Antibiotics from human use are contaminating rivers worldwide, study shows
Published in PNAS Nexus , the study is the first to estimate the scale of global river contamination from human antibiotics use. Researchers calculated that about 8,500 tonnes of antibiotics — nearly one-third of what people consume annually — end up in river systems around the world each year even after in many cases passing through wastewater systems.
'While the amounts of residues from individual antibiotics translate into only very small concentrations in most rivers, which makes them very difficult to detect, the chronic and cumulative environmental exposure to these substances can still pose a risk to human health and aquatic ecosystems,' said Heloisa Ehalt Macedo, a postdoctoral fellow in geography at McGill and lead author of the study.
The research team used a global model validated by field data from nearly 900 river locations. They found that amoxicillin, the world's most-used antibiotic, is the most likely to be present at risky levels, especially in Southeast Asia, where rising use and limited wastewater treatment amplify the problem.
'This study is not intended to warn about the use of antibiotics — we need antibiotics for global health treatments — but our results indicate that there may be unintended effects on aquatic environments and antibiotic resistance, which calls for mitigation and management strategies to avoid or reduce their implications,' said Bernhard Lehner, a professor in global hydrology in McGill's Department of Geography and co-author of the study.
The findings are especially notable because the study did not consider antibiotics from livestock or pharmaceutical factories, both of which are major contributors to environmental contamination.
'Our results show that antibiotic pollution in rivers arising from human consumption alone is a critical issue, which would likely be exacerbated by veterinarian or industry sources of related compounds' said Jim Nicell, an environmental engineering professor at McGill and co-author of the study. 'Monitoring programs to detect antibiotic or other chemical contamination of waterways are therefore needed, especially in areas that our model predicts to be at risk.'
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For the past decade, Sughra Ayaz has traveled door to door in southeastern Pakistan, pleading with parents to allow children to be vaccinated against polio as part of a global campaign to wipe out the paralytic disease. She hears their demands and fears. Some are practical – families need basics like food and water more than vaccines. Others are simply unfounded – the oral doses are meant to sterilize their kids. Amid rampant misinformation and immense pressure for the campaign to succeed, Ayaz said, some managers have instructed workers to falsely mark children as immunized. And the vaccines, which must be kept cold, aren't always stored correctly, she added. 'In many places, our work is not done with honesty,' Ayaz said. The World Health Organization and partners embarked on their polio campaign in 1988 with the bold goal of eradication — a feat seen only once for human diseases, with smallpox in 1980. 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Dr. Zulfiqar Bhutta, who has served on advisory groups for WHO, the Gates Foundation and others, said campaign officials should listen to the criticism of its tactics. 'Continuing blindly with the same strategies that we have relied on since eradication began is unlikely to lead to a different result,' he said. Internal WHO reports reviewing vaccination drives in Afghanistan and Pakistan over the past decade – given to AP by current and former staffers – show that as early as 2017, local workers were alerting significant problems to senior managers. The documents flagged multiple cases of falsified vaccination records, health workers being replaced by untrained relatives and workers improperly administering vaccines. On numerous occasions, WHO officials noted, 'vaccinators did not know about vaccine management,' citing failure to keep doses properly cold. They also found sloppy or falsified reporting, with workers noting 'more used vaccine vials than were actually supplied.' According to an August 2017 report from Kandahar, Afghanistan, local government authorities and others interfered in choosing vaccinators, 'resulting in the selection of underage and illiterate volunteers.' Vaccination teams worked 'in a hurried manner,' reports said, with 'no plan for monitoring or supervision.' A team in Nawzad, Afghanistan, covered just half of the intended area in 2017, with 250 households missed entirely. Village elders said no one visited for at least two years. Vaccine workers and health officials in Afghanistan and Pakistan confirmed the issues in the documents and told AP it's hard for campaign leadership to grasp the difficulties in the field. Door-to-door efforts are stymied by cultural barriers, unfounded stories about vaccines, and the region's poverty and transience. 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Before the first polio vaccine was developed in 1955, the disease — spread mostly from person to person, through contaminated water and via fecal particles — was among the world's most feared, paralyzing hundreds of thousands of children annually. People avoided crowded places during epidemics, and hospital wards filled with children encased in iron lungs after the virus immobilized their breathing muscles. Polio is mainly spread when people are exposed to water infected with the virus. In countries with poor sanitation, children often become infected when they come into contact with contaminated waste. WHO says that as long as a single child remains infected, kids everywhere are at risk. Eradication demands near-perfection – zero polio cases and immunizing more than 95% of children. But public health leaders and former WHO staffers say campaign efforts are far from perfect, and many question the oral vaccine. The oral vaccine – proven to be safe and effective — has been given to more than 3 billion children. But there are some extremely rare side effects: Scientists estimate that for every 2.7 million first doses given, one child will be paralyzed by the live polio virus in the vaccine. In even rarer instances, the live virus can mutate into a form capable of starting new outbreaks among unimmunized people where vaccination rates are low. Worldwide, several hundred vaccine-derived cases have been reported annually since at least 2021, with at least 98 this year. Most public health experts agree the oral vaccine should be pulled as soon as possible. But they acknowledge there simply isn't enough injectable vaccine — which uses no live virus and doesn't come with the risks of the oral vaccine — to wipe out polio alone. The injectable vaccine also is more expensive and requires more training to administer. More than two dozen current and former senior polio officials told AP the agencies involved haven't been willing to even consider revising their strategy to account for some of the campaign's problems. Dr. Tom Frieden, a former director of the U.S. Centers for Disease Control and Prevention who sits on an independent board reviewing polio eradication, said it would be impossible to eliminate polio without the oral vaccine. But he's urged authorities to find ways to adapt, such as adopting new methods to identify polio cases more quickly. Since 2011, he and colleagues have issued regular reports about overall program failures. 'There's no management,' he said, citing a lack of accountability. Last year, former WHO scientist Dr. T. Jacob John twice emailed WHO Director-General Tedros Adhanom Ghebreyesus calling for a 'major course correction.' John shared the emails with AP and said he's received no response. 'WHO is persisting with polio control and creating polio with one hand and attempting to control it by the other,' John wrote. In his response to AP, WHO polio director Ahmed said the oral vaccine is a 'core pillar' of eradication strategy and that 'almost every country that is polio-free today used (it) to achieve that milestone.' 'We need to step back and really care for the people,' he said. 'The only way we can do that in large parts of the world is with oral polio vaccine.' Ahmed also pointed to the success WHO and partners had eliminating polio from India, once considered a nearly impossible task. In the four years before polio was wiped out there, health workers delivered about 1 billion doses of the oral vaccine to more than 170 million children. Today, nearly all of the world's polio cases – mostly in Africa and the Middle East – are mutated viruses from the oral vaccine, except for Afghanistan and Pakistan. Scott Barrett, a Columbia University professor, called for an inquiry into how things went so wrong – particularly with a failed effort in 2016, when authorities removed a strain from the oral vaccine. They miscalculated, leading to outbreaks in more than 40 countries that paralyzed more than 3,000 children, according to an expert report commissioned by WHO. Last year, a mutated virus traced to that effort paralyzed a baby in Gaza. 'Unless you have a public inquiry where all the evidence comes out and WHO makes serious changes, it will be very hard to trust them,' he said. With an annual budget of about $1 billion, the polio initiative is among the most expensive in all of public health. This year, the U.S. withdrew from WHO, and President Donald Trump has cut foreign aid. WHO officials have privately admitted that sustaining funding would be difficult without success. Some say the money would be better spent on other health needs. 'We have spent more than $1 billion (in external polio funding) in the last five years in Pakistan alone, and it didn't buy us any progress,' said Roland Sutter, who formerly led polio research at WHO. 'If this was a private company, we would demand results.' Villagers, too, have protested the cost, staging hundreds of boycotts of immunization campaigns since 2023. Instead of polio vaccines, they ask for medicine, food and electricity. In Karachi, locals told AP they didn't understand the government's fixation on polio and complained of other issues — dirty water, heroin addiction. Workers are accompanied by armed guards; Pakistani authorities say more than 200 workers and police assigned to protect them have been killed since the 1990s, mostly by militants. The campaign also is up against a wave of misinformation, including that the vaccine is made from pig urine or will make children reach puberty early. Some blame an anti-vaccine sentiment growing in the U.S. and other countries that have largely funded eradication efforts and say it's reaching even remote areas of Afghanistan and Pakistan. In suburban southwest Pakistan, Saleem Khan, 58, said two grandchildren under 5 were vaccinated over his family's objections. 'It results in disability,' said Khan, without citing evidence for his belief. 'They are vaccinated because officials reported our refusal to authorities and the police.' Svea Closser, professor of international health at Johns Hopkins University, said Pakistan and Afghanistan were less resistant to immunization decades ago. Now, people are angry about the focus on polio and lack of help for diseases like measles or tuberculosis, she said, spurring conspiracy theories. 'Polio eradication has created a monster,' Closser said. It doesn't help, she added, that in this region, public trust in vaccine campaigns was undermined when the CIA organized a fake hepatitis drive in 2011 in an attempt to get DNA and confirm the presence of Osama bin Laden or his family. Workers see that continued mistrust every day. In a mountainous region of southeastern Afghanistan where most people survive by growing wheat and raising cows and chickens, a mother of five said she'd prefer that her children be vaccinated against polio, but her husband and other male relatives have instructed their families to reject it. They believe the false rumors that it will compromise their children's fertility. 'If I allow it,' the woman said, declining to be named over fears of family retribution, 'I will be beaten and thrown out.'
