By Steven E. Panter, P.G., CGWP and Nancy Rothman, Ph.D.
In July 2020, New York State (NYS) adopted Drinking Water Standards (DWS) for the Emerging Contaminants 1,4-dioxane, perfluorooctanoic acid (PFOA), and perfluorooctanoic sulfonate (PFOS). The compound 1,4-dioxane is used as a stabilizer for chlorinated solvents. PFOA and PFOS are two Polyfluorinated Alkyl Substances (PFAS), man-made chemicals used in water repellent applications, non-stick surfaces, and firefighting foam (aqueous film-forming foam or AFFF), among other things. PFAS are commonly referred to as “forever chemicals” as they occur widely and persistently in the environment. As approval of these standards is imminent, DW suppliers will be required to begin testing for these Emerging Contaminants.
The NYS DWS for 1,4-dioxane at one part per billion (ppb or μg/L) is the first in the nation and the DWS for PFOA and PFOS at 10 parts per trillion (ppt or ng/L) each are among the lowest in the nation. These very low standards were adopted to protect drinking water resources and safeguard citizens. NYS is committed to enforcing these DWS and, in addition, plans future actions to protect NY communities as recently stated in a press release from Governor Cuomo’s office: “New York will conduct monitoring at Superfund, brownfield, potential firefighting foam hot spots, and inactive landfill sites to determine whether PFAS impacts are detectable. The State will build upon its work to date to address emerging contaminants through a suite of legal and regulatory actions coupled with swift on-the-ground response for sites where contamination is detected.” 
PFOA and PFOS are only two compounds comprising the class of PFAS. Environmental advocates are asking NYS to consider expanding the DWS to include additional compounds (e.g., PFNA). Therefore, sites currently testing for PFOA and PFOS need to not only ensure that sensitivity requirements are met (non-detects are at or below the DWS) for these two compounds but should also test for a broader list of PFAS to capture additional compounds that may be regulated in the future.
Achieving compliance with the new DWS for these Emerging Contaminants requires accurate values for non-detects. This means that very low reporting limits must be achieved through the use of sensitive sample preparation and analysis methods such as Isotope Dilution techniques and state-of-the-art instrumentation including Gas Chromatography/Mass Spectrometry operated in the Selected Ion Monitoring mode (GC/MS-SIM) for 1,4-dioxane and Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) for PFAS analysis to ensure that the values for the non-detects are below the DWS.
The technical nuances of how these compounds are analyzed and the data interpreted could mean the difference between unnecessary investigation/remediation verses moving the site to closure. Key quality control (QC) measures including method and field blanks, laboratory control samples, matrix spikes, field duplicates, and surrogate results must be evaluated to determine whether the results are reliable or potentially biased. Critical QC issues include false positives and false negatives, which may result in requiring action where no action is required or not taking an action when there is potential for risk. As the complexity of the matrices increases from drinking water to groundwater with entrained particles and on to other impacted environmental media such as soils and sediments, the complexity of the analyses and data interpretation also increases. Understanding the data quality is paramount to decision-making when combining data sets from one sampling event to another or from one laboratory to another.
At FLS, we can assist you in addressing these issues and help you avoid unnecessary follow-up sampling and re-work where these compounds pose potential health, environmental, and regulatory problems. We have assembled an expert team to focus on Emerging Contaminants that includes FLS project engineers, senior analytical chemists from New Environmental Horizons (NEH), and environmental legal counsel. FLS (http://flemingleeshue.com) specializes in understanding federal, state and local regulations that drive remediation, regulatory compliance, data management, and data analysis. NEH (http://neh-inc.com) specializes in the planning and evaluation of chemical data for use in regulatory decisions and risk assessment with senior chemists that lead policy and guidance for 1,4-dioxane and PFAS on the Interstate Technology and Regulatory Council (ITRC). Please contact us at firstname.lastname@example.org or 212-675-3225 to see how we can help you meet your project goals.