Introduction

The major ways cadmium exposure occurs in the general population are through:

• ingestion of cadmium found in certain foods, and
• cigarette smoking since the tobacco plant takes up cadmium avidly from the environment.

The non-smoking public receives the majority of their exposure through food. The main route of cadmium exposure for smokers is via tobacco smoke (National Toxicology Program 2004; Mannino et al. 2004).

Cadmium exposure in the workplace takes place during mining and work with cadmium containing ores. Additional occupational exposure may occur during manufacture of products containing cadmium such as paints and during work such as plating, soldering, and welding (National Institute of Occupational Safety and Health, 1990).

Inhalation

Inhalation is a major route of occupational exposure.

Cadmium air levels can be thousands of times greater in the workplace than in the general environment. For example, the OSHA permissible exposure limit (PEL) of cadmium fume or cadmium oxide in the workplace is 0.1 mg/m³, whereas concentrations of cadmium in ambient air are 1 x 10^-6 mg/m³ in non-industrialized areas and 4 x 10^-5 mg/m³ in urban areas (ATSDR 1999). Therefore, non-occupational exposures from air are not expected to pose hazards of adverse health effects.

Cigarette smokers in the general population are exposed to cadmium through inhalation.

There is about 2.0 µg of cadmium in a cigarette, of which nearly 2-10% is transferred to cigarette smoke (Mannino et al. 2004). Smokers typically have cadmium blood and body burdens more than double those of nonsmokers (Waalkes et al. 2003). Clinicians should be aware that, in general, smokers will have higher urinary cadmium than nonsmokers (Mannino et al. 2004).

Ingestion

Oral ingestion is the major route of exposure for the nonsmoking general population.

However, background levels of cadmium in food, water, and ambient air are not a health concern for the general North American population. Typical dietary intake is about 30-50 micrograms per day (µg/day), (Satarug 2003; NTP 2004) but normal individuals absorb only a small proportion of an orally ingested dose (1-10%) (Horiguchi et al. 2004). However, worldwide, there are areas with very high levels of cadmium in the soil. Crop uptake of cadmium in these areas can lead to significant dietary exposures to the people living nearby. For example, in the Jinzu and Kakehashi river basins in Japan, there are areas with soil contaminated with cadmium. Rice absorbs the cadmium and a lifetime of eating this cadmium-contaminated rice can lead to a serious kidney and bone disorder called “Itai-Itai” disease, especially in women (Kobayashi et al. 2006; Ezaki et al. 2003).

Skin

There are negligible amounts of cadmium exposure through the skin. It is not considered a major route of exposure to this chemical.

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