College of Science News
SHIN STUDYING POSSIBLE LINK BETWEEN ENVIRONMENTAL CHEMICALS, RISK OF AUTISM IN CHILDREN
An environmental health scientist at The University of Texas at Arlington is studying whether a link exists between the risk of autism in children and exposure to environmental chemicals.
Hyeong-Moo Shin, assistant professor in the Department of Earth and Environmental Sciences, is using a $436,273, two-year grant from the National Institute of Environmental Health Sciences for his project, titled “Exposure to Perfluorinated Compounds and Risk for Autism Spectrum Disorders”.
While considerable research has been done into the genetic factors associated with autism spectrum disorders (ASD), much less is known of the non-genetic causes, including exposure to environmental chemicals. Shin’s project is focusing on perfluorinated compounds (PFCs) as a chemical class of interest, because they are used in a large variety of consumer products, including food packaging, textiles and non-stick coatings on cookware. PFCs are widely used to make everyday products more resistant to water, stains, and grease.
“PFCs have neurologic or neuro-developmental toxicity in experiments with laboratory animals,” Shin said. “Also, at least 5 million people in the U.S. are currently drinking water contaminated with PFCs above a health advisory level. The overall goal of this project is to determine whether exposure to PFCs at an early developmental stage – in the pregnancy or breastfeeding periods – is associated with risk for ASD.”
Shin is utilizing data from a pair of population studies to test his hypothesis. One is titled CHARGE (Childhood Autism Risk from Genetics and Environment), a population-based case-control study that has enrolled over 1,800 index children and their families. The CHARGE study began in 2003 and is the first large, population-based case-control investigation of environmental causes and risk factors for autism and developmental delay. The study provides a large number of cases (children with ASD) and controls (typically developing, or TD, children), along with blood samples from mothers when their children were 2 to 4 years old.
The other study is titled MARBLES (Markers of Autism Risk in Babies – Learning Early Signs) and is a prospective cohort, enrolling pregnant women who already have a child with ASD and are therefore at high risk for delivering another child with ASD. The MARBLES study, which began in 2006, investigates possible pre-natal and post-partum biological and environmental exposures and risk factors that may contribute to the development of autism. It is designed to identify causes and early markers of ASD.
Through their research, Shin and his colleagues hope to (1) determine whether exposure to PFCs at an early developmental stage is associated with risk for ASD; (2) evaluate associations between exposure sources and modifiers obtained in questionnaires and medical records and individual PFC serum measurements; and (3) develop a pharmacokinetic model using prospective measurements from the MARBLES study to reconstruct PFC exposure levels during pregnancy and breastfeeding periods for CHARGE participants.
“From CHARGE, which provides a large number of final diagnoses (ASD or TD), we will use direct measures in the mother’s blood as a proxy for early life children’s exposure during pregnancy and breastfeeding,” Shin said. “From MARBLES, which provides more accurate time-specific exposure measurements than CHARGE, we will use direct measures in the mothers’ blood collected during pregnancy and breastfeeding periods.”
Shin says that it is anticipated that the PFC levels in mothers’ blood samples taken when their children were 2 to 4 years old will be a good marker of exposure due to the relatively long elimination half-life of PFCs in the body. He will also capitalize on the MARBLES longitudinal biomarker measurements to reconstruct PFC exposure levels during pregnancy and breastfeeding periods for participants in CHARGE and then test the same hypothesis using reconstructed estimates.
The researchers will conduct PFC analysis of randomly selected blood samples from the mothers of 225 ASD case children and 225 controls (TD) in the CHARGE study, along with 1 to 3 blood samples from 209 mothers in the MARBLES study.
“Our project thereby achieves three things: a large sample size; precise characterization of PFC exposures during specific developmental periods; and associations of PFCs with cases of ASD that were confirmed by highly trained, research reliable clinicians using gold standard instruments,” Shin said. “This study will improve understanding of temporal changes in body burden from pregnancy through the first few years post-partum and provide uniquely high-quality data on the role of early PFC exposures in ASD.”
Arne Winguth, associate professor and chair of the Department of Earth and Environmental Sciences, said Shin’s project will provide valuable information about the relationship between products found in virtually every U.S. household and the risk of developing autism spectrum disorders in young children. The project also further advances the University’s goal of improving health and the human condition, which is one of the main pillars of UTA’s Strategic Plan 2020: Bold Solutions | Global Impact.
“Dr. Shin’s study has the potential to go a long way in increasing our understanding of some of the environmental factors that contribute to ASD, which are little-known to this point,” Winguth said. “This is the kind of research which could lead to development of new ways to limit the effects of autism and one day hopefully prevent it altogether.”
Shin’s research interests include environmental fate and transport modeling; exposure assessment; exposure reconstruction; pharmacokinetic modeling; and epidemiology. He received a B.S. in Environmental Engineering from Yonsei University in South Korea in 2005, an M.S. in Environmental Engineering from Carnegie Mellon University in 2007 and a Ph.D. in Environmental Health Sciences from the University of California-Irvine in 2011. He worked as a postdoctoral researcher at the University of California-Davis from 2011-16 and joined UTA in August 2016.