Identity and Toxicological Profile of Biocides Used in Hydraulic Fracturing – Analytical Data Considerations for Use in Risk Assessment

Oral Presentation

Prepared by A. Pawlisz, A. LeBeau
Conestoga-Rovers & Associates, 1755 Wittington Place, Suite 500, Dallas, TX, 75234, United States


Contact Information: apawlisz@craworld.com; 972-679-7872


ABSTRACT

Hydraulic fracturing (i.e., fracking) has maintained its exponential growth as the premier technology to extract natural gas and oil from shale formations. Hydraulic fracturing consists of injecting water, friction reducers, proppants, disinfectants, surfactants, thickeners, scale inhibitors, corrosion inhibitors, and acids to promote flow of hydrocarbons otherwise bound in tight formations not accessible by traditional drilling methods. The rapid explosion of volume and extent of fracking exploration has led to community, regulator, and health practitioner concerns over the potential health effects associated with exposure to fracking fluid constituents. Many of the disclosed ingredients are cited as harmless. However, there are certain chemical groups, such as antimicrobials, that have specific (by design) adverse biological activity. This presentation focuses on the identity and toxicity of fracking fluid constituents listed as having a disinfectant function. Each constituent is ranked according to its toxicity, percentage in fracking fluid, and frequency of use. Results show that approximately 100 hydraulic fluid additives are categorized as biocidal and/or antimicrobial. Some of the more commonly listed disinfectants are glutaraldehyde, naphthalene, ethoxylated nonylphenol, and tetrakis hydroxymethylphosphonium sulfate. Aldehydes were found to be the most common toxic ingredients, with the average content in fracking fluid of 2.5%. The toxicity and use synopsis on biocides is discussed in context of analytical data needs to perform a risk assessment.