According to a study conducted in Belgium, environmental exposure to cadmium, a common pollutant in industrialized countries, increases the risk of lung cancer. These results were published in Lancet Oncology.

Cadmium is a metal that naturally occurs in the earth’s crust. Cadmium is used in batteries, pigments, metal coatings, and plastics. It is often extracted during the production of other metals, such as zinc.[1]

Environmental exposure to cadmium occurs through contaminated food or water, tobacco smoke, or polluted air. Cadmium persists in the human body long after exposure, and has been classified as cancer-causing by the International Agency for Research on Cancer (IARC). Previous studies of cadmium and cancer have focused primarily on occupational exposure to cadmium. There is less information about environmental exposure to cadmium.

To assess whether environmental exposure to cadmium increases the risk of cancer, particularly lung cancer, researchers in Belgium

compared cancer rates in an area of the country with high cadmium levels to cancer rates in an area of the country with low cadmium levels.[2]

In the high-exposure area, the elevated cadmium levels were the result of three zinc smelters. Though cadmium production by these smelters has stopped or greatly decreased, levels of cadmium in the environment remain high.

The study enrolled a total of 994 people: 521 from the high-exposure area and 473 from the low-exposure area. Participants were enrolled between 1985 and 1989 and followed until June 30, 2004.

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For each study participant, cadmium levels were measured in urine and in a soil sample from the participant’s garden. Information was also collected about other factors that may influence cancer risk, such as smoking, medical history, and occupational exposure to cadmium.

  • Urinary levels of cadmium were significantly higher in people who lived in the high-exposure area than in people who lived in the low-exposure area (12.3 nmol/day vs. 7.7 nmol/day). Cadmium levels in soil were also higher in the high-exposure area.
  • Study participants experienced a total of 50 fatal cancers and 20 non-fatal cancers. Eighteen of the fatal cancers and one of the non-fatal cancers were lung cancer.
  • Participants who lived in the high-exposure area had a four-fold increased risk of lung cancer compared to participants who lived in the low-exposure area.
  • A doubling of urinary cadmium was linked with a 70% increased risk of lung cancer and a 30% increased risk of all cancers combined.
  • A doubling of soil cadmium was linked with a 57% increased risk of lung cancer.
  • The link between environmental cadmium exposure and lung cancer was not explained by differences in age, sex, smoking, or occupational exposure to cadmium.

The researchers conclude that environmental exposure to cadmium increases the risk of lung cancer. They warn that pollution that occurred in the past, and that may be continuing in some areas, continues to pose a health hazard.

References:

[1] Agency for Toxic Substances and Disease Registry. ToxFAQs™: Cadmium. June 1999. Available at (accessed January 17, 2006).

[2] Nawrot T, Plusquin M, Hogervorst J et al. Environmental Exposure to Cadmium and Risk of Cancer: A Prospective Population-Based Study. Lancet Oncology. Early online publication January 16, 2006.

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