A new study based in Pennsylvania measured health indicators of children born far, near, and very near, fracking sites. The study showed an effect that reached out to about 3 kilometers, but that was much stronger within about 1 kilometer, from fracking sites. The effects included lower birth weight and similar differences that are associated with in utero stress.
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.
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Im surprised at there seemed to be no mention of prevailing winds around sites, if examining exposure.
Im not sure they are even examining exposure! Just distance. Is that an accurate proxy ?
If the hypothysis thingy is that various chemicals cause harm in utero , why not look at children of female employees at the sites, who would likely have the most exposure?
Of course employees may have hazard controls that minimize exposure, that nearby residents dont have, as a confounder .
Theres something a bit odd about the science in this, to my non academic eyes.
It seems haphazard and a bit lazy, in that they dont seem to have gathered data or done experiments themselves. Its more of a statistical exercise.
Its not that hard to set up monitoring stations for chemicals is it? To go into peoples homes
and swab some surfaces?
Do blood tests of women and children?
Its also not immediatly clear what the null hypothysis is.
Im in no way saying the stats or data is incorrect.
Feeling tired and niggly.
They are explicitly not examining exposure, and are clear on that.
All of the things you are suggesting are good ideas, and impossible to fund without some reason to do so.
You start with the epidemiology, like this paper.
Wind direction presumes an air carried agent. That nay be jumping the gun
No odd at all for this type of study. I do wonder how proximity to the sites and economic status are linked: usually sites are in lower income areas, and sorting the effects of the pollution from issues related to economic status can be difficult.
They did address other variables and did matched pairs analysis, etc.
I didn’t see a direct analysis for status, but I’ll read it again.
” Limiting the sample to births to mothers living within 15 km, as shown in column (2), has little effect on the estimates, despite the sharp reduction in sample size.”
and
“The vector Xit of observable maternal and child characteristics includes indicators for child gender, maternal race and ethnicity (African-American, Hispanic, missing), mother’s age (<20, 20 to 24, 25 to 29, 30 to 34, 35+, missing), mother’s education (
Just recently back from my son’s wedding — and remembered this post.
I saw the items you quote when I read the article. Perhaps I need to think a bit more about whether those address the issue I mentioned above. I didn’t think they did, but will go over it again.