Three decades of Bangladesh data show high risk of child mortality in flood-prone areas

A new study by researchers at the Scripps Institution of Oceanography at UC San Diego and UC San Francisco estimates that 152,753 excess child deaths were attributable to living in flood-prone areas in Bangladesh over the Last 30 years. Additionally, during the study period, children born during rainy months were at higher risk of death than those born during dry months.

The article is published in the Proceedings of the National Academy of Sciences.

The findings begin to unveil the long-term public health impacts of recurring environmental hazards such as floods, wildfires or extreme heat, many of which are becoming more common or severe due to climate change, Tarik Benmarhnia said. , co-author of the study and associate. professor at Scripps Oceanography who studies climate change and health.

Benmarhnia and his co-authors were motivated to undertake this study as a way to move beyond cataloging the acute public health impacts of natural hazards linked to climate change.

“We wanted to document what happens when, year after year, certain communities are exposed to these climate hazards,” Benmarhnia said.

Benmarhnia and his co-authors wanted to find a way to examine the long-term public health burden of living in flood-prone areas in terms of infant mortality and Bangladesh seemed to offer an opportunity to quantify this burden on a long period.

“Child mortality is an indicator of easily preventable negative health consequences,” Benmarhnia said. “If we fail to prevent child mortality, problems of malnutrition, mental health and communicable diseases are also likely to arise. From a public health perspective, child mortality is only the tip of the line. ‘iceberg.”

Bangladesh is located in the Ganges-Brahmaputra-Meghna river basin, which also flows through Tibet, Nepal, Bhutan and northern India and is home to more than 618 million people. Every year, the monsoon season brings significant flooding to Bangladesh, and these floods are expected to become more frequent and extreme due to climate change.

To examine the long-term health implications of repeated exposure to flooding, the study combined a well-established spatially resolved flood zone mapping tool and health data from 58,945 mothers and 150,081 births collected by the US AID Demographic and Health Surveys (DHS). program between 1988 and 2017. The study compared mothers who were nearly identical in other measurable characteristics that may impact infant mortality, such as wealth and education, and differed only in the risk of flooding of their birthplace.

“We wanted to isolate the effect of living in flood-prone areas as much as possible from other factors that might change the risk of infant mortality,” Benmarhnia said.

The study estimated that living in flood-prone areas was associated with an additional infant mortality risk of 5.3 additional deaths per 1,000 births compared to living in non-flood-prone areas over a 30-year period between 1988 and 2017, with children born. During rainy months, the risk of death is higher than those born during dry months.

The researchers then used national demographic data, weighted statistical analysis, and the same flood-prone mapping tools to extrapolate their results with this initial group to the entire country of Bangladesh. This nationwide analysis estimates that 152,753 excess child deaths were attributable to living in flood-prone areas in Bangladesh over the past 30 years.

The study results do not indicate any particular mechanism for how exposure to flooding might lead to increased child mortality, and Benmarhnia said investigating potential causes would be a necessary step in developing effective interventions. That said, he suggested that flooding can impact food security and financial stability, particularly for farming communities.

Benmarhnia said the results suggest that focusing only on the immediate effects of flooding might underestimate their impact on population health and that the effects on child mortality, in particular, appear to manifest themselves on a longer time scale. long. The study also provides a model for measuring the long-term health impacts of flooding and a generalizable example of how to study the long-term health effects of climate-related environmental risks.

The role of climate change was not explicitly included in the analysis, Benmarhnia said, but he said there was a continued increase in the overall risk of infant mortality over the three decades of the study.

“We haven’t quantified the role of climate change, but it’s the elephant in the room,” Benmarhnia said. “Although our data cannot explicitly link our results to climate change, they are consistent with the idea that climate change worsens flooding and the public health impacts that result from it.”

In light of their findings, the study authors are now investigating the potential for seasonal nutrition interventions that could strengthen food security when communities are most at risk from flooding and other climate-sensitive exposures.

“We need to think about and face the long-term consequences of other climate hazards and so-called extreme weather events,” Benmarhnia said. “We may also need to redefine our concept of extreme. The intensity is extreme but these environmental risks like flooding are becoming less and less rare. We may need to reframe these issues as recurring problems and not just as emergency situations.”

In addition to Benmarhnia, the study was co-authored by François Rerolle, a postdoctoral researcher at UC San Francisco and Scripps Oceanography, and Benjamin Arnold of UC San Francisco.