Many industrial chemicals that are used in the hydro-fracking process are known to be hormone disruptors that negatively affect reproductive hormones in humans. A recent study has now revealed that they can also disrupt thyroid and glucocorticoid hormone receptors, which play a vital role in maintaining optimal health.

According to researcher Christopher Kassotis, a PhD student at the University of Missouri, Columbia:

Among the chemicals that the fracking industry has reported using most often, all 24 that we have tested block the activity of one or more important hormone receptors. The high levels of hormone disruption by endocrine-disrupting chemicals (EDCs) that we measured, have been associated with many poor health outcomes, such as infertility, cancer and birth defects.

Kassotis points out that any wastewater spills that occur during the fracking operations -- which involves pumping vast amounts of water mixed with chemicals into the ground to crack open rocks deep underground to release the shale gas trapped within -- could contaminate both surface water and groundwater sources.

In a previous study, the researchers examined water samples collected from fracking sites in Garfield County, Colorado, where spills were known to have occurred, and compared them to water samples collected from areas situated some distance from hydro-fracking sites. The water samples collected from the drilling sites spills exhibited moderate to high levels of EDC chemicals that disrupted both female (estrogen) hormones and male (androgen) hormones, while the water samples collected in areas distant from fracking operations had little effect on human reproduction hormones.

This latest study expands on the earlier research to gain a better understanding of whether fracking chemicals disrupts other vital hormone receptors in the human body besides the estrogen and androgen reproductive hormone receptors (receptors are cellular proteins that hormones bind to in order to carry out their function). The researchers were particularly interested to see whether the chemicals had any effect on the following hormones: progesterone, glucocorticoid, and thyroid, which respectively play vital roles in reproduction; immune response and fertility; and metabolism, brain development and maintaining good health.

After testing 24 the hormone disrupting ability of the most common hydro-fracking chemicals the researchers found the following:

• 20 prohibited estrogen from binding to the cellular protein receptor, and thus disrupted natural functioning
• 17 blocked the androgen receptor
• 10 chemicals inhibited the progesterone receptor
• 10 chemicals inhibited the glucocorticoid receptor
• 7 chemicals inhibited the thyroid receptor

According to Kassotis, these chemicals have not been measured in local drinking water samples. Although they may not show up in the same high concentrations in drinking water at areas situated in close proximity to drilling sites, he cautions that tested drinking water typically contains an array of EDCs, and when these chemicals are mixed together their hormone-disrupting effects can be exacerbated and become far worse than that of any of these chemicals acting alone.

We don't know what the adverse health consequences might be in humans and animals exposed to these chemicals," Kassotis said, "but infants and children would be most vulnerable because they are smaller, and infants lack the ability to break down these chemicals.