Table of Contents
Background
Copper (Cu) is a naturally occurring element found in a variety of forms in the environment and is an essential plant and animal nutrient. However, it can be toxic when consumed at high concentrations. Both natural and anthropogenic sources account for Cu spread in the environment. Natural sources of Cu mainly include weathering of Cu-containing minerals while anthropogenic sources comprise industrial activities such as mining, smelting, manufacturing, and the use of Cu-based pesticides in agriculture. Air, water, and soil are the main media that contribute to Cu spread in the environment and ultimately have adverse impacts on aquatic life, terrestrial plants, animals, and human health. Cu can contaminate drinking water in a variety of ways associated with human activities. Major sources of Copper in drinking water include corrosion of Cu pipes in the plumbing system, agricultural activities, various industrial activities, and Cu fittings and fixtures in the plumbing system. From these sources, Cu can contaminate the underground aquifers and surface water through leaching and runoff processes.
Being a reactive metal, it can also chelate with other organics and inorganics in water to form complex molecules. The reactivity of Cu mainly depends on various chemical factors such as pH and redox potential. Furthermore, studies also demonstrate the co-occurrence of Cu with other metals such as Fe, Pb, As, etc. in drinking water. According to WHO, drinking water must have Cu levels below 2 mg/L as chronic exposure to Cu above this limit may cause various health problems. Moreover, the presence of Cu in water can also discolor it and give a metallic taste making water inappropriate for drinking. Studies suggest that the amount of Cu in drinking water is relatively small concentration. In the US, EPA has set an MCL of 1.3 mg/L for Cu in drinking water. This means the amount of Cu in drinking water should not exceed the prescribed MCL to ensure its safe human consumption. For this, water suppliers in the US are required to regularly monitor Cu levels in drinking water on a regular basis and consumers must be notified in case elevated Cu levels are detected and demand suitable actions by suppliers to reduce the Cu levels below MCL. Moreover, if the consumer also has concerns related to the quality of drinking water, he must contact the local water supplier or EPA for further assistance. It is important to note that elevated Cu levels in drinking water can pose significant public health concerns.
Consumption of elevated Cu through drinking water may cause symptoms including cramps, nausea, and vomiting. It is also suggested that Cu poisoning from drinking water is generally avoidable because of its taste threshold concentrations between 1-2 mg/L. So, any concentration above this range makes water unsuitable to drink because of its metallic odor and unpleasant color. Copper can be more harmful to infants and low-age group children due to their poorly developed immune systems and any education institutions are required by law to perform school water testing for copper. Its high levels can cause infantile cirrhosis, a rare liver disease that can be fatal. Furthermore, liver injury and kidney diseases have also been associated with Cu toxicity.
Importantly, a high concentration of Cu in the body can cause Wilson’s disease which is a rare genetic disorder in which the patient can not properly excrete Cu from the body leading to Cu accumulation in the liver, brain, and other organs. Such accumulation can result in a variety of health implications mainly including liver damage, neurological symptoms, and psychiatric disorders. Apart from its adverse impacts on human health at a high concentration, Cu also possesses beneficial properties for humans at low concentrations and is involved in some key enzymatic reactions. For this, scientists have suggested a daily requirement of 2 mg/L of Cu from different sources for good health. To ensure a Cu-free drinking water supply to the consumers, suitable treatment of water must be performed before its supplied to the US residents.
Scientific evidence supports the beneficial role of Cu when taken in traces. It has been reported that Cu plays a key role in the improved immune system and its deficiency is linked with many key enzymatic and oxidative stress functions (Taheri et al. 2021). Further, it has been suggested that Cu can be helpful in developing immune responses against SARS-CoV-2 (Raha et al. 2020). However, Cu can become toxic when its consumption is for a longer period which results in Cu accumulation in various tissues of the body. This can happen because of underlying genetic defects associated with Cu metabolism, exposure to elevated Cu levels from the environment, or through the use of certain medications.
After getting metabolized, Cu enters the cell and is transported into the mitochondria where it can disrupt enzymatic functions associated with energy production (Rossi et al. 2004; Sun et al. 2022). Further, it has been demonstrated that Cu can interfere with enzyme functions involved in neurotransmitters synthesis and other signaling molecules inside the cell (Grubman and White 2017). The generation of reactive oxygen species causing oxidative stress is also linked with high Cu accumulation in the cell which can damage proteins, lipids, and DNA leading to increased susceptibility to infection (Uriu-Adams and Keen 2005). At the molecular level, Cu can also alter functions of transcription factors resulting in altered gene expression and hence contributing to the disease development (Muller et al. 2007).
In order to prevent copper toxicity, the body has mechanisms in place to tightly regulate copper absorption, transport, and excretion. These include transporters that pump copper out of cells, and metallothioneins, a class of proteins that can bind to and sequester excess copper (Dameron and Harrison 1998; Neyrolles et al. 2015). In humans, once ingested, the absorption of Cu primarily takes place in the small intestine where it is also susceptible to a competitive inhibition from other metals such as Fe and Zn (Potera 2004). Although increased exposure to Cu through drinking water in the US is not a major concern, however, to ensure the safety of public health, regular monitoring and treatment of drinking water should be carried out to keep the Cu levels within the MCL
Detection Methods and Removal Strategies
Copper in drinking water can be detected using various methods based on accuracy, sensitivity, and operating costs. Standard methods describe atomic absorption spectroscopy (AAS) to be a cost-effective and most widely used method for Cu detection in water with high accuracy based on its attached detection system i.e. FAAS/GFAAS. The method is capable of achieving detection limits at mg/L with high accuracy while µg concentrations can also be detected under specialized instrument operating conditions. AAS uses light absorption at a specific wavelength to measure the Cu concentration in a water sample.
For more high sensitivity and detection at very low levels, ICP-MS or ICP-OES are used which utilize high-powered plasma to ionize the Cu in a water sample and measure the resulting concentrations using mass spectrometry. Some other methods are also available that provide estimated levels of Cu in drinking water. These methods include colorimetric methods which use chemical reagents to change the color of the sample in the presence of Cu ions. The intensity of the color is directly proportional to the amount of Cu present in a sample. Further, voltammetry and spectrophotometry are also used for small-scale detection where estimated results are desired.
Any concentration detected above the EPA-prescribed MCL for Cu must be treated using the appropriate method to ensure a safe drinking water supply. The ion exchange method is among the widely used method for Cu removal from drinking water in which a resin bed of ions is used that replaces Cu ions with other metal ions such as Na and zeolite (Siu et al. 2016). Activated carbon filtration is also an effective method for removing Cu from drinking water where water is passed through a bed of activated carbon which absorbs or binds to Cu ions facilitating its removal from drinking water (Kalpakli and Koyuncu 2007).
Reverse osmosis is another widely used method for Cu and other impurities removal from drinking water by using a semipermeable membrane and water is passed through pressure which results in the trapping of Cu present in water (Lin et al. 2014). Moreover, chemical treatment can also be used for Cu removal by adding chemicals that bind to Cu ions and form precipitates that can be removed by filtration. Recently, research is also ongoing on the use of biochar for water purification and initial findings have shown promise for its use in Cu and other heavy metals removal from water. Additionally, biochar can be easily regenerated by heating in the presence of an oxidizing agent, allowing it to be reused multiple times (Trakal et al. 2014). It is always recommended to consult a professional before deciding the best treatment method for your case.
Public Perspective
Following frequently asked questions (FAQs) try to address some general public concerns in the US, especially the NYC region.
The US EPA has determined that copper levels in drinking water should not exceed 1300 µg/L. No adverse health effects would be expected if this level is not exceeded. Measures should be taken to reduce exposure to copper if this level is exceeded.
Copper can be removed up to 97-98% with a reverse osmosis water filter. Cartridges using activated carbon can also remove copper from water by using adsorption.
A high level of copper usually leaves a metallic or unpleasant bitter taste in the drinking water. This water may not be safe to drink and you should contact your drinking water provider or have the water professionally tested.
Boiling water does not eliminate copper. If there is copper in your water, boiling may increase copper levels. If you have copper in the pipes inside your home or if you aren’t sure if you do, consider testing your water.
Symptoms of long-term exposure include Anemia (low red blood cell count), burning sensation, chills, convulsions, dementia, diarrhea, difficulty in speaking, and fever.
Your state certification officer can recommend laboratories that perform water analysis, including tests for copper. Professional testing can be expensive, and it can take a while for you to receive results.
In more severe forms, Cu toxicity can lead to heart and kidney failure and liver damage.
Some treatment options for acute and chronic Cu toxicity include chelation, gastric lavage (stomach pumping), medications, and hemodialysis.
Cu in a small amount is essential for good health. However, exposure to higher doses can be harmful. Long-term exposure to copper dust can irritate your nose, mouth, and eyes, and cause headaches, dizziness, nausea, and diarrhea.
Over time, there is too much Cu for your liver to store, and it can cause liver damage. The extra Cu also can get into your bloodstream and collect in other organs as well as in your eyes and brain, and damage these structures.
Conclusion
Cu is a heavy metal with beneficial properties to humans in traces. Its high concentration in drinking water for long periods can be a public health concern and cause various diseases. USEPA has regulated Cu in drinking water and defined its MCL to ensure a safe drinking water supply to the consumers.
Cu may contaminate drinking water through various natural and anthropogenic sources and once detected above MCL it must be ensured to remove excess Cu from water by using appropriate treatment methods. Epidemiological data on humans is so far limited and there is a need of conducting cross-sectional investigations to explore the extent of Cu toxicity at the population level using cutting-edge technologies.
References
Dameron CT, Harrison MD. 1998. Mechanisms for protection against copper toxicity. The American journal of clinical nutrition. 67(5):1091S-1097S.
Grubman A, White A. 2017. Copper and molecular aspects of cell signaling. Molecular, genetic, and nutritional aspects of major and trace minerals. Elsevier. p. 85-99.
Kalpakli YK, Koyuncu I. 2007. Characterization of activated carbon and application of copper removal from drinking water. Annali di Chimica: Journal of Analytical, Environmental and Cultural Heritage Chemistry. 97(11‐12):1291-1302.
Lin L, Xu X, Papelis C, Cath TY, Xu P. 2014. Sorption of metals and metalloids from reverse osmosis concentrate on drinking water treatment solids. Separation and Purification Technology. 134:37-45.
Muller P, van Bakel H, van de Sluis B, Holstege F, Wijmenga C, Klomp LW. 2007. Gene expression profiling of liver cells after copper overload in vivo and in vitro reveals new copper-regulated genes. JBIC Journal of Biological Inorganic Chemistry. 12(4):495-507.
Neyrolles O, Wolschendorf F, Mitra A, Niederweis M. 2015. Mycobacteria, metals, and the macrophage. Immunological reviews. 264(1):249-263.
Potera C. 2004. Copper in drinking water: Using symptoms of exposure to define safety. National Institue of Environmental Health Sciences.
Raha S, Mallick R, Basak S, Duttaroy AK. 2020. Is copper beneficial for covid-19 patients? Medical hypotheses. 142:109814.
Rossi L, Lombardo MF, Ciriolo MR, Rotilio G. 2004. Mitochondrial dysfunction in neurodegenerative diseases associated with copper imbalance. Neurochemical research. 29(3):493-504.
Siu P, Koong LF, Saleem J, Barford J, McKay G. 2016. Equilibrium and kinetics of copper ions removal from wastewater by ion exchange. Chinese Journal of Chemical Engineering. 24(1):94-100.
Sun Q, Li Y, Shi L, Hussain R, Mehmood K, Tang Z, Zhang H. 2022. Heavy metals induced mitochondrial dysfunction in animals: Molecular mechanism of toxicity. Toxicology.153136.
Taheri S, Asadi S, Nilashi M, Abumalloh RA, Ghabban NM, Yusuf SYM, Supriyanto E, Samad S. 2021. A literature review on beneficial role of vitamins and trace elements: Evidence from published clinical studies. Journal of Trace Elements in Medicine and Biology. 67:126789.
Trakal L, Šigut R, Šillerová H, Faturíková D, Komárek M. 2014. Copper removal from aqueous solution using biochar: Effect of chemical activation. Arabian Journal of Chemistry. 7(1):43-52.
Uriu-Adams JY, Keen CL. 2005. Copper, oxidative stress, and human health. Molecular aspects of medicine. 26(4-5):268-298.
- Yasir A. Rehman, Ph.D.
Dr. Rehman was born in Rawalpindi, Pakistan. He completed his MSc from PMAS – Arid Agriculture University Rawalpindi in 2011 where his thesis comprised a health risk assessment of subjects living in the vicinity of wastewater channels in urban settings and its relationship with the incidence of Malaria.
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OTHER RESEARCH ON WATER CONTAMINANTS BY DR. YASIR
