Pesticide use on sports fields may have left more than 100 Christchurch schools with potentially contaminated land.
The Canterbury Regional Council said 85 percent of the schools in the greater Christchurch area may be affected and has identified 124 schools as having potentially contaminated soils which have been included on the Listed Land Use Register.
The council said schools were identified because of past use of pesticides on sports fields, as well as fuel storage for heating systems.
Land contamination team leader Davina McNickel said on Monday the cause in many cases could be weedkiller. She said types of sprays used in the past don't quickly disappear, but does not expect the levels of chemicals to be high.
Canterbury Medical Officer of Health Dr Ramon Pink said the contaminated land poses a low health risk, but as a general precaution pupils should wash hands after contact with school gardens and with other soil.