Fine Particulate Matter and Children: How Does Exposure Affect Cognition?

Higher levels of ammonium nitrates were associated with worse learning and memory outcomes among US children aged 9 to 10, according to study findings published in Environmental Health Perspectives.  

Researchers conducted a cross-sectional study to explore how ambient concentrations of fine particulate matter (aerodynamic diameter, ≤2.5 μm) component mixtures relate to neurocognitive outcomes in 9- and 10-year-old children in the US, as well as investigate source-specific effects of these associations.

Yearly concentrations of 15 chemical components of fine particulate matter were estimated based on the addresses of children from the Adolescent Brain Cognitive Development (ABCD) Study, which enrolled those aged 9 and 10 at baseline who were fluent in English and able to complete the baseline visit magnetic resonance imaging (MRI).

Based on the 15 components, 6 major fine particulate matter sources were identified, including crustal, ammonium sulfate, biomass burning, traffic, ammonium nitrate, and industrial and residual fuel burning.

The National Institutes of Health (NIH) Toolbox was used to derive general cognitive ability, executive function, and learning and memory scores. To investigate associations between fine particulate matter components’ mixture, their potential sources, and children’s cognitive scores, weighted quantile sum and linear regression models were utilized.

A total of 8589 participants were included in the weighted quintile sum regression analyses, while 8588 participants were included in the final sample.

According to mixture modeling, cumulate exposure was associated with worse cognitive performance across all 3 outcome domains. Shared overlap in detrimental effects were found driven by ammonium nitrates, silicon, and calcium.

Source-specific negative associations were identified between the following exposures and cognitive outcomes:

• Ammonium nitrates and learning and memory;
• Traffic and executive function; and,
• Crustal and industrial mixtures and general cognitive ability.

In contrast, positive relationships were unexpectedly demonstrated between traffic and general ability, as well as biomass burning and executive function.

A primary limitation of this study was the cross-sectional design.

“Our findings imply different profiles of exposure-cognition associations that shared overlap in detrimental effects of ammonium, nitrates, silicon, calcium, and zinc,” the researchers concluded.