Bioaccumulation of sediment-associated dinonylnaphthalene sulfonates in the freshwater mussel Lampsilis siliquoidea and oligochaete Tubifex tubifex

Naphthalene sulfonic acids (NSAs) are used primarily as additives in a wide range of industrial products (e.g., rubber materials, coatings, sealants, fuels, paints). Based on modeled physicochemical properties, NSAs would likely partition into sediments or the tissues of biota in an aquatic system. This study examined the potential for three NSAs, dinonylnaphthalene disulfonic acid (DNDS), barium dinonylnaphthalene sulfonate (BaDNS), and calcium dinonylnaphthalene sulfonate (CaDNS), to accumulate in the tissue of a freshwater mussel (Lampsilis siliquoidea) and oligochaete worm (Tubifex tubifex). The ability of L. siliquoidea to depurate accumulated chemical was also assessed. Mussels were exposed via sand spiked with CaDNS for 25 d, and then transferred to clean water where their ability to depurate the chemical over an additional 28 d was monitored. Worms were exposed to each of the three NSAs via spiked sediment for 28 d. NSA concentrations were measured separately in gill, foot, and remaining soft tissues (viscera) for mussels and in whole body tissue samples of worms. For L. siliquoidea, the largest concentration of CaDNS was measured in the gill tissue; once removed from CaDNS exposure, mussels were able to depurate up to 87% of the CaDNS from their tissues in 28 days. The biota-sediment accumulation factors (28-d BSAFs) for T. tubifex were 2.8-5.2, 0.53-0.76, and 0.83-1.11 for DNDS, BaDNS, and CaDNS, respectively. For mussel gill and viscera, BCF_K values were 14.07 and 16.39, respectively. When BAF_Ks were calculated using the concentration of CaDNS in sand, they were 1.11 and 1.29 for mussel gill and viscera, respectively. These values are much lower than what would be necessary to classify this chemical as bioaccumulative; however, the BSAFs for DNDS in T. tubifex indicated a potential biomagnification concern if this compound were to occur in the aquatic environment.

The influence of organic carbon on the toxicity of sediment-associated dinonylnaphthalene sulfonic acids to the benthic invertebrates Tubifex tubifex and Hyalella azteca

Naphthalene sulfonic acids (NSAs) are used extensively in industrial applications as dispersants in dyes, rubbers, and pesticides, and as anti-corrosive agents in coatings, gels, and sealants. This study examined the toxicity of three NSA congeners, barium dinonylnaphthalene sulfonate (BaDNS), calcium dinonylnaphthalene sulfonate (CaDNS), and dinonylnaphthalene disulfonic acid (DNDS), to two benthic species, Tubifex tubifex and Hyalella azteca. Two substrates with different levels of organic carbon (sediment [2%] and sand [0%]) were used in toxicity tests. Juvenile production was the most sensitive endpoint for T. tubifex: the 28-d EC50s were <18.2, 22.2, and 64.0 μg/g dw in sand and 281.3, 361.6, and 218.9 μg/g dw in sediment for BaDNS, CaDNS, and DNDS, respectively. The 28-d LC50s for H. azteca were similar among compounds: 115.3, 82.1, and 49.0 μg/g dry weight (dw) in sand, and 627.3, 757.9, and >188.5 μg/g dw in sediment, for BaDNS, CaDNS, and DNDS, respectively. However, when LC50s were estimated based on concentrations of NSAs measured in overlying water (which can be an important route of exposure for H. azteca), BaDNS and CaDNS were 3-4 orders of magnitude more toxic than DNDS. The NSAs examined were >3-fold more toxic when present in substrates with no organic carbon (e.g., sand) for all H. azteca endpoints where LC/EC50s could be calculated and for sublethal endpoints for T. tubifex. The organic carbon content of the sediment appears to have acted as a sink and reduced NSA toxicity by decreasing bioavailability. Environmental sediment samples were collected from 12 river sites across southern Ontario. The maximum concentration of CaDNS observed in sediment collected from this region was 2.8 μg/g dw in sediment with 2% organic carbon; 100-fold lower than the lowest EC10 in the current study.

N-phenyl-1-naphthylamine (PNA) Accumulates in Snapping Turtle (Chelydra serpentina) Liver Activating the Detoxification Pathway

Substituted phenylamine antioxidants (SPAs) are used in Canadian industrial processes. SPAs, specifically N-phenyl-1-naphthylamine (PNA), have received very little attention despite their current use in Canada and their expected aquatic and environmental releases. There is a research gap regarding the effects of PNA in wildlife; therefore, Chelydra serpentina (common snapping turtle) was studied due to its importance as an environmental indicator species. A chronic experiment was performed using PNA spiked food (0 to 3446 ng/g) to determine its toxicity to juvenile C. serpentina. A significant increase in cyp1a mRNA level was observed in the liver of turtles exposed to 3446 ng/g PNA, suggesting that phase I detoxification is activated in the exposed animals. Additionally, a significant decrease in cyp2b transcript level was observed at the two lowest PNA doses, likely indicating another metabolic alteration for PNA. This study helped determine the molecular effects associated with a PNA exposure in reptiles.

Toxicity of dinonylnaphthalene sulfonates to Pimephales promelas and epibenthic invertebrates

Dinonylnaphthalene sulfonic acids (NSAs) are high production volume chemicals that are used primarily as additives in a wide range of industrial products (i.e., coatings, sealants, fuels, metal-extractants, paints, rubber materials). This study examined the effect of three NSA congeners on freshwater organisms: barium dinonylnaphthalene sulfonate (BaDNS), calcium dinonylnaphthalene sulfonate (CaDNS), and dinonylnaphthalene disulfonic acid (DNDS). Chronic effects were characterized by exposing fertilized fathead minnow eggs to sediment-associated NSAs and measuring various developmental and growth endpoints for 21 d. No effects in hatch success and larval growth were observed when fathead minnow eggs were exposed to CaDNS and DNDS concentrations up to 246 and 798 μg/g dry weight, respectively, in spiked sediment (~2% organic carbon). However, when NSAs were associated with substrate containing no organic carbon (sand), EC50s for fathead minnow hatch success, larval growth, biomass production, and overall survival were 58.3, 18.8, 15.5, and 13.8 μg/L, respectively, for CaDNS. Acute effect characterization was also conducted in water-only exposures for the three NSA congeners using the freshwater amphipod Hyalella azteca, the pulmonate snail Planorbella pilsbryi, and larval freshwater mussels Lampsilis cardium and Lampsilis siliquoidea. The sulfonate salts (BaDNS and CaDNS) were significantly more acutely toxic to all tested invertebrates in the water-only exposures, with LC50s ranging from 0.47 to 12.1 μg/L, compared to DNDS (LC50s ≥ 98.2 μg/L). This is the first study to provide empirical data on the aquatic toxicity of three NSA congeners.

Bioaccumulation of sediment-associated substituted phenylamine antioxidants in Tubifex tubifex and Lampsilis siliquoidea

Substituted phenylamine antioxidants (SPAs) are additives in a variety of commercial polymers (e.g., lubricants, plastics, etc.). Based on their physicochemical properties, if SPAs were to enter an aquatic system, they would likely partition into sediment and have the capacity to bioaccumulate in biota. This study investigated the potential of four sediment-associated SPAs, diphenylamine (DPA), N-phenyl-1-naphthalene (PNA), N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (DPPDA), and 4,4'-methylene-bis[N-sec-butylaniline] (MBA) to accumulate in the tissues of freshwater mussels (Lampsilis siliquoidea) and oligochaete worms (Tubifex tubifex). Mussels and worms were exposed to sediment spiked with individual SPAs for 28 d. The concentration of SPAs was measured in the gill, gonad, and remaining viscera of the mussels and entire body of the worms. The majority of biota-sediment accumulation factors (28-d BSAFs) for the different tissues of mussels were < 1. The highest concentrations of SPAs were consistently observed in the gill tissue of mussels relative to the gonad and viscera. The 28-d BSAFs for DPPDA and MBA for worms were < 1, and for DPA and PNA, they ranged from 0.38-2.13 and 1.54-33.24, respectively. The higher 28-d BSAFs observed for worms compared to mussels were likely because worms are endobenthic and feed on sediment-associated organic matter. PNA and DPPDA have similar octanol-water partition coefficients (Kow) but greater 28-d BSAFs were observed for PNA compared to DPPDA for both species. This observation provides evidence that biota may be able to metabolize and/or excrete SPAs with similar physicochemical properties at considerably different rates. The 28-d BSAFs observed for sediment-associated SPAs are lower than those typically required for a chemical to be classified as bioaccumulative.

Toxicity of sediment-associated substituted phenylamine antioxidants on the early life stages of Pimephales promelas and a characterization of effects on freshwater organisms

Substituted phenylamine antioxidants (SPAs) are high production volume chemicals that are incorporated into a variety of commercial products (e.g., polymers, dyes, lubricants). There are few data on chronic toxicity of SPAs to fish and no data on the toxicity of SPAs to the early life stages of fish. The physicochemical properties of SPAs would suggest that if they were to enter an aquatic ecosystem they would partition into sediment. Therefore, the present study focused on investigating the chronic effect of sediment-associated SPAs to the early life stages of the fathead minnow (Pimephales promelas). Eggs and larvae were exposed to sediment spiked with diphenylamine (DPA), N-phenyl-1-napthylamine (PNA), N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (DPPDA), or 4,4'-methylene-bis[N-sec-butylaniline] (MBA). The most sensitive endpoint for DPA, PNA, and DPPDA was total survival with 21-d median lethal concentrations (LC50s) based on concentration in overlying water of 1920, 74, and 35 μg/L, respectively. The most sensitive endpoint for MBA was growth with a 21-d median effective concentration (EC50) of 71 μg/L. The same endpoints were the most sensitive in terms of concentrations of DPA, PNA, DPPDA, and MBA in sediment (101, 54, 111, and 76 μg/g dry wt, respectively). Species sensitivity distributions (SSDs) were constructed for each SPA based on acute and chronic toxicity data generated in the present study and found in the literature. Overall, P. promelas was in the midrange of chronic sensitivity, with the most sensitive species being Tubifex tubifex. The SSDs indicate that DPA based on concentration in water is the least toxic to aquatic biota of the 4 SPAs investigated. The constructed SSDs indicate that a concentration in water and sediment of 1 μg/L and 1 μg/g dry weight, respectively, would be protective of >95% of the aquatic species tested. Environ Toxicol Chem 2017;36:2730-2738. © 2017 SETAC.

Effect of substituted phenylamine antioxidants on three life stages of the freshwater mussel Lampsilis siliquoidea

Substituted phenylamines (SPAs) are incorporated into a variety of consumer products (e.g., polymers, lubricants) in order to increase the lifespan of the products by acting as a primary antioxidant. Based on their physicochemical properties, if SPAs were to enter the aquatic environment, they would likely partition into sediment. No studies to date have investigated the effect of sediment-associated SPAs on aquatic organisms. The current study examined the effect of four SPAs (diphenylamine (DPA); N-phenyl-1-napthylamine (PNA); N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (DPPDA); 4,4'-methylene-bis[N-sec-butylaniline] (MBA)) on three different life stages of the freshwater mussel, Lampsilis siliquoidea. The viability of larvae (glochidia) of L. siliquoidea and Lampsilis fasciola was assessed after 48 h of exposure to SPAs in water. The 48-h EC50s for glochidia viability of L. siliquoidea were 5951, 606, 439, and 258 μg/L for DPA, PNA, DPPDA, and MBA, respectively, and 7946, 591, 137, and 47 μg/L, respectively, for L. fasciola. Juvenile (7-15 months) and adult L. siliquoidea were exposed to sediment-associated SPAs for 28 d. LC50s for juvenile mussels were 18, 55, 62, and 109 μg/g dry weight (dw) of sediment for DPA, PNA, DPPDA, and MBA, respectively. Adult mussels were exposed to sub-lethal concentrations of sediment-associated SPAs in order to investigate reactive oxygen species (ROS), lipid peroxidation and total glutathione in the gill, gonad, and digestive gland tissue, and viability and DNA damage in hemocytes. No significant concentration-dependent trend in any of these biochemical and cellular endpoints relative to the concentration of sediment-associated SPAs was observed in any tissues. Investigations into the concentration of SPAs in the aquatic environment are required before a conclusion can be made on whether these compounds pose a hazard to the different life stages of freshwater mussels.

Variation in the toxicity of sediment-associated substituted phenylamine antioxidants to an epibenthic (Hyalella azteca) and endobenthic (Tubifex tubifex) invertebrate

Substituted phenylamine antioxidants (SPAs) are produced in relatively high volumes and used in a range of applications (e.g., rubber, polyurethane); however, little is known about their toxicity to aquatic biota. Therefore, current study examined the effects of chronic exposure (28 d) to four sediment-associated SPAs on epibenthic (Hyalella azteca) and endobenthic (Tubifex tubifex) organisms. In addition, acute (96-h), water-only exposures were conducted with H. azteca. Mortality, growth and biomass production were assessed in juvenile H. azteca exposed to diphenylamine (DPA), N-phenyl-1-napthylamine (PNA), N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (DPPDA), or 4,4'-methylene-bis[N-sec-butylaniline] (MBA). Mortality of adult T. tubifex and reproduction were assessed following exposure to the four SPAs. The 96-h LC50s for juvenile H. azteca were 1443, 109, 250, and >22 μg/L and 28-d LC50s were 22, 99, 135, and >403 μg/g dry weight (dw) for DPA, PNA, DPPDA, and MBA, respectively. Reproductive endpoints for T. tubifex (EC50s for production of juveniles > 500 μm: 15, 9, 4, 3.6 μg/g dw, for DPA, PNA, DPPDA, and MBA, respectively) were an order of magnitude more sensitive than endpoints for juvenile H. azteca and mortality of adult worms. The variation in toxicity across the four SPAs was likely related to the bioavailability of the sediment-associated chemicals, which was determined by the chemical properties of the SPAs (e.g., solubility in water, Koc). The variation in the sensitivity between the two species was likely due to differences in the magnitude of exposure, which is a function of the life histories of the epibenthic amphipod and the endobenthic worm. The data generated from this study will support effect characterization for ecological risk assessment.

Impact of selected wastewater constituents on the removal of sulfonamide antibiotics via ultrafiltration and micellar enhanced ultrafiltration

To better understand the environmental mobility of sulfonamide antibiotics and develop improved processes for their removal during wastewater treatment, stirred cell ultrafiltration (UF) experiments were conducted using both synthetic and real wastewater effluent. The interactions between selected sulfonamides (sulfaguanidine, sulfathiazole and sulfamerazine), solids and dissolved organic matter were systematically explored. The further impact of micellar enhanced ultrafiltration (MEUF), a process in which surfactants are added at micellar concentrations to enhance removal of various trace contaminants from aqueous streams, was then explored by using a cationic surfactant, cetyltrimethylammonium bromide (CTAB). Ultrafiltration of sulfonamides in the absence of other materials generally removed only 15-20% of the antibiotics. The presence of micellar solutions of CTAB generally improved removal of sulfonamides over UF alone, with rejections ranging from 20 to 74%. Environmental solids (sediment) further increased retention of sulfonamides using both UF and MEUF, but the presence of DOM did not influence rejection. Similar trends were observed on UF and MEUF of real effluent samples that had been spiked with the sulfonamides, confirming the environmental relevance of the observed interactions between sulfonamides, surfactant, and wastewater constituents. The results demonstrate that MEUF processes can be designed for the selective removal of such trace contaminants as sulfonamide antibiotics.

Toxicity of four sulfonamide antibiotics to the freshwater amphipod Hyalella azteca

Sulfonamides are a widely used class of antibiotics; however, there are few toxicological data available with which to conduct environmental risk assessments for these compounds. Therefore, the toxicity of four sulfonamides (sulfaguanidine, sulfathiazole, sulfamerazine, and sulfasalazine) to Hyalella azteca was assessed in chronic (four-week), water-only exposures. Survival was evaluated weekly, and growth was measured at the end of the test. Four-week lethal concentrations associated with 50% mortality (LC50s) for sulfaguanidine, sulfathiazole, and sulfamerazine were 0.90, 1.6, and 3.9 µM, respectively. Sulfaguanidine caused effects on survival more quickly and at lower concentrations than sulfathiazole or sulfamerazine. These differences were more pronounced at week 1 than week 4, when sulfaguanidine LC50s were 8 to 20 times lower and 2 to 4 times lower, respectively. Growth was affected by sulfathiazole but was a less sensitive end point than survival, with an effective concentration associated with 50% reduction in growth (EC50) of 13 µM, whereas sulfaguanidine and sulfamerazine caused negligible effects on growth. Sulfasalazine had no effect on survival or growth at any concentration tested, up to 13 µM. The effects observed in the present study occurred at concentrations exceeding those typically found in environmental waters. However, given that LC50s decreased with exposure duration (except for sulfasalazine), the present study demonstrates the importance of conducting longer-term tests to adequately assess the environmental toxicity of sulfonamides.

Determination of sulfonamide antibiotics in wastewater: A comparison of solid phase microextraction and solid phase extraction methods

In recent years, pharmaceutical and personal care products (PPCPs) have been detected in diverse environments (including groundwater, river water, and municipal wastewater). In order to evaluate their environmental impact, PPCPs must first be accurately determined. In this study, we focused on developing methods to accurately determine 10 sulfonamide antibiotics: sulfaguanidine, sulfacetamide, sulfadiazine, sulfathiazine, sulfapyridine, sulfamerazine, sulfamethazine, sulfamethoxazole, sulfadimethoxine, and sulfasalazine. While sulfonamides can easily be determined in pure water, wastewater influent and effluent collected from sewage treatment plants in Burlington and Toronto (Ontario) were found to generate confounding matrix effects. In an effort to overcome these matrix effects, we developed a solid phase microextraction (SPME) method to determine sulfonamides. Of the five different fiber assemblies investigated, the carbowax/divinylbenzene (CW/DVB) fiber produced the optimal response to sulfonamides. The SPME method was further optimized for sorption time (20min), solution salinity (10%, w/v, KCl), pH (4.5), and static desorption time (30min). When compared to solid phase extraction (SPE) using MCX cartridges, we observed that despite having higher MDLs and poorer sensitivity, SPME possessed the advantage of speed and reduced solvent usage. Most importantly, in contrast to SPE, when we applied the SPME method to fortified wastewater samples, we were generally able to accurately determine (i.e., recover) those sulfonamides that were present. Therefore, we conclude that SPME is a viable method for overcoming matrix effects in environmental samples.

Occurrence and reductions of pharmaceuticals and personal care products and estrogens by municipal wastewater treatment plants in Ontario, Canada

Over the last ten years there have been reports of pharmaceuticals and personal care product (PPCP) residuals in municipal wastewater treatment plant (WWTP) effluents. The principle goal of this study was specifically to expand and in some cases establish a Canadian database for the presence of selected acidic drugs, triclosan, polycyclic musks, and selected estrogens in MWWTP influent and effluent. The impact of treatment configuration (e.g. lagoons, conventional activated sludge (CAS), and CAS followed by media filtration (CAS+filtration)) was also examined. For CAS systems, the most prevalent treatment type, the effect of operating temperature and SRT was evaluated. Selected PPCPs included ten acidic pharmaceuticals (i.e. a group of pharmaceuticals that are extractable at a pH of 2 or less), triclosan, five polycyclic musks and two estrogens. The pharmaceuticals and musks were selected on the basis of levels of use in Canada; reported aquatic toxicity effects; and the ability to analyze for the compounds at low levels. Twelve MWWTPs discharging into the Thames River, the second largest river in southwestern Ontario, were surveyed. The only common characteristic of acidic drugs is their extraction pH as they differ in their intended biological function and chemical structure. Many organics degraded by WWTP processes benefit from warm temperatures and long SRTs so the impact of these variables warranted additional attention. Influent concentrations and reductions for acidic drugs reported by this study were compared to other Canadian studies, when available, and European investigations. The data of this study seems consistent with other reports. Ten acidic drugs were considered by this study. Three were consistently present at non-quantifiable levels (e.g. CLF, FNP and FNF). Additionally, one analyte, SYL, presented results that were so inconsistent that the values were not analysed. The remaining six acidic pharmaceuticals were placed into three categories. IBU and NPX members of the first category had consistently high reductions. At the level of reduction achieved (i.e. median reduction of greater than 93%) and any effect of treatment type or operating characteristics would be subtle and non-discernable given the analytical noise. In the second group are KTP and IND, and definitive comments are difficult to make on the impact of treatment type and operational considerations due to a sparse data set (i.e. many influent values were at non-quantifiable concentrations). Median reductions were in the 23% to 44% range. In the last category are GMF and DCF which have median reductions of 66% and -34%, respectively. Several negative reduction values in the data set (i.e. twelve of twenty six sampling events) suggest that DCF may be deconjugated under certain conditions. This warrants further evaluation when analytical methods for measuring human metabolites of DCF are available. For both GMF and DCF, reduction does not appear to be strongly influenced by SRTs up to 15 days, while SRTs over 30 days were associated with more frequent non-quantifiable effluent levels of DCF. This would suggest that better treatment would be provided by lagoons and CAS systems with extended aeration. Preliminary data suggests that temperature does not play a strong role in the reduction of these compounds. Triclosan (TCL) was detected at concentrations of 0.01-4.01 microg/L in influent samples and 0.01-0.324 microg/L in effluent samples. Reduction of TCL ranged from 74% to 98%. Lagoon treatment seems to be the best TCL reduction as it was present in the influent and effluent at quantifiable and non-quantifiable concentrations, respectively, on nine of nine sampling occasions. Influent and reduction values of five polycyclic musks (e.g. ADBI, AHMI, ATII, HHCB, and AHTN) were examined over the course of this study. AHMI was predominantly present at non-quantifiable concentrations. HHCB and AHTN were present at the highest concentrations. A comparison between Canadian values and those of European studies indicate that in general polycyclic musk concentrations in Canadian MWWTP effluents are 5-10 times lower. More extensive European and Canadian databases would be useful in confirming this initial observation. Median reductions for the five remaining musks range between 37% and 65% in CAS systems. CAS+filtration systems would be expected to have higher reductions if musks were bound to the effluent solids. This trend is not apparent but this may be due to the small size of the data set. In lagoon systems, musk reduction for HHCB and AHTN are approximately 98-99%. For ADBI and ATII musk, there are no numerical reduction values as most often the effluent concentration was non-quantifiable. In some instances, both the influent and effluent concentrations were non-quantifiable. The hormones 17-beta-estradiol (E2) and estrone (E1) were detected at concentrations of 0.006 to 0.014 and 0.016 to 0.049 microg/L, respectively. E2 was not detected in any effluent samples (<0.005 microg/L) whereas E1 was detected in effluent samples from CAS treatment plants (median of 0.008 microg/L), and in one sample from lagoons. These data demonstrate that there are detectable levels of PPCPs entering Canadian waterways at trace levels, and that only some of these compounds are being reduced in a significant proportion by municipal wastewater treatment processes.