Chung Shan-shan, program director of the Master of Science in Environmental and Public Health Management at the Hong Kong Baptist University, explains how to dispose of unused antibiotics with care. (HONEY TSANG / CHINA DAILY)
HONG KONG — An alarming amount of antibiotics tossed away by Hong Kong households into landfills are found to persist — even after decades — with its residues continuously spewed into waters and damaging marine creatures and public health, a recent study found.
The research results were released on Tuesday by environmental scientists at the Hong Kong Baptist University (HKBU). It’s the city’s first study looking into antibiotic concentration amidst leachates from the landfill, a liquid that trickles from garbage piles.
A high concentration of antibiotic residues in environment can lead to antibiotic resistance in bacteria and is going to reverberate along the food chain.
Chung Shan-shan, Program Director, Master of Science in Environmental and Public Health Management, Hong Kong Baptist University
Researchers found that ciprofloxacin (CIP), an antibiotic commonly used to treat various bacterial infections like urinary tract infection, has accumulated and reached a disturbing level, exceeding the safety level by five to 53 times in disposal areas.
Among the three landfill sites the team probed between 2015 and 2016, CIP was found to be at its highest concentration in untreated leachates in West New Territories (WENT) landfill in Tuen Mun, at 3,410 ng/L. The figure is 53 times the safety level, also known as the predicted no effect concentrations (PNECs), at 61 ng/L.
Even the treated leachate in WENT landfill — considered a less toxic waste water after removing its sludge and breaking down organic compounds that goes directly into Hong Kong waters — had its CIP concentration standing high at 1,259 ng/L, over 20 times the PNEC for CIP.
The WENT landfill is still in service.
While the two other study sites, the two landfills closed for over 20 years namely the Pillar Point Valley in Tuen Mun and the Shuen Wan in Tai Po, showed lower CIP concentrations, with their highest levels recorded at 898 ng/L and 1,061 ng/L, respectively.
“A high concentration of antibiotic residues in environment can lead to antibiotic resistance in bacteria and is going to reverberate along the food chain,” said Chung Shan-shan, program director of the Master of Science in Environmental and Public Health Management at the HKBU.
“It will first start from marine creatures, and, eventually, afflict human beings,” said Chung, who is the lead researcher spearheading the investigation.
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Due to the imprudent use of antibiotics, the antimicrobial resistance to CIP has long been observed and is on the rise worldwide. The problem is expected to go downhill as the usage of CIP in town surged from only 3 registered drugs with CIP in 2015 to 100 drugs in 2018.
This March 6, 2013 photograph shows a landfill in the new territories of Hong Kong as the Chinese city of Shenzhen looms in the background. A recent study conducted by environmental scientists of the Hong Kong Baptist University has found ciprofloxacin at its highest concentration in untreated leachates in West New Territories landfill in the city. (PHILIPPE LOPEZ / AFP)
In an earlier interview with Kao Yi-tsun, a Hong Kong microbiologist at the University of Hong Kong, who is committed to discovering solutions to conquer superbugs, Kao stressed that antibiotic resistance is a global concern greatly threatening the public health. He related it as “a can of worms” that descended from indiscriminate use of antibiotics.
Echoing Kao, Chung said the antibiotics indiscriminately dumped by households and drug manufacturing plants are the two predominant sources left in landfills.
She suggested the government set up a stringent monitoring system to keep track of antibiotic levels in landfill leachates.
“The government should also learn from Shanghai and Austria and consider implementing a ‘drug take-back program’ to collect unused medication and preclude them from going into landfills and polluting the environment,” she said.
Chung’s study, funded by the HKSAR government, examined concentrations of seven common antibiotics in landfills.
The other two antibiotics found to be above the acceptable levels are erythromycin and trimethoprim, which are used respectively to treat bacterial infections in respiratory system and water infection such as cystitis.
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