Given this finding, it is estimated that about 29,000 newborns are born in fracking danger zones per year in the US.

The study is in Science Advances. Here is the abstract, which is pretty clear:

The development of hydraulic fracturing (“fracking”) is considered the biggest change to the global energy production system in the last half-century. However, several communities have banned fracking because of unresolved concerns about the impact of this process on human health. To evaluate the potential health impacts of fracking, we analyzed records of more than 1.1 million births in Pennsylvania from 2004 to 2013, comparing infants born to mothers living at different distances from active fracking sites and those born both before and after fracking was initiated at each site. We adjusted for fixed maternal determinants of infant health by comparing siblings who were and were not exposed to fracking sites in utero. We found evidence for negative health effects of in utero exposure to fracking sites within 3 km of a mother’s residence, with the largest health impacts seen for in utero exposure within 1 km of fracking sites. Negative health impacts include a greater incidence of low–birth weight babies as well as significant declines in average birth weight and in several other measures of infant health. There is little evidence for health effects at distances beyond 3 km, suggesting that health impacts of fracking are highly local. Informal estimates suggest that about 29,000 of the nearly 4 million annual U.S. births occur within 1 km of an active fracking site and that these births therefore may be at higher risk of poor birth outcomes.

Hydraulic fracturing and infant health: New evidence from Pennsylvania, 2017, by Janet Currie, Michael Greenstone, and Katherine Meckel. Science Advances 3(12) 13 December 2017.

Consider the “Infant Health Index.” Ghis ranges from 0 to 1, with one the healthiest. The index incorporates birth weight, anomalies, and indicators of bad health at the time of birth. The following graphic shows the health index as it is observed (on average) over a range of distances form fracking sites.

Caption for the graphic, from Science Advances:

Effect of fracturing on infant health index, county fixed effects. The left y axis of the graph indicates coefficients and CIs from a version of Eq. 1 in which “Near” is replaced with 15 distance indicators representing the proximity of maternal residence to well sites; the coefficients represent the in utero effect on infant health of hydraulic fracturing (that is, conception occurs after well spud date) at 1-km intervals from the well site. The data sources for the regression are the universe of birth certificates issued in Pennsylvania from 2004 to 2013 and the Pennsylvania DEP Internal Operator Well Inventory. We exclude births with missing values for gestation length or latitude/longitude of maternal residence. We calculate the distance between maternal residence and well sites using Vincenty’s formula. The infant health index ranges from 0 to 1; an increase indicates better health. The regression specification includes year FE, month of birth FE, and county of maternal residence FE. The following demographic controls are also included: mother is married, marital status missing, maternal race and ethnicity (black, Hispanic, missing), maternal education (no HS, HS diploma, some college, college, advanced degree, missing), maternal age (<20, 20 to 24, 25 to 29, 30 to 34, 35+, missing), child is male, child sex missing, and child parity (first, second, third, fourth born and higher, parity missing). Standard errors are clustered on maternal ID. The right y axis plots average yearly births at each distance from a well site.

Low birth weight may actually be handy in areas where large energy related industry control the politics well enough to carry out environmentally horrendous activities such as fracking. Such industries may have mining operations going on somewhere, and they can transfer the ensmallened children, after they’ve grown up enough, to wherever they need to work in the mines. Smaller people will fit into smaller holes, and take up less of the valuable air at such localities.

But the parents of these children may have different ideas. Lower birth weight is associated with various helth risks such as a shorter life span, behavioral disorders such as attention deficit, asthma, lower levels of intelligence or academic performance, and so on. The study at hand notes that “… one large-scale study of twin pairs in Norway found that a 10% difference in birth weight in their predominantly low–birth weight pairs was associated with a 1% difference in the probability of graduating from high school and a 1% difference in earnings, with outcomes all being better for the higher-weight twin.” So, generally, the low birth weight outcome is seen as a bad thing.

The assumption here is that chemicals used in fracking poison the immediate environment, and affect pregnant women an their babies. The exact pathway of the pollutants and the exact physiological process are unknown as yet. Longer term studies may address those issues, but let us hope that there can’t be such long term studies because fracking, and in general dependence on the highly polluting petroleum industry to make us all incredibly happy as they have done so far, will end sooner.

Clinton has been doing well in “The South.” Of course, defining what “The South” is is pretty tricky. I divided up the states by “Deep South” vs. Other, so all the usual orginal deep south states count as “southern” except Florida. You know what they say about Florida. “The farther south you go, the farther north you get.” Also, Texas is not deep south in the traditional sense.

Using this rough division, Clinton wins all the time in the “Deep South” and Sanders wins some and loses some in the other states, as shown in this handy dandy graphic:

This is good news for Sanders, because the three big states coming up are New York, Pennsylvania, and California, and they are not in the deep south. Of the remaining states, only Kentucky is southern. So, this biases future primaries, given this one variable, towards Sanders.

Being “deep south” vs. not is in and of itself a bit of a meta-variable, associated with other factors with in the Democratic Party, mainly ethnicity.