Multiple environmental factors linked to childhood obesity
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Multiple environmental factors linked to childhood obesity

by Freya Lucas

June 25, 2020

Children who are exposed to smoking and air pollution and children who live in densely populated areas with low walkability have been pinpointed by an international study as being more likely to be obese. 


The study, co-led by scientists at the Barcelona Institute for Global Health (ISGlobal) and the University of Southern California (USC) is the first to comprehensively profile environmental factors linked to childhood obesity, with research showing that a higher body mass index (BMI) during childhood is associated with exposure to smoking – both in the womb and while growing up – as well as air pollution and certain characteristics seen in some urban areas. Differences in socioeconomic status did not explain these results.


The findings, which were recently published in the journal Environmental Health Perspectives, explore the concept of exposome – the measure of all the exposures of an individual in a lifetime and how those exposures relate to health. An individual’s exposure begins before birth and includes insults from environmental and occupational sources.


While many people are familiar with genomes, and understand how genetic makeup affects health and wellbeing outcomes, studies such as this one attempt to clarify how health is affected by every environmental influence from conception onward. This new approach contrasts with a traditional method for probing population health, zeroing in on one or two environmental factors in a given investigation.


The researchers examined 173 factors – 77 during pregnancy and 96 during childhood. These included air pollutants, families’ human-made surroundings and access to green space, tobacco smoke and chemical pollutants such as heavy metals and pesticides, in 1,300 children aged 6 to 11 years from six European countries: France, Greece, Lithuania, Norway, Spain and the United Kingdom. 


Data about the women and their children have been gathered, starting at pregnancy, through a collaborative longitudinal research project known as the Human Early Life Exposome (HELIX) study.


Mothers’ smoking during pregnancy was the most prominent association with high BMI among children, and the only prenatal factor with a significant association. Additionally, high BMI was associated with exposure to secondhand smoke, as measured through levels of a certain chemical in childrens’ urine samples. Taken together, these findings suggest that kicking the habit – or never picking it up – is one way that parents can safeguard the long-term health of their offspring.


“This is quite an important message,” lead author Dr Lida Chatzi said. 


“Maternal smoking during pregnancy and exposures to secondhand smoke are quite prevalent worldwide.”


Exposure to air pollution, both indoors and out, was another factor linked to higher BMI. Specific pollutants were nitrogen dioxide – a component of automobile exhaust and other gases released when fossil fuels burn – as well as particles in the atmosphere.


Certain attributes of the areas where children live also showed a strong correlation with BMI. BMI was higher for children who live in densely populated areas. But BMI was lower for those who went to school in areas that are denser in facilities such as businesses, community services, educational institutions, restaurants and shopping – a proxy for a neighborhood’s walkability.


A better understanding of the impact of environmental exposure, researchers said, could create opportunities to take action that reverses the trend of increasing childhood obesity, ultimately mitigating its long-term dangers.


To read the work in full, please see here

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