BEIJING — The Chinese government released a report on Thursday that said nearly one-fifth of its arable land was polluted, a finding certain to raise questions about the toxic results of China’s rapid industrialization, its lack of regulations over commercial interests and the consequences for the national food chain.

The report, issued by the Ministry of Environmental Protection and the Ministry of Land Resources, said 16.1 percent of the country’s soil was polluted, including 19.4 percent of farmland. The report was based on a study done from April 2005 to last December on more than 2.4 million square miles of land across mainland China, according to Xinhua, the state news agency.

The report said that “the main pollution source is human industrial and agricultural activities,” according to Xinhua. More specifically, factory waste products, irrigation of land by polluted water, the improper use of fertilizers and pesticides, and livestock breeding have all resulted in tainted farmland, the report said.

The study found that 82.8 percent of the polluted land was contaminated by inorganic material. The most common pollutants were cadmium, nickel and arsenic, and the levels of these materials in the soil had risen sharply since land studies in 1986 and 1990. The level of cadmium had risen by 50 percent in the southwest and in coastal areas and by 10 percent to 40 percent in other regions, Xinhua reported. The soil in southern China is more polluted than in the north.