Unlike air pollution, soil contamination cannot be so easily seen. Yet it is arguably more harmful to health, due to its impact on food safety. The release of a mainland government study showing that almost one-fifth of surveyed land had been degraded by toxic heavy metals is a much-needed acknowledgement of the nature and scale of the problem. With the risks and challenges having been laid bare, there is a better chance of real action now being taken.
And the challenge is enormous. Samples taken from across 6.3 million square kilometres - two-thirds of China's land area - showed 16.1 per cent of soil and 19.1 per cent of arable land had been contaminated. The main pollutants were cadmium, nickel and arsenic, the result of three decades of rapid economic expansion and industrial growth that had paid little heed to the environment. Already, 3.4 million hectares of land is unfit for farming and much of the rest has been stripped of its productivity by uncontrolled pesticide and fertiliser use.
Authorities were at first reluctant to release the findings of the eight-year study; the Ministry of Environmental Protection last year rejected a request filed by a Beijing lawyer on the grounds that the data was a state secret. But scandals involving cadmium-tainted rice and the identification of villages near factories where cancer levels are above national averages have raised awareness of soil and land contamination. That feeds into growing concern over the environment, particularly air and water pollution, leading Beijing to rethink its growth-at-all-costs policy. Premier Li Keqiang last month said the government was "declaring war" on pollution.
Revitalising damaged agricultural land is an expensive and time-consuming process. Billions of yuan will be needed and during the years of decontamination, food imports may have to be increased. The report was accompanied by a promise of improved protection and better legislation. These are sensible and necessary moves; China cannot afford inaction or foot-dragging on so important a matter.