Soil contamination incidents rose in fiscal 2000, marking the third straight yearly increase, the Environment Ministry said Tuesday.
The increase in cases by five to 134 marks the highest total since the survey began a decade ago, ministry officials said.
Most incidents occurred at urban factories or areas with a history of handling chemicals or harmful substances. Contamination cases are defined as those in which residue chemicals exceed government standards.
Of the 134 contamination cases, 72 were due to pollution from heavy metals, such as lead or mercury, 44 stemmed from volatile organic compounds, such as trichloroethylene, while the remaining 18 showed evidence of both types of pollution, according to the ministry. Trichloroethylene is often used in industrial cleaners.
Most cases surfaced following voluntary surveys by landowners prior to redevelopment or by those seeking environmental accreditation, officials said.
Observers said the number of cases will probably increase again if a bill sent to the Diet earlier this month is enacted and takes effect next year. It would make contamination surveys obligatory for facilities that have handled harmful chemicals.