Huge piles of phosphogypsum containing hazardous chemicals were found in close proximity to villages and potable water sources in Sichuan Province, leading to calls for a government investigation into the situation, according to a report released Tuesday by Greenpeace East Asia, an environmental organization.

Phosphogypsum is a plentiful byproduct left over from the production of phosphate fertilizer. Greenpeace collected nine samples from five companies in several villages in Sichuan, a major phosphorus production province, and tested them for fluoride and heavy metals at a third-party laboratory.

Harmful heavy metals including arsenic, cadmium, chromium and mercury were detected in all nine samples, but they did not exceed national standards. Excessive levels of fluoride were detected in four samples from Lomon Corporation, Sichuan Hongda Chemical Industry and Yingfeng Industries Limited, with the highest one from Lomon, which was seven times higher than national standards permit.

The national standard requires that hazardous waste be stored no fewer than 800 meters away from residential areas and 150 meters away from surface water and be enclosed by protective fences.

All four piles of the fertilizer byproduct that contained excessive levels of fluoride failed to meet those regulatory requirements.

None of the three fertilizer companies named in the report could be reached for comment as of late Tuesday.

"Lomon started piling near our village and river in October 2007. We have been suffering from the smell and dust, and excessive scaling appeared in our water. Many people got sick," Zhao Fenghua, a villager of Baiyi village in Mianzhu, told the Global Times.

Zhao and two other villagers bought an excavator in November 2011 to remove the pile, which was 20 meters high and covered 78,000 square meters, and had been abandoned by the company.  They sold the phosphogypsum to recycling companies that use it in building materials after Lomon ignored their request to remove it.

"Further research is needed to evaluate its influence on the soil and groundwater but the problem in Sichuan is only the tip of the iceberg," said Lang Xiyu, Greenpeace East Asia actions campaigner.

China has accumulated over 250 million tons of phosphogypsum, according to data from the China Phosphate Fertilizer Industry Association (CPFIA). It can be used in various industrial fields but it also contains fluoride, which can cause severe harm to human health.

Wu Xiyan, director of CPFIA, told the Global Times that there is no national standards for storing piles of phosphogypsum, and many companies, including big ones like Lomon, lack technology and awareness. "It's a top priority for us to draft guidelines and supervise them," said Wu.

Lang told the Global Times that Greenpeace had filed an information disclosure application last week with governments in Mianzhu, Deyang and Shifang seeking details of the environmental evaluation and asking that an investigation be launched.