Degradation and inactivation of chromosomal and plasmid encoded resistance genes/ARBs and the impact of different matrices on UV and UV/H2O2 based advanced oxidation process.

This study reports a structured investigation on the degradation kinetics of different types (gyrAR,tetAR, qnrSR) and conformational forms (chromosomal, plasmids) of ARGs and mobile genetic elements (intl-1, plasmids) as a function of water matrix (DI water, phosphate buffer, wastewater) with UV and UV/H2O2 treatments. Extracellular, intracellular and the free-ARGs fate were tracked to infer the impact of various parameters on the degradation efficacy of the treatment process. The degradation profile of e-ARGs (118-454 bp) showed 1-4 log reductions but did not correlate strongly to amplicon size indicating the importance of active sites distribution and/or types of ARGs for UV induced gene damage. The i-ARGs showed similar degradation rates compared to e-ARGs for UV in phosphate buffer (PBS) but showed (1.3-2 times) slower rates for i-ARGs with UV/H2O2 due to scavenging of OH radicals by the cellular components. While the ARB inactivation was effective, but ARG damage was not supplemental as i-ARGs and f-ARGs persisted. In the wastewater matrix, generation of radical species was contributing to improved degradation rates from UV/H2O2 treatment, specifically for f-ARGs resulting in significantly improved degradation (p<0.05) compared to PBS. These indicates a non-selective nature of attack from radical species generated from UV irradiation on the effluent organic matter (EfOM) than sequenced based damage to the genes from UV. For the plasmid degradation, conformational differences pertaining to the supercoiled structures and intracellular forms influenced slower (1.2-2.8 times) UV mediated gene damage rate as opposed to chromosomal ARGs. These results can be useful for better assessing UV based treatment processes for effective ARG removal.

Default predicted no-effect target concentrations for antibiotics in the absence of data for the protection against antibiotic resistance and environmental toxicity.

The pharmaceutical manufacturing industry, via the AMR Industry Alliance, has developed and implemented steps to help minimize the potential impact of pharmaceutical manufacturing on the spread of antimicrobial resistance (AMR). One of these steps was to publish predicted no-effect concentrations (PNECs) to serve as targets for antibiotic manufacturing wastewater effluent risk assessments aimed to help protect environmental receptors and to mitigate against the spread of antibiotic resistance. Concentrations below which adverse effects in the environment are not expected to occur (PNECs) were first published in 2018 and are updated annually. The current list now stands at 125 antibiotics; however, it is recognized that this list does not encompass all manufactured antibiotics. Therefore, a statistical evaluation of currently available data was conducted and a default PNEC of 0.05 µg/L for antibiotics in the absence of other data was derived. Integr Environ Assess Manag 2022;18:863-867. © 2022 Merck, Sanofi, Johnson & Johnson Services, Inc, F.Hoffmann-La Roche Ltd, Teva Pharmaceuticals, GlaxoSmithKline, Novartis Pharma AG, and Pfizer lnc. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Exposure assessment of 17alpha-ethinylestradiol in surface waters of the United States and Europe.

An evaluation of measured and predicted concentrations of 17-ethinylestradiol in surface waters of the United States and Europe was conducted to develop expected long-term exposure concentrations for this compound. Measured environmental concentrations (MECs) in surface waters were identified from the literature. Predicted environmental concentrations (PECs) were generated for European and U.S. watersheds using the GREAT-ER and PhATE models, respectively. The majority of MECs are nondetect and generally consistent with model PECs and conservative mass balance calculations. However, the highest MECs are not consistent with concentrations derived from conservative (worst-case) mass balance estimates or model PECs. A review of analytical methods suggests that tandem or high-resolution mass spectrometry methods with extract cleanup result in lower detection limits and lower reported concentrations consistent with model predictions and bounding estimates. Based on model results using PhATE and GREAT-ER, the 90th-percentile low-flow PECs in surface water are approximately 0.2 and 0.3 ng/L for the United States and Europe, respectively. These levels represent conservative estimates of long-term exposure that can be used for risk assessment purposes. Our analysis also indicates that average concentrations are one to two orders of magnitude lower than these 90th-percentile estimates. Higher reported concentrations (e.g., greater than the 99th-percentile PEC of approximately 1 ng/L) could result from methodological problems or unusual environmental circumstances; however, such concentrations are not representative of levels generally found in the environment, warrant special scrutiny, and are not appropriate for use in risk assessments of long-term exposures.

In vitro estrogenic activity of representative endocrine disrupting chemicals mixtures at environmentally relevant concentrations.

Exposure to mixtures of endocrine disrupting compounds (EDCs) has been hypothesized to produce potential synergistic or antagonistic effects that can cause undesired effects that are not reflected by the individual compounds. In this study, the estrogenic activities of 11 EDCs of global environmental concern were systematically investigated using the yeast estrogen screen (YES). The contribution of the individual chemical to the total endocrine activity of environmentally relevant mixtures was evaluated. Compared to 17ß-estradiol (E2) as a standard, estrone (E1), estriol (E3), ethinyl estradiol (EE2), bisphenol-A (BPA), and genistein (GEN) showed estrogenic effects, while dibutyl phthalate (DBP), n-butyl benzyl phthalate (BBP), Bis(2-ethylhexyl) phthalate (DEHP), nonyl phenol (NP) and 4-tert-octyl phenol (OP) showed anti-estrogenic effects. The 11 EDCs mixture at a constant environmentally relevant ratio also showed estrogenic activity. The mixtures data were fit to concentration addition (CA), response addition (RA) and interaction (IR) models, respectively. The IR model was not statistically different from the observed value and better predicted results than the CA model for mixtures of all 11 compounds. For the mixtures with the 6 estrogenic compounds only, additive effects were observed, and the data were well predicted by the CA and IR models. Further, in the 11 EDCs mixture the presence of EE2 at an environmentally relevant concentration did not increase the estrogenic activity as compared to a 10 EDCs mixture without EE2.

Environmental risk assessment of metformin and its transformation product guanylurea: II. Occurrence in surface waters of Europe and the United States and derivation of predicted no-effect concentrations.

Metformin (MET), CAS 1115-70-4 (Metformin hydrochloride), is an antidiabetic drug with high usage in North America and Europe and has become the subject of regulatory interest. A pharmaceutical industry working group investigated environmental risks of MET. Environmental fate and chronic effects data were collated across the industry for the present risk assessment. Predicted environmental concentrations (PECs) for MET were modeled for the USA and Europe using the PhATE and GREAT-ER models, respectively. PECs were compared with measured environmental concentrations (MECs) for the USA and Europe. A predicted no effect concentration (PNEC) of 1 mg/L for MET was derived by deterministic procedures, applying an assessment factor of 10 to the lowest no observed effect concentration (i.e., 10 mg/L) from multiple chronic studies with algae, daphnids and fish. The PEC/PNEC and MEC/PNEC risk characterization ratios were <1, indicating no significant risk for MET with high Margins of Safety (MOS) of >868. MET is known to degrade during wastewater treatment to guanylurea (GUU, CAS 141-83-3), which we have shown to further degrade. There are no GUU toxicity data in the literature; hence, chronic studies for GUU were conducted to derive a PNEC of 0.16 mg/L. PECs were derived for GUU as for MET, plus MECs were retrieved from the literature. The PEC/PNEC and MEC/PNEC risk characterization ratios for GUU were also <1, with an MOS of >6.5. Based on standard risk assessment procedures for both MET and its transformation product GUU, there is no significant risk to aquatic life.

Science-based Targets for Antibiotics in Receiving Waters from Pharmaceutical Manufacturing Operations.

In 2016, the United Nations declared the need for urgent action to combat the global threat of antimicrobial resistance (AMR). In support of this effort, the pharmaceutical industry has committed to measures aimed at improving the stewardship of antibiotics both within and outside the clinic. Notably, a group of companies collaborated to specifically address concerns related to antibiotic residues being discharged from manufacturing sites. In addition to developing a framework of minimum environmental expectations for antibiotic manufacturers, science-based receiving water targets were established for antibiotics discharged from manufacturing operations. This paper summarizes the holistic approach taken to derive these targets and includes previously unpublished, company-generated, environmental toxicity data.

Environmental risk assessment of metformin and its transformation product guanylurea. I. Environmental fate.

Metformin (MET) is a pharmaceutical with very high use worldwide that is excreted in unchanged form, leading to concern about potential aquatic life impacts associated with MET, and its primary transformation product guanylurea (GUU). This study presents, in two companion papers, a risk assessment following internationally accepted guidelines of MET and GUU in surface water based on literature data, previously unpublished studies, and a new degradation test that resolves conflicting earlier results. Previous studies have shown that MET is removed during sewage treatment, primarily through transformation to GUU. In addition, measurements in WWTPs suggest that MET is not only transformed to GUU, but that GUU is further biodegraded. A prolonged inherent biodegradation test strongly suggests not only primary transformation of MET to GUU, but also subsequent full mineralization of GUU, with both degradation phases starting after a clear lag phase. MET may partition from surface water to sediment, where both transformation to GUU and in part mineralization is possible, depending on the presence of competent degrading microorganisms. In addition, MET may form non-extractable residues in sediments (12.8-73.5%). Both MET and GUU may be anaerobically degraded during sludge digestion, in soils or in sediments. Bioconcentration factor (BCF) values in crops and most plants are close to 1 suggesting low bioaccumulation potential, moreover, at least some plants can metabolize MET to GUU; however, in aquatic plants higher BCFs were found, up to 53. Similarly, neither MET nor GUU are expected to bioaccumulate in fish based on estimated values of BCFs ≤3.16.

Use of acute and chronic ecotoxicity data in environmental risk assessment of pharmaceuticals.

For many older pharmaceuticals, chronic aquatic toxicity data are limited. To assess risk during development, scale-up, and manufacturing processes, acute data and physicochemical properties need to be leveraged to reduce potential long-term impacts to the environment. Aquatic toxicity data were pooled from daphnid, fish, and algae studies for 102 active pharmaceutical ingredients (APIs) to evaluate the relationship between predicted no-effect concentrations (PNECs) derived from acute and chronic tests. The relationships between acute and chronic aquatic toxicity and the n-octanol/water distribution coefficient (D(OW)) were also characterized. Statistically significant but weak correlations were observed between toxicity and log D(OW), indicating that D(OW) is not the only contributor to toxicity. Both acute and chronic PNEC values could be calculated for 60 of the 102 APIs. For most compounds, PNECs derived from acute data were lower than PNECs derived from chronic data, with the exception of steroid estrogens. Seven percent of the PNECs derived from acute data were below the European Union action limit of 0.01 µg/L and all were anti-infectives affecting algal species. Eight percent of available PNECs derived from chronic data were below the European Union action limit, and fish were the most sensitive species for all but 1 API. These analyses suggest that the use of acute data may be acceptable if chronic data are unavailable, unless specific mode of action concerns suggest otherwise.

A risk-based approach to managing active pharmaceutical ingredients in manufacturing effluent.

The present study describes guidance intended to assist pharmaceutical manufacturers in assessing, mitigating, and managing the potential environmental impacts of active pharmaceutical ingredients (APIs) in wastewater from manufacturing operations, including those from external suppliers. The tools are not a substitute for compliance with local regulatory requirements but rather are intended to help manufacturers achieve the general standard of "no discharge of APIs in toxic amounts." The approaches detailed in the present study identify practices for assessing potential environmental risks from APIs in manufacturing effluent and outline measures that can be used to reduce the risk, including selective application of available treatment technologies. These measures either are commonly employed within the industry or have been implemented to a more limited extent based on local circumstances. Much of the material is based on company experience and case studies discussed at an industry workshop held on this topic.

Environmental assessment of 5-ethylidene-2-norbornene using modeled and measured fate and effects results.

Several predictive models were used to assess aquatic exposure, persistence (P) and potential for long-range transport (LRT) of 5-ethylidene-2-norbornene (ENB). Such estimations are components of the assessment process for persistent, bioaccumulative and toxic (PBT) substances, which are also referred to as persistent organic pollutants (POPs). An ecological exposure assessment for ENB from manufacturing activities was conducted based on physical/chemical properties, monitoring data, and degradation, transport and distribution estimates. Based on the results of several model predictions, chronic exposure of aquatic organisms is not expected, due to the anticipated residence time of ENB in aquatic ecosystems. These modeled results consistently predict ENB does not present the potential to persist in the environment. Volatilization from water to the air is calculated to occur at a relatively rapid rate for ENB based on its Henry's Law constant. Once in the air, ENB is expected to degrade rapidly due to oxidation by hydroxyl radicals and ozone based on calculated atmospheric half-lives of 57 and 27 min, respectively. Additionally, ENB is not predicted to undergo long-range transport based on the short atmospheric half-life due to oxidation by hydroxyl radicals and ozone. Additionally, based on predicted exposure from site-specific emission using the EPA model EFAST, ENB is not expected to reach concentrations of concern for chronic aquatic toxicity endpoints.

An integrated approach for prioritizing pharmaceuticals found in the environment for risk assessment, monitoring and advanced research.

Numerous active pharmaceutical ingredients (APIs), approved prior to enactment of detailed environmental risk assessment (ERA) guidance in the EU in 2006, have been detected in surface waters as a result of advancements in analytical technologies. Without adequate knowledge of the potential hazards these APIs may pose, assessing their environmental risk is challenging. As it would be impractical to commence hazard characterization and ERA en masse, several approaches to prioritizing substances for further attention have been published. Here, through the combination of three presentations given at a recent conference, "Pharmaceuticals in the Environment, Is there a problem?" (Nîmes, France, June 2013) we review several of these approaches, identify salient components, and present available techniques and tools that could facilitate a pragmatic, scientifically sound approach to prioritizing APIs for advanced study or ERA and, where warranted, fill critical data gaps through targeted, intelligent testing. We further present a modest proposal to facilitate future prioritization efforts and advanced research studies that incorporates mammalian pharmacology data (e.g., adverse outcomes pathways and the fish plasma model) and modeled exposure data based on pharmaceutical use.

Predicted-no-effect concentrations for the steroid estrogens estrone, 17ß-estradiol, estriol, and 17α-ethinylestradiol.

The authors derive predicted-no-effect concentrations (PNECs) for the steroid estrogens (estrone [E1], 17ß-estradiol [E2], estriol [E3], and 17α-ethinylestradiol [EE2]) appropriate for use in risk assessment of aquatic organisms. In a previous study, they developed a PNEC of 0.35 ng/L for EE2 from a species sensitivity distribution (SSD) based on all available chronic aquatic toxicity data. The present study updates that PNEC using recently published data to derive a PNEC of 0.1 ng/L for EE2. For E2, fish were the most sensitive taxa, and chronic reproductive effects were the most sensitive endpoint. Using the SSD methodology, we derived a PNEC of 2 ng/L for E2. Insufficient data were available to construct an SSD for E1 or E3. Therefore, the authors used in vivo vitellogenin (VTG) induction studies to determine the relative potency of the steroid estrogens to induce VTG. Based on the relative differences between in vivo VTG induction, they derive PNECs of 6 and 60 ng/L for E1 and E3, respectively. Thus, for long-term exposures to steroid estrogens in surface water (i.e., >60 d), the PNECs are 6, 2, 60, and 0.1 ng/L for E1, E2, E3, and EE2, respectively. Higher PNECs are recommended for short-term (i.e., a few days or weeks) exposures.

Endocrine disruption due to estrogens derived from humans predicted to be low in the majority of U.S. surface waters.

In an effort to assess the combined risk estrone (E1), 17ß-estradiol (E2), 17α-ethinyl estradiol (EE2), and estriol (E3) pose to aquatic wildlife across United States watersheds, two sets of predicted-no-effect concentrations (PNECs) for significant reproductive effects in fish were compared to predicted environmental concentrations (PECs). One set of PNECs was developed for evaluation of effects following long-term exposures. A second set was derived for short-term exposures. Both sets of PNECs are expressed as a 17ß-estradiol equivalent (E2-eq), with 2 and 5 ng/L being considered the most likely levels above which fish reproduction may be harmed following long-term and short-term exposures, respectively. A geographic information system-based water quality model, Pharmaceutical Assessment and Transport Evaluation (PhATE™), was used to compare these PNECs to mean and low flow concentrations of the steroid estrogens across 12 U.S. watersheds. These watersheds represent approximately 19% of the surface area of the 48 North American states, contain 40 million people, and include over 44,000 kilometers of rivers. This analysis determined that only 0.8% of the segments (less than 1.1% of kilometers) of these watersheds would have a mean flow E2-eq concentration exceeding the long-term PNEC of 2.0 ng/L; only 0.5% of the segments (less than 0.8% of kilometers) would have a critical low flow E2-eq exceeding the short-term PNEC of 5 ng/L. Those few river segments where the PNECs were exceeded were effluent dominated, being either headwater streams with a publicly owned treatment works (POTW), or flowing through a highly urbanized environment with one or several POTWs. These results suggest that aquatic species in most U.S. surface waters are not at risk from steroid estrogens that may be present as a result of human releases.

Pharmaceuticals and personal care products in the environment: what are the big questions?

BACKGROUND: Over the past 10-15 years, a substantial amount of work has been done by the scientific, regulatory, and business communities to elucidate the effects and risks of pharmaceuticals and personal care products (PPCPs) in the environment. OBJECTIVE: This review was undertaken to identify key outstanding issues regarding the effects of PPCPs on human and ecological health in order to ensure that future resources will be focused on the most important areas. DATA SOURCES: To better understand and manage the risks of PPCPs in the environment, we used the "key question" approach to identify the principle issues that need to be addressed. Initially, questions were solicited from academic, government, and business communities around the world. A list of 101 questions was then discussed at an international expert workshop, and a top-20 list was developed. Following the workshop, workshop attendees ranked the 20 questions by importance. DATA SYNTHESIS: The top 20 priority questions fell into seven categories: a) prioritization of substances for assessment, b) pathways of exposure, c) bioavailability and uptake, d) effects characterization, e) risk and relative risk, f ) antibiotic resistance, and g) risk management. CONCLUSIONS: A large body of information is now available on PPCPs in the environment. This exercise prioritized the most critical questions to aid in development of future research programs on the topic.

An assessment of potential exposure and risk from estrogens in drinking water.

BACKGROUND: Detection of estrogens in the environment has raised concerns in recent years because of their potential to affect both wildlife and humans. OBJECTIVES: We compared exposures to prescribed and naturally occurring estrogens in drinking water to exposures to naturally occurring background levels of estrogens in the diet of children and adults and to four independently derived acceptable daily intakes (ADIs) to determine whether drinking water intakes are larger or smaller than dietary intake or ADIs. METHODS: We used the Pharmaceutical Assessment and Transport Evaluation (PhATE) model to predict concentrations of estrogens potentially present in drinking water. Predicted drinking water concentrations were combined with default water intake rates to estimate drinking water exposures. Predicted drinking water intakes were compared to dietary intakes and also to ADIs. We present comparisons for individual estrogens as well as combined estrogens. RESULTS: In the analysis we estimated that a child's exposures to individual prescribed estrogens in drinking water are 730-480,000 times lower (depending upon estrogen type) than exposure to background levels of naturally occurring estrogens in milk. A child's exposure to total estrogens in drinking water (prescribed and naturally occurring) is about 150 times lower than exposure from milk. Adult margins of exposure (MOEs) based on total dietary exposure are about 2 times smaller than those for children. Margins of safety (MOSs) for an adult's exposure to total prescribed estrogens in drinking water vary from about 135 to > 17,000, depending on ADI. MOSs for exposure to total estrogens in drinking water are about 2 times lower than MOSs for prescribed estrogens. Depending on the ADI that is used, MOSs for young children range from 28 to 5,120 for total estrogens (including both prescribed and naturally occurring sources) in drinking water. CONCLUSIONS: The consistently large MOEs and MOSs strongly suggest that prescribed and total estrogens that may potentially be present in drinking water in the United States are not causing adverse effects in U.S. residents, including sensitive subpopulations.

Derivation of an aquatic predicted no-effect concentration for the synthetic hormone, 17 alpha-ethinyl estradiol.

17alpha-Ethinyl estradiol (EE2) is a synthetic estrogen widely used in combination with other steroid hormones in oral contraceptives and in the contraceptive patch. EE2 has been detected in sewage treatment plant effluents in the low nanogram -per-liter range and occasionally in surface waters in the U.S., U.K., Canada, Brazil, Germany, and elsewhere. The mode of action is receptor-mediated, and estrogen receptors exist in mammals and other vertebrates. A large number of studies on the effects of EE2 on aquatic organisms exist. One hundred English language studies published between 1994 and 2007, one as yet unpublished study, and findings published in conference proceedings (in German) were compared to published data quality criteria to identify the most relevant studies for deriving a predicted no-effect concentration (PNEC). Reproduction in fish was identified as the most sensitive end point in aquatic species. A species sensitivity distribution was constructed using no observed effect concentrations (NOECs) for reproductive effects from 39 papers in 26 species, resulting in a median hazardous concentration at which 5% of the species tested are affected (HC5,50) of 0.35 ng/L. After comparing this HC5,50 to all of the laboratory and field-derived toxicity information available for EE2, we recommend using 0.35 ng/L as the PNEC for EE2 in surface water. This PNEC is below 95% of the existing NOECs for effects on reproduction and is also below virtually all of the NOECs for vitellogenin induction in the key fish reproduction studies.

Occupational exposure limits: an approach and calculation aid for extended work schedule adjustments.

Past reviews of occupational exposure limit (OEL) adjustments have covered both decision logic and calculation methods to derive factors to assure protection of workers on extended (also known as unusual) work shifts. The approaches reviewed included several Haber's rule based methods, several variants of single compartment toxicokinetic (TK) models, and physiologically based pharmacokinetic modeling. These models calculate OEL adjustment factors based on the work shift and the uptake and elimination of the toxicant. A key parameter of the TK models is the biologic half-life of the toxicant, but reliable data for the half-life are not available for all substances of concern. A spreadsheet is presented that implements TK calculations, with one of the presented TK calculation alternatives not dependent on half-life data. This half-life data independent approach is suggested as a viable option for situations when the toxicant's half-life is unknown or uncertain.

Evaluation of a sampling method for the measurement of occupational exposures to ethylene.

In an effort to assess the scope of occupational exposures to ethylene, the Olefins Panel of the American Chemistry Council designed and conducted a research project to develop and apply a sampling and analytical method to measure workplace exposure. The method uses packed Carbosieve S-III thermal desorption tubes (Supelco, Bellefonte, Pa.) with a low sample collection flow rate. The tubes were analyzed by thermal desorption gas chromatography. The methodology was validated for both 15-min short-term exposure limit and 8-hr time-weighted average (TWA) samples in the laboratory prior to the field study. The effects of varying sampling flow rate (2, 5, 10, and 25 mL/min) and temperature (25 and 35 degrees C) on sample breakthrough time were assessed at a constant relative humidity of 90%. Breakthrough times decreased linearly with sampling flow rate and temperature. The optimal sampling flow rate and temperature at 90% relative humidity were 2 mL/ min and 25 degrees C. A full-shift TWA sample can be collected using two tubes for up to 4 hours each at a flow rate of 2 mL/min, while a STEL sample can be collected at 25 mL/min flow rate. The evaluation indicated samples can be stored under ambient conditions for a period up to 14 days without significant sample loss. Field measurements were performed at 14 petrochemical facilities within North America. The mean 8-hour TWA ethylene concentration (71 sample pairs) was 2.6 ppm (range: <0.05 to 2100 ppm). Significant ethylene concentrations were observed for only two of the 73 TWA sample pairs. Each of these two samples was obtained from the same facility, and only one tube of the sample pairs showed a high ethylene concentration (3200 ppm and 4200 ppm, respectively) for the 1600 ppm and 2100 ppm TWA sample. The first tube of each of these two sample pairs showed no detectable levels. Further, 69 of 71 sample pairs had TWA concentrations below 13 ppm. The mean of 26 short-term exposure limit samples was 16 ppm (range: <0.05 to 63 ppm), with only one sample above 50 ppm. The results of this study indicate that airborne concentrations of ethylene can be effectively measured using Carbosieve S-III packed thermal desorption tubes under typical workplace conditions.