Human health risks
For non-smokers, the area of greatest concern in terms of long-term exposure to elevated levels of Cd is from dietary intake. An increase in consumption of crops grown in Cd-contaminated soils or drinking water may lead to accumulation of toxic levels in the body. Human Cd toxicity was first reported in the 1950s in Japan. The health hazard became known as Itai-Itai disease and resulted from the consumption of rice grown in a contaminated floodplain downstream of lead-zinc mining activities.
Cadmium in soils may come from a number of different sources, including high naturally-occurring background levels, atmospheric deposition, sewage sludge or phosphate-based mineral fertilizers (see environmental/or what are fertilizer section). It has been argued that, depending on the region, increasing Cd levels in soils may be primarily related to the application of high-Cd phosphate-based mineral fertilizers. Monitoring Cd content in soils and water, as well as in input sources, are thus an important step to determine whether adverse health effects may occur. The most relevant factor for Cd uptake in plants is soil pH. Established agricultural management practices include liming, which increases Cd adsorption in soil and thus reduces its bioavailability for uptake by plants.