Christopher P. Higgins

Bio: Christopher P. Higgins is an academic researcher from Colorado School of Mines. The author has contributed to research in topics: Chemistry & Medicine. The author has an hindex of 46, co-authored 156 publications receiving 9803 citations. Previous affiliations of Christopher P. Higgins include Oregon State University & Johns Hopkins University.

Sorption of Perfluorinated Surfactants on Sediments

Abstract: The sorption of anionic perfluorochemical (PFC) surfactants of varying chain lengths to sediments was investigated using natural sediments of varying iron oxide and organic carbon content. Three classes of PFC surfactants were evaluated for sorptive potential: perfluorocarboxylates, perfluorosulfonates, and perfluorooctyl sulfonamide acetic acids. PFC surfactant sorption was influenced by both sediment-specific and solution-specific parameters. Sediment organic carbon, rather than sediment iron oxide content, was the dominant sediment-parameter affecting sorption, indicating the importance of hydrophobic interactions. However, sorption also increased with increasing solution [Ca2+] and decreasing pH, suggesting that electrostatic interactions play a role. Perfluorocarbon chain length was the dominant structural feature influencing sorption, with each CF2 moiety contributing 0.50−0.60 log units to the measured distribution coefficients. The sulfonate moiety contributed an additional 0.23 log units to the ...

A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)?

Abstract: More than 3000 per- and polyfluoroalkyl substances (PFASs) are, or have been, on the global market, yet most research and regulation continues to focus on a limited selection of rather well-known long-chain PFASs, particularly perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and their precursors. Continuing to overlook the vast majority of other PFASs is a major concern for society. We provide recommendations for how to proceed with research and cooperation to tackle the vast number of PFASs on the market and in the environment.

Detection of Poly- and Perfluoroalkyl Substances (PFASs) in U.S. Drinking Water Linked to Industrial Sites, Military Fire Training Areas, and Wastewater Treatment Plants.

Abstract: Drinking water contamination with poly- and perfluoroalkyl substances (PFASs) poses risks to the developmental, immune, metabolic, and endocrine health of consumers. We present a spatial analysis of 2013–2015 national drinking water PFAS concentrations from the U.S. Environmental Protection Agency’s (US EPA) third Unregulated Contaminant Monitoring Rule (UCMR3) program. The number of industrial sites that manufacture or use these compounds, the number of military fire training areas, and the number of wastewater treatment plants are all significant predictors of PFAS detection frequencies and concentrations in public water supplies. Among samples with detectable PFAS levels, each additional military site within a watershed’s eight-digit hydrologic unit is associated with a 20% increase in PFHxS, a 10% increase in both PFHpA and PFOA, and a 35% increase in PFOS. The number of civilian airports with personnel trained in the use of aqueous film-forming foams is significantly associated with the detection of ...

Determining Transport Efficiency for the Purpose of Counting and Sizing Nanoparticles via Single Particle Inductively Coupled Plasma Mass Spectrometry

Abstract: Currently there are few ideal methods for the characterization of nanoparticles in complex, environmental samples, leading to significant gaps in toxicity and exposure assessments of nanomaterials. Single particle-inductively coupled plasma-mass spectrometry (spICPMS) is an emerging technique that can both size and count metal-containing nanoparticles. A major benefit of the spICPMS method is its ability to characterize nanoparticles at concentrations relevant to the environment. This paper presents a practical guide on how to count and size nanoparticles using spICPMS. Different methods are investigated for measuring transport efficiency (i.e., nebulization efficiency), an important term in the spICPMS calculations. In addition, an alternative protocol is provided for determining particle size that broadens the applicability of the technique to all types of inorganic nanoparticles. Initial comparison, using well-characterized, monodisperse silver nanoparticles, showed the importance of having an accurate...

Persistence of Perfluoroalkyl Acid Precursors in AFFF-Impacted Groundwater and Soil

Abstract: Several classes of polyfluorinated chemicals that are potential precursors to the perfluorinated carboxylates and sulfonates are present in aqueous film-forming foams (AFFF). To assess the persistence of these AFFF-derived precursors, groundwater, soil, and aquifer solids were obtained in 2011 from an unlined firefighter training area at a U.S. Air Force Base where AFFF was regularly used between 1970 and 1990. To measure the total concentration of perfluorinated carboxylate and sulfonate precursors in archived AFFF formulations and AFFF-impacted environmental samples, a previously developed assay that uses hydroxyl radical to oxidize precursors to perfluorinated carboxylates was adapted for these media. This assay was employed along with direct measurement of 22 precursors found in AFFF and a suite of other poly- and perfluoroalkyl substances (PFASs). On a molar basis, precursors accounted for 41–100% of the total concentration of PFASs in archived AFFF formulations. In the training area, precursors meas...

Perfluoroalkyl and polyfluoroalkyl substances in the environment: Terminology, classification, and origins

Abstract: The primary aim of this article is to provide an overview of perfluoroalkyl and polyfluoroalkyl substances (PFASs) detected in the environment, wildlife, and humans, and recommend clear, specific, and descriptive terminology, names, and acronyms for PFASs. The overarching objective is to unify and harmonize communication on PFASs by offering terminology for use by the global scientific, regulatory, and industrial communities. A particular emphasis is placed on long-chain perfluoroalkyl acids, substances related to the long-chain perfluoroalkyl acids, and substances intended as alternatives to the use of the long-chain perfluoroalkyl acids or their precursors. First, we define PFASs, classify them into various families, and recommend a pragmatic set of common names and acronyms for both the families and their individual members. Terminology related to fluorinated polymers is an important aspect of our classification. Second, we provide a brief description of the 2 main production processes, electrochemical fluorination and telomerization, used for introducing perfluoroalkyl moieties into organic compounds, and we specify the types of byproducts (isomers and homologues) likely to arise in these processes. Third, we show how the principal families of PFASs are interrelated as industrial, environmental, or metabolic precursors or transformation products of one another. We pay particular attention to those PFASs that have the potential to be converted, by abiotic or biotic environmental processes or by human metabolism, into long-chain perfluoroalkyl carboxylic or sulfonic acids, which are currently the focus of regulatory action. The Supplemental Data lists 42 families and subfamilies of PFASs and 268 selected individual compounds, providing recommended names and acronyms, and structural formulas, as well as Chemical Abstracts Service registry numbers. Integr Environ Assess Manag 2011;7:513–541. © 2011 SETAC

Of Theory and Practice

Abstract: Much has been written about theory and practice in the law, and the tension between practitioners and theorists. Judges do not cite theoretical articles often; they rarely "apply" theories to particular cases. These arguments are not revisited. Instead the Essay explores the working and interaction of theory and practice, practitioners and theorists. The Essay starts with a story about solving a legal issue using our intellectual tools - theory, practice, and their progenies: experience and "gut." Next the Essay elaborates on the nature of theory, practice, experience and "gut." The third part of the Essay discusses theories that are helpful to practitioners and those that are less helpful. The Essay concludes that practitioners theorize, and theorists practice. They use these intellectual tools differently because the goals and orientations of theorists and practitioners, and the constraints under which they act, differ. Theory, practice, experience and "gut" help us think, remember, decide and create. They complement each other like the two sides of the same coin: distinct but inseparable.

Sources, fate and transport of perfluorocarboxylates.

Abstract: This review describes the sources, fate, and transport of perfluorocarboxylates (PFCAs) in the environment, with a specific focus on perfluorooctanoate (PFO). The global historical industry-wide emissions of total PFCAs from direct (manufacture, use, consumer products) and indirect (PFCA impurities and/or precursors) sources were estimated to be 3200−7300 tonnes. It was estimated that the majority (∼80%) of PFCAs have been released to the environment from fluoropolymer manufacture and use. Although indirect sources were estimated to be much less important than direct sources, there were larger uncertainties associated with the calculations for indirect sources. The physical−chemical properties of PFO (negligible vapor pressure, high solubility in water, and moderate sorption to solids) suggested that PFO would accumulate in surface waters. Estimated mass inventories of PFO in various environmental compartments confirmed that surface waters, especially oceans, contain the majority of PFO. The only environm...