the mitsui mining & smelting company began discharging cadmium into the jinzū river, as a byproduct of mining operations. residents in the surrounding area subsequently consumed rice grown in cadmium-contaminated irrigation water. they experienced softening of the bones and kidney failure. the origin of these symptoms was not clear; possibilities raised at the time included "a regional or bacterial disease or lead poisoning". in 1955, cadmium was identified as the likely cause and in 1961 the source was directly linked to mining operations in the area. in february 2010, cadmium was found in walmart exclusive miley cyrus jewelry. wal-mart continued to sell the jewelry until may, when covert testing organised by associated press confirmed the original results. in june 2010 cadmium was detected in the paint used on promotional drinking glasses for the movie shrek forever after, sold by mcdonald's restaurants, triggering a recall of 12 million glasses. remediation a metal edta anion. pb displaces ca in na2 to give na2, which is passed out of the body in urine. in humans, heavy metal poisoning is generally treated by the administration of chelating agents. these are chemical compounds, such as cana2edta (calcium disodium ethylenediaminetetraacetate) that convert heavy metals to chemically inert forms that can be excreted without further interaction with the body. chelates are not without side effects and can also remove beneficial metals from the body. vitamin and mineral supplements are sometimes co-administered for this reason. soils contaminated by heavy metals can be remediated by one or more of the following technologies: isolation; immobilization; toxicity reduction; physical separation; or extraction. isolation involves the use of caps, membranes or below-ground barriers in an attempt to quarantine the contaminated soil. immobilization aims to alter the properties of the soil so as to hinder the mobility of the heavy contaminants. toxicity reduction attempts to oxidise or reduce the toxic heavy metal ions, via chemical or biological means into less toxic or mobile forms. physical separation involves the removal of the contaminated soil and the separation of the metal contaminants by mechanical means. extraction is an on or off-site process that uses chemicals, high-temperature volatization, or electrolysis to extract contaminants from soils. the process or processes used will vary according to contaminant and the characteristics of the site. benefits some elements otherwise regarded as toxic heavy metals are essential, in small quantities, for human health. these elements include vanadium, manganese, iron, cobalt, copper, zinc, selenium, strontium and molybdenum. a deficiency of these essential metals may increase susceptibility to heavy metal poisoning.