The Hai River in Tianjin, China
Rivers near Beijing and Tianjin in the north and in the Pearl River Delta in the south contain some of the highest concentrations of antibiotics in China's waterways, according to a study that cites the overuse of the drugs in humans and farm animals.
China has about a fifth of the world's population, but it accounts for nearly half of the world's consumption of antibiotics, according to the study, conducted by the Guangzhou Institute of Geochemistry, under the Chinese Academy of Sciences. "China is the world's biggest consumer," said Ying Guangguo, the lead researcher, in a telephone interview.
Total consumption in 2013 was 162,000 tons, with humans consuming 48 percent and animals the rest, the study said. A major concern about the overuse of antibiotics is that it can contribute to the proliferation of drug-resistant bacteria, undercutting the effectiveness of existing medications.
"Although our study does not show directly that high levels of antibiotics in water would lead to drug resistance in humans, antibiotic pollutants have negative impacts on the ecosystem," Mr. Ying said. "And since we are living in the environment and interacting with it, it will eventually affect our health."
Most of the drugs entered the waterways through human and animal excretion, Mr. Ying said, and the areas around the Hai River in the north and Pearl River in the south are densely populated. "There are also large numbers of livestock farms, especially poultry and pig farms," he said.
Antibiotics are added to livestock feed to help bolster production to meet the rising demand for animal protein from Chinese consumers.
"There are no regulations for poultry and pig farms in China for how to manage their wastewater," Mr. Ying said. "It all depends on the environmental consciousness of farm owners. Small owners tend to discharge wastewater directly into rivers because wastewater treatment is expensive."
Antibiotics are freely prescribed in China but can also be bought without a prescription. "The government has started to monitor and limit the use of antibiotics in major hospitals in big cities," Mr. Ying said. "However, there is no regulatory system for small hospitals and clinics."
The study, which was published last month in Environmental Science & Technology, a journal of the American Chemical Society, is one of the first comprehensive studies of the problem in China, examining 58 river basins.
5月，这项研究的报告在美国化学学会（American Chemical Society）的杂志《环境科学与技术》 （Environmental Science and Technology） 上发表，它是首批对中国的这个问题进行详细研究的项目之一，共研究了58个流域。
"It can provide a reference and guidance for the authorities to set up a regulatory system to measure and control the use of antibiotics," Mr. Ying said.