BEIJING, July 14 -- Farmer Lao Liao keeps more than 2,000 pigs in south China's Guangdong Province, but he worries about the cost of keeping them healthy.

It's not just the economic cost, but price paid by the environment.

"It worries me giving the pigs so many veterinary drugs to prevent them from getting ill," says Liao.

His worry is reflected in a series of maps drawn by scientists, which have also sparked concern among the wider public.

New research by scientists at the Guangzhou Institute of Geochemistry of the Chinese Academy of Sciences (CAS) shows that China consumed 162,000 tons of antibiotics in 2013, or more than half of the global total. About 52 percent was used on livestock and 48 percent by humans. More than 50,000 tons ended up in the water and soil.

Based on the data of antibiotics usage and emissions along 58 major river basins in China, scientists drew a series of maps showing antibiotic pollution. They were recently published in the academic journal, Environmental Science &Technology.

The maps show that developed provinces such as Guangdong, Jiangsu, Zhejiang and Hebei are seriously polluted. The antibiotics emissions concentration in the densely populated east China is six times that in west China.

The average in Chinese rivers is about 303 nanograms per liter, compared with 9 nanograms per liter in Italy, 120 nanograms per liter in the United States, and 20 nanograms per liter in Germany.

"China lacks supervision on the use of antibiotics, with insufficient information about usage and emissions into the environment," says Ying Guangguo, a lead scientist on the study.

The research, which is aimed at gathering comprehensive data on antibiotics usage and emissions, has lasted for 10 years, focusing on 36 frequently used antibiotics types, Ying says.

The antibiotics in the environment mainly come from sewage, medical wastewater, animal husbandry and aquaculture wastewater, experts say.

"During the research, we found that some pig farms, especially large-scale farms with more than 10,000 pigs, add more than a dozen antibiotics in the fodder and water. It's really horrible," Ying says.

And medical abuse of antibiotics is also common. Prescription of antibiotics in China's large hospitals is basically well controlled, but medium-sized and small hospitals and the animal husbandry industry lack supervision, Ying says.

Some doctors depend on antibiotics as an immediate remedy, and hospitals encourage doctors to use them because their sale brings more profit.

"Antibiotics can cause drug-resistance in the human body and the ecological system. The use of antibiotics must be strictly controlled," Ying says.

The research will provide data and theoretical support for government regulation of antibiotics use and pollution, says Ying.

The per-capita antibiotics use in China is five to eight times that of Western countries, the research shows.

"Although the residual antibiotics in the environment will not directly harm people, the real danger is intensified bacterial resistance," Ying says.

Experts say the emergence of "superbacteria" and "multi-drug resistant bacteria" is a result of antibiotic pollution, killing microflora in the environment.

Li Lanjuan, an infectious diseases expert at the 1st Hospital Affiliated to the Zhejiang University and an academician of the Chinese Academy of Engineering, says China is on the verge of extensive drug resistance. This would lead to a greater risk of surgical infection, even in routine operations such as cesareans and hip replacements.

Children are the most vulnerable. Shanghai Fudan University tested more than 1,000 children aged 8 to 11 in Shanghai, and Jiangsu and Zhejiang provincecs in April, and found that almost 60 percent of urine samples contained antibiotics.

About a quarter of the samples contained two or more antibiotics. Some showed as many as six kinds of antibiotics. The tests also found three kinds of antibiotics normally only used on livestock and poultry in the samples.

Antibiotic resistance is recognized as a major threat to public heath everywhere in the world, and urgent actions are needed, the World Health Organization (WHO) warned in a statement released in June.

"This limits our ability to treat infectious diseases and contributes to the deaths of hundreds of thousands of people globally every year caused by diseases that were easily treatable before," the WHO statement says.