Cadmium in water: origin, health risks, regulations, and filtration
Cadmium is a toxic metal naturally present in low concentrations in the Earth's crust. Mining, metallurgical, and industrial activities, the manufacturing and disposal of batteries, and certain phosphate fertilizers can increase its presence in the environment. In drinking water, it can come from contaminated sources, industrial discharge, or the corrosion of certain metallic materials. Prolonged exposure can, in particular, damage the kidneys and affect the skeletal system.
- Chemical symbol
- Cd
- Atomic number
- 48
- Family
- Toxic metal
- EU Value
- 5 µg/L
What is cadmium?
Cadmium is a chemical element with the symbol Cd and atomic number 48. It is a metal naturally found in certain ores, particularly those containing zinc, lead, or copper.
Cadmium is rarely mined for itself. It is generally obtained as a byproduct of the refining of other metals. It has no known biological function in humans and can gradually accumulate in the body.
Keep in mind: diet and smoking are often significant sources of exposure to cadmium. Drinking water can nevertheless contribute to exposure when a source or an installation is contaminated.
What is cadmium used for?
Cadmium has been used in various industrial applications due to its anti-corrosion properties, stability, and electrochemical characteristics.
- Nickel-cadmium rechargeable batteries;
- Anti-corrosion coatings and metal surface treatments;
- Pigments used in certain plastics, paints, and ceramics;
- Metal alloys and certain solders;
- Electrical and electronic components;
- Certain photovoltaic cells, particularly those using cadmium telluride;
- Former stabilizers incorporated into certain plastics.
Many uses have been limited in Europe due to the toxicity of cadmium and its persistence in the environment. However, it remains present in some equipment, industrial waste, and older devices.
How does cadmium get into water?
Erosion of rocks and soils
Cadmium can be released naturally through the weathering of rocks and ores. Natural concentrations are generally low, but they can be higher in certain geological contexts.
Mining and metallurgical activities
The extraction, crushing, and refining of ores containing zinc, lead, or copper can produce residues loaded with cadmium. Drainage water or poorly managed discharge can then contaminate soils, rivers, and groundwater.
Industry and waste management
Surface treatment facilities, battery manufacturing, electronic waste, pigments, and certain metallurgical industries can release cadmium into the environment.
Phosphate fertilizers
Certain phosphate ores naturally contain cadmium. Their prolonged use as fertilizer can contribute to its accumulation in agricultural soils, and subsequently to its transfer to plants, surface water, or groundwater.
Corrosion of certain materials
In some installations, cadmium can come from the corrosion of galvanized pipes, solders, fittings, or metallic components containing cadmium impurities.
How does cadmium behave in water and soils?
The behavior of cadmium depends in particular on pH, water hardness, the presence of organic matter, carbonates, sulfides, and suspended particles.
In acidic or low-mineral water, cadmium can be more mobile and more present in dissolved form. Under other conditions, it can bind to clays, metal oxides, or organic matter.
The total presence of cadmium does not always allow for the determination of the proportion actually dissolved. This distinction can influence the choice of analytical method and treatment process.
What are the health risks of cadmium?
Cadmium absorbed by the body is eliminated very slowly. It can accumulate, mainly in the kidneys and the liver. Health effects depend on the dose, the duration of exposure, and the route of exposure.
Renal damage
The kidney is considered an organ particularly sensitive to chronic exposure to cadmium. Prolonged accumulation can damage the renal tubules and disrupt the reabsorption of certain proteins and essential substances.
Effects on bones
Cadmium can contribute to bone fragility, particularly through its effects on the kidneys, calcium metabolism, and bone mineralization. Consequences can include decreased bone mineral density and an increased risk of fractures.
Respiratory effects
Respiratory effects are mainly associated with the inhalation of dust or fumes containing cadmium in certain professional or industrial contexts.
Carcinogenicity
Cadmium and its compounds are recognized as carcinogenic to humans, mainly on the basis of studies concerning inhalation exposure. This classification does not mean that every trace in water automatically leads to cancer: the risk depends on the level and duration of exposure.
Chronic exposure can remain silent for a long period. The absence of taste, odor, or immediate symptoms therefore does not rule out exposure.
What are the effects of cadmium on the environment?
Cadmium is a persistent element: it does not degrade in the environment. It can accumulate in soils, sediments, plants, and certain organisms.
In aquatic environments, its toxicity varies depending on water hardness, pH, and the chemical form of the metal. It can affect the growth, reproduction, and survival of fish, invertebrates, and other aquatic organisms.
The accumulation of cadmium in agricultural soils is also a concern, as some plants can absorb it and subsequently contribute to human exposure through food.
What is the limit for cadmium in drinking water?
The European Union sets a parametric value of 5 micrograms per liter for cadmium in water intended for human consumption.
| Reference | Value | Nature of the value |
|---|---|---|
| European Union | 5 µg/L | Parametric value set by the European Directive on water intended for human consumption. |
| World Health Organization | 3 µg/L | Guideline value established to limit chronic exposure, particularly due to renal effects. |
| United States – EPA | 5 µg/L | Regulatory maximum concentration of 0.005 mg/L in relevant public networks. |
A value of 5 µg/L corresponds to 0.005 mg/L and approximately 5 ppb in water.
The values from the WHO, the European Union, and the EPA do not have the exact same legal status. The European value is a regulatory value applicable in the Union, while the WHO value is an international health recommendation.
How can I tell if water contains cadmium?
Dissolved cadmium generally cannot be identified by taste, odor, or color. A laboratory analysis is required to measure its concentration.
Depending on the context, the analysis may focus on:
- total cadmium;
- dissolved cadmium after filtration of the sample;
- metallic particles present in the water;
- complementary parameters such as pH, hardness, zinc, lead, copper, and conductivity.
The sampling protocol must be adapted to the suspected origin. Sampling after stagnation may be useful when plumbing contamination is suspected, while sampling after running the tap may better represent the quality of the supplied source.
What technologies can reduce cadmium in water?
The appropriate process depends on the concentration, pH, water hardness, and the form in which the cadmium is present.
Technologies that can be used include:
- certain specialized adsorbent media;
- certain ion exchangers;
- properly sized reverse osmosis;
- coagulation, precipitation, and filtration in collective installations;
- pH correction and corrosion control;
- replacement of plumbing materials when they are the source of contamination.
Not all activated carbon filters automatically reduce cadmium. Performance must be established by a test specific to the model, the concentration tested, and the conditions of use.
When contamination is confirmed, water analysis is recommended after the system is installed. Periodic checks help verify that the filter remains effective before it becomes saturated.
Results of Imperial testing for cadmium
Cadmium is included in the performance analysis table published for Monderma Imperial GF and Imperial AMB filters. Tests were performed by Envirotek Laboratories in the United States.
Cadmium: result indicated in the Envirotek table
Clarification on the calculation: when the final concentration is indicated as less than 0.5 ppb, it is below the limit declared by the laboratory. The exact reduction could therefore be greater than 90%, but the table displays a value of 90.0%. This value is used without extrapolation.
The summary table does not by itself specify the proportion of dissolved versus particulate cadmium nor all the characteristics of the test water. The result should not be generalized to all waters without taking into account the conditions of the protocol.
Actual results may vary depending on pH, mineralization, initial concentration, flow rate, contact time, maintenance, and the duration of cartridge use.
Testing performed according to an NSF/ANSI protocol does not necessarily mean the entire filter is NSF certified for cadmium reduction. Official certifications and performance reports must be presented separately.
View Monderma certifications and analysesFrequently asked questions about cadmium in water
Can you see or smell cadmium in water?
No. Dissolved cadmium generally produces no characteristic odor, taste, or color. Only an analysis can measure its concentration.
Is cadmium naturally present in water?
It can be released naturally by certain rocks and minerals. However, mining, metallurgical, industrial, and agricultural activities can increase its presence in the environment.
What is the limit for cadmium in drinking water?
The European Union sets a parametric value of 5 µg/L. The WHO uses a guideline value of 3 µg/L, and the US EPA sets a maximum contaminant level of 5 µg/L.
Does boiling water remove cadmium?
No. Boiling does not remove dissolved cadmium. Water loss through evaporation may even increase its concentration in the remaining volume.
Can cadmium come from pipes?
Yes, in certain situations. It can notably come from the corrosion of galvanized pipes, fittings, solder, or metal components containing cadmium as an impurity.
Does an activated carbon filter always remove cadmium?
No. Standard activated carbon does not automatically guarantee cadmium reduction. You must verify that a specific test exists for the filter in question.
Which organ is most sensitive to cadmium?
The kidneys are particularly sensitive to chronic exposure. Cadmium can accumulate there progressively and impair certain renal functions.
Associated contaminants
Cadmium belongs to the category of toxic metals and trace elements. You may also consult the fact sheets dedicated to other metals likely to be present in water.
Scientific and administrative sources
This fact sheet is primarily based on public agencies, international institutions, and government scientific databases. No commercial blogs, comparison sites, or affiliate websites are used as health sources.
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World Health Organization – Cadmium in drinking water
Chemical fact sheet presenting the origins, health effects, and the
guideline value for cadmium.
Consult the official WHO fact sheet -
World Health Organization – Cadmium and health
Information on the effects of cadmium on the kidneys, skeletal system,
and respiratory system.
Consult the WHO health page -
European Union – Directive (EU) 2020/2184
Official text regarding the quality of water intended for human
consumption.
Consult the directive on EUR-Lex -
EUR-Lex – Essential drinking water standards
Official summary indicating a value of 5 µg/L for cadmium.
Consult the official summary -
Environmental Protection Agency – Drinking water regulation
Official table of regulated contaminants, with a maximum concentration
of 0.005 mg/L for cadmium.
Consult EPA regulations -
PubChem – National Institutes of Health
Official data on the element cadmium, its symbol, and atomic number.
Consult the PubChem entry -
Monderma – Lab certifications and analyses
Certifications, reports, and analysis table for the filters in
question.
View Monderma certifications and analyses
