is a naturally occurring element. Although cadmium is present
at low concentrations in all soils, its accumulation in soil and
hence through the food chain may lead to a health risk in humans.
can cause health problems in humans after long-term exposure.
It accumulates in the body, principally in the kidneys, leading
to gradual renal dysfunction if exposure is high over a long period.
While cadmium can induce effects on organs other than the kidneys,
the effects generally occur at doses higher than those associated
with renal effects. Population-based studies in Japan and Belgium
have shown a clear relationship between indicators of renal dysfunction
and environmental and occupational exposure to cadmium.
average intake of cadmium in the Australian diet is also well
within safe limits set by health authorities. While it is anticipated
that the Australian population is unlikely to experience cadmium-related
health problems, the potential for any increased health risk should
be addressed. Cadmium is recognised internationally as a potential
health risk and the World Health Organization has established
guidelines for a ‘tolerable’ level of intake.
Australia, natural levels of cadmium in the soil are low by world
standards. Phosphate fertiliser has been a major source of cadmium
additions to agricultural soil in Australia. The Australian fertiliser
industry has made significant reductions in the cadmium contents
in fertilisers over the last 10 years. It now uses rock phosphate
with lower cadmium concentrations for local manufacture.
recent years, the practice of adding sewage biosolids and green
wastes to soils in Australia through recycling has also contributed
to cadmium levels. Together with the effects of long-term fertiliser
use, this has the potential to increase the level of cadmium in
Australian food above the maximum concentrations acceptable to
health authorities, with consequent implications for human health
and international trade. /p>
Australia, through Food Standards Australia New
Zealand, has prescribed maximum levels (MLs) for cadmium in food
commodities. MLs have been set to be consistent with public health
and safety and to be reasonably achievable from a sound production
and natural resource management perspective. Consideration has
also been given to Australia's and New Zealand's international
trade obligations under the World Trade Organization's Sanitary
and Phytosanitary Agreement and Technical Barrier to Trade Agreement.
A full list of Australian MLs for cadmium can be found at www.foodstandards.gov.au/foodstandardscode/.
Many soil and management factors influence the extent to which agricultural crops take up cadmium. These include crop type and variety, soil acidity and salinity, irrigation water quality, fertiliser history and management. For crops such as potatoes and grain legumes, guidelines are available to farmers to assist in minimising cadmium uptake. Avoiding soils and waters with high salinity is one example.