Nanoparticles (NPs) in contact with biological fluids experience changes in surface chemistry that can impact their biodistribution and downstream physiological impact. One such change involves the formation of a protein corona (PC) on the surface of NPs. Here we present a foundational study on PC formation following the incubation of polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs, 50 nm) in the plasma of smallmouth bass (Micropterus dolomieu). PC formation increases with exposure time and is also affected by gender, with AgNPs incubated in male plasma having slightly thinner PCs and less negative zeta potentials than those incubated in female plasma. Proteomic analysis also revealed gender-specific differences in PC composition: in particular, egg-specific proteins (vitellogenin (VTG) and zona pellucida (ZP) were identified only in PCs derived from female plasma, raising the possibility of their roles in AgNP-related reproductive toxicity by promoting their accumulation in developing oocytes.

During the past decade, use of organophosphate compounds as flame retardants and plasticizers has increased. Numerous studies investigating biomarkers (i.e., urinary metabolites) demonstrate ubiquitous human exposure and suggest that human exposure may be increasing. To formally assess temporal trends, we combined data from 14 U.S. epidemiologic studies for which our laboratory group previously assessed exposure to two commonly used organophosphate compounds, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP). Using individual-level data and samples collected between 2002 and 2015, we assessed temporal and seasonal trends in urinary bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) and diphenyl phosphate (DPHP), the metabolites of TDCIPP and TPHP, respectively. Data suggest that BDCIPP concentrations have increased dramatically since 2002. Samples collected in 2014 and 2015 had BDCIPP concentrations that were more than 15 times higher than those collected in 2002 and 2003 (10β = 16.5; 95% confidence interval from 9.64 to 28.3). Our results also demonstrate significant increases in DPHP levels; however, increases were much smaller than for BDCIPP. Additionally, results suggest that exposure varies seasonally, with significantly higher levels of exposure in summer for both TDCIPP and TPHP. Given these increases, more research is needed to determine whether the levels of exposure experienced by the general population are related to adverse health outcomes.

Per- and polyfluoroalkyl substances (PFASs) are highly persistent synthetic chemicals, some of which have been associated with cancer, developmental toxicity, immunotoxicity, and other health effects. PFASs in grease-resistant food packaging can leach into food and increase dietary exposure. We collected ~400 samples of food contact papers, paperboard containers, and beverage containers from fast food restaurants throughout the United States and measured total fluorine using particle-induced γ-ray emission (PIGE) spectroscopy. PIGE can rapidly and inexpensively measure total fluorine in solid-phase samples. We found that 46% of food contact papers and 20% of paperboard samples contained detectable fluorine (>16 nmol/cm2). Liquid chromatography/high-resolution mass spectrometry analysis of a subset of 20 samples found perfluorocarboxylates, perfluorosulfonates, and other known PFASs and/or unidentified polyfluorinated compounds (based on nontargeted analysis). The total peak area for PFASs was higher in 70% of samples (10 of 14) with a total fluorine level of >200 nmol/cm2 compared to six samples with a total fluorine level of <16 nmol/cm2. Samples with high total fluorine levels but low levels of measured PFASs may contain volatile PFASs, PFAS polymers, newer replacement PFASs, or other fluorinated compounds. The prevalence of fluorinated chemicals in fast food packaging demonstrates their potentially significant contribution to dietary PFAS exposure and environmental contamination during production and disposal.

Pavement sealcoat products contain high concentrations of unsubstituted polycyclic aromatic hydrocarbons (PAHs), but the assessment of the potential toxicological impact is limited without the inclusion of PAH derivatives. This study determined the concentrations of 23 unsubstituted PAHs, 11 high molecular weight-PAHs (MW302-PAHs), and 56 PAH derivatives, including 10 methyl-PAHs (MPAHs), 10 heterocyclic-PAHs (Hetero-PAHs), 26 nitrated-PAHs (NPAHs), and 10 oxygenated-PAHs (OPAHs) in coal-tar and asphalt based sealcoat products and time point scrapes. Inclusion of MW302-PAHs resulted in an increase of 4.1-38.7% in calculated benzo[a]pyrene-carcinogenic equivalent (B[a]Peq) concentrations for the coal-tar based products. Increases in some NPAH and OPAH concentrations were measured after application, suggesting the possibility of photochemical transformation of unsubstituted PAHs. The Ames assay indicated that the asphalt based product was not mutagenic, but the coal-tar based sealcoat products were. The zebrafish developmental toxicity tests suggested that fractions where NPAHs and OPAHs eluted have the most significant adverse effects.

Qualitatively and quantitatively, we have demonstrated that airborne polychlorinated biphenyl (PCB) concentrations in the air surrounding New Bedford Harbor (NBH) are caused by its water PCB emissions. We measured airborne PCBs at 18 homes and businesses near NBH in 2015, with values ranging from 0.4 to 38 ng m-3, with a very strong Aroclor 1242/1016 signal that is most pronounced closest to the harbor and reproducible over three sampling rounds. Using U.S. Environmental Protection Agency (U.S. EPA) water PCB data from 2015 and local meteorology, we predicted gas-phase fluxes of PCBs from 160 to 1200 μg m-2 day-1. Fluxes were used as emissions for AERMOD, a widely applied U.S. EPA atmospheric dispersion model, to predict airborne PCB concentrations. The AERMOD predictions were within a factor of 2 of the field measurements. PCB emission from NBH (110 kg year-1, average 2015) is the largest reported source of airborne PCBs from natural waters in North America, and the source of high ambient air PCB concentrations in locations close to NBH. It is likely that NBH has been an important source of airborne PCBs since it was contaminated with Aroclors more than 60 years ago.

Exposure to poly and perfluoroalkyl substances (PFASs) has been associated with adverse health effects in humans and wildlife. Understanding pollution sources is essential for environmental regulation but source attribution for PFASs has been confounded by limited information on industrial releases and rapid changes in chemical production. Here we use principal component analysis (PCA), hierarchical clustering, and geospatial analysis to understand source contributions to 14 PFASs measured across 37 sites in the Northeastern United States in 2014. PFASs are significantly elevated in urban areas compared to rural sites except for perfluorobutane sulfonate (PFBS), N-methyl perfluorooctanesulfonamidoacetic acid (N-MeFOSAA), perfluoroundecanate (PFUnDA) and perfluorododecanate (PFDoDA). The highest PFAS concentrations across sites were for perfluorooctanate (PFOA, 56 ng L-1) and perfluorohexane sulfonate (PFOS, 43 ng L-1) and PFOS levels are lower than earlier measurements of U.S. surface waters. PCA and cluster analysis indicates three main statistical groupings of PFASs. Geospatial analysis of watersheds reveals the first component/cluster originates from a mixture of contemporary point sources such as airports and textile mills. Atmospheric sources from the waste sector are consistent with the second component, and the metal smelting industry plausibly explains the third component. We find this source-attribution technique is effective for better understanding PFAS sources in urban areas.

It is amazing how much we learn to perceive things through units that become common in our lives. On a cool autumn morning, you look at the thermostat in the United States and from experience you know how to choose the perfect coat for 52 °F. However, if you hear the temperature in Gallargues-le-Montueux, France, reached 46 °C (this past July), you probably have to Google a temperature conversion to change it to Fahrenheit (115 °F) to understand it. When you go to work and drive on a road posted at 35 mph, you know what that speed feels like, but what if you were in Europe and it was posted in kph? Or what if a European tells you the mileage for her car in liters per 100 km, and you struggle to relate that to numbers you know based on miles per gallon. We develop a sense of things based on experience with certain units, and when those are different, you lose your perception of the quantity. Most of us do not have a basic sense of the amount of energy we consume for different activities in our lives. One reason is that we find it difficult to compare things that have different units, even if they describe the same property (such as temperature), and units of energy are particularly challenging! We often make comparisons based on something we can relate to, such as saying how many football fields we could cover or how many Olympic size pools we could fill. It is more difficult to relate energy units within one context, such as energy for our apartment or house, to other things in our life, such as fuel for our car. We need common units to be able to become literate in the amount of energy we consume for different activities in our lives, especially if we are going to substantially reduce our energy consumption. Consider the myriad of energy and power (energy per time) units we experience in our life that can include calories (cal), Calories (Cal, or 1 kcal equal to 1000 cal), watts (W), kilowatt hours (kWh), British thermal units (BTU), horsepower (hp), and megajoules (Mj). For example, the following list includes some energy and power units for a few things in our lives: With all of these different units, it seems impossible to compare energy used for these different activities. For example, is our household energy use of 30 kWh per day, or ∼900 kWh per month, more or less than the energy used for commuting to and from work each day? We could spend an afternoon calculating these and other unit conversions and then trying to make sense of it all, or we could more simply choose a common unit for all of these numbers. For example, if we use kWh for a single day, we have Note that these units are in energy use per day (kWh/d), which has units of power, and a gallon of gasoline is included as a reference point. Some of these units makes sense to compare, but for others, such comparisons are awkward. For example, the 120 hp engine from your car translates to an engine rated at 2160 kWh, but you would not (I hope) operate your car all day at its maximum power. These units of kWh also span different time frames (you do not eat continuously all day), and some units lack a more personal connection, such as food units in kWh. To make comparison of energy units easier, and to express them in terms of something to which we can all relate, I propose a new unit called the daily energy unit, D. One thing that all people in all countries share is needing to eat every day. Therefore, we can define 1 D as the average energy in the food consumed by a healthy, well-fed person each day (2000 Cal = 2000 kcal = 8.4 Mj = 2.3 kWh), which is about the energy needed to power a 100 W lightbulb all day (2.3 kWh/24 h). For the cases described above, with an adjustment on vehicle use, we now can express everything in units of D as Now we have everything in our life expressed in units that will have meaning for our daily activities. Of course these numbers will vary depending on your particular situation. Maybe you need to eat less than the stated average and you consume 0.9 D, or you have been on vacation and eating 1.5 D? Want to lose a pound of fat? You will need to lose 1.75 D (3500 kcal/lb of fat, or 3.9 D/kg). Do not forget that it is easier to gain a D than to lose one! A practical unit for power for a horse is based on the average daily food consumed by a horse (10 D), or 10 times that needed by a human. The D unit comparison shows just how amazing gasoline is in terms of energy storage! A gallon of gas contains 14 D (3.7 D per liter), so using a gallon of gas for your daily commute can consume about as much power as your home for a day. The daily average vehicle energy use in the list above is calculated for all light duty transportation vehicles divided by the number of people in the United States, which indicates ∼1.5 gallons of gas used daily per person. What is a reasonable amount of energy consumption for a person in a modern, industrial world? The Swiss Federal Institute of Technology in Zürich (ETH Zurich) has proposed a 2000 W society, or about 20 D. Currently, each person in Switzerland consumes about 53 D, or approximately half that of a person in the United States. Going solar? While the amount of solar energy you can capture with a standard solar panel varies by location, for a standard 250 W panel you might obtain an average of 0.43 D, which means you need ∼30 panels on your roof just to break even with your home energy use. Have an electric car? You will need 2.3 D (assuming 5.4 kWh for 18 miles) compared to the same commute using a gallon of gas (14 D), or another five or six solar panels for that daily commute. Using the D unit to quantify your energy use can bring a tangible sense of energy use to everything we do on the basis of something we all understand: how much food we need to eat every day. Unlike temperature in Fahrenheit, Celsius, or Kelvin, the one thing we have in common is needing to eat. Starting to use the same units for energy for food, heating, transportation, and everything else in our lives will enable us to appreciate the magnitude of this journey we are undertaking to totally transform our energy infrastructure to be based on solar, wind, and other forms of renewable energy. Views expressed in this editorial are those of the author and not necessarily the views of the ACS. This article has not yet been cited by other publications.

In 1969, the vocal musical group The Fifth Dimension wrote a song about the coming of the Age of Aquarius, which would be filled with “harmony and understanding”, an age filled with humanity, universal love, and light. Well, we might still be waiting for the emergence of the first few of these, but perhaps we are finally seeing the true dawn of the age of light. Los Angeles is set to ink a deal to build a solar farm that could provide 7% of the city’s electricity at an astonishingly low cost of $0.020/kWh with battery power at $0.013/kWh to even out electricity provided to the grid. This new solar plant will create a 0.4 GW power plant, producing 876000 kWh of electricity annually, without the need to burn any fuel or consume any water. To put those numbers in perspective, electricity produced by natural gas is approximately $0.04/kWh, with coal at $0.05/kWh. Large fossil fuel and nuclear power plants typically produce 0.5 to 1 GW. This is a good start to nearly completely decarbonize the large electrical power needs of this city. It is amazingly economical and also desperately needed to slow climate change due to the release of CO2 into the atmosphere from the combustion of fossil fuels. What does this dawn of the “age of light” mean for future environmental technologies? One option long researched by environmental scientists is photocatalytic water treatment. However, decades of research have failed to produce impactful commercial processes. Given the importance of integrating solar power into our water infrastructure, however, it may be premature to give up on this general direction of research. The advent of inexpensive solar-produced electricity, combined with affordable storage, could enable more direct approaches by using solar electricity to drive electrochemical processes, particularly at decentralized or remote treatment locations, although there are many challenges for applications using these electrochemical technologies. The main problems are associated with side reactions produced with the different electrodes, and the low conductivity of drinking water. Mixed metal oxide electrodes (MMOs), also known as dimensionally stable anodes (DSAs), have been used for years for chlorine gas production in salt solutions, as these electrodes have low overpotentials for chloride ions, making them effective for producing disinfectants and oxidizing organic matter. Boron-doped diamond (BDD) electrodes have high oxygen overpotentials, making them better suited for direct oxidation of organic contaminants in water, and they can have a side benefit of producing ozone and hydrogen peroxide disinfectants. BDDs, however, are many times more expensive than MMOs, although prices for both electrodes could decrease with advances in materials and through mass manufacturing. In water treatment applications MMOs and BDDs unfortunately produce, to different extents, chlorates, perchlorates, bromates, Trihalomethanes, and other disinfection byproducts. The development of electrodes better targeted to drive specific reactions without these unwanted byproducts could help advance direct electrochemical applications in water treatment. The low conductivity of water is a particular concern for environmental engineers designing systems for water treatment, compared to industrial processes in which highly conductive electrolytes can be used. Such environmental electrochemistry and water treatment studies are therefore welcome topics for ES&T and ES&T Letters. Most water treatment processes already use chemical disinfectants produced by electrochemical processes, such as chlorine, hydrogen peroxide, and ozone. Chlorine gas is produced using Pt catalysts and a cation exchange membrane made of Nafion, a polyperfluoroalkyl chemical, and NaCl brine solutions to generate Cl2 at the anode and H2 at the cathode. Hydrogen peroxide is produced using H2 gas, a palladium catalyst, and a chemical mediator such as anthraquinone. Both of these disinfectants are generated off site and then transported on site for use. Methods that do not rely on precious metals and processes that could be implemented at the point of use could help enable more sustainable processes and improve safety by avoiding their transport over long distances. Ozone and ultraviolet light can be produced locally, so these processes could be more easily be integrated into a solar energy-drivenwater treatment process train. Although it may seem improbable today, there may also be applications of electrochemical reactors for used water treatment. For many years, placing membranes into domestic wastewater was considered to be impractical, but today membrane bioreactors are common for used water treatment. Perhaps the same story will unfold for electrochemical systems such as microbial fuel cells or for ammonia recovery using electrochemical separation processes, which are currently nascent treatment processes that are not yet practial for commercial applications. One niche electrochemical treatment system that has reached commercial production is an advanced electrochemical reactor developed by researchers at the California Institute of Technology for complete recycling of water in latrines that are off grid. The energy demands for these systems are quite high at 35 Wh/L, compared to conventional complete wastewater treatment systems that operate at 0.6 Wh/L, but the need for only a few inexpensive solar power panels at each site makes the system feasible. These systems are not suitable for potable water uses, however, due in large part to the production of chlorinated byproducts. Installed global solar power has already reached 0.5 TW, and it could double in just the next three or four years. Solar panels that float on water treatment plant ponds or sit on nearby land and produce the power more remotely are being installed and are already being integrated into treatment systems. Such solar arrays will reduce net electrical grid power consumption or provide additional inexpensive power to enable more effective or sustainable disinfection or chemical removals. Figuring out how to transform our water infrastructure in the coming age of light will certainly be a challenge, but it will be an enjoyable and needed adventure moving into our enlightened future. Views expressed in this editorial are those of the author and not necessarily the views of the ACS. This article has not yet been cited by other publications.