Why should soil pollution data be kept a “state secret”?

The Ministry of Environmental Protection (MEP) has refused Beijing lawyer Dong Zhengwei’s request for soil pollution data – claiming the data is a “state secret.”
In late January this year, Beijing lawyer Dong Zhengwei submitted two freedom of information requests to the Ministry of Environmental Protection (MEP), asking for the methodology used and data collected during a nationwide survey of soil pollution, and for details of the sources of soil pollution and measures being taken to prevent it. 
On February 24 the MEP provided this information — except for the data collected during the survey, which is described as a “state secret”.
Dong does not believe the MEP has adequate reasons to do this. He wrote on his blog that the 10th article of China’s open information regulations requires governments at county-level and above to proactively disclose information. And according to the 11th article, information on environmental protection, monitoring and surveys are key areas for disclosure. Soil pollution data should, therefore, be disclosed. 
Dong said that “the 9th article of the Law on Guarding State Secrets does not explicitly list environmental information as a type of state secret. If it is to be regarded as a state secret, confirmation is required from the appropriate level of the National Administration for the Protection of State Secrets.” The MEP’s reply included no such confirmation. 
He told chinadialogue that the refusal was probably due to the fact that pollution is severe, hard to manage and will upset the public. Soil pollution can impact the human body via food, groundwater and the air, affecting human health and homes – the public should have the right to know and supervise. 
China’s soil pollution problem is both chronic and severe. As early as 2006, the State Environmental Protection Agency (later the MEP) and the Ministry of Land invested one billion yuan in a nationwide survey of the issue. According to the newspaper Southern Weekend, that study took four years, but despite eager media anticipation, none of the gathered data has been released. 
China’s soil pollutants come mostly from agricultural chemicals; heavy metals such as cadmium, arsenic and mercury released by mines; and oil and fuel. Soil pollution can spread to food and water – something that was brought to public attention in 2011, when Caixin.com published a report on cadmium-contaminated rice, and the Yunnan Information Daily covered river pollution from dumped chromium. 
Ma Jun, director of the Institute for Public and Environmental Affairs, told Legal Daily that soil pollution data is a sensitive matter, and that the MEP could adopt the same method used with PM 2.5 data – partial publication and explanations, backed up with measures to improve things. 
Dong himself has already applied for a reconsideration of the decision, in the hope that the data will yet be disclosed.