Babies born with weights less than 5 lbs 8 ounces (2,500 grams), can face a host of health challenges and an increased risk for chronic health problems like diabetes and heart disease later in life. Now, for the first time, researchers at The University of New Mexico have linked industrial air pollution to the state's above-average rates of babies born with low birthweight in a study published in the Journal of Environmental Management.
About one in 12 babies in the United States is born with low birthweight, but in New Mexico, the rate is nearly one in 10, according to March of Dimes. While the connection between low birth weight and air pollution has been researched before in other places, the study, "Industrial air pollution and low birth weight in New Mexico, USA," is the first of its kind in New Mexico. The study examined the relationship between industrial emissions that mothers were exposed to at their residential locations while pregnant and the weight of their babies at birth.
The research team included members of the UNM Department of Geography and Environmental Studies: Assistant Professor Xi Gong, Ph.D. Candidate Yanhong Huang, and Associate Professor Yan Lin; as well as Jenny Duong from New Mexico Department of Health; Assistant Professor Shuguang Leng from UNM Department of Internal Medicine; Professor F. Benjamin Zhan from Texas State University; Professor Yan Guo from University of Miami; and Associate Professor Li Luo from UNM Department of Internal Medicine.
The team used data from the New Mexico Department of Health and the Environmental Protection Agency in an emission weighted proximity model to quantify exposure intensity by home address. They analyzed New Mexico birth certificates from 2008 to 2017, which included 233,340 babies with normal birth weight and 22,375 babies with low birth weight (defined as less than 2500 grams in the study). Researchers also compared information on demographic and medical factors between both groups for the analysis.
"We wanted to find out if industrial air pollution is a risk factor for low birthweight in New Mexico and we were able to identify five air pollutants that show significant positive associations to low birthweight," Huang said.
Low birth weight can contribute to the development of diabetes, heart disease, high blood pressure, developmental disabilities, metabolic syndrome and obesity later in life. It can also create immediate challenges for babies like retinopathy, and problems with breathing and digestion, according to March of Dimes.
The study relied on annual emissions data from the EPA's Toxic Release Inventory Program, which requires industrial facilities in the U.S. to submit detailed emissions reports each year, and air quality monitoring data from the EPA's Air Quality System DataMart to determine the amounts of air pollutants pregnant people were exposed to.
Researchers discovered that residential exposures to several pollutants during pregnancy had positive associations with low birthweight in babies: 1,2,4-trimethylbenzene, benzene, chlorine, ethylbenzene, and styrene. Each of the pollutants is the result of industrial operations and the researchers found that the closer pregnant people lived to facilities generating those pollutants, the more likely they were to have a baby with low birthweight.
While many of the pollutants have been identified as contributors to low birthweight in previous studies, this study identified 1,2,4-trimethylbenzene for the first time. The publication is the first individual-based study conducted over a long period in New Mexico that examines the effects of air pollution on low birthweight.
The study found that emissions were largely concentrated in the northwest region, southeast region and Albuquerque area. Researchers suggest further research should emphasize the southeastern part of the state, which is close to more than 50 industrial facilities in Texas that emit the five chemicals identified in the study.
"We hope these results can be used to help the public and government officials better understand the environmental risks of industrial air pollutants," Gong said. Gong and Huang will next work on a similar study focused on industrial air pollution and cancer rates in New Mexico.
