Meta-Analysis Comparing Nominal and Measured Concentrations of Perfluorooctanoic Acid and Perfluorooctane Sulfonate in Aquatic Toxicity Studies Across Various Experimental Conditions.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are among the most frequently detected chemicals among the per- and polyfluoroalkyl substances in aquatic environments. Because of their high detection frequency, persistence, and potential toxicity, interest in both PFOA and PFOS has increased in recent years. However, a substantial number of PFOA and PFOS toxicity tests only report nominal, or unmeasured, treatment concentrations, which may complicate the determination of protective values. In addition, previous literature has indicated that differences between nominal and measured concentrations of both PFOA and PFOS could be linked to experimental conditions (e.g., feeding regimes for test organisms, test vessel material [glass or plastic], use of solvent, and the presence of substrate). Therefore, this critical review examined whether nominal and measured concentrations were in close agreement with each other among the current PFOA and PFOS aquatic toxicity literature and if experimental conditions were associated with any observed differences. Nominal and measured concentrations in the current PFOA and PFOS aquatic toxicity literature generally displayed a high degree of linear correlation and relatively low median percent differences. Correlations between measured and nominal concentrations were >0.98 for PFOA and >0.95 for PFOS in freshwater tests across experimental conditions. For saltwater tests, correlations of >0.84 were observed for PFOA and PFOS (separate and combined) across experimental conditions. While measured PFOA and PFOS toxicity tests are generally preferred, the present meta-analysis demonstrated that experimental conditions had little influence on observed discrepancies between nominal and measured concentrations, with the exception of PFOS saltwater tests and PFOA and PFOS freshwater studies that contained substrate. Unmeasured tests with these conditions should be considered carefully based on project needs, with the caveat that the data sets for these two experimental conditions were limited. Environ Toxicol Chem 2023;42:2289-2301. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

Perfluorooctane Sulfonate in US Ambient Surface Waters: A Review of Occurrence in Aquatic Environments and Comparison to Global Concentrations.

Perfluorooctane sulfonate (PFOS) is one of the dominant perfluoroalkyl substances (PFAS) detected in aquatic ecosystems. It has been used in a wide range of industrial and consumer products for decades. The unique properties of PFOS, including its stability and resistance to degradation, have made it highly persistent in the aquatic environment. Because of its persistence, potential toxicity, and occurrence in aquatic ecosystems, interest in PFOS has increased in recent decades. Despite this interest, current information on the environmental distribution of PFOS in ambient surface waters of the United States is fairly limited. This critical review summarizes the currently available literature on PFOS occurrence in surface waters across the United States and highlights existing data gaps. Available data are largely from a handful of study areas with known PFAS manufacturing or industrial uses, with much of the data collected from freshwater systems in eastern states and the upper Midwest. Measured PFOS concentrations in surface waters vary widely, over 8 orders of magnitude, with the highest concentrations occurring downstream from manufacturing and industrial use plants, areas near aqueous film-forming foam-use sites, and sites where PFOS precursors were used in textile treatment. Non-point source-related occurrences are highest near urbanized areas with high population densities. Current data illustrate the occurrence of PFOS in surface waters across multiple US states. Additional data are needed to better understand PFOS occurrence in US aquatic ecosystems, particularly in estuarine and marine systems and where monitoring data are not available (e.g., southwestern, central, and western United States). Additional PFOS occurrence data would provide valuable information on potential spatial and temporal variability in surface waters and possible risks posed to aquatic ecosystems. Environ Toxicol Chem 2021;40:2425-2442. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.

The effects of the psychiatric drug carbamazepine on freshwater invertebrate communities and ecosystem dynamics.

Freshwater ecosystems are persistently exposed to pharmaceutical pollutants, including carbamazepine. Despite the ubiquity and recalcitrance of carbamazepine, the effects of this pharmaceutical on freshwater ecosystems and communities are unclear. To better understand how carbamazepine influences the invertebrate community and ecosystem dynamics in freshwaters, we conducted a mesocosm experiment utilizing environmentally relevant concentrations of carbamazepine (200 and 2000 ng/L). Mesocosms were populated with four gastropod taxa (Elimia, Physa, Lymnaea and Helisoma), zooplankton, filamentous algae and phytoplankton. After a 31 d experimental duration, structural equation modeling (SEM) was used to relate changes in the community structure and ecosystem dynamics to carbamazepine exposure. Invertebrate diversity increased in the presence of carbamazepine. Additionally, carbamazepine altered the biomass of Helisoma and Elimia, induced a decline in Daphnia pulex abundance and shifted the zooplankton community toward copepod dominance. Lastly, carbamazepine decreased the decomposition of organic matter and indirectly altered primary production and dissolved nutrient concentrations. Changes in the invertebrate community occurred through both direct (i.e., exposure to carbamazepine) and indirect pathways (i.e., changes in food resource availability). These data indicate that carbamazepine may alter freshwater community structure and ecosystem dynamics and could have profound effects on natural systems.

Relationships between the psychiatric drug carbamazepine and freshwater macroinvertebrate community structure.

Pharmaceutical pollutants are commonly detected in surface waters and have the potential to affect non-target organisms. However, there is limited understanding of how these emerging contaminants may affect macroinvertebrate communities. The pharmaceutical carbamazepine is ubiquitous in surface waters around the world and is a pollutant of particular concern due to its recalcitrance and toxicity. To better understand the potential effects of carbamazepine on natural macroinvertebrate communities, we related stream macroinvertebrate abundance to carbamazepine concentrations. Macroinvertebrate and water samples were collected from 19 streams in central Indiana in conjunction with other stream physiochemical characteristics. Structural equation modeling (SEM) was used to relate macroinvertebrate richness to carbamazepine concentrations. Macroinvertebrate richness was positively correlated with increasing concentrations of carbamazepine. From the SEM we infer that carbamazepine influences macroinvertebrate richness through indirect pathways linked to Baetidae abundance. Baetidae abundance influenced ephemeropteran abundance and FBOM percent organic matter, both of which altered macroinvertebrate richness. The pharmaceutical carbamazepine may alter freshwater macroinvertebrate species composition, which could have significant consequences to ecosystem processes.

The effects of the pharmaceutical carbamazepine on life history characteristics of flat-headed mayflies (Heptageniidae) and aquatic resource interactions.

Pharmaceutical pollutants are commonly detected in freshwater ecosystems around the world and have biological effects on aquatic organisms. However, current understanding of the influence this contaminant class has on freshwater communities and ecosystems is lacking. Recently the scientific community has called for research focusing on certain pharmaceuticals due to their ubiquity and potential toxicity. Carbamazepine is one of these pharmaceuticals. To better understand the effect carbamazepine has on life history characteristics of aquatic organisms and consumer-resource interactions, we quantified the influence of carbamazepine on the development, growth and behavior of mayfly nymphs (Stenonema sp.) and the alterations in food consumer-resource interactions between Stenonema and algae (Chaetophora). Microcosms were assembled in a factorial design containing algae and mayfly nymphs native to central Indiana and dosed with environmentally relevant concentrations of carbamazepine. From this ecotoxicological experiment we were able to infer that carbamazepine at 2,000 ng/L influenced the development and behavior of Stenonema nymphs and the body dimensions of adult individuals. However, it appears that carbamazepine does not influence consumer-resource interactions at concentrations found in surface waters. The pharmaceutical carbamazepine may influence the behavior, growth and development of mayflies, which could have significant consequences at the population, community and ecosystem level.