workers who handle chromate-containing products and those who grind and/ or weld stainless steel. Workers who are exposed to hexavalent chromium are at increased risk of developing lung cancer, asthma, or damage to the nasal epithelia and skin. Within the
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...
, the use of hexavalent chromium in electronic equipment is largely prohibited by the
Restriction of Hazardous Substances Directive The Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Unio ...
and the European Union regulation on
Registration, Evaluation, Authorisation and Restriction of Chemicals Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) is a European Union regulation dating from 18 December 2006. REACH addresses the production and use of chemical substances, and their potential impacts on both human h ...
.


Toxicity

Hexavalent chromium compounds are
genotoxic Genotoxicity is the property of chemical agents that damage the genetic information within a cell causing mutations, which may lead to cancer. While genotoxicity is often confused with mutagenicity, all mutagens are genotoxic, but some genotoxic s ...
carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...
s. Due to its structural similarity to
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
, chromate (a typical form of chromium(VI) at neutral pH) is transported into cells via
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
channels. Inside the cell, hexavalent chromium(VI) is reduced first to pentavalent chromium(V) then to trivalent chromium(III) without the aid of any enzymes. The reduction occurs via direct electron transfer primarily from
ascorbate Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) and ...
and some nonprotein
thiol In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl gro ...
s.
Vitamin C Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) ...
and other
reducing agent In chemistry, a reducing agent (also known as a reductant, reducer, or electron donor) is a chemical species that "donates" an electron to an (called the , , , or ). Examples of substances that are commonly reducing agents include the Earth met ...
s combine with chromate to give chromium(III) products inside the cell. The resultant chromium(III) forms stable complexes with
nucleic acid Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main ...
s and
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
s. This causes strand breaks and Cr–DNA adducts which are responsible for mutagenic damage. According to Shi et al., the DNA can also be damaged by
hydroxyl radical The hydroxyl radical is the diatomic molecule . The hydroxyl radical is very stable as a dilute gas, but it decays very rapidly in the condensed phase. It is pervasive in some situations. Most notably the hydroxyl radicals are produced from the ...
s produced during reoxidation of pentavalent chromium by
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3 ...
molecules present in the cell, which can cause double-strand breakage. Both insoluble salts of lead and barium chromates as well as soluble chromates were negative in the implantation model of lung
carcinogenesis Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abnor ...
. Yet, soluble chromates are a confirmed
carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...
so it would be prudent to consider all chromates carcinogenic. Chronic inhalation from occupational exposures increases the risk of respiratory cancers. The most common form of lung
malignancies Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not ...
in chromate workers is squamous cell carcinoma. Ingestion of chromium(VI) through drinking water has been found to cause cancer in the
oral cavity In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on t ...
and
small intestine The small intestine or small bowel is an organ (anatomy), organ in the human gastrointestinal tract, gastrointestinal tract where most of the #Absorption, absorption of nutrients from food takes place. It lies between the stomach and large intes ...
. It can also cause irritation or ulcers in the stomach and intestines, and toxicity in the liver. Liver toxicity shows the body's apparent inability to detoxify chromium(VI) in the GI tract where it can then enter the circulatory system. Of 2,345 unsafe products in 2015 listed by the EU Commission for Justice, Consumers and Gender Equality some 64% came from China, and 23% were clothing articles, including leather goods (and shoes) contaminated with hexavalent chromium. Chromate-dyed textiles or chromate-tanned leather shoes can cause skin sensitivity. In the U.S., the OSHA PEL for airborne exposures to hexavalent chromium is . The U.S.
National Institute for Occupational Safety and Health The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the C ...
proposed a REL of 0.2 µg/m3 for airborne exposures to hexavalent chromium. Hexavalent chromium is present in drinking water and public water systems. Based on the findings of the
National Toxicology Program The National Toxicology Program (NTP) is an inter-agency program run by the United States Department of Health and Human Services to coordinate, evaluate, and report on toxicology within public agencies. The National Toxicology Program is headqua ...
(NTP)—which is headquartered in the
National Institute of Environmental Health Sciences The National Institute of Environmental Health Sciences (NIEHS) conducts research into the effects of the environment on human disease, as one of the 27 institutes and centers of the National Institutes of Health (NIH). It is located in the Rese ...
(NIEHS)—in 2014, California established a state-wide drinking water standard of 10
parts per billion In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, th ...
(ppb)—micrograms per liter (MCL) of 10 ppb—"specifically for hexavalent chromium, not total chromium." For drinking water, the
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...
(EPA) does not have a Maximum Contaminant Level (MCL) for hexavalent chromium.


Remediation of hexavalent chromium in groundwater and drinking water

There are mainly three types of methods to remediate hexavalent chromium in ground water and drinking water: # Reduction of toxicity; # Removal technologies; and; # Containment technologies Reduction of toxicity of hexavalent chromium involves methods using chemicals, microbes and plants. Some removal technologies include transporting contaminated soil offsite to a landfill, using ion exchange resins to reduce chromium(VI) concentrations to less than detectable limit and granular
activated carbon Activated carbon, also called activated charcoal, is a form of carbon commonly used to filter contaminants from water and air, among many other uses. It is processed (activated) to have small, low-volume pores that increase the surface area availa ...
(GAC) filter. Containment technologies can be employed with the use of physical barriers such as grouts, slurries or sheet piling. Attempts have been made to test the removal or reduction of hexavalent chromium from aqueous solutions and environment. For example, a research study conducted by the School of Industrial Technology,
University Sains Malaysia Universiti Sains Malaysia ( 'Science University of Malaysia'; abbreviated as USM) is a public research university in Malaysia. Founded on 1 June 1969 as a statutory body with its own constitution, it is among the oldest institutes of higher l ...
in 2010 found that
chitosan Chitosan is a linear polysaccharide composed of randomly distributed β-(1→4)-linked D-glucosamine (deacetylated unit) and ''N''-acetyl-D-glucosamine (acetylated unit). It is made by treating the chitin shells of shrimp and other crustacean ...
coated with poly 3-methyl thiophene can be effectively employed for removal of hexavalent chromium ions from aqueous solutions. Chitosan is a very cheap, economical, and environmentally friendly substrate for coating of this polymer. Adsorption of chromium(VI) is found to be effective in the lower pH range and at higher temperatures and subsequent desorption is readily achieved upon alkaline treatment of the adsorbent. Another study done by the American Industrial Hygiene Association indicates that the airborne hexavalent chromium in acidic mists of an electroplating tank collected on PVC filters was reduced over time after mist generation. A number of other emerging technologies for removing chromium from water are also currently under research, including the use of
cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
ic metal-organic frameworks to selectively
adsorb Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a f ...
chromium
oxyanions An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determine ...
. ''
Thermus ''Thermus'' is a genus of thermophilic bacteria. It is one of several bacteria belonging to the '' Deinococcota'' phylum. ''Thermus'' species can be distinguished from other genera in the family ''Thermaceae'' as well as all other bacteria by ...
scotoductus'', an extremophile living in hot water as well as inhabiting domestic water heaters (per study), are capable of reducing Cr(VI). Experiments with activated sludge have also shown its ability to reduce Cr(VI) to Cr(III).


Exposure and safety issues

Hexavalent chromium is a constituent of
tobacco smoke Tobacco smoke is a sooty aerosol produced by the incomplete combustion of tobacco during the smoking of cigarettes and other tobacco products. Temperatures in burning cigarettes range from about 400 °C between puffs to about 900 °C d ...
.


Australia


Kooragang Island, New South Wales

Hexavalent chromium was released from the Newcastle Orica Koorgang Island
ammonium nitrate Ammonium nitrate is a chemical compound with the chemical formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is ...
plant on August 8, 2011. The incident occurred when the plant entered the 'start up' phase after the completion of a five-yearly maintenance overhaul. The "High Temperature Shift catalyst began the process of 'reduction'" where steam passes through the catalyst bed and out the SP8 vent stack. At this time lower temperatures in parts of the plant caused some of the steam to condense lower which caused chromium(VI) from the catalyst bed to dissolve into the liquid present. The amount of condensate overwhelmed the drainage arrangements resulting in the emission of condensate through the SP8 vent stack. The leak went undetected for 30-minutes releasing 200 kg of chromium(VI) into the atmosphere exposing up to 20 workers at the plant and 70 nearby homes in Stockton. The town was not notified of the exposure until three days later on the Wednesday morning, and sparked a major public controversy, with Orica criticized for playing down the extent and possible risks of the leak. The office of Environment and Heritage in Stockton collected 71 samples. Low levels of chromium were detected in 11 of them. These 11 samples were taken within six residential blocks close to the Orica plant, two of which were from water samples collected immediately south of the six block area. The Select Committee on the Kooragnang Island Orica Chemical Leak released their report on the incident in February 2012. They found Orica's approach to addressing the leak's impact was grossly inadequate. Orica failed to realize the potential impact that
prevailing winds In meteorology, prevailing wind in a region of the Earth's surface is a surface wind that blows predominantly from a particular direction. The dominant winds are the trends in direction of wind with the highest speed over a particular point on ...
would have on an emission 60 meters high. Orica failed to inspect the area immediately downwind and notify the Office of Environment and Heritage until August 9, 2011. In Orica's initial report to the Office of Environment and Heritage they failed to disclose that the emissions had escaped off-site. In the initial report to WorkCover Orica did not disclose potential impacts on workers as well as that the substance emitted was chromium(VI). Orica's Emergency Response plan was not well understood by employees particularly about notification procedures. The original notification of residents in Stockton was only to households immediately downwind of the emission which failed to realize the potential for contamination of the surrounding area as well. The information presented at the original notification downplayed potential health risks and subsequently provided incomplete information and has led to a lack of trust between Stockton residents and Orica officials. In 2014, Orica plead guilty to nine charges before the Land and Environment court and was fined $768,000. NSW Health findings ruled that it is very unlikely that anyone in Stockton would later develop cancer as a result of the incident.


Bangladesh

Toxic poultry feed contaminated by chromium-based
leather Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and hog ...
tanning waste products (as opposed to the non-toxic process of vegetable tanned leather) has been shown to have entered the food supply in
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mo ...
through chicken meat, the most common source of protein in the country. Tanneries in
Hazaribagh Thana Hazaribagh ( bn, হাজারীবাগ) is a Thana of Dhaka District in the Division of Dhaka, Bangladesh. Hazaribagh is part of Old Town, Dhaka, Bangladesh. 95% of Bangladesh's tanneries, which is where animal skins are processed to make l ...
, an industrial neighborhood of
Dhaka Dhaka ( or ; bn, ঢাকা, Ḍhākā, ), List of renamed places in Bangladesh, formerly known as Dacca, is the Capital city, capital and List of cities and towns in Bangladesh, largest city of Bangladesh, as well as the world's largest ...
, emit around of toxic waste each day, and generate as much as per day of scraps, trimmed raw hide, flesh and fat, which are processed into feed by neighborhood recycling plants and used in chicken and fish farms across the country. Chromium levels ranging from per kilogram were found in different organs of chickens which had been fed the tannery-scraps feed for two months, according to Abul Hossain, a chemistry professor at the
University of Dhaka The University of Dhaka (also known as Dhaka University, or DU) is a public research university located in Dhaka, Bangladesh. It is the oldest university in Bangladesh. The university opened its doors to students on July 1st 1921. Currently i ...
. The study estimated up to 25% of the chickens in Bangladesh contained harmful levels of chromium(VI).


Greece


Eastern Central Greece

The chemistry of the groundwater in eastern
Central Greece Continental Greece ( el, Στερεά Ελλάδα, Stereá Elláda; formerly , ''Chérsos Ellás''), colloquially known as Roúmeli (Ρούμελη), is a traditional geographic region of Greece. In English, the area is usually called Central ...
(central
Euboea Evia (, ; el, Εύβοια ; grc, Εὔβοια ) or Euboia (, ) is the second-largest Greek island in area and population, after Crete. It is separated from Boeotia in mainland Greece by the narrow Euripus Strait (only at its narrowest poi ...
and the
Asopos Asopos ( el, Ασωπός; also Latinised as Asopus) is a village and a former municipality in Laconia, Peloponnese, Greece. Since the 2011 local government reform it is part of the municipality Monemvasia Monemvasia ( el, Μονεμβασιά, ...
valley) revealed high concentrations of hexavalent chromium in groundwater systems sometimes exceeding the Greek and the EU drinking water maximum acceptable level for total chromium. Hexavalent chromium pollution in Greece is associated with industrial waste. By using the GFAAS for total chromium, diphenylcarbazide-Cr(VI) complex colorimetric method for hexavalent chromium, and flame-AAS and
ICP-MS Inductively coupled plasma mass spectrometry (ICP-MS) is a type of mass spectrometry that uses an inductively coupled plasma to ionize the sample. It atomizes the sample and creates atomic and small polyatomic ions, which are then detected. It is ...
for other toxic elements, their concentrations were investigated in several groundwater samples. The contamination of water by hexavalent chromium in central Euboea is mainly linked to natural processes, but there are anthropogenic cases.


Thebes–Tanagra–Malakasa (Asopos) basin

In the Thebes
Tanagra Tanagra ( el, Τανάγρα) is a town and a municipality north of Athens in Boeotia, Greece. The seat of the municipality is the town Schimatari. It is not far from Thebes, and it was noted in antiquity for the figurines named after it. The T ...
Malakasa basin of Eastern
Central Greece Continental Greece ( el, Στερεά Ελλάδα, Stereá Elláda; formerly , ''Chérsos Ellás''), colloquially known as Roúmeli (Ρούμελη), is a traditional geographic region of Greece. In English, the area is usually called Central ...
, an area that supports many industrial activities, concentrations of chromium (up to Cr(VI)) and Inofyta (up to Cr(VI) were found in the urban water supply of
Oropos Oropos ( el, Ωρωπός) is a small town and a municipality in East Attica, Greece. The village of Skala Oropou, within the bounds of the municipality, was the site an important ancient Greek city, Oropus, and the famous nearby sanctuary of ...
). Chromium(VI) concentrations ranging from Cr(VI) were found in groundwater that is used for
Thiva Thebes (; ell, Θήβα, ''Thíva'' ; grc, Θῆβαι, ''Thêbai'' .) is a city in Boeotia, Central Greece. It played an important role in Greek myths, as the site of the stories of Cadmus, Oedipus, Dionysus, Heracles and others. Archaeologi ...
's water supply.
Arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, b ...
concentrations up to along with chromium(VI) levels up to were detected in
Schimatari Schimatari ( el, Σχηματάρι) is a town and a former municipality in Boeotia, Greece. Since the 2011 local government reform it is part of the municipality Tanagra, of which it is the seat and a municipal unit. The municipal unit has an area ...
's water supply. In the Asopos River, total chromium values were up to , hexavalent chromium was less than , with other toxic elements relatively low.


Iraq

In 2008, defense contractor
KBR KBR can stand for: * KBR (company), formerly Kellogg, Brown & Root, US * KBR (news agency), an Indonesian radio news agency * KBR Park, Hyderabad, India * Kafa language, spoken in Ethiopia * Key-based routing in computer networking * Potassium bro ...
was alleged to have exposed 16 members of the
Indiana National Guard The Indiana National Guard (INNG) is a component of the United States Armed Forces, the United States National Guard and the Military Department of Indiana (MDI). It consists of the Indiana Army National Guard, the Indiana Air National Guard, ...
, as well as its own workers, to hexavalent chromium at the Qarmat Ali water treatment facility in
Iraq Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, translit=Komarî Êraq is a country in Western Asia. It is bordered by Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq ...
in 2003. Later, 433 members of the Oregon National Guard's 162nd Infantry Battalion were informed of possible exposure to hexavalent chromium while escorting KBR contractors. One of the National Guard soldiers, David Moore, died in February 2008. The cause was lung disease at age 42. His death was ruled service-related. His brother believes it was hexavalent chromium. On November 2, 2012, a
Portland, Oregon Portland (, ) is a port city in the Pacific Northwest and the largest city in the U.S. state of Oregon. Situated at the confluence of the Willamette and Columbia rivers, Portland is the county seat of Multnomah County, the most populous ...
jury found KBR negligent in knowingly exposing twelve National Guard soldiers to hexavalent chromium while working at the Qarmat Ali water treatment facility and awarded damages of $85 million to the plaintiffs.


United States


History of the EPA's chromium policies in the United States

Prior to 1970, the federal government had limited reach in monitoring and enforcing environmental regulations. Local governments were tasked with environmental monitoring and regulations, such as the monitoring of heavy metals in wastewater. Examples of this can be seen in larger municipalities, such as:
Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = List of sovereign states, Count ...
,
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world ...
, and
New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...
. A specific example was in 1969, when the Chicago Metropolitan Sanitary District imposed regulations on factories that were identified as having large amounts of heavy metal discharge. On December 2, 1970, the
Environmental Protection Agency A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale ...
(EPA) was formed. With the formation of the EPA, the federal government had the funds and the oversight to influence major environmental changes. Following the formation of the EPA, the United States saw groundbreaking legislations, such as the
Clean Water Act The Clean Water Act (CWA) is the primary federal law in the United States governing water pollution. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters; recognizing the responsibiliti ...
(1972) and the
Safe Drinking Water Act The Safe Drinking Water Act (SDWA) is the principal federal law in the United States intended to ensure safe drinking water for the public. Pursuant to the act, the Environmental Protection Agency (EPA) is required to set standards for drinking wa ...
(1974). The
Federal Water Pollution Control Act Federal or foederal (archaic) may refer to: Politics General *Federal monarchy, a federation of monarchies *Federation, or ''Federal state'' (federal system), a type of government characterized by both a central (federal) government and states or ...
(FWPCA) of 1948 was amended in 1972 to what is more commonly known as the
Clean Water Act The Clean Water Act (CWA) is the primary federal law in the United States governing water pollution. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters; recognizing the responsibiliti ...
(CWA). The subsequent amendments provided a basis for the federal government to begin regulating pollutants, implementing wastewater standards, and increasing funding for water treatment facilities among other things. Two years later in 1974, the
Safe Drinking Water Act The Safe Drinking Water Act (SDWA) is the principal federal law in the United States intended to ensure safe drinking water for the public. Pursuant to the act, the Environmental Protection Agency (EPA) is required to set standards for drinking wa ...
(SDWA) was passed by congress. The SDWA aimed to monitor and protect the United States' drinking water, and the water sources it is drawn from. In 1991, as part of the SDWA, the EPA placed chromium under its list of maximum contaminant level goals (MCLG), to have a maximum contaminant level (MCL) of 100 ppb. In 1996, the SDWA was amended to include a provision known as the Unregulated Contaminant Monitoring Rule (UCMR). Under this rule, the EPA issues a list of 30 or less contaminants that are not normally regulated under the SDWA. Chromium was monitored under the third UCMR, from January 2013 through December 2015. The EPA uses data from these reports to assist in making regulatory decisions.


Current policies in the United States

The current EPA standard in measuring chromium is in reference to total chromium, both trivalent and hexavalent. Often, trivalent and hexavalent chromium are mentioned together, when in fact, each possess vastly different properties. At the risk of impacting public health, distinctions between the two chromiums must be clearly made in any publication containing information about chromium. These delineations are critical, as hexavalent chromium is carcinogenic, whereas trivalent chromium is not. In 1991, the MCL for chromium exposure was set based on potential of "adverse dermatological effects" related to long-term chromium exposure. Chromium's MCL of 100 ppb has not changed since its 1991 recommendation. In 1998, the EPA released a toxicological review of hexavalent chromium. This report examined current literature, at the time, and came to the conclusion that chromium was associated with various health issues. , "no federal or state laws restrict the carcinogen's presence in drinking water," according to the
Natural Resources Defense Council The Natural Resources Defense Council (NRDC) is a United States-based 501(c)(3) non-profit international environmental advocacy group, with its headquarters in New York City and offices in Washington D.C., San Francisco, Los Angeles, Chicago, Bo ...
(NRDC). In December 2013, the NRDC won a lawsuit against the
California Department of Public Health The California Department of Public Health (CDPH) is the state department responsible for public health in California. It is a subdivision of the California Health and Human Services Agency. It enforces some of the laws in the California Health ...
, and the state was required to issue a standard on the maximum contaminant level (MCL) for chromium by "no later than June 15, 2014." The MCL was added to the California Code of Regulations but, in 2017, another court ruled that the standard must be eliminated because the California Department of Public Health had not proven that the standard was economically feasible. Before the EPA can adjust the policy on chromium levels in drinking water, they have to release a final human health assessment. The EPA mentions two specific documents that are currently under review to determine whether or not to adjust the current drinking water standard for chromium. The first study the EPA mentioned that is under review is a 2008 study conducted by the Department of Health and Human Services National Toxicology Program. This study looks at chronic oral exposure of hexavalent chromium in rats, and its association with cancer. The other study mentioned is a human health assessment of chromium, titled ''Toxicological Review of Hexavalent Chromium''. The final human health assessment is currently in the stage of draft development. This stage is the first of seven. The EPA gives no forecast to when the review will be finalized, and if a decision will be made.


Military applications

Since
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
, the
United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, ...
relied on hexavalent chromium compounds to protect its vehicles, equipment, aviation and missile systems from corrosion. The wash primer was sprayed as a pretreatment and protective layer on bare metal. From 2012 to 2015,
Army Research Laboratory The U.S. Army Combat Capabilities Development Command Army Research Laboratory (DEVCOM ARL) is the U.S. Army's foundational research laboratory. ARL is headquartered at the Adelphi Laboratory Center (ALC) in Adelphi, Maryland. Its largest sing ...
conducted research on a wash primer replacement, as a part of the DoD's effort to eliminate the use of toxic wash primers in the military. Studies indicated that the wash primers contained hazardous air pollutants, and high levels of volatile organic compounds. The project resulted in the ARL qualifying three wash primer alternatives in 2015 for use on Army depots, installations, and repair facilities. The research led to the removal of chromate products from Army facilities in 2017. For their efforts on the wash primer replacement, the ARL researchers won the
Secretary of the Army The secretary of the Army (SA or SECARMY) is a senior civilian official within the United States Department of Defense, with statutory responsibility for all matters relating to the United States Army: manpower, personnel, reserve affairs, insta ...
's "Award for Environmental Excellence in Weapon System Acquisition" for the 2016 fiscal year.


Pending regulations in the United States

The EPA currently limits total chromium in drinking water to 100 parts per billion, but there is no established limit specifically for chromium(VI). The
Office of Environmental Health Hazard Assessment The Office of Environmental Health Hazard Assessment, commonly referred to as OEHHA (pronounced oh-EEE-ha), is a specialized department within the cabinet-level California Environmental Protection Agency ( CalEPA) with responsibility for evaluatin ...
(OEHHA) the
California Environmental Protection Agency The California Environmental Protection Agency, or CalEPA, is a state cabinet-level agency within the government of California. The mission of CalEPA is to restore, protect and enhance the environment, to ensure public health, environmental qu ...
proposed a goal of 0.2 parts per billion in its technical support draft in 2009, despite a 2001 state law requiring a standard be set by 2005. A final Public Health Goal of 0.02 ppb was published in the technical support document in July 2011.


California


= Davenport

= Monterey Bay Unified Air Pollution Control District monitored airborne levels of hexavalent chromium at an elementary school and fire department, as well as the point-source. They concluded that there were high levels of hexavalent chromium in the air, originating from a local cement plant, called
Cemex CEMEX S.A.B. de C.V., known as Cemex, is a Mexican multinational building materials company headquartered in San Pedro, near Monterrey, Mexico. It manufactures and distributes cement, ready-mix concrete and aggregates in more than 50 countries ...
.Health Services Agency. (2008, Nov. 18). ''Air Quality Issues in the Town of Davenport''. Retrieved from: The levels of hexavalent chromium were 8 to 10 times higher than the air district's acceptable level at Pacific Elementary School and the Davenport Fire Department. The
County of Santa Cruz Santa Cruz County (), officially the County of Santa Cruz, is a county on the Pacific coast of the U.S. state of California. As of the 2020 census, the population was 270,861. The county seat is Santa Cruz. Santa Cruz County comprises the Sa ...
sought help of the Health Services Agency (HSA) to investigate the findings of the Air District's report. Cemex voluntarily ceased operations due to the growing concern within the community, while additional air samples were analyzed. The HSA worked with Cemex to implement engineering controls, such as dust scavenging systems and other dust mitigation procedures. Cemex also made a change in the materials they used, trying to replace current materials with materials lower in chromium. The HSA also monitored the surrounding schools to determine if there were any health risks. Most schools came back with low levels, but in the case of higher levels a contractor was hired to clean up the chromium deposits. This case highlights the previously unrecognized possibility that hexavalent chromium can be released from cement-making.


= Paramount

= In 2016, air quality officials began investigating elevated levels of hexavalent chromium in Paramount, California. The city of Paramount created an action project that included more code enforcement to aid AQMD inspectors and the launch of ParamountEnvironment.org to keep the public informed. Over time, efforts by SCAQMD and the city of Paramount have been effective lowering emissions to acceptable levels.


= Hinkley

= Hexavalent chromium was found in drinking water in the southern California town of Hinkley and was brought to popular attention by the involvement of
Erin Brockovich Erin Brockovich (née Pattee; born June 22, 1960) is an American legal clerk, consumer advocate, and environmental activist who, despite her lack of education in the law, was instrumental in building a case against Pacific Gas & Electric Compan ...
and Attorney
Edward Masry Edward Louis Masry (July 29, 1932 – December 5, 2005) was an American lawyer, a partner in the law firm of Masry & Vititoe and also a mayor and city councilman for the City of Thousand Oaks, California. With the help of his legal assistant Erin ...
. The source of contamination was from the evaporating ponds of a PG&E (
Pacific Gas and Electric The Pacific Gas and Electric Company (PG&E) is an American investor-owned utility (IOU). The company is headquartered in the Pacific Gas & Electric Building, in San Francisco, California. PG&E provides natural gas and electricity to 5.2 milli ...
) natural gas pipeline compressor station about 2 miles southeast of Hinkley. Between 1952 and 1966, chromium(VI) was used to prevent corrosion in the cooling stacks. The wastewater was dumped into the unlined evaporating ponds, and the chromium(VI) leaked into the groundwater. The 580 ppb chromium(VI) in the groundwater in Hinkley exceeded the 100-ppb total chromium maximum contaminant level (MCL) set by the
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...
(EPA). It also exceeded the California MCL of 50 ppb () for all types of chromium. California first established an MCL specifically for hexavalent chromium in 2014, set at 10 ppb; prior to that only total chromium standards applied. A later study found that from 1996 to 2008, 196 cancers were identified among residents of the census tract that included Hinkley—a slightly lower number than the 224 cancers that would have been expected given its demographic characteristics. This finding conflicted with the conclusions reached by the EPA and California's Department of Public Health that chromium(VI) does in fact cause cancer, as explained in a 2013
Center for Public Integrity The Center for Public Integrity (CPI) is an American nonprofit investigative journalism organization whose stated mission is "to reveal abuses of power, corruption and dereliction of duty by powerful public and private institutions in order to ...
article published in ''Mother Jones'', critically evaluating that and other studies by researcher John Morgan. When a PG&E background study of chromium(VI) was conducted, average chromium(VI) levels in Hinkley were recorded as 1.19 ppb with a peak of 3.09 ppb. PG&E's Topock compressor station averaged 7.8 ppb and peaked at 31.8 ppb. The California MCL standard was still 50 ppb at the completion of this background study. The
Office of Environmental Health Hazard Assessment The Office of Environmental Health Hazard Assessment, commonly referred to as OEHHA (pronounced oh-EEE-ha), is a specialized department within the cabinet-level California Environmental Protection Agency ( CalEPA) with responsibility for evaluatin ...
(OEHHA) of the California EPA proposed in 2009 a health goal of 0.06 ppb of chromium(VI) in drinking water. In 2010, Brockovich returned to Hinkley in the midst of claims that the plume was spreading despite PG&E's cleanup activities. PG&E continues to provide bottled water for Hinkley residents, as well as offering to buy their homes. All other ongoing cleanup documentation is maintained at California EPA's page.


Illinois

In
Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = List of sovereign states, Count ...
's first ever testing for the toxic metal contaminant, results show that the city's local drinking water contains levels of hexavalent chromium more than 11 times higher than the health standard set in California in July 2011. The results of the test showed that the water which is sent to over 7 million residents had average levels of 0.23 ppb of the toxic metal. California's Office of Environmental Health Hazard Assessment designated the nation's new "public health goal" limit as 0.02 ppb. Echoing their counterparts in other cities where the metal has been detected, Chicago officials stress that local tap water is safe and suggest that if a national limit is adopted, it likely would be less stringent than California's goal. The
Illinois Environmental Protection Agency The Illinois Environmental Protection Agency (Illinois EPA) of the state of Illinois is the primary body concerned with the protection of the environment for the state. The Illinois EPA's mission is "to safeguard environmental quality, consistent ...
(Illinois EPA) has developed a chromium(VI) strategic plan which outlines tasks in order to reduce the levels of chromium(VI) in Illinois' drinking water. One of which is to work with the U.S. EPA to provide significant technical assistance to the City of Chicago to ensure they quickly develop an effective chromium(VI) specific monitoring program that makes use of the U.S. EPA-approved methods.


Massachusetts

Cambridge Plating Company, now known as Purecoat North, was an electroplating business in
Belmont, Massachusetts Belmont is a town in Middlesex County, Massachusetts. It is a western suburb of Boston, Massachusetts, United States; and is part of the Greater Boston metropolitan area. At the time of the 2020 U.S. Census, the town's population stood at 27,29 ...
. A report was conducted by the
Agency for Toxic Substances and Disease Registry The Agency for Toxic Substances and Disease Registry (ATSDR) is a federal public health agency within the United States Department of Health and Human Services. The agency focuses on minimizing human health risks associated with exposure to haz ...
(ATSDR), to evaluate the association between environmental exposures from the Cambridge Plating Company and health effects on the surrounding community. The report indicated that residents of Belmont were exposed to chromium via air emissions, as well as groundwater and soil.Agency for Toxic Substances and Disease Registry, Public Health Assessment for Cambridge Plating Company. (2007, Dec. 17). ''Evaluation of Environmental Concerns and Cancer Incidence in Belmont and Surrounding Communities.'' Retrieved from However, six types of cancer were evaluated, and the incidence was actually found to be average, in most cases, across all types, if not a little bit lower than average. For example, in kidney cancer the number of observed cases was 7 versus an expected 16. While that was the case for most diseases, it was not for all. The incidence of leukemia among females was elevated in Belmont, MA during 1982–1999 (32 diagnoses observed vs. 23.2 expected). Elevations in females were due to four excess cases in each time period (11 diagnoses observed vs. 6.9 expected during 1988–1993; 13 diagnoses observed vs. 8.7 expected during 1994–1999) while elevations among males were based on one to three excess cases. ATSDR deemed Cambridge Plating as an Indeterminate Public Health Hazard in the past, but No Apparent Public Health Hazard in the present or future.


Missouri

In 2009, a lawsuit was filed against Prime Tanning Corporation of St. Joseph, Missouri, over alleged hexavalent chromium contamination in
Cameron, Missouri Cameron is a city in Clinton, DeKalb and Caldwell counties in the U.S. state of Missouri. The population was 8,513 at the 2020 census. The Clinton and Caldwell counties portion of Cameron are part of the Kansas City, MO– KS Metropolitan ...
. A cluster of brain tumors had developed in the town that was above average for the population size of the town. The lawsuit alleges that the tumors were caused by waste hexavalent chromium that had been distributed to local farmers as free fertilizer. In 2010 a government study found hexavalent chromium within the soil but not at levels that were hazardous to human health. In 2012, the case ruled that $10 million would be distributed to over a dozen farmers affected in the northwest Missouri area. The Tanning Corporation still denies that their fertilizer caused any harm. Some residents claim that the tumors were a direct cause from the chromium exposure, but it is difficult to determine what other future impacts might arise from exposure in the specific Missouri counties.


Michigan

On December 20, 2019, a green substance leaking onto
I-696 Interstate 696 (I-696) is an east–west List of auxiliary Interstate Highways, auxiliary Interstate Highway in the Metro Detroit region of the US state of Michigan. The Michigan State Trunkline Highway System, state trunkline highway is als ...
, in Madison Heights, was identified as hexavalent chromium that had leaked from a basement of a local company, Electro-Plating Services. In July 2022, an employee at the automotive supply company Tribar Technologies overrode alarms, leading to the release of hexavalent chromium into the Wixom wastewater system. The state of Michigan issued a no-contact order with Huron River water near the spill, but this order was lifted after revised estimates concluded that less than 20 pounds of chromium had reached the river.


Texas

On April 8, 2009, the
Texas Commission on Environmental Quality The Texas Commission on Environmental Quality (TCEQ) is the environmental agency for the state of Texas. The commission's headquarters are located at 12100 Park 35 Circle in Austin. The fourth largest environmental agency in the United States (an ...
(TCEQ) collected ground water samples from a domestic well on West County Road 112 in
Midland, Texas Midland is a city in and the county seat of Midland County, Texas, United States. A small part of Midland is in Martin County. At the 2020 census, Midland's population was 132,524. It is the principal city of the Midland, Texas metropolitan ...
(U.S.), in response to a resident complaint of yellow water. The well was found to be contaminated with chromium(VI). The Midland groundwater reached higher levels of contamination than the EPA mandated maximum contaminant level (MCL) of 100 parts per billion. The current groundwater plume of chromium lies under approximately 260 acres of land at the West County Road 112 Groundwater Site. In response, the TCEQ installed filtration systems on water-well sites that showed contamination of chromium. , TCEQ had sampled water from 235 wells and has installed over 45 anion-exchange filtration systems from this site determined to be centered at 2601 West County Road 112, Midland, Texas. The TCEQ continues to sample wells surrounding the area to monitor the movement of the plume. In addition, they continue to monitor the effectiveness of the anion-exchange filtration systems by sampling on a year-quarterly and the filters are maintained at no cost to the residents. , the West County Road 112 Ground Water site was added to the
National Priorities List The National Priorities List (NPL) is the priority list of hazardous waste sites in the United States eligible for long-term remedial investigation and remedial action (cleanup) financed under the federal Superfund program. Environmental Protec ...
(NPL) also known as the Superfund List by the U.S. Environmental Protection Agency (EPA). From 2011 to 2013, TCEQ installed groundwater monitors and conducted groundwater sampling. In 2013, TCEQ began sampling residential soil and confirmed that it was contaminated from use of the contaminated groundwater for garden and lawn care. According to the EPA, ongoing investigations have not concluded the source of the contamination and cleanup solutions are still being developed. Until such investigations are complete and remediation established, residents will continue to be at risk for health effects from exposure to the groundwater contamination.


Wisconsin

On January 7, 2011 it was announced that
Milwaukee Milwaukee ( ), officially the City of Milwaukee, is both the most populous and most densely populated city in the U.S. state of Wisconsin and the county seat of Milwaukee County. With a population of 577,222 at the 2020 census, Milwaukee i ...
, Wisconsin had tested its water and hexavalent chromium was found to be present. Officials stated that it was in such small quantities that it was nothing to worry about, although this contaminant is a carcinogen. In Wisconsin, Milwaukee's average chromium(VI) level is 0.194 parts per billion (the EPA recommended maximum contaminant level (MCL) is 100 ppb). All 13 water systems tested positive for chromium(VI). Four out of seven systems detected the chemical in
Waukesha County Waukesha County () is a county in the U.S. state of Wisconsin. As of the 2020 United States Census, the population was 406,978, making it the third-most populous county in Wisconsin. Its county seat and largest city is Waukesha. Waukesha Co ...
, and both
Racine Jean-Baptiste Racine ( , ) (; 22 December 163921 April 1699) was a French dramatist, one of the three great playwrights of 17th-century France, along with Molière and Corneille as well as an important literary figure in the Western traditi ...
and Kenosha Counties had the highest levels averaging more than 0.2 parts per billion. Further testing was being conducted .City defends water safety
''Milwaukee Wisconsin Journal Sentinel'', January 7, 2011
There was no further information available .


See also

*
California Proposition 65 (1986) Proposition 65 (formally titled The Safe Drinking Water and Toxic Enforcement Act of 1986, and also referred to as Prop 65) is a California law passed by direct voter initiative in 1986 by a 63%–37% vote. Its goals are to protect drinking water s ...


References


External links


ATSDR Case Studies in Environmental Medicine: Chromium Toxicity
U.S.
Department of Health and Human Services The United States Department of Health and Human Services (HHS) is a cabinet-level executive branch department of the U.S. federal government created to protect the health of all Americans and providing essential human services. Its motto is ...

Hexavalent Chromium National Emphasis Program
*
3M US: OSHA Hexavalent Chromium Standard – An overview of the Chromium Six (CrVI) standard
*

* ttp://www.osha.gov/SLTC/hexavalentchromium/index.html US OSHA Health and Safety Topics: Hexavalent Chromium"
National Institute for Occupational Safety and Health – Hexavalent Chromium
* {{Chromium compounds Chromium compounds Chromium(VI) compounds Element toxicology IARC Group 1 carcinogens Occupational safety and health