In the world's largest study into the long-term health impacts of flooding, scientists have quantified the widespread and shocking ways in which this traumatic experience affects people. The results call for urgent action to address these potentially deadly issues.
The research team led by Monash University professors Yuming Guo and Shanshan Li looked at more than 300 million hospital records of people across 747 communities in eight countries where flooding occurs, and found that this type of natural disaster spikes hospital visits by 26% overall. Flooding events from 2010 to 2019 in Australia, Vietnam, Brazil, Canada, Chile, Thailand, New Zealand and Taiwan were studied, along with hospital records to identify patterns.
Digging further into the data, the scientists discovered that there were widespread increases in hospitalizations for: cardiovascular diseases (35%), respiratory diseases (30%), infectious diseases (26%), digestive diseases such as gastroenteritis (30%), mental health disorders (11%), diabetes (61%), cancer (34%), nervous system disorders (34%), and renal diseases (40%).
And beyond the immediate trauma and floodwater risks, these long-term issues impacted people for up to seven months and potentially beyond.
"Among populations exposed to floods, the risks of hospitalization increased immediately (except that respiratory diseases and mental disorders increased gradually) and returned to normal around 210 days (90 days for infectious diseases and 150 days for mental disorders) after floods," the team wrote.
The post-flood hospital admissions were highest among those aged under 20 and people aged 60 and above.
While there are obvious immediate health concerns when flooding occurs – including, of course, drowning and electrocution – until now, there's been little research into enduring conditions that emerge in the wake of the event, or existing conditions that lack access to treatment in the months following. In the immediate aftermath, floodwaters provide the ideal breeding ground for insects carrying infectious diseases, as well as water supply contamination. Evacuations can displace residents and complicate health conditions further.
"Even when temporary shelters are provided, insufficient sanitation facilities often result in hygiene issues, increasing the likelihood of respiratory, digestive and infectious diseases," the researchers wrote. "Furthermore, access [to] and capacity [of] healthcare services may be impaired after floods, leading to delays in regular medical interventions, which include dialysis for renal diseases, chemotherapy and radiotherapy for cancer, and medication regimens for cardiovascular diseases, respiratory diseases, infectious diseases, digestive diseases, mental disorders, diabetes, nervous system disorders and renal diseases.
"Finally, long-term psychological stress (for example, from property damage and financial losses) can worsen or induce adverse health outcomes by compromising the immune system, disrupting sleep, leading to substance abuse and diminishing self-care," they added.
While there may not be a whole lot that people have control over when it comes to living through a natural disaster, the study offers insights into the multifaceted way that an event like a serious flood can put widespread strain on human health.
"The health impact of floods may have been underestimated and will further exacerbate as climate changes,” Guo said. "[There will be] an escalation in the severity, duration and frequency of floods due to the more frequent extreme precipitation events and rising sea levels due to global warming.”
Around 23% of the world's population is currently vulnerable to serious flooding, and there's no shortage of scientific evidence that suggests this is only going to increase.
While the study has its limitations – the generalized findings don't account for disadvantaged communities with poor access to health services, which are disproportionately affected by disasters – the researchers believe it's an important and often-overlooked aspect of the fallout from a flooding event.
"This study fills a gap in the knowledge about the associations between floods and hospitalization risks, based on a multi-country/territory dataset and standard time-series statistical methods," they wrote. "Policymakers and health professionals should raise awareness of the increased hospitalization demands from a broad range of diseases after floods to improve disaster-response strategies and health system resilience."
The research was published in the journal Nature Water.
Source: Monash University