Children living in areas with high levels of air pollution have weaker spelling, reading and maths skills, a new study warns.
They also have poorer levels of inhibitory control – the cognitive ability to stop an automatic thought, action or feeling, the study claims.
The authors recruited pregnant women from three areas in New York City – Washington Heights, Central Harlem and the South Bronx.
They recorded levels of exposure to a carcinogenic pollutant and followed up on their child’s performance around a decade later.
While the reason for the link remains unconfirmed, the researchers suggest that exposure to the pollutant may affect disrupt the development of the fetus in the womb.
During the fetal period, the rapidly-developing brain is vulnerable to ‘neurotoxic insults’, the researchers say, that may subsequently manifest ‘as adverse physical and mental health outcomes in childhood and adulthood’.
Children exposed to elevated levels of air pollution have poor inhibitory control during late childhood and poor academic skills in early adolescence, experts in New York report (stock image)
WHAT ARE PAHs?
Polycyclic aromatic hydrocarbons (PAHs) are substances that can form when meats are cooked at very high temperatures, like on a backyard grill.
High levels of PAHs, which are also in cigarette smoke and car exhaust, are associated with cancers in laboratory animals, although it’s uncertain if that’s true for people.
Despite this, the European Union Commission Regulation has established the most suitable indicators for the occurrence and carcinogenic potency of PAHs in food and attributed maximum levels for these compounds in foods.
The study has been conducted by researchers at the Columbia Center for Children’s Environmental Health (CCCEH) at Columbia University Mailman School of Public Health and Columbia University Irving Medical Center.
‘This study adds to a growing body of literature showing the deleterious health effects of prenatal exposure to air pollution on child health outcomes, including academic achievement,’ said study author Julie Herbstman, CCCEH director and associate professor of environmental health sciences at Columbia Mailman School.
‘Reducing levels of air pollution may prevent these adverse outcomes and lead to improvements in children’s academic achievement.’
The study followed 200 children enrolled in a longitudinal cohort study in Northern Manhattan and the Bronx, led by CCCEH researchers.
The cohort initially consisted of their mothers while pregnant, recruited from obstetrics and gynecology clinics at New York Presbyterian Hospital and Harlem Hospital between 1998 and 2006.
Researchers collected measures of prenatal airborne polycyclic aromatic hydrocarbons (PAH, a major component of air pollution) that the women were exposed to during the third trimester of pregnancy.
‘While all humans are exposed to PAH through air and dietary sources, differential placement of outdoor pollution sources increases risk for exposure among low-income, urban, and minority communities,’ the experts say.
The women had to wear special filters attached to backpacks that sampled the air and its contaminants.
During the third trimester, the fetus is highly vulnerable to environmental contaminants such as PAH, which have already been linked to cancer.
PAHs are created when products like coal, oil, gas, aerosols, rubbish and even meat on the barbeque are burned. They’re known for remaining in the environment for long periods of time.
Over a decade after the air samples were captured, tests of inhibitory control were administered at or around age 10 and tests of academic achievement, at or around age 13.
Inhibitory control assesses a participant’s ability to ‘inhibit automatic responses and instead activate a novel response’, the researchers explain.
‘Inhibitory control is commonly operationalized by tasks that measure an individual’s ability to inhibit a prepotent response in favor of a less habitual response.’
First, the child was instructed to name shapes (squares and circles) or the direction of arrows as fast as possible.
Next, the child was instructed to name the other shape or arrow direction instead – so saying ‘square’ for each circle and ‘circle’ for each square.
The authors recruited pregnant women from three areas in New York City – Washington Heights (pictured), Central Harlem and the South Bronx
‘Children with poor inhibitory control are less able to override a common response in favor of a more unusual one – such as the natural response to say “up” when an arrow is facing up or “go” when a light is green – and instead say “down” or “stop” said co-author Professor Amy Margolis at Columbia University Irving Medical Center.
‘By compromising childhood inhibitory control, prenatal exposure to air pollution may alter the foundation upon which later academic skills are built.’
The experts found that the children exposed to elevated levels of air pollution were more likely to have poor inhibitory control during late childhood, as well as poor academic skills in early adolescence.
Difficulty with inhibition in late childhood was found to be a precursor to later air pollution-related academic problems.
Polycyclic aromatic hydrocarbons (PAHs) are substances that can form when meats are cooked at very high temperatures, like on a backyard grill
In high-pollution areas, such as New York City, schools should work on interventions that help to improve inhibitory control, according to the authors of the study, which has been published in the journal Environmental Research.
‘When evaluating student’s learning problems and formulating treatment plans, parents and teachers should consider that academic problems related to environmental exposures may require intervention focused on inhibitory control problems, rather than on content-related skill deficits, as is typical in interventions designed to address learning disabilities,’ Professor Margolis said.
The new findings align with prior Columbia research that found a DNA marker for PAH exposure was associated with ADHD symptoms.
In this study, 33 children based in New York were found to have high levels of exposure to PAHs, as measured in umbilical cord blood shortly after birth.
Of those, 13 were diagnosed with ADHD hyperactive-impulsive subtype, seven the inattentive subtype, and 13 had both.
Household aerosols including deodorants and cleaning sprays release more harmful smog chemicals per year than all the VEHICLES in the UK, scientists warn
Household aerosols now release more harmful volatile organic compounds (VOCs) than all vehicles in the UK, a study reveals.
In 2017, the UK population emitted around 60,000 tonnes of VOCs from aerosols but only around 30,000 tonnes from UK cars running gasoline.
But even accounting for all forms of road transport in the country – not just cars, but motorbikes, vans, lorries and buses – aerosols still emit more VOCs, the experts say.
VOCs are a large group of odorous chemicals, many of which are released by cleaning and beauty products, burning fuel and cooking.
Exposure to some VOCs has been linked to term chronic health effects, including lung conditions, liver and kidney damage, nerve problems and cancer.
‘Virtually all aerosol based consumer products can be delivered in non-aerosol form, for example as dry or roll-on deodorants, bars of polish not spray,’ said study author Professor Alastair Lewis from University of York’s Department of Chemistry.
‘Making just small changes in what we buy could have a major impact on both outdoor and indoor air quality, and have relatively little impact on our lives.’
Read more: Household aerosols release more harmful smog chemicals than UK cars