The Government is developing new environmental standards to help local councils deal with soil contamination.
Environment Minister Nick Smith says the past use of chemicals and hazardous substances in industry, agriculture and horticulture has left a legacy of contamination.
He says while the problem is not as serious as in many other industrialised countries, there are sites that pose a risk to public and environmental health.
Dr Smith says the new standard will provide clear guidance to councils on the appropriate use of land, depending on the soil contamination, and define acceptable levels of concentration.
A 10-week consultation period on the draft National Environmental Standard on assessing and managing contaminants in soil began on Saturday.