Case-Control Analysis of Birth Outcomes in Relation to Residential Proximity to Mountaintop Removal Mining During Pregnancy in Kentucky, 2000 - 2017

Case-control analysis of birth outcomes in relation to residential proximity to mountaintop removal mining during pregnancy in Kentucky, 2000-2017 Specific Aims Cross sectional and ecological studies have demonstrated clear associations between maternal residence in coal mining communities and poor birth outcomes, including low birthweight [1] and a variety of birth defects [2, 3]. One study examined a specific technique used in coal mining, mountaintop removal (MTR), and concluded that this type of mining was associated with high rates of several types of birth defects in surrounding communities.[2] Mountaintop removal mining is especially controversial due to its extreme reshaping of the natural environment. To reach thin seams of coal buried within strata of other types of rock, miners will remove entire mountaintops or mountainsides, displacing huge volumes of rock and soil "overburden" to nearby valleys or other low-lying areas. This process could liberate trace elements or minerals harmful to human health, polluting the local air and water. Those studies completed so far, however, have lacked the ability to control for relevant individual factors-e.g., age, smoking-that are known to influence risk of low birthweight and birth defects. To date, we are unaware of any other type of observational study that has addressed this issue. A population-based case-control study, however, could allow for adjustment of individual­level factors such as smoking status, maternal age, BMI, pre-existing health conditions, and gestational age. In this study, our overall objective is to use case-control study designs to characterize the relationship between residential proximity to active mountaintop removal mining and birth outcomes, using birth certificates data as the source of information on birth outcomes and other relevant maternal factors. This study thus encompasses two separate but complementary aims focused on birth outcomes: 1. Conduct o case-control analysis ofneurol tube and urogenital defects among newborns in Appalachian Kentucky in relation to the family home's proximity to active MTR sites In this aim we will examine neural tube, musculoskeletal, and urogenital defects because they severe birth defects that are noticeable immediately, or very shortly after birth, and are recorded on a birth certificate. Neural tube defects were associated with coal mining in a Chinese study,[3] and musculoskeletal and urogenital defects were significantly associated with MTR mining in a study from the Central Appalachian region.[2] Maternal address is listed on the birth certificate, and will enable us to precisely geocode the residence in relation to MTR sites. Live births with neural tube (Spina bifida and anencephaly) urogenital (hypospadias), and musculoskeletal (omphalocele, gastroschisis, and cleft palate or lip) defects from Kentucky's Appalachian counties will comprise cases, and controls will be comprised of births without defects matched to cases by maternal age and month of birth. Spatial data layers describing the exact locations of active MTR sites every year from 1985 through 2015 are available from SkyTruth,[4] a non-profit organization that monitors publicly-available satellite imagery and other remote sensing data for threats to the environment and human health. Using geographic information system (GIS) software, these data will enable us to determine distance to the nearest MTR mining site, and/or density of MTR mining in the local area, during the year of gestation, when exposures would be most relevant to birth outcomes. After case-control matching and GIS analysis, we will implement a multivariable logistic regression model in Stata 15.1 (StataCorp., College Station, TX) to obtain separate odds ratios that estimate risk of neural tube, urogenital, and musculoskeletal defects among children born to women living in proximity to MTR sites during pregnancy, adjusting for other factors that may impact these types of birth defects, such as pre-pregnancy health conditions. 2. Conduct a case-control analysis of/ow birthweight among newborns in Appalachian Kentucky in relation to the family home's proximity to active MTR sites. To address this aim, we will conduct an analysis similar to Aim 1, but will instead define cases as live births with a birthweight less than 2500 grams, and controls as live births with a birthweight of 2500 grams or greater. For the analysis we will match cases and controls on maternal age and gestational age, and adjust for BMI, pre-pregnancy medical conditions, parity, and other potentially relevant factors in a multivariable logistic regression model to estimate risk of low birthweight among the children born to women living in proximity to MTR sites during pregnancy.