Environmental factor – February 2022: Extramural documents of the month
By Adeline Lopez
Air pollution affects children’s brain structure
Exposure to fine particulate matter (PM2.5) during childhood can alter brain architecture, according to a NIEHS-funded study. This study was the first to document links between exposure to air pollution at levels below regulatory standards and white matter connectivity in children in the United States. White matter connectivity is essential for communication between the cognitive and emotional regions of the brain.
The researchers used data from nearly 8,000 nine- and 10-year-old children across the United States. They estimated PM2.5 exposure by incorporating advanced machine learning models and each child’s residential address. They examined brain white matter architecture using magnetic resonance imaging, advanced diffusion-weighted imaging and biophysical modeling, and analyzed associations with pollution exposure. air.
There were strong associations between PM2.5 levels and differences in white matter structure and diffusivity. Diffusivity is used to examine structural integrity and variations in the space between cells and cerebrospinal fluid. PM2.5 increased a type of release that indicates changes in the cellular composition of white matter pathways in brain regions important for attention, emotional processing, and memory. Some regions were only affected on the left side of the brain, which controls language and logic, and others were affected on both sides of the brain.
Since most of the study population had PM2.5 exposures below regulatory levels set by the U.S. Environmental Protection Agency, the team suggested that further air quality improvements are needed to protect the developing brain.
Quote: Burnor E, Cserbik D, Cotter DL, Palmer CE, Ahmadi H, Eckel SP, Berhane K, McConnell R, Chen JC, Schwartz J, Jackson R, Herting MM. 2021. Association of outdoor ambient fine particles with intracellular white matter microstructural properties in children. JAMA Netw Open 4(12):e2138300.
Exposure to phthalates linked to hypercholesterolemia and cardiovascular disease
NIEHS-funded researchers found that exposure to phthalates was associated with higher plasma cholesterol levels and markers of cardiovascular disease. They also shed light on the role of the pregnane X protein receptor (PXR) in the underlying mechanism.
PXR is involved in the process of breaking down food components, pharmaceutical drugs, and harmful chemicals in the liver and intestines. However, the protein has only recently been linked to changes in cholesterol and other lipids linked to cardiovascular disease.
To better understand this role, the team exposed mice with PXR variations to dicyclohexyl phthalate (DCHP), a widely used phthalate plasticizer. They examined normal mice, mice with human PXR proteins, mice lacking PXR and mice with deficient PXR in the intestines. They measured circulating cholesterol levels and used targeted lipidomics to measure biomarkers of cardiovascular disease.
DCHP strongly activated PXR, leading to higher cholesterol levels in normal mice and mice with human PXR. Mice lacking PXR and those with PXR deficiency in the intestines did not have hypercholesterolemia. Mice exposed to DCHP with a higher PXR also had higher blood levels of lipids called ceramides, which are associated with a higher risk of cardiovascular disease in humans. Similarly, increased expression of genes involved in cholesterol and ceramide production was associated with higher exposure to DCHP depending on PXR status.
According to the authors, these results provide new insights into how exposure to phthalates and other endocrine disruptors (EDCs) increases the risk of cardiovascular disease in humans and improves our understanding of gene-EDC interactions in humans. people predisposed to cardiovascular diseases.
Quote: Sui Y, Meng Z, Chen J, Liu J, Hernandez R, Gonzales MB, Gwag T, Morris AJ, Zhou C. 2021. Effects of dicyclohexyl phthalate exposure on PXR activation and lipid homeostasis in mice. Environ Health Perspective 129(12):127001.
Database reveals toxic metals in private well water in North Carolina
Leveraging two decades of well water data in North Carolina (NC), NIEHS-funded researchers reported that residents are exposed to arsenic and lead above Agency standards US Environmental Protection Agency (EPA). Their publicly available database provides a valuable tool for researchers and citizens of the state to identify areas of greatest concern.
The team built the NCWELL database to house testing information for 28 metals in nearly 118,000 geocoded NC wells collected over 20 years. They analyzed the data to identify the populations and areas most at risk of single and concurrent contamination by toxic metals.
Arsenic and lead were detected above EPA limits of 10 and 15 parts per billion (ppb), respectively, in more than 2,500 tests. Manganese was detected above the EPA lifetime health advisory limit in nearly 5% of samples and above secondary aesthetic standards, such as taste and odor, in nearly 25% of the tests. According to the authors, maximum detection levels of 806 ppb for arsenic, 105,440 ppb for lead and 46,300 ppb for manganese are of concern.
Geographic differences across the state allowed the team to rank at-risk populations by county based on metal concentrations and the proportion of residents dependent on well water. In the mixture analysis, they identified four groups of counties with distinct exposure attributes. For example, one group had a high co-occurrence of arsenic and manganese and another had a high occurrence of lead.
According to the team, the database and methodology can be used to identify priority geographic regions for contaminants and call for universal screening of private wells.
Quote: Eaves LA, Keil AP, Rager JE, George A, Fry RC. 2021. Analysis of New NCWELL Database Highlights Two Decades of Toxic Metal Co-Occurrence in Private North Carolina Well Water: Implications for Public Health and Environmental Justice. Sci Total Environ; doi:10.1016/j.scitotenv.2021.151479 [Online 9 November 2021].
Researchers Document Benefits of NYC’s Fuel Oil Ban
NIEHS-funded researchers have linked a ban on a type of heating oil in New York City (NYC) to improved air quality. By using sophisticated statistical approaches and combining multiple data sources, the researchers provided a useful framework for assessing the benefits of this policy.
The team quantified reductions in air pollution between 2011 and 2016 attributable to the Clean Heat program, which was created in 2012 to eliminate the use of certain heating oils and switch to cleaner forms of energy . They analyzed air pollution data from the NYC Air Community Survey and used a terrestrial regression model to estimate pollutant levels in areas where no direct measurements were taken.
They included census-level data on fuel conversion in buildings and the average year of construction. The researchers also incorporated data on the kilometers traveled by different vehicles to account for traffic-related pollution. Finally, the team considered median household income to determine if and how these reductions vary by neighborhood socioeconomic status. Using advanced statistical methods, they investigated the association between fuel conversion following the ban and changes in air pollution concentrations.
They found significant reductions in particulate matter, nitrogen dioxide and sulfur dioxide attributable to the ban, independent of other sources of pollution, such as traffic. These reductions were similar regardless of neighborhood socioeconomic status.
According to the team, these changes are likely to lead to potential health benefits and improve population health outcomes in the city.
Quote: Zhang L, He MZ, Gibson EA, Perera F, Lovasi GS, Clougherty JE, Carrión D, Burke K, Fry D, Kioumourtzoglou MA. 2021. Assessing the Impact of the Clean Heat Program on Air Pollution Levels in New York City. Environ Health Perspective 129(12):127701.
(Adeline Lopez is a research and communications specialist for MDB Inc., a contractor to the NIEHS Division of Extramural Research and Training.)