A cluster of birth defects in which suckling foals inhaled milk into their lungs has been linked to water contaminated with aromatic hydrocarbons, most likely from nearby fracking, according to researchers.
A well that employs hydraulic fracturing, or fracking, was located within a mile of the Pennsylvania farm, Cornell University researcher Kathleen Mullen and her colleagues reported the journal, Science of The Total Environment.
The tracheal milk aspiration issue, formally known as dysphagia, was eliminated on the farm once water filtration equipment was installed, the study team reported.
The foal cluster occurred between 2014 and 2016. The owner of the affected property also owned a farm 420km to the east, in New York State where fracking does not occur, with breeding mares moved between the farms.
The broodmares either spent their entire gestation on one farm or moved to the other farm in late gestation. Broodmares were fed the same commercial concentrate and hay was sourced from a single supplier.
Sixty-five foals were born in the time period in question, 17 of which were dysphagic. Of the 17 dysphagic foals, six were from mares that spent their entire gestation on the Pennsylvania farm. The other 11 were born to mares who had moved from the New York to Pennsylvania farm in mid to late gestation.
Mothers of the dysphagic Pennsylvania foals, when they foaled at the New York farm, never had a subsequent abnormal foal, even if they had lived on the Pennsylvania property for the first half of gestation.
Dsyphagia is an uncommon condition in foals, typically affecting fewer than 1 percent of newborns.
The affected newborns in the study showed a strong suckle reflex and an altered, subdued mental activity.
The researchers found that the odds of dysphagia occurring in a foal increased with the number of months each pregnant mare spent on the Pennsylvania farm.
Colts were more likely to be born dysphagic than females.
The study team from Cornell University and Oregon State University spent 21 months exploring the issue in a broad process that involved analyzing blood and tissue samples from the mares and foals on each farm, physical examinations, and the testing of water, soil and feed samples from both farms.
They conducted passive sampling of air and water from each property for polycyclic aromatic hydrocarbons (PAHs).
The key difference in samples between the two farms was found in the well water. Concentrations of a group of PAHs were higher in the Pennsylvania farm water than they were in the New York farm supply.
The researchers said that, with the exception of May 2016 samples, most of the forensic ratios for the Pennsylvania well-water samples reflected a petrogenic signature, supporting fracking activities as a possible source.
The installation of a water filtration and treatment system on the Pennsylvania property dropped the levels of PAHs in the drinking water, and no cases of dysphagia were reported in foals born in subsequent years (2017–2019).
The researchers said they had systematically eliminated known causes of dysphagia and performed a comprehensive toxicological investigation of biological and environmental samples from both farms.
“A similar study of these environmental variables would be nearly impossible to undertake in humans,” they said.
The study team noted that PAHs have been identified in other studies in both water and air near fracking wells.
Between 2000 and 2013, the US Environmental Protection agency estimated that about 3900 public water systems, serving 8.6 million people, had at least one well in which fracking was employed within a mile of their water source.
There is concern, they say, that the rapid rate of fracking is outpacing the scientific understanding of its health and environmental impacts.
Of the 632 chemicals reported to be used in such operations between 2005 and 2009, 353 are known to cause adverse health effects.
“Human, animal and environmental exposures to these chemicals arise from contamination of soil and water resources and from emissions of volatile and semi-volatile organic compounds, including PAHs.”
They suggest that future studies should quantify PAHs in biological samples in animals that live in areas with active fracking to evaluate the toxicity of the mixture of PAHs at the concentrations seen in the current study.
More work is also needed to establish if there are long-term health effects (other than dysphagia) of fetal exposures for both humans and animals.
“Notably, this study demonstrates that domestic large animals such as horses can serve as important sentinels for human health risks associated with (fracking) activities,” they said.
The study team comprised Mullen, who is affiliated with Littleton Equine Medical Center in Colorado and Cornell University; Brianna Rivera, Lane Tidwell and Kim Anderson, with Oregon State University; and Renata Ivanek and Dorothy Ainsworth, also with Cornell University.
Environmental surveillance and adverse neonatal health outcomes in foals born near unconventional natural gas development activity
Kathleen R. Mullen, Brianna N. Rivera, Lane G.Tidwell, Renata Ivanek, Kim A.Anderson and Dorothy M. Ainsworth
Science of The Total Environment, Volume 731, 20 August 2020, 138497