No-effect Concentration Research Articles

Summary of historical terrestrial toxicity data for the brominated flame retardant tetrabromobisphenol A (TBBPA): effects on soil microorganisms, earthworms, and seedling emergence.

This article summarizes historical and recent research on the terrestrial toxicology of tetrabromobisphenol A (TBBPA). Despite its ubiquitous use and presence in the environment, little published data is available to evaluate the terrestrial ecotoxicity of TBBPA. The purposes of this paper are to enable broad access to a series of TBBPA ecotoxicity tests (nitrogen transformation, earthworm survival/reproduction, and seedling emergence/growth) that were conducted in support of regulatory risk assessments, and to summarize available research in the terrestrial toxicity of TBBPA. In these studies, no significant effect of TBBPA on nitrogen transformation was observed up to the highest concentration [1000mg/kg dry weight (d.w.) soil]. The no-observed-effect concentrations (NOECs) for seedling emergence ranged from 20 to 5000mg/kg d.w. Sensitivities were soybeans < corn ≈ onion ≈ tomato < ryegrass < cucumber; the most sensitive endpoints being seedling dry weight and height. The 28-day earthworm mortality NOEC was > 4840mg/kg d.w. The most sensitive terrestrial endpoint was earthworm reproduction with a half maximal effective concentration (EC50) of 0.12mg/kg d.w. soil. Based on this sensitive terrestrial endpoint, the EU derived a predicted no-effect concentration (PNEC) for soil of 0.012mg/kg wet weight soil (EU 2008). We did not identify a more sensitive/lower point of departure for terrestrial toxicity endpoints in the published literature. On the basis of this PNEC, the EU concluded there was potential risk for environmental effects near TBBPA manufacturing sites, but no additional risk provided that no sewage sludge was applied to agricultural land (EU 2008).

Prevalence of selected pharmaceuticals in surface water receiving untreated sewage in northwest Pakistan

This study investigated the occurrence of four non-steroidal anti-inflammatory drugs (NSAIDs) and four benzodiazepines/anti-depressants (ADs) in municipal wastewater in Mardan city, Pakistan, and in River Kabul and River Indus receiving untreated sewage. Liquid chromatography with a triple quadrupole tandem mass spectrometry (LC-MS/MS) was used for the analysis of paracetamol, diclofenac, ibuprofen, and codeine (NSAIDs) and diazepam, bromazepam, lorazepam, and temazepam (ADs). Except codeine and lorazepam, all the target compounds were observed in sewage and surface water in various concentrations. In sewage, paracetamol was found at the higher end (32.4μg/L) of the reported ranges in literature for other countries. Results of river samples showed that the target compounds were usually lower in concentration than the respective EC50 values for aquatic organisms. However, the levels for paracetamol and ibuprofen were critical depicting the consequence of untreated disposal. Environmental risk assessment by estimating the risk quotient (RQ) as the ratio of measured environmental concentration and predicted no-effect concentration showed medium to high (RQ > 1 and 0.1 < RQ < 1) risk from paracetamol and ibuprofen to aquatic organisms in River Kabul and Kalpani stream, Pakistan.

Acute sensitivity of three Cladoceran species to different types of microplastics in combination with thermal stress

Microplastics (<5 mm, MP) are ubiquitously distributed in the environment, causing increasing concern regarding their potential toxicity to organisms. To date, most research has focussed on the impacts of MPs on marine and estuarine organisms, with fewer studies focussing on the effects of microplastics on freshwater ecosystems, especially under different environmental conditions. In the present study, the sensitivity of two temperate Cladoceran species, Daphnia magna and Daphnia pulex, and a smaller tropical species Ceriodaphnia dubia, to primary microplastics (PMP) and secondary (weathered) microplastics (SMP) was assessed. A prolonged acute toxicity assay (up to 72 or 96 h) was performed at 18°, 22°, and 26 °C, to determine the influence of temperature as an additional stressor and survival data were analysed using toxicokinetic-toxicodynamic (TK-TD) model. Acute sensitivity of D. magna and D. pulex to both PMP and SMP increased sharply with temperature, whereas that of C. dubia remained relatively stable across temperatures. C. dubia was the most sensitive species at 18 °C, followed by D. pulex and D. magna, which were of comparable sensitivity. However, this ranking was reversed at 26 °C as could be seen from the No Effect Concentration (NEC) estimates of the TK-TD model. In addition, SMP and PMP had a similar effect on D. magna and D. pulex, but PMP was more toxic to C. dubia. Effects on survival were strongly time-dependent and became substantially more severe after the standard 48 h test period. Our results indicate that sensitivity to microplastics may differ between species for different types of microplastics, and could be drastically influenced by temperature albeit at high exposure concentrations.

Identification, contribution, and estrogenic activity of potential EDCs in a river receiving concentrated livestock effluent in Southern Taiwan

We assessed 22 selected endocrine-disrupting compounds (EDCs) and other emerging, potentially endocrine-active compounds with estrogenic activity from the waters of the Wuluo River, southern Taiwan. This watershed receives high amounts of livestock and untreated household wastewaters. The river is surrounded by concentrated animal feedlot operations (CAFOs). River water samples were analyzed for selected compounds by liquid chromatography-tandem mass spectrometry (LC-MS/MS), T47D-KBluc reporter gene assay, and E-screen cell proliferation in vitro bioassay. Total concentrations of ∑alkylphenolic compounds (bisphenol A, 4-nonylphenol, t-nonylphenol, octylphenol, nonylphenol mono-ethoxylate, nonylphenol di-ethoxylate) were much higher than ∑estrogens (estrone, 17 β-estradiol, estriol, 17ß-ethynylestradiol, diethylstilbestrol), ∑preservatives (methyl paraben, ethyl paraben, propyl paraben, butyl paraben), ∑UV-filters (benzophenone, methyl benzylidene camphor, benzophenone-3), ∑antimicrobials (triclocarben, triclosan, chloroxylenol), and an insect repellent (diethyltoluamide) over four seasonal sampling periods. The highest concentration was found for bisphenol A with a mean of 302 ng/L. However, its contribution to estrogenic activity was not significant due to its relatively low estrogenic potency. Lower detection rates were found for BP, EE2, TCS, and PCMX, while DES and EP were not detected. E1 and E2 levels in raw water samples were 50% higher than the predicted no-effect concentrations (PNEC) for aquatic organisms of 6 and 2 ng/L, respectively. The potency of estrogenic activity ranged from 11.7 to 190.1 ng/L E2T47D-Kbluc and 6.63 to 84.5 ng/L E2E-Screen for extracted samples. Importantly, estrone contributed 50% of the overall activity in 60% and 44% of the samples based on T47D-KBluc and MCF-7 bioassays, followed by 17 ß-estradiol, highlighting the importance of total steroid estrogen loading. This study demonstrates that the estrogenic activity of target chemicals was comparable to levels found in different countries worldwide. More intense wastewater treatment is required in areas of intensive agriculture in order to prevent adverse impacts on the ambient environment and aquatic ecosystems.

Marine environmental risk assessment and acute water quality criterion for pentachlorophenol in coastal waters.

Pentachlorophenol (PCP) is a organochlorine biocide that, unlike most other organochlorines, is still in use as timber preservative. Its water solubility, high toxicity, bioaccumulation potential, and the concentrations reported in estuarine waters (up to 0.1 µg L-1) indicate it may pose a risk in coastal environments. Aquatic environrmental regulations are commonly based on standard freshwater organisms that may not represent the sensitivity of marine species. The present study consists of a water quality criteira reevalutation of PCP in coastal waters based on toxicity tests conducted recording sensitive endpoints of marine species representative of coastal ecosystems, following QA/QC standard procedures. The toxicity thresholds (EC10) found were 4.69 µg L-1 for Paracentrotus lividus sea-urchin embryos, 6.47 µg L-1 for Mytilus galloprovincialis mussel larvae, and 78.4 µg L-1 for Isochrysis galbana cells. Therefore, there is only one order of magnitude between the predicted no-effect concentration (PNEC) for early life stages of bivalves and echinoderms and the maximum concentrations actually recorded in coastal water, which yields a remarkable risk quotient for PCP in these highly productive marine habitats. In addition, we have reviewed the ecotoxicological data on PCP toxicity on marine species representative of the main systematic groups, from algae to chordates, and derived a probabilistic acute saltwater quality criterion of 2.66 µg L-1, intended to protect 95% of the marine species. Lack of adequate protection for marine ecosystems in some current PCP national guidelines has been identified.

Presence of antibiotic residues in various environmental compartments of Shandong province in eastern China: Its potential for resistance development and ecological and human risk

ObjectivesTo investigate the occurrence of antibiotic residues in different types of environmental samples including water samples in rural Shandong province, China. Further, to characterize the potential ecological risk for development of antibiotic resistance in the environment, and the potential direct human health risk of exposure to antibiotics via drinking water and vegetables. MethodsEnvironmental samples (n = 214) (river water, waste water, drinking water, sediments, manure, soil and edible parts of vegetables) were collected in twelve villages in Shandong province in eastern China. High performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was used to determine the concentration of antibiotic residues. The ratio of the measured environmental concentrations (MEC) to the predicted no-effect concentrations (PNEC) was used to evaluate the ecological risk (risk quotient, RQ) for development of antibiotic resistance. The potential risks to human health through exposure to antibiotics in drinking water were assessed by comparing measured environmental concentrations (MEC) and predicted no-effect concentration in drinking water (PNECDW), and in vegetables by comparing estimated daily intake (EDI) to ADI. ResultsSulfapyridine, sulfamethoxazole, ciprofloxacin, enrofloxacin, levofloxacin, norfloxacin, chloramphenicol, florfenicol, doxycycline, and metronidazole were detected at concentrations ranging between 0.3 and 3.9 ng/L in river water, 1.3 and 12.5 ng/L in waste water, 0.5 and 21.4 ng/L in drinking water, 0.31 and 1.21 μg/kg in river sediment, 0.82 and 1.91 μg/kg in pig manure, 0.1 and 11.68 μg/kg in outlet sediment, 0.5 and 2.5 μg/kg in soil, and 6.3 and 27.2 μg/kg in vegetables. The RQs for resistance development were >1 for enrofloxacin, levofloxacin, and ranged between 0.1 and 1 for ciprofloxacin. MECs/PNECDW ratios were <1 from exposure to antibiotics through drinking water for both adults and children. EDI/ADI ratios were <0.1 from exposure to antibiotics by vegetable consumption. ConclusionsAntibiotic pollutants were ubiquitous in various environmental compartments of Shandong province of China. Risk estimates indicated a potential for the measured levels of enrofloxacin, levofloxacin and ciprofloxacin in waste water to pose an ecological risk for resistance selection, and further studies are needed to validate this finding. The investigated antibiotics did not appear to pose an appreciable direct human health risk from environmental exposure through drinking water or vegetables consumption. However, they might still pose a risk for resistance development.

Ecotoxicological potential of the biocides terbutryn, octhilinone and methylisothiazolinone: Underestimated risk from biocidal pathways?

The use of biocides by industry, agriculture and households increased throughout the last two decades. Many new applications with known substances enriched the variety of biocidal pollution sources for the aquatic environment. While agriculture was the major source for a long time, leaching from building facades and preservation of personal care and cleaning products was identified as new sources in the last few years. With the different usage forms of biocidal products the complexity of legislative regulation increased as well. The requirements for risk assessment differ from one law to another and the potential risk of substances under different regulations might be underestimated. Still EC50 and predicted no-effect concentration (PNEC) values gained from testing with different species are the core of environmental risk assessment, but ecotoxicological data is limited or lacking for many biocides. In this study the biocides widely used in facade coatings and household products terbutryn, octhilinone and methylisothiazolinone were tested with the Daphnia magna acute immobilisation assay, the neutral red uptake assay and the ethoxyresorufin-O-deethylase (EROD) assay, performed with rainbow trout liver (RTL-W1) cells. Further, the MTT assay with the ovarian cell line CHO-9 from Chinese hamster was used as mammalian model. Octhilinone induced the strongest effects with EC50 values of 156μg/l in the D. magna assay, while terbutryn showed the weakest effects with 8390μg/l and methylisothiazolinone 513μg/l respectively. All other assays showed higher EC50 values and thus only weak effects. EROD assays did not show any effects. With additional literature and database records PNEC values were calculated: terbutryn reached 0.003μg/l, octhilinone 0.05μg/l and methylisothiazolinone 0.5μg/l. Potential ecotoxicological risks of these biocides are discussed, considering environmental concentrations.

Toxicity of a Quinaldine-Based Liquid Organic Hydrogen Carrier (LOHC) System toward Soil Organisms Arthrobacter globiformis and Folsomia candida.

The study aims to establish a preliminary environmental assessment of a quinaldine-based LOHC system composed of hydrogen-lean, partially hydrogenated, and fully hydrogenated forms. We examined their toxicity toward the soil bacteria Arthrobacter globiformis and the Collembola Folsomia candida in two exposure scenarios, with and without soil, to address differences in the bioavailability of the compounds. In both scenarios, no or only slight toxicity toward soil bacteria was observed at the highest test concentration (EC50 > 3397 μmol L-1 and >4892 μmol kg-1 dry weight soil). The effects of the three quinaldines on F. candida in soil were similar, with EC50 values ranging from 2119 to 2559 μmol kg-1 dry weight soil based on nominal concentrations. Additionally, corrected pore-water-concentration-based EC50 values were calculated by equilibrium partitioning using soil/pore-water distribution coefficients. The tests without soil (simulating pore-water exposure) revealed higher toxicity, with LC50 values between 78.3 and 161.6 μmol L-1 and deformation of the protective cuticle. These results assign the compounds to the category "harmful to soil organisms". Potential risks toward the soil environment of the test compounds are discussed on the basis of predicted no-effect concentrations.

Environmental fate and ecotoxicological risk of the antibiotic sulfamethoxazole across the Katari catchment (Bolivian Altiplano): Application of the GREAT-ER model

Antibiotics are emergent contaminants that can induce adverse effects in terrestrial and aquatic organisms. The surface water compartment is of particular concern as it receives direct waste water discharge. Modeling is highlighted as an essential tool to understand the fate and behavior of these compounds and to assess their ecotoxicological risk. This study aims at testing the ability of the GREAT-ER model in simulating sulfamethoxazole (SMX) concentrations in the surface waters of the arid high-altitude Katari catchment (Bolivian Altiplano), assessing the sensitivity of the parameters considered, and evaluating the ecotoxicological risk posed. The model predicted the general spatial pattern of SMX concentrations. No contaminant abatement was observed during the wet season, supporting the idea that non-point sources, such as runoff and remobilization processes, play an important role during that season. During the dry season, the abatement capacity was 91%, suggesting that natural attenuation, particularly photodegradation, is high during low flow. Pharmaceutical consumption was the parameter that influenced the environmental concentrations the most. The ratio of Predicted Environmental Concentrations to predicted no-effect concentrations varied between 0.14 and 26.6 for the wet season and between 0.14 and 7.6 for the dry season depending on the river stretch.

Effects of the neonicotinoids acetamiprid and thiacloprid in their commercial formulations on soil fauna

Neonicotinoids are the most prominent group of insecticides in the world and are commercialized in over 120 countries for the control of agricultural pests mainly due to their broad-spectrum activity and versatility in application. Though non-target soil organisms are likely to be exposed during application, there is paucity of information in scientific literature regarding their sensitivity to neonicotinoids. This study attempts to fill this gap by evaluating, under laboratory conditions, the chronic toxicity of the neonicotinoids thiacloprid and acetamiprid, through their commercial formulations (CF), to the soil invertebrates Folsomia candida, Eisenia andrei and Enchytraeus crypticus. Results obtained indicate that the relative reproductive sensitivity of the test organisms can be expressed as: F. candida = E. andrei > E. crypticus (for acetamiprid CF) and E. andrei > F. candida > E. crypticus (for thiacloprid CF). To extrapolate from laboratory test results to field conditions, predicted environmental concentrations (PECs) and predicted no-effect concentrations were derived. Calculated toxicity-exposure ratios (TER = EC10/PEC) were below trigger values for acetamiprid and thiacloprid, when estimated with initial PEC. While estimated hazard quotients (HQ = PEC/PNEC), were greater than the European Commission trigger value. Therefore, with the current data under standard environmental risk assessment schemes it can be considered that the risk of thiacloprid and acetamiprid to the soil compartment is unacceptable. However, further research into the effects of these substances on different organisms is required to increase the confidence in the risk assessment estimates for instance, by calculating hazardous concentrations using species sensitivity distribution curves.

Derivation of aquatic predicted no-effect concentration (PNEC) for ibuprofen and sulfamethoxazole based on various toxicity endpoints and the associated risks

For pharmaceuticals, the ecological risk assessment based on traditional endpoints of toxicity could not be properly protective in the long run since the mode of action could vary because they are intended for different therapeutic uses. In this study, the predicted no-effect concentrations (PNECs) of two selected pharmaceuticals, ibuprofen (IBU) and sulfamethoxazole (SMX), were derived based on either traditional endpoints of survival and growth data or some nonlethal endpoints such as reproduction, biochemical and molecular data. The PNECs of IBU based on biochemical-cellular and reproduction data were 0.018 and 0.026 μg L−1 that were significantly lower than those derived from other endpoints, while the lowest PNEC for SMX derived from growth data with the concentration of 0.89 μg L−1. Ecological risk assessment was performed for IBU and SMX to the aquatic environment by applying hazard quotient and probabilistic distribution based quotient (DBQs) methods. The results showed that the probability of DBQs of IBU exceeding 0.1 was 11.2%, while for SMX the probability was 0.9% that could be neglected.

Acute Toxicity and Ecological Risk Assessment of Benzophenone-3 (BP-3) and Benzophenone-4 (BP-4) in Ultraviolet (UV)-Filters.

Ultraviolet (UV)-absorbing chemicals (UV filters) are used in personal care products for the protection of human skin and hair from damage by UV radiation. Although these substances are released into the environment in the production and consumption processes, little is known about their ecotoxicology effects. The acute toxicity and potential ecological risk of UV filters benzophenone-3 (BP-3) and benzophenone-4 (BP-4) on Chlorella vulgaris, Daphnia magna, and Brachydanio rerio were analyzed in the present study. The EC50 values (96 h) of BP-3 and BP-4 on C. vulgaris were 2.98 and 201.00 mg/L, respectively. The 48 h-LC50 of BP-3 and BP-4 on D. magna were 1.09 and 47.47 mg/L, respectively. The 96 h-LC50 of BP-3 and BP-4 on B. rerio were 3.89 and 633.00 mg/L, respectively. The toxicity of a mixture of BP-3 and BP-4 on C. vulgaris, D. magna, and B. rerio all showed antagonistic effects. The induced predicted no-effect concentrations of BP-3 and BP-4 by the assessment factor method were 1.80 × 10−3 and 0.47 mg/L, respectively, by assessment factor (AF) method, which were both lower than the concentrations detected in the environment at present, verifying that BP-3 and BP-4 remain low-risk chemicals to the aquatic ecosystem.

Combinatory effects of low concentrations of 17α-etinylestradiol and citalopram on non-reproductive behavior in adult zebrafish (Danio rerio)

Sewage effluents contain pharmaceuticals, personal care products and industrial chemicals, exposing aquatic organisms to complex mixtures. The consequences of exposure to combinations of different classes of drugs in fish are largely unknown. In this study, we exposed adult zebrafish (Danio rerio) males and females for two weeks to low, environmentally relevant concentrations of the endocrine disrupting chemical 17α-etinylestradiol (EE2) and the selective serotonin re-uptake inhibitor (SSRI) citalopram, alone and in combination, and analyzed behaviors of importance for population fitness, scototaxis (light/dark preference), the novel tank test and shoal cohesion. Control water contained 0.4ng/L EE2 and the measured exposure concentrations were 0.9ng/L EE2 (nominal 0.1) and 1ng/L EE2 (nominal 0.5). The measured concentrations of citalopram were 0.1 (nominal 0.1) and 0.4μg/L (nominal 0.5). Both EE2 exposures increased anxiety in males in the scototaxis test, with significantly longer latency periods before entering and fewer visits to the white zone of the tank. The combined exposures (0.9ng/L EE2+0.1μg/L citalopram and 1ng/L EE2+0.4μg/L citalopram) resulted in abolishment of effects of EE2, with shorter latency period and more transitions to white than for fish exposed to EE2 alone. In the novel tank test, the results surprisingly indicated lower anxiety after both EE2 and citalopram exposure. Significantly more transitions to the upper half of the tank observed in males exposed to 0.1μg/L citalopram alone compared to control males. Males exposed to EE2 (0.9ng/L) had shorter latency period to the upper half. Combination exposure resulted in a longer latency and fewer transitions to the upper half compared to both control, EE2- and citalopram-exposed males. Males exposed to the combination spent significantly less time in the upper half than males EE2 or citalopram-exposed males. Females exposed to 1ng/L EE2 had fewer transitions to the upper half than the control group and females exposed to 0.4μg/L citalopram. In the shoaling test, males exposed to 0.1μg/L citalopram+0.9ng/L EE2 showed more transitions away from peers than males exposed to 0.1μg/L citalopram alone. In conclusion, low concentrations of EE2, closely above the predicted no effect concentration (NOEC) of 0.1ng/L, created anxiety-like behavior in zebrafish males. Citalopram showed marginal effects at these low concentrations but in the combination exposure the behavioral effects of EE2 were abolished. This is an initial effort to understand the effects of cocktails of anthropogenic substances contaminating aquatic environments.

Environmental Risk Assessment Strategy for Nanomaterials.

An Environmental Risk Assessment (ERA) for nanomaterials (NMs) is outlined in this paper. Contrary to other recent papers on the subject, the main data requirements, models and advancement within each of the four risk assessment domains are described, i.e., in the: (i) materials, (ii) release, fate and exposure, (iii) hazard and (iv) risk characterisation domains. The material, which is obviously the foundation for any risk assessment, should be described according to the legislatively required characterisation data. Characterisation data will also be used at various levels within the ERA, e.g., exposure modelling. The release, fate and exposure data and models cover the input for environmental distribution models in order to identify the potential (PES) and relevant exposure scenarios (RES) and, subsequently, the possible release routes, both with regard to which compartment(s) NMs are distributed in line with the factors determining the fate within environmental compartment. The initial outcome in the risk characterisation will be a generic Predicted Environmental Concentration (PEC), but a refined PEC can be obtained by applying specific exposure models for relevant media. The hazard information covers a variety of representative, relevant and reliable organisms and/or functions, relevant for the RES and enabling a hazard characterisation. The initial outcome will be hazard characterisation in test systems allowing estimating a Predicted No-Effect concentration (PNEC), either based on uncertainty factors or on a NM adapted version of the Species Sensitivity Distributions approach. The risk characterisation will either be based on a deterministic risk ratio approach (i.e., PEC/PNEC) or an overlay of probability distributions, i.e., exposure and hazard distributions, using the nano relevant models.

Study of pharmaceuticals in surface and wastewater from Cuernavaca, Morelos, Mexico: Occurrence and environmental risk assessment

The present work describes the first known study to date on the occurrence of pharmaceuticals in surface water and wastewater of Cuernavaca, the capital of the state of Morelos (México). Selected pharmaceuticals (a total of 35) were extracted from the collected water samples with a generic solid phase extraction (SPE) protocol and determined in the sample extracts by means of high-performance liquid chromatography coupled to electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS). A screening level risk assessment combining the measured environmental concentrations (MECs) with dose-response data based on predicted no-effect concentrations (PNECs) was also applied to estimate Hazard Quotients (HQs) for the pharmaceuticals detected in the investigated area. A total of twelve pharmaceuticals were found in the water samples analyzed, with detection frequencies above 78% and in most cases of 100%. Overall, the most abundant pharmaceuticals in surface water were the analgesic and anti-inflammatory drugs naproxen (732–4880ng/L), acetaminophen (354–4460ng/L), and diclofenac (258–1398ng/L), and the lipid regulator bezafibrate (286–2100ng/L). On the contrary, other compounds like the β-blocker atenolol and the psychiatric drug carbamazepine were found at only a few ng or tens of ng per liter in the Apatlaco River. Despite the fact that some of the most abundant compounds showed good removal (>97%) during wastewater treatment, concentrations downstream the WWTP were only slightly lower than upstream. This indicates the existence of additional inputs of untreated wastewater into the river. Based on the obtained HQ-values, the concentrations of ibuprofen, sulfamethoxazole, diclofenac and naproxen present in the river could pose a high toxicity risk for the aquatic ecosystem. These findings highlight these pharmaceuticals as relevant organic contaminants in the area of study and the need to further monitor them in order to adopt appropriate measures to safeguard the ecosystem, and eventually human health.

Ecotoxicological risk assessment of chosen pharmaceuticals detected in surface waters

ABSTRACTThe goal of this work was to assess the risk posed by the presence of ciprofloxacin, 17α-ethinylestradiol and 5-fluorouracil in aquatic ecosystems based on chronic single-species ecotoxicological tests. There were 23 species used in this study: one cyanobacterium, three green algae, one higher plant, one protozoan, two crustaceans, two fish, 12 bacteria and one fungus (yeast). The risk assessment was performed on the basis of the PEC/PNEC ratio (PEC – predicted environmental concentration, PNEC – predicted no-effect concentration). PNEC was calculated using an assessment factor and statistical extrapolation models. The risk in relation to aquatic organisms proved to be high. The potentially affected fraction of aquatic species in the presence of pharmaceutical active ingredients, depending on the calculation method and the selected concentration in surface waters (predicted or measured), ranged from 6.26 to 27.84% for ciprofloxacin, 2.13 to 18.74% for 17α-ethinylestradiol and 4.96 to 39.28% for 5-fluorouracil. The study indicates several gaps in the existing guidelines, which may be considered within the guideline-revision process.

Caffeine and paraxanthine in aquatic systems: Global exposure distributions and probabilistic risk assessment

This study presents one of the most complete applications of probabilistic methodologies to the risk assessment of emerging contaminants. Perhaps the most data-rich of these compounds, caffeine, as well as its main metabolite (paraxanthine), were selected for this study. Information for a total of 29,132 individual caffeine and 7442 paraxanthine samples was compiled, including samples where the compounds were not detected. The inclusion of non-detect samples (as censored data) in the estimation of environmental exposure distributions (EEDs) allowed for a realistic characterization of the global presence of these compounds in aquatic systems. EEDs were compared to species sensitivity distributions (SSDs), when possible, in order to calculate joint probability curves (JPCs) to describe the risk to aquatic organisms. This way, it was determined that unacceptable environmental risk (defined as 5% of the species being potentially exposed to concentrations able to cause effects in>5% of the cases) could be expected from chronic exposure to caffeine from effluent (28.4% of the cases), surface water (6.7% of the cases) and estuary water (5.4% of the cases). Probability of exceedance of acute predicted no-effect concentrations (PNECs) for paraxanthine were higher than 5% for all assessed matrices except for drinking water and ground water, however no experimental effects data was available for paraxanthine, resulting in a precautionary deterministic hazard assessment for this compound. Given the chemical similarities between both compounds, real effect thresholds, and thus risk, for paraxanthine, would be expected to be close to those observed for caffeine. Negligible Human health risk from exposure to caffeine via drinking or groundwater is expected from the compiled data.

Occurrence, distribution and environmental risk of pharmaceutically active compounds (PhACs) in coastal and ocean waters from the Gulf of Cadiz (SW Spain)

In this study, we have evaluated the occurrence and distribution of 78 pharmaceuticals in different aquatic marine environments from the Gulf of Cadiz (SW Spain) for the first time. The obtained results revealed that pharmaceuticals were present in seawater at total concentrations ranging 61–2133 and 16–189ngL−1 in coastal and oceanic transects, respectively. Potential marine pollution hotspots were observed in enclosed or semi-enclosed water bodies (Cadiz Bay), showing concentrations that were one or two orders of magnitude higher than in the open ocean. The presence of these chemicals in local sewage treatment plants (STPs), one of the main contamination sources, was also assessed, revealing total concentrations of up to 23μgL−1 in effluents. PhACs with the highest detection frequencies and concentrations in the sampling region were analgesics and anti-inflammatories followed by antibiotics in the case of samples from Cadiz Bay or caffeine in oceanic seawater samples. Risk quotients, expressed as ratios between the measured environmental concentration (MEC) and the predicted no-effect concentrations (PNEC) were higher than 1 for two compounds (gemfibrozil and ofloxacin) in effluent of Jerez de la Frontera sewage treatment plant (STP). No high environmental risk was detected in both coastal and oceanic sampling areas, although the information available about the effects of these chemicals on marine biota is still very limited and negative effects on non-target species cannot be discarded.

Updated species sensitivity distribution evaluations for acute and chronic lead toxicity to saltwater aquatic life.

The US Environmental Protection Agency's (USEPA's) ambient water quality criteria (AWQC) for lead (Pb) in salt water were developed in 1984. The acute and chronic criteria are 210 and 8.1 μg/L dissolved Pb, respectively. Because data were limited in 1984, the chronic criterion was derived using an acute-to-chronic ratio, but there are now sufficient toxicity data such that an acute-to-chronic ratio is no longer needed. Based on the data now available, the proposed updated acute and chronic salt water Pb AWQC (following USEPA methods) are 100 and 10 µg/L, respectively. In the European Union, a chronic salt water predicted no-effect concentration based on the median 5th percentile hazardous concentration (HC5-50) was developed in 2008 for the Registration, Evaluation, Authorisation, and Restriction of Chemicals program, which forms the basis for deriving chronic environmental quality standards for Pb in European marine waters. The salt water HC5-50 previously derived for Pb was 6.1 μg/L, whereas the proposed, updated chronic salt water HC5-50 derived following European Union methods is 11.0 µg/L. Thus, despite differences in derivation methodologies, the proposed AWQC and HC5-50 values are very consistent. Studies evaluating the effect of water quality factors on bioavailability and toxicity of Pb in salt water are limited; the effect of water quality on Pb toxicity in salt water should be considered in future studies. Environ Toxicol Chem 2017;36:2974-2980. © 2017 SETAC.

A validated algorithm for selecting non-toxic chemical concentrations

The maximal chemical concentration that causes an acceptably small or no effect in an organism or isolated cells is an often-sought-after value in toxicology. Existing approaches to derive this value have raised several concerns; thus, it is often chosen case-by-case based on personal experience. To overcome this ambiguity, we propose an approach for choosing the non-toxic concentration (NtC) of a chemical in a rational, tractable way. We developed an algorithm that identifies the highest chemical concentration that causes no more than 10% effect (= EC10) including the modeled 95% confidence intervals and considering each of the measured biological replicates; and whose toxicity is not significantly different from no effect. The developed algorithm was validated in two steps: by comparing its results with measured and modeled data for 91 dose-response experiments with fish cell lines and/or zebrafish embryos; and by measuring actual effects caused by NtCs in a separate set of experiments using a fish cell line and zebrafish embryos. The algorithm provided an NtC that is more protective than NOEC (no-observed-effect-concentration), NEC (modeled no-effect concentration), EC10 and BMD (benchmark dose). Despite focusing on small-scale bioassays here, this study indicates that the NtC algorithm could be used in various systems. Its application to the survival of zebrafish embryos and to metabolic activity in cell lines showed that NtCs can be applied to different effect measurements, time points, and levels of biological organization. The algorithm is available as Matlab and R source code, and as a free, user-friendly online application.