Cadmium and cancer risk

Cadmium is a rare metal found in the Earth’s crust. It’s naturally occurring, but also toxic. It can be dispersed into the air, soil and water, where you may come into contact with it in a number of ways, such as through cigarette smoke, and in products including:

• Batteries
• Pigments
• Metal coatings
• Plastics

The World Health Organization (WHO) considers exposure to cadmium to be a “major public health concern,”—and lists cadmium as a human carcinogen, meaning it’s a substance known to cause cancer.

It’s often found bonded to other elements (which create cadmium compounds), such as:

• Oxygen
• Sulfur
• Chlorine

For example, cadmium and oxygen make the compound known as cadmium oxide. This form of cadmium, which may be found in the air and inhaled, is a toxin that has been shown to affect workers in industries such as manufacturing.

Cadmium is also typically found as the following compounds:

• Cadmium chloride
• Cadmium sulfate
• Cadmium sulfide

How are people exposed to cadmium?

Cadmium exposure may be damaging during short-term, acute exposures, but it’s more likely to become an issue with chronic exposure over time because it builds up in certain areas of your body, and the body is slow to process it out.

Cadmium mostly accumulates in the following parts of the body:

• Kidneys
• Liver
• Bones

The amount of cadmium most people are exposed to (through air, water and food) is generally very low, but it’s likely to be higher near:

• Factories
• Incinerators
• Other industrial areas that work with cadmium-related materials

Where you may be exposed to cadmium

In your daily life, you may be exposed to cadmium in a variety of ways.

Through the air: Cadmium may be released into the atmosphere, where it’s carried by wind to other areas and/or inhaled when used in:

• Mining
• Smelting
• Manufacturing

Through the soil:

• Once released into the air, cadmium may be absorbed by soil, where it’s then carried into the food chain as plants absorb it through their roots. Just like in humans, it takes a very long time for cadmium to be processed out of plants and animals, so it’s likely to be carried onto us when we eat them.
• Cadmium may also be found in phosphate fertilizers and some sewage.

Through water: Cadmium may end up falling back down as rain or leaching into water sources after being absorbed into the soil. This happens especially in areas near mines or factories, but it’s not usually a problem in groundwater in general.

Through smoke:

• Both actively smoking tobacco and breathing in secondhand smoke may expose you to cadmium.
• A small amount of cadmium may be released into the air and soil through natural events such as forest fires or volcanic eruptions.

At work, people may be exposed in any of the above ways, through air, soil, water or smoke. Though the National Cancer Institute notes that occupational exposure to cadmium has declined since the 1970s, as more regulatory protections have been put in place.

• You may be exposed to cadmium at your job if you work in:
  • Metal refining
  • Smelting
  • Battery, plastic and pigment manufacturing
  • Landfill operations
  • Electronics recycling
  • Composting
  • Waste collection
• Heating of products that contain cadmium is one way it’s released into the air.
• Cadmium may also be ingested through contact with contaminated hands, or food in the workplace or dust.

How does cadmium affect humans?

People are typically exposed to cadmium by inhaling it (either through the air or cigarette smoke) or ingesting it through foods with trace amounts.

Cadmium generally accumulates in the kidneys, and it takes decades for the body to process it out. Therefore, if cadmium exposure continues, cadmium builds up in your body and tends to stay in the kidneys.

Once cadmium is in the kidneys, it may affect your body in several ways. It may lead to:

• Kidney stones
• Weak bones
• Osteoporosis

If food with high levels of cadmium is ingested, it may cause:

• Stomach irritation
• Vomiting
• Diarrhea

Cadmium that is inhaled may:

• Directly irritate the lungs, leading to acute pneumonitis (inflammation of the air sacs), which makes it difficult to breathe
• Possibly lead to pulmonary edema, or fluid in the lungs

At its most severe, this exposure may be deadly. Researchers can measure the amount of cadmium in the blood and/or urine of people in a certain area to monitor cadmium levels and understand how this exposure may be affecting their health.

How are cadmium and cancer linked?

Several national and worldwide organizations have made statements about the cancer-causing properties of cadmium. The WHO has classified it as a known human carcinogen, and the U.S. National Toxicology Program also considers cadmium, as well as its compounds (such as cadmium oxide), to be a known carcinogen.

Researchers continue trying to determine how cadmium causes cancer and exactly which cancers are linked to this type of exposure. Studies reviewed in Cancer Causes & Control consistently showed that low-level environmental exposure to cadmium is a risk factor for developing cancer in general.

Lung cancer seems to have the strongest link to cadmium exposure. Current research shows that measuring the level of cadmium in the blood of smokers or former smokers may enable early detection of lung cancer.

Besides lung cancer, there’s limited evidence that cadmium exposure is linked to kidney and prostate cancers, meaning some studies have found a connection, whereas others haven’t. More research is needed, but generally researchers suspect an association.

The same goes for bladder cancer and hormone-related cancers, such as endometrial, ovarian and breast cancers. Some studies have also suggested a link between thyroid cancer and cadmium exposure. Research is ongoing, however, and the link between cadmium and some of these cancers isn’t necessarily a causal link, but an association is still being looked at.

In terms of prevention, researchers are studying ways to remove cadmium from food sources and natural resources to lower the amount of exposure.

What if you suspect you’ve been exposed to high levels of cadmium?

Some exposure to trace amounts of cadmium in the environment is expected, but if you think your exposure to cadmium has been above average due to your line of work or where you live, below are some actions you may take.

• Avoid smoking: Smoking tobacco and breathing in secondhand smoke expose your lungs to cadmium.
• Alert your doctor if you think you’ve been exposed to high levels of cadmium: Your doctor may order testing if you’re considered to be at a higher risk for cadmium-related health problems, including cancer, and may recommend you see a pulmonary, renal or skeletal disease expert.
• Make sure you have enough iron in your diet: Low levels of iron make it more likely that your body will absorb cadmium if exposed to it. Iron is found in:
  • Fortified cereals
  • Meats
  • Seafood
  • Beans
  • Spinach
• Keep an eye on exposure and hygiene if you work with materials that have cadmium. If you may be exposed to cadmium at work, reduce the chance of high-level exposure via:
  • Proper ventilation
  • Limiting the time you work with cadmium-related materials
  • Wearing the proper personal protective equipment to limit inhalation and ingestion
• If you work with jewelry or paints, even in a nonwork capacity just as a hobby, you should be aware of potential cadmium exposure as well.