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Cadmium Exposure and Testing

May 3rd, 2010

By Elisabeth Lutanie, Ph.D.Cadmium Exposure and Testing

Cadmium is a transitional metal that can have harmful cumulative effects on the human body. This article explains what cadmium is, where it comes from, how people get exposed to it, and how laboratories can test for it.

What is Cadmium?

Cadmium (Cd, atomic number 48) is a silver- or bluish-white metal in the group 12 of the periodic table. It is usually found with an oxidation state of +2 and combined with other elements such as oxygen (cadmium oxide), chlorine (cadmium chloride), or sulfur (cadmium sulfate, cadmium sulfide). It is also a cumulative poison associated with an array of syndromes such as renal dysfunction, reproductive toxicity, and bone defects. It is classified as a human carcinogen (Group 1) by the International Agency for Research on Cancer [1], and as a probable human carcinogen (Group B1) by the Environmental Protection Agency (EPA).  

Although its absorption in humans is relatively low, cadmium can accumulate in the body and become a major concern over time when individuals are chronically exposed to cadmium. The exact half-life of cadmium in the body is not known, but it is thought to be as long as 30 years [2]. This long half-life results mainly from the fact that humans do not have an effective cadmium elimination pathway.

Where Does Cadmium Come From?

Cadmium is released to the atmosphere both from natural sources and from human activities. Industrial activities such as combustion of fossil fuel, incineration of municipal or industrial wastes, and phosphate fertilizer manufacturing are the main sources of atmospheric cadmium. Cadmium air levels are usually thousands of times greater in the workplace of people involved in mining or manufacturing industries than in the general environment; people can be exposed to atmospheric cadmium from the smelting and refining of metals or from the air in plants that make cadmium products such as batteries (e.g. nickel-cadmium), coatings, pigments, or plastics.

Cadmium Exposure and Testing

Cadmium occurs naturally in zinc, lead, copper, and other ores which can serve as sources to ground and surface waters, especially when in contact with soft, acidic waters. However, groundwater rarely contains high levels of cadmium unless it is contaminated by mining, discharges from industrial facilities or sewage treatment plants, or seepage from hazardous waste sites. Cadmium can also be released into drinking water by corrosion of some galvanized plumbing and water pipes.

Cadmium concentrations in drinking water supplies are typically less than 1 µg/L (1 ppb). The Environmental Protection Agency (EPA) and some states regulate the amount of cadmium discharged in industrial wastewaters, and the EPA has established a maximum contaminant level (MCL) for cadmium in drinking water of 5 µg/L (5 ppb), suggesting that drinking water containing cadmium levels less or equal to the MCL are safe. The MCL value is also the lowest level to which water systems can reasonably be required to remove cadmium from the water, given the present technology and resources [3]. 

How are People Exposed to Cadmium?

The main exposure to cadmium, in people, occurs through the consumption of foods and drinking water, the inhalation of cadmium particles from ambient air or cigarette smoke, and the incidental ingestion of contaminated dust or soil. Foods (e.g. grains, cereals, leafy vegetables) that have been contaminated through water and crops grown on polluted soil are the highest source of cadmium exposure for the general population [4]. People with low calcium, protein, or iron reserves appear to absorb cadmium more efficiently and may be at increased risk of developing toxicity.

Cigarettes are also a significant source of cadmium exposure. Tobacco leaves accumulate large amounts of cadmium and it has been estimated that tobacco smokers (at one pack per day) typically have cadmium blood and body burdens at least twice as high as non-smokers [5]. Each cigarette contains 1 to 3 μg of cadmium and approximately 10% is inhaled into a smoker’s lungs during active smoking. [6]

Lately it’s been reported that people are being exposed to cadmium from some jewelry. According to a study by the Associated Press (AP) cadmium emerged as a safety concern after AP’s investigation revealed that lab tests conducted on 103 pieces of low-priced children’s jewelry found 12 items with cadmium content above 10 percent of the total weight. [7]

How Do Laboratories Test for Cadmium?

Quantitative determination of cadmium can be performed using a variety of methods and techniques, including:

  • Atomic absorption spectroscopy (AAS) with either a graphite furnace (GFAA, EPA Method 213.2) or flame (FAA, EPA Method 231.1)
  • Inductively coupled plasma techniques (ICP) using optical emission spectroscopy (ICP-OES) or atomic emission spectroscopy (ICP-AES, EPA method 200.7)
  • Mass spectrometry (ICP-MS, EPA method 200.8)
  • Electrochemical techniques such as adsorptive cathodic stripping voltametry (ACSV) [8, 9], potentiometric stripping analysis (PSA) [10], and liquid chromatography [10] are also used to analyze and separate cadmium (Cd (II))

Laboratories such as Columbia Analytical Services offer a range of analytical testing methods for cadmium, including ICP-AES and ICP-MS. The choice of the detection procedure is based on various parameters, including quality data requirements and sample media.

Cadmium Exposure and Testing

ICP/AES and ICP/MS are the most commonly used instruments for testing both biological materials and environmental samples, although GFAAS is still appropriate for certain applications. ICP-MS offers the best sensitivity and generally provides excellent selectivity. For aqueous samples, a typical reporting limit is 0.02 ug/L, 1/25th of the MCL. Analysis by ICP/AES with axial viewing is simpler, but also less sensitive (i.e., the typical reporting limit is approximately 0.5 ug/L). Reporting limits for solid samples are in the general range of 0.05 mg/kg by ICP/MS and 0.1 mg/kg for ICP/OES.

Environmental samples analyzed by ICP/AES or ICP/MS usually undergo an acid digestion procedure, a pre-concentration treatment via chemical separation, or a direct aspiration (with no preparation). The three most common methods used for cadmium sample digestion are:

1) Dry-ashing in a conventional oven followed by acid dissolution of the residue
2) Oxidative acid digestion by heating in a pressure vessel
3) Oxidative acid digestion at atmospheric pressure

Much progress has been made in the development of easy-to-use on-site tests for fast detection of trace levels of cadmium in food and environmental samples. Various commercial kits are available that allow individuals to screen quickly for cadmium on solid surfaces or in liquids, although the kits have a higher detection limit than the more sophisticated laboratory procedures.

References:

    1. IARC monographs volumes 1-100A, April 2009

    2. D.H. Kuss, A. Schmidt, T.L. Diepgen, “Occupational relevance of positive standard patch-test results in employed persons with an initial report of an occupational disease”. Int Arch Occup Environ Health, 75 (2002)

    3. D. Monticelli, E. Ciceri, C. Dossi, “optimization and validation of an automated voltammetric stripping technique for ultratrace metal analysis”, Anal. Chim. Acta, 594, 192-198 (2007)

    4. EFSA, “Cadmium in food – Scientific opinion of the panel on contaminants in the food chain” (January 30, 2009)

    5. Agency for Toxic Substances & Disease Registry – Cadmium Toxicity http://www.atsdr.cdc.gov/csem/cadmium/. (Last accessed 3/25/10)

    6. World Health Organization, 1992. (http://www.cadmium.org/env_exp.html) (Last accessed 3/25/10)

    7. Associated Press, http://hosted.ap.org/dynamic/stories/U/US_CADMIUM_JEWELRY?SITE=NEYOR&SECTION=HOME&TEMPLATE=DEFAULT (Last accessed 3/25/2010.)

    8. S.E. Yilmaz, M. Turkoglu, S. Kaya, “concentrations of cadmium and lead heavy metals in Dardanelles seawater, Environm Monit Assess., 125, 91-98 (2007)

    9. C.R. Tarley, V.S. Santos, A.C. Baeta, A.C. Pereira, L.T. Kubota, “Simultaneous determination of zinc, cadmium, and lead in environmental water by potentiometric stripping analysis (PSA) using multiwalled carbon nanotube electrode”, J. Hazard Mater., 169, 256-262 (2009)

    10. J. Cooper, J. A. Bolbot, S. Saini, S.J. Setford, Electrochemical method for the rapid on site screening of cadmium and lead in soil and water samples, Water, Air, & Soil Pollution, 179, 183-195 (2007)

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9 Responses to “Cadmium Exposure and Testing”

  1. sunil kumar Says:

    hi
    i am also done the icp ms of my pore water samples from typical estuarine wet land and find amazing facts rewarding the conc. level of Cd in vertical core. thanks for additional information.
    sunil

  2. Mike ODell Says:

    I’ve been sick for nine months now. I have bad to severe chest pains front and back every day. Headaches and joint pain. I’ve been tested for berrilum lead and fume fever. And nothing. The doctors wont release me to go back to work because of my shortness of breath. Any suggestions? Thanks. Mike O’Dell

  3. admin Says:

    Hello!

    Your questions are more appropriate for health care professionals. Our expertise is in testing samples of various matrices primarily for environmental contaminates. Hopefully, appropriate persons can help you. Best wishes.

    Dee O’Neill
    Columbia Analytical Services, Inc.

  4. Valerie K Says:

    I am a jewelry maker as a hobby and I often purchase metal alloy (zinc) beads directly from China. I have recently learned of the dangers of Cadmium. Can you recommend a good testing kit/method to test the inventory I have on hand, and also tell me what the ‘acceptable levels’ of cadmium are for such use as jewelry making. My items are not used by children, so I am assuming there is no ingestion of the beads, just the normal wear. I am concerned about my continued exposure to the materials however.

    Thank you,

    Valerie K.

  5. admin Says:

    Hi Valerie,

    I would suggest that you discuss your potential exposure with your doctor. I know of no testing kit on the market that would allow you to test for the levels of cadmium needed to ensure your materials do not pose health risks. To ensure your zinc alloy does not include cadmium, you may want to purchase it from a vendor that can provide a certificate that it is cadmium-free. If they are reputable, they will have such a certificate. Thanks,

    Dee O’Neill
    ALS-Columbia

  6. Payton Gary Says:

    Hello, my name is Payton,

    I’ve been looking for an expert on cadmium as I have a few questions. I am from Stambaugh Middle School in the United States, and I am on the school’s Robotics team. We have a robotics competition coming up in which we are required to complete a research project on food contamination. Our topic is Cadmium in rice. We’ve decided to ask you a few questions since you seem to have an expertise that no one else possesses on the matter.

    1. Is Cadmium magnetic?

    2. Can Cadmium be evaporated and/or washed out of rice? Is it easy or difficult?

    3. Has Cadmium been a serious problem lately? Within the past 5 years?

    4. We’ve created a solution which consists of this: “an assembly line machine that with run large tubs of rice through a filter/washing station onto a conveyer belt that will heat the rice causing any infected water to evaporate, it will repeat this process about 3 times. Every 10 tubs will also be sampled for Cadmium.” Does this solution sound plausible to you?

    Thank you for your time,
    -Payton Gary

  7. Bryan Sigaran Says:

    can you find the potency and dose of cadmium

  8. Bimal Patel Says:

    i want to test cadmium in zinc solution by any easy method basically is it possible by titration method ?

  9. shiv Says:

    hi,

    I am looking some lab instruments for detects test like mercury ,zinc,cadmium etc..
    Please advise me.

    Thanks,
    Shiv

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