By Angel Hsu and William Miao. This post originally appeared on Scientific American.

On March 17, the Chinese Ministry of Environmental Protection and the Ministry of Land and Resources released the first-ever results of a nationwide soil pollution survey that took place from 2005 to 2013. International media have commended the release, which revealed startling statistics such as one-fifth of arable land is polluted and contaminated with inorganic chemicals like cadmium, nickel and arsenic. On the surface, it seems, soil pollution, which was once a “state secret,” is no longer.

Overall, the report admits that the situation is “not optimistic.” The survey further reveals that inorganic pollutants are the primary contaminants in China’s soil. Chronic exposure to cadmium can lead to kidney disease, and was recently found to be present in almost half of the rice tested in the city of Guangzhou, the capital city in Southeastern Guangdong province. Arsenic, which is a water contaminant, can lead to skin lesions and skin cancer. These pollutants result from industrial waste from factories and mines as well as automobile exhaust. Irrigation using polluted water resulting from the use of fertilizers and pesticides, as well as raising livestock, can also cause soil contamination.

Soil pollution is a serious concern in China, particularly with respect to the human health implications resulting from contaminated water and food. However, while this report represents a significant step toward greater transparency with respect to pollution in China, it still lags in some key aspects and raises questions as to what can be done about the problem, the full extent of which is still unknown.

Breaking down the soil statistics
My colleagues and I reviewed the survey results and relevant regulations on soil and found that there are major gaps. First, it should be noted that none of the raw data or full survey results were released to the public, and likely will not be. When the government completed its first national pollution census in 2010, the raw data were never publicly released, despite findings that revealed a doubling in the extent of water pollution.

Second, careful attention should be paid to how exactly the statistics and findings are worded in the report. While the headlines suggest 16.1 percent, or one-fifth, of soil is contaminated, the report is more nuanced. According to our translation, the government surveyed “approximately 6.3 million square kilometers” of arable land, including woodlands, grasslands, unused and construction lands, of which 16.1 percent of surveyed points (点位 or dianwei) “exceed limits.” Exactly what these limits are was not made explicit in the report itself, but are available here (in Chinese). While a subtle distinction, it should be noted that the report actually does not go as far as specifying the total area of land that is contaminated, but rather a percentage of sampled points.

While the sampling techniques do have scientific grounding, exactly how the survey was conducted was not included in the initial report. Instead, government officials held a press conference (in Chinese) to explain some of the results of the survey. Essentially, the total surveyed area of 6.3 million square kilometers was divided into 8 kilometer by 8 kilometer plots (an area larger than Manhattan), each containing one point. Officials admitted that the soil survey results only provide an aggregate, macro picture of soil quality in China because the variability of conditions makes it difficult to be comprehensive or accurate using only points. What’s disturbing is that some areas could potentially be more polluted than these sampling points describe. It’s akin to saying that the entire soil quality of Manhattan is homogenous; the actual situation could be much worse than what these statistics show.

What now?
The twelfth Five-Year Plan includes a 30 billion yuan ($4.8 billion) commitment to address soil pollution. However, compared to the amount that the State Council approved last July to tackle air pollution—$277 billion—the amount allocated to soil seems to be a drop in the bucket. Part of the reason for this discrepancy is the lack of pubic awareness about soil pollution; the Chinese are comparatively much more aware of the dangers of air and water pollution.

Remediation of soil is also difficult, both from a technical and regulatory perspective. China lacks any type of soil remediation standard and regulations for pollution levels in soil are outdated. As a result, a lot of polluted farmland goes untreated. The potential consequences for agriculture could certainly threaten food provision in China, where in December 2013 the country’s Ministry of Land Resources deemed some 8.24 million acres of arable land (around one-fourth of the total) unfit for farming.

While the initial soil pollution survey is a start, it’s not enough. It took almost nine years for the government to reach such meager and incomplete results. More details about the spatial location of sampling sites and the levels of exceedance for individual points, as well as the release of the raw survey results, would provide better clarity and much-needed transparency to understand how prevalent the problem may be. As the survey stands, there is too much left open to interpretation. Without access to the full raw data and results of the survey, it may be impossible to know exactly what the government in China may be nuancing with these statistics. Such numbers, while providing a starting point, may be hiding a much more dangerous truth beneath their surface.

Peter Hirsch, a Masters of Environmental Management candidate of the Yale School of Forestry and Environmental Studies, designed the following infographic.