Ambient Water Quality Criteria Research Articles

Health risk assessment and development of human health ambient water quality criteria for PCBs in Taihu Basin, China

Polychlorinated biphenyls (PCBs) are a class of typical persistent organic pollutants (POPs) with carcinogenicity and extensively found in diverse environmental mediums. The Taihu Basin is one of the most economically developed regions in China, and it has also caused a lot of historical legacy and unconscious emissions of PCBs, posing a threat to the health of people in the region. This study counted the concentrations of PCBs in five environmental media (water, soil, air, dust, and food) in the Taihu Basin from 2000 to 2020 and used Monte Carlo simulation to simulate the multi-channel exposure of PCBs in people of different ages (children, teenagers, and adults), and evaluated their noncarcinogenic and carcinogenic health risks. Finally, the human health ambient water quality standards (AWQC) for PCBs were obtained using regional exposure parameters and bioaccumulation factors. The results showed that the pollution of PCBs in the Taihu Basin was relatively serious in China. The concentration of PCBs in dust is higher than other environmental media. And exposure to water and food is the main exposure pathway for PCBs in the population of the region. Besides, PCBs pose no noncarcinogenic risk to people in this region, but their carcinogenic risk to residents exceeds the safety threshold. Among the three population groups, adults have the highest risk of cancer, and prevention measures need to be taken by controlling the intake of related foods and the concentration of PCBs in water. The following human health AWQC values of the PCBs in Taihu Basin is 3.2 × 10−9 mg/L.

Freshwater environment risk assessment and derivation of human health ambient water quality criteria for SCCPs in China

Short-chain chlorinated paraffins (SCCPs, CxH2x+2−yCly, where x = 10 to 13 and y = 3 to x) are a complex family of emerging contaminants that have been identified as persistent, bioaccumulative and toxic (PBT) substances. Because of their persistence, high toxicity, bioaccumulation and long-distance mobility, SCCPs were added to the list of controlled POPs in the Stockholm Convention in 2017. China is the largest producer and user of SCCPs all over the world, thus SCCPs have been widely distributed in the freshwater environment. But the ecological risk and human health risk of SCCPs in China were still less evaluated. This study collected and screened the exposure data of SCCPs in freshwater environment in China, and then evaluated the freshwater and sediments ecological risk of SCCPs by risk quotient (RQ) method and the human health risk by margin of exposure (MOE) method. Our results showed that the pollution of SCCPs in the freshwater environment in China was not optimistic. The ecological risks and human health risks had occurred, and even there were high ecological risks occurred in some regions in China. Besides, because of the absence of the concentration threshold of SCCPs to protect human health in freshwater at present, we derived the human health ambient water quality criteria (AWQC) values of SCCPs based on exposure data and bioaccumulation factor (BAF) in China. The human health AWQC values of SCCPs ranged from 14.99 ng L−1 to 154.54 ng L−1 in different regions in China, and the national human health AWQC value was determined as 24.08 ng L−1. This study will provide the scientific references for the management and control of SCCPs in China, especially for the formulation of standard of water environmental quality for SCCPs.

QSAR-QSIIR-based prediction of bioconcentration factor using machine learning and preliminary application

Bioconcentration factor (BCF) is one of the important parameters for developing human health ambient water quality criteria (HHAWQC) for chemical pollutants. Traditional experimental method to obtain BCF is time-consuming and costly. Therefore, prediction of BCF by modeling has attracted much attention. QSAR (Quantitative Structure-Activity Relationship) model based on molecular descriptor is often used to predict BCF, however, in order to improve the accuracy of prediction, previous models are only applicable for prediction for a single category of substance and a single species, and cannot meet the needs of BCF prediction of pollutants lacing toxicity data. In this study, optimized 17 traditional molecular descriptor and five kinds of bioactivity descriptor were selected from more than 200 molecular descriptor and 25 kinds of biological activity descriptors. A QSAR-QSIIR (Quantitative Structure In vitro-In vivo Relationship) model suitable for multiple chemical substances and whole species is constructed by using optimized 4-MLP machine learning algorithm with selected molecular and bioactivity descriptors. The constructed model significantly improves the prediction accuracy of BCF. The R2 of verification set and test set are 0.8575 and 0.7924, respectively, and the difference between predicted BCF and measured BCF is mostly less than 1.5 times. Then, BCF of BTEX in Chinese common aquatic products is predicted using the constructed QSAR-QSIIR model, and the HHAWQC of BTEX in China are derived using the predicted BCF, which provides a valuable reference for establishment of China’s BTEX water quality standards.

The Application of Reference Dose Prediction Model to Human Health Water Quality Criteria and Risk Assessment.

Oral reference dose (RfD) is a key parameter for deriving the human health ambient water quality criteria (AWQC) for non-carcinogenic substances. In this study, a non-experimental approach was used to calculate the RfD values, which explore the potential correlation between toxicity and physicochemical characteristics and the chemical structure of pesticides. The molecular descriptors of contaminants were calculated using T.E.S.T software from EPA, and a prediction model was developed using a stepwise multiple linear regression (MLR) approaches. Approximately 95% and 85% of the data points differ by less than 10-fold and 5-fold between predicted values and true values, respectively, which improves the efficiency of RfD calculation. The model prediction values have certain reference values in the absence of experimental data, which is beneficial to the advancement of contaminant health risk assessment. In addition, using the prediction model constructed in this manuscript, the RfD values of two pesticide substances in the list of priority pollutants are calculated to derive human health water quality criteria. Furthermore, an initial assessment of the health risk was performed by the quotient value method based on the human health water quality criteria calculated by the prediction model.

Rapid screening of polybrominated diphenyl ethers in water by solid-phase microextraction coupled with ultrahigh-resolution mass spectrometry.

Polybrominated diphenyl ethers (PBDEs) are considered emerging organic contaminants that attract more attention in the environment. Herein, online coupling of solid-phase microextraction and ultrahigh-resolution mass spectrometry was developed for rapid screening of eight PBDEs in water samples. This procedure was completed in 22min, about 6 times faster than the routine workflow such as solid-phase extraction coupled with gas chromatography-mass spectrometry. Thermal desorption and solvent-assisted atmospheric pressure chemical ionization were developed for the effective coupling of solid-phase microextraction (SPME) with ultrahigh-resolution mass spectrometry (UHRMS), which contributed to the signal enhancement and made the methodology feasible for environmental screening. The limits of detection and quantification were 0.01-0.50ng/mL and 0.05-4.00ng/mL, respectively. The recoveries were 57.2-75.2% for quality control samples at spiking levels of 0.8-10ng/mL (4-50ng/mL for BDE209), with relative standard deviation less than 19.0%. Twelve water samples from different river sites near industrial areas were screened using the developed method. The results showed that BDE-209 was the dominant PBDE (1.02-1.28ng/mL in positive samples), but its amount was lower than the human health ambient water quality criteria. Consequently, the developed method provides a rapid and reliable way of evaluating contamination status and risks of PBDEs in aqueous environment.

Comparison of Multiple Linear Regression and Biotic Ligand Models for Predicting Acute and Chronic Zinc Toxicity to Freshwater Organisms.

Multiple linear regression (MLR) models for predicting zinc (Zn) toxicity to freshwater organisms were developed based on three toxicity-modifying factors: dissolved organic carbon (DOC), hardness, and pH. Species-specific, stepwise MLR models were developed to predict acute Zn toxicity to four invertebrates and two fish, and chronic toxicity to three invertebrates, a fish, and a green alga. Stepwise regression analyses found that hardness had the most consistent influence on Zn toxicity among species, whereas DOC and pH had a variable influence. Pooled acute and chronic MLR models were also developed, and a k-fold cross-validation was used to evaluate the fit and predictive ability of the pooled MLR models. The pooled MLR models and an updated Zn biotic ligand model (BLM) performed similarly based on (1) R2 , (2) the percentage of effect concentration (ECx) predictions within a factor of 2.0 of observed ECx, and (3) residuals of observed/predicted ECx versus observed ECx, DOC, hardness, and pH. Although fit of the pooled models to species-specific toxicity data differed among species, species-specific differences were consistent between the BLM and MLR models. Consistency in the performance of the two models across species indicates that additional terms, beyond DOC, hardness, and pH, included in the BLM do not help explain the differences among species. The pooled acute and chronic MLR models and BLM both performed better than the US Environmental Protection Agency's existing hardness-based model. We therefore conclude that both MLR models and the BLM provide an improvement over the existing hardness-only models and that either could be used for deriving ambient water quality criteria. Environ Toxicol Chem 2023;42:393-413. © 2022 SETAC.

Distribution, health risk assessment, and water quality criteria of phthalate esters in Poyang Lake, China

Although China has been the main manufacturer and consumer of phthalate esters (PAEs), human health ambient water quality criteria (AWQCs) have not been proposed for these chemicals. In this study, the distribution and bioaccumulation of six PAEs (dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), bis (2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP)) were investigated in 11 edible fish species collected from Poyang Lake, China. The results showed that the total concentrations of the six PAEs in the fish ranged between 118.63 and 819.84 μg/kg wet weight (mean of 327.50 ± 190.44 μg/kg). DMP, DEP, DBP, and DEHP were detected in all samples, of which DEHP and DBP were two of the most predominant phthalates, accounting for more than 90% of the total PAEs. The DEHP concentrations in fish with different habitat preferences were different, demersal species were significantly higher than pelagic species (p < 0.05). The mean natural logarithmic bioaccumulation factors (log BAFs) of PAEs increased with increasing lipophilicity of the substances, which yielded the following regression equation: log BAF (L/kg) = 0.103 log Kow + 2.158 (r2 = 0.940, p < 0.05, n = 4). Using this quantitative structure–activity relationship to calculate BAFs for the remaining undetected substances (BBP and DnOP) to derive AWQCs. According to the natural parameters, the human health AWQCs relating to PAE concentrations for water and fish consumption were derived as 9.4 × 103 (DMP), 5.0 × 102 (DEP), 4.2 × 101 (DBP), 1.1 (BBP), 8.6 × 10− 2 (DEHP), and 2.0 (DnOP) μg/L. Human health risk assessment indicated that the dietary intake of DEHP may exert a carcinogenic effect on residents of the Poyang Lake region. The results provide important input to assess the health risk posed by PAEs contaminated surface water.

Human health ambient water quality criteria and risk assessment of pentachlorophenol in Poyang Lake Basin, China.

Pentachlorophenol (PCP) has been widely used as an insecticide for killing oncomelania (the intermediate host of schistosome) in China and leads to severe environmental contamination. Poyang Lake, as the largest freshwater lake and bird habitat in China, was once a schistosomiasis epidemic area. In this study, the concentrations of PCP in water and aquatic products from Poyang Lake were determined and analyzed, and then the human health ambient water quality criteria (AWQC) was derived based on native parameters of Poyang Lake basin. Finally, a comprehensive analysis of the health risks of drinking water and different types of aquatic products consumption was carried out. The results showed that PCP concentrations were ranged from 0.01 to 0.43μg/L in surface water and 3.90 to 85.95μg/kg in aquatic products. Due to the carcinogenicity of PCP, the human health AWQC for PCP are 0.02μg/L for consumption of water and organisms and 0.03μg/L for consumption of organisms only. Deterministic and probabilistic risk analysis indicated that the non-carcinogenic risk of PCP were acceptable in Poyang Lake, while the carcinogenic risk cannot be ignored. The health risks of PCP caused by aquatic products consumption were higher than that by drinking water. The percentages of acceptable risk for the population in Poyang Lake Basin were 99.95% at acceptable level of 10-4. Based on the sensitivity analysis, the impact of PCP concentrations on health risk values ranged from 53 to 82%. The study provided valuable information for regional water quality criteria development and water quality assessment.

Ambient water quality criteria derived using probabilistic risk assessment.

National recommendations for numeric human health ambient water quality criteria (AWQC) for toxic substances are derived by the US Environmental Protection Agency (USEPA) using a deterministic approach that combines point estimates for exposure, toxicity, and acceptable risk. In accordance with the Clean Water Act, states, territories, and authorized tribes must either adopt these recommendations or modify and replace them with criteria using an alternative, scientifically defensible method. Recent reports have criticized the deterministic approach, stating that it suffers from compounded conservatism by selecting upper percentiles or maximum values for multiple inputs and that it cannot directly determine what portion of the population a given criterion protects. As an alternative, probabilistic risk assessment (PRA) has been promoted as a more transparent and robust method for deriving AWQC. Probabilistic risk assessment offers several advantages over the deterministic approach. For example, PRA uses entire data distributions rather than upper-percentile point estimates to specify exposures, thereby reducing compounded conservatism. Additionally, because it links acceptable risk targets with specific segments of the exposed population, PRA-based AWQC demonstrably protects multiple subsets of the population. To date, no study has quantitatively compared deterministic and PRA approaches and resulting AWQC using national inputs consistent with USEPA guidance. This study introduces a PRA method for deriving AWQC and presents case studies to compare probabilistically derived AWQC with USEPA's 2015 recommendations. The methods and results of this work will help federal and state regulators, water quality managers, and stakeholders better understand available approaches to deriving AWQC and provide context to assumption- and method-specific differences between criteria. Integr Environ Assess Manag 2023;19:501-512.© 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

An analysis of the use of the relative source contribution term in derivation of drinking water standards using perfluorooctanoic acid as an example.

The relative source contribution (RSC) term has long been used by the US Environmental Protection Agency (USEPA) and state regulatory agencies in setting criteria in water. The RSC reflects the proportion of the total daily intake of a chemical that can be derived from water when all other sources of exposure (e.g., food, air) are considered. This term is applied by the USEPA and state regulatory agencies when deriving ambient water quality criteria, maximum contaminant level goals, and drinking water health advisories for noncarcinogenic and threshold carcinogenic compounds. The value assigned to the RSC term affects the calculated criteria directly, with the allowable concentration in water decreasing with a decreasing RSC. A default RSC value of 20%-applied by regulatory entities in the USA for more than 40 years-assumes that 80% of an individual's exposure to a chemical's reference dose is from nonwater sources. Although the RSC is a chemical-specific parameter, there are few instances where a value other than the default of 20% has been approved and used. In 2000, USEPA outlined the process for developing chemical-specific RSC values, yet primary use of the default RSC value has continued since then. This article reviews USEPA's methodology for deriving chemical-specific RSC values and provides a case example using perfluorooctanoic acid (PFOA) to explore how the USEPA and state regulatory agencies are applying USEPA's guidance. The case study highlights inconsistent derivation of the RSC term, rooted in limitations in the current methodology. We suggest additional clarification of and more thoughtful use of the available data that may not meet USEPA's current adequacy requirements. We also recommend that the USEPA discuss recommendations for using biomonitoring data to set RSCs. Integr Environ Assess Manag 2023;19:605-612. © 2022 SETAC.

Occurrence, health risk assessment and water quality criteria derivation of six personal care products (PCPs) in Huangpu River, China.

Personal care products (PCPs) have shown adverse health effects on humans. However, their health risk associated with fish consumption and relevant water quality criteria are still not well documented. This study investigated the occurrence and health risk of six PCPs (triclosan, bisphenol-A, and four commonly used organic ultraviolet (UV) filters, i.e., homosalate (HMS), 4-methylbenzylidene camphor (4-MBC), oxybenzone (BP-3), and octocrylene (OC)). River water and three trophic levels of fish species were collected from Huangpu River in Shanghai. The concentration range of the six PCPs were 1.48-89.76ng/L in water and 0.40-10.75ng/g dry weight in fish. Estimated daily intake (EDI) and target hazard quotient (THQ) of the PCPs indicated that consuming these fish would not pose non-carcinogenic risks. The maximum allowable fish consumption rates ranged from 85 to 1760 and 155 to 3230 meals per month for children and adults, respectively. As to the four organic UV filters, it is the first time to report the fish consumption advisories. Finally, the human health ambient water quality criteria (AWQC) values of HMS, 4-MBC, BP-3, OC, TCS, and BPA (i.e., 0.1218, 0.7311, 0.3494, 0.0477, 235.8, and 154.7μg/L, respectively) were proposed, and they can serve as a valuable technical reference for global development and revision of aquatic environmental quality standards for these emerging contaminants.

Using a Probabilistic Model and Local Parameters to Improve the Reliability of Ambient Water Quality Criteria for the Protection of Human Health: A Case Study of Organophosphate Esters in China

Water quality criteria for the protection of human health (HHWQC) are crucial for the management of aquatic environmental quality. However, previous studies derived HHWQC using only deterministic approaches, which may under/overprotect target populations. This paper improved the methodology for criteria development and applied it to organophosphate esters (OPEs). Missing model parameters, including the trophic level-specific fish consumption rate (FIn) and lipid fraction (fl(TL,n)), were derived according to China’s conditions. The trophic level-specific national bioaccumulation factors (BAFs) for OPEs (5.05–14,281 L/kg) were calculated based on field-measured BAFs in surface freshwater across China and were dominated by the hydrophobicity of compounds. Then, the probabilistic approach was introduced to HHWQC derivation (0.1120–400.5 μg/L), and the results were compared with those derived by the deterministic method (0.1024–664.5 μg/L), which demonstrated that the probabilistic approach derived HHWQC more accurately. The contributions of organism ingestion to the HHWQC for OPEs were steady (<10%) with log Kow<3.5, increased linearly (10–90%) within a log Kow of 3.5–5.5, and then leveled off. Regarding the effects of carcinogenic OPEs, approximately 10% of the studied freshwater in China displays significant risks to human health. This study is significant for the scientific development of HHWQC worldwide and the management of pollutants in water.

Evaluation of silver nanoparticle acute and chronic effects on freshwater amphipod (Hyalella azteca).

Silver nanoparticles (AgNPs) are known to cause ecotoxic effects, but there are no existing derived ambient water quality criteria (AWQC) for these nanomaterials to protect freshwater aquatic life due to insufficient toxicological data. We exposed Hyalella azteca to silver nitrate, citrate-coated AgNPs (citrate-AgNPs), and polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) in a 10-day and 28-day water-only static renewal system with clean sand as a substrate for the amphipods and compared their point estimates with the United States Environmental Protection Agency (USEPA) AWQC for silver. We observed that all treatments decreased the survival, growth, and biomass of H. azteca, and the order of toxicity was AgNO3 > citrate-AgNPs > PVP-AgNPs. The LC50s of AgNO3, citrate-AgNPs, and PVP-AgNPs were 3.0, 9.6, and 296.0µg total Ag L-1, respectively, for the acute exposure and 2.4, 3.2, and 61.4µg total Ag L-1, respectively, for the chronic exposure. Acute and chronic EC20s of citrate-AgNPs ranged from 0.5 to 3.5µg total Ag L-1 while that of PVP-AgNPs ranged from 31.2 to 175µg total Ag L-1 for growth and biomass. Both Ag+ released from AgNPs and the nanoparticles contributed to the observed toxicity. The dissolution and toxicity of AgNPs were influenced by surface coating agents, particle size, and surface charge. Most point estimates for AgNPs were above AWQC for silver (4.1µg L-1) and the lowest concentration (0.12µg/L) at which Ag is expected to cause chronic adverse effects to freshwater aquatic life. Our study demonstrates that the current AWQC for silver, in general, is protective of freshwater aquatic life against AgNPs tested in the present study.

Deriving convincing human health ambient water quality criteria for benzo[a]pyrene and providing basis for the water quality management: The impacts of national bioaccumulation factors and probabilistic modeling

Science-based water quality criteria are the cornerstone of water quality standards. This paper improved the methodology for the derivation of human health water quality criteria (HHWQC) and applied it for benzo[a]pyrene (BaP) to provide a scientific basis for the management of polycyclic aromatic hydrocarbons (PAHs) in surface waters. First, the national bioaccumulation factors (BAFs) for BaP were derived using field-measured BAFs and field-measured biota-sediment accumulation factors (BSAFs) across China, respectively, which results were comparable and demonstrated the reliability of the obtained national BAFs for BaP. The HHWQC for BaP derived using the probabilistic approach were 3.98–4.70 ng/L and were comparable with those derived by the deterministic approach, suggesting the accuracy of derived HHWQC for BaP. Through the probabilistic approach, the probability distributions of lifetime incremental cancer risk from BaP in water were provided and the consumption rates of aquatic products at trophic level 2 and 3 were identified as factors influencing risks of BaP significantly. The derived HHWQC for BaP in China are approximately 33–36 times higher than those in the United States because of the high national BAFs and cancer slope factor of BaP used for the United States. In addition, the recommended HHWQC for BaP conform to the situation in China and are approximately 1.5 times higher than the standard value of BaP in the current National Surface Water Quality Standard (GB 3838-2002) in China (2.80 ng/L), which will play an important role in the amendment of National Surface Water Quality Standard in the future. Approximately 36% of the studied surface freshwater in China contains BaP with levels exceeding the recommended HHWQC, suggesting the pollution of BaP in surface freshwater is severe and needs to be given more attention. This study is significant for the scientific development of HHWQC worldwide and the management of pollutants in water.

Ecological and health risk assessments and water quality criteria of heavy metals in the Haihe River

Heavy metal pollution is an issue of wide concern owing to the toxic and bioaccumulative properties of many heavy metals and their tendencies to persist in the environment. The Haihe River is an important river in the Beijing–Tianjin–Hebei region, and heavy metal pollution of the basin has attracted considerable attention. This study determined the concentrations of 14 heavy metals (As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, and Zn) in water, sediments, and fish samples from the Haihe River basin. The results showed that the concentrations ranged from 0.08 μg L−1 to 60.49 μg L−1 in water, 0.11 mg kg−1 to 229.20 mg kg−1 in sediments, and 0.01 mg kg−1 to 11.72 mg kg−1 in fish. We derived the ambient water quality criteria (AWQC) value of each heavy metal with respect to human health, and then performed a comprehensive risk assessment according to the native parameters. The human health AWQC values for the assessed 14 heavy metals ranged from 0.16 μg L−1 to 726.53 μg L−1. The health risks posed by As, Cr, Hg, and Sb and the ecological risks associated with Ni, Cu, Cr, Zn, Cd, Co, Hg, and Sn were found to be issues of concern. The results of a sensitivity analysis revealed that the highest contributing parameter was i) the concentration in water (Cw) for Cd, Co, Mn, Sb, and Sn; ii) the intake rate of water (IRw) for As, Ba, Cr, Hg, Ni, Pb, and Se; and iii) the concentration in fish (Cf) for Cu and Zn. The results of this research could contribute to the information required for water quality assessments and the development of water quality standards.

Health risk assessment and development of human health ambient water quality criteria for PBDEs in China

Polybrominated diphenyl ethers (PBDEs) are not only a class of highly efficient brominated flame retardants (BFRs) but also a class of typical persistent organic pollutants (POPs) that are persistent and widely distributed in various environmental media. This study examined the concentrations of PBDEs in five environmental media (water, soil, air, dust, and food) and two human body media (human milk and blood) in China from 2010 to 2020. In addition, this study conducted multi-pathway exposure health risk assessments of populations of different ages in urban, rural, key regions, and industrial factories using the Monte-Carlo simulation. Finally, the human health ambient water quality criteria (AWQC) of eight PBDEs were derived using Chinese exposure parameters and bioaccumulation factors (BAFs). The results showed that the eastern and southeastern coastal regions of China were heavily polluted by PBDEs, and the variation trends of the ΣPBDEs concentrations in the different exposure media were not consistent. PBDEs did not pose a risk to urban and rural residents in ordinary regions, but the hazard indexes (HIs) for residents in key regions and occupational workers exceeded the safety threshold. Dust exposure was the primary exposure pathway for urban and rural residents in ordinary regions, but for residents in key regions and occupational workers, dietary exposure was the primary exposure pathway. BDE-209 was found to be the most serious individual PBDE congener in China. The following human health AWQC values of the PBDEs were derived: drinking water exposure: 0.233–65.2 μg·L−1; and drinking water and aquatic products exposure: 8.51 × 10−4–1.10 μg·L−1.

Stream Salamanders are Relatively Tolerant of Salty Streams.

The application of road salt as a deicing agent is common, but investigations of potential negative effects of salt runoff on stream salamanders have been limited. Additionally, modern stormwater management practices should influence the delivery of salt ions to streams. We used data loggers in streams draining watersheds with and without stormwater management ponds and acute 96-h LC50 tests to investigate exposure of, and road salt toxicity among, two widespread salamanders in the Eastern USA, northern dusky salamanders (Desmognathus fuscus) and northern two-lined salamanders (Eurycea bislineata). In streams below stormwater ponds, base levels of conductivity were elevated throughout the year and elevated Cl- levels led to more frequent acute and chronic exceedances of U.S. Environmental Protection Agency ambient water quality criteria for Cl- when compared to streams draining watersheds with no stormwater management ponds. However, five of the six streams studied had exceedance frequencies suggesting Cl- associated with road salt application represented a persistent threat to aquatic life. Larval stream salamanders were relatively tolerant of salt, not exhibiting any lethal effects over a 96-h period until chloride levels exceeded 5000mg/L for both species, and concentrations in streams rarely exceeded these levels and only for very short periods of time. Our results suggest road salts are not having acute lethal effects on salamanders in the streams we studied, but exceedance of U.S. Environmental Protection Agency ambient water quality standards for Cl- suggest the potential for sublethal and indirect effects of Cl- on salamander populations that require further study.

Human health ambient water quality criteria for 13 heavy metals and health risk assessment in Taihu Lake

Human health ambient water quality criteria for 13 heavy metals and health risk assessment in Taihu Lake

Acute and Chronic Toxicity Testing of Drinking Water Treatment Residuals in Freshwater Systems.

The beneficial use of drinking water treatment residuals (DWTRs) faces barriers due primarily to uncertainties and concerns about their potential environmental impacts. We used total and water leachable toxic metal concentrations and 2 benthic organism-based bioassays to identify suitable DWTR substrates for introduction to freshwater systems. Using total metal contents and the consensus probable effect concentration concept, 3 DWTRs were selected and used in elutriate and toxicity studies. The concentrations of water leachable Ag, As, Cd, Cu, Cr, Ni, Pb, and Zn were below the US Environmental Protection Agency's ambient water quality criteria. Using the long-term 65-d life cycle Chironomus tentans test and 4 different endpoints (survival, adult emergence, egg case production, and number of eggs produced per female), no statistical differences were found between the DWTR treatments and the controls. Similarly, results obtained using the 10-d Hyalella azteca test showed no toxicity. However, although both survival and growth were recorded in all bioassays, the results of the 10-d C. tentans and the 28-d H. azteca tests were ambiguous. For C. tentans, 2 of the 3 DWTRs resulted in significantly lower survival rates compared to the controls. For H. azteca, no significant growth differences were observed between controls and DWTR treatments, but 2 of the 3 DWTRs resulted in significantly lower survival rates than the controls. Overall, these results suggest that certain DWTR substrates could be suitable for introduction to aquatic systems. Environ Toxicol Chem 2021;40:2005-2014. © 2021 SETAC.

Chronic Toxicity of Cobalt to Marine Organisms: Application of a Species Sensitivity Distribution Approach to Develop International Water Quality Standards.

Water quality standards for cobalt (Co) have yet to be developed for the European Union or the United States. The primary objective of the present study was to produce a data set comprising marine Co toxicity data that could be used by both the European Union and the United States to determine a predicted-no-effect concentration and ambient water quality criteria, respectively. Ten marine species, ranging from algae to fish, were subjected to chronic Co toxicity tests that were designed to meet international water quality testing standards. Chronic 10% effect concentration values ranged from a low of 1.23 µg dissolved Co/L for red algae (Champia parvula) to a high of 31 800 µg dissolved Co/L for sheepshead minnow (Cyprinodon variegatus). The species sensitivity ranking for chronic marine Co exposure was as follows (from most to least sensitive): C. parvula > Neanthes arenaceodentata (polychaete) > Americamysis bahia (mysid shrimp) > Skeletonema costatum (marine diatom) > Dendraster excentricus (sand dollar) > Mytilus galloprovincialis (mussel) > Strongylocentrotus purpuratus (purple sea urchin) > Crassostrea gigas (oyster) > Dunaliella tertiolecta (marine flagellate) > C. variegatus. Chronic test results indicated that invertebrate and plant species were substantially more sensitive to Co exposure than fish. The chronic toxicity data were used to calculate a species sensitivity distribution, from which a hazardous concentration 5th percentile of 7.09 µg dissolved Co/L (95% CI 0.025-47.3 µg Co/L) was derived. Environ Toxicol Chem 2021;40:1405-1418. © 2021 SETAC.