Toxicity Of Linear Alkylbenzene Sulfonate Research Articles

Applications of the RTgill-W1 Cell Line for Acute Whole-Effluent Toxicity Testing: In Vitro-In Vivo Correlation and Optimization of Exposure Conditions.

The cell line RTgill-W1 was evaluated as an in vitro alternative model for acute fish whole-effluent toxicity (WET) testing. We determined the 50% effective concentration (EC50) that reduces the viability of RTgill-W1 cells for selected toxicants commonly found in effluent samples and correlated those values with the respective 50% lethal concentration (LC50) of freshwater (fathead minnow, Pimephales promelas) and marine (sheepshead minnow, Cyprinodon variegatus) fish species obtained from the literature. Excluding low water-soluble organics and the volatile sodium hypochlorite, significant correlations were measured for metal, metalloids, ammonia, and higher water-soluble organics between in vitro EC50 values and in vivo LC50 values for both species. Typically, toxicity studies with RTgill-W1 cells are conducted by adding salts to the exposure medium, which may affect the bioavailability of toxicants. Osmotic tolerance of RTgill-W1 cells was found between 150 and 450 mOsm/kg, which were set as the hypoosmotic and hyperosmotic limits. A subset of the toxicants were then reexamined in hypoosmotic and hyperosmotic media. Copper toxicity decreased in hyperosmotic medium, and nickel toxicity increased in hypoosmotic and hyperosmotic media. Linear alkylbenzene sulfonate toxicity was not affected by the medium osmolality. Overall, RTgill-W1 cells have shown potential for applications in measuring metal, metalloids, ammonia, and water-soluble organic chemicals in acute WET tests, as well as complementing current toxicity identification and reduction evaluation strategies. In the present study, RTgill-W1 cells have been established as a valid animal alternative for WET testing, and we show that through manipulation of medium osmotic ranges, sensitivity to nickel was enhanced. Environ Toxicol Chem 2021;40:1050-1061. © 2020 SETAC.

Toxicity of linear alkylbenzene sulfonate to aquatic plant Potamogeton perfoliatus L.

Aquatic plants play an important role in maintaining the health of water environment in nature. Studies have shown that linear alkylbenzene sulfonate (LAS), a type of omnipresent pollutant, can cause toxic damage to aquatic plants. In the present research, we studied the physiological and growth response of submerged plant Potamogeton perfoliatus L. to different concentrations of LAS (0.1, 1.0, 10.0, 20.0, and 50.0mgl-1). The results showed that LAS is toxic to P. perfoliatus, and the toxicity is dose-dependent. Only slightly reversible oxidative damages were observed in the physiological parameters of P. perfoliatus when P. perfoliatus was exposed to lower LAS doses (< 10mgl-1): soluble sugar, soluble protein, H2O2, and malondialdehyde (MDA) content in P. perfoliatus increased significantly at 0.1mgl-1 and then returned to normal levels at 1.0mgl-1. Antioxidant enzymes were activated before the LAS concentration reached 10mgl-1, and the activities of superoxide dismutase (SOD), catalase (CAT), and photosynthesis pigment content declined significantly when the concentration of LAS exceeded 10mgl-1. In addition, at higher concentrations (20-50mgl-1) of LAS, dry weight and fresh weight of P. perfoliatus showed significant declines. The results indicate that LAS above 10mgl-1 can cause serious physiological and growth damage to P. perfoliatus.

Study on the membrane bioreactor for treating surfactant wastewater

Abstract The main component of surfactant is linear alkylbenzene sulfonate (LAS), which is toxic to the ecological environment and can cause serious harm. In this study, some activated sludge was taken from the aerobic and anaerobic tank of a sewage treatment plant in Shenzhen, then cultivated and domesticated in a membrane bioreactor with artificial surfactant wastewater. The start-up phase of the reactor adapted the constant-flux filtration, and the HRT was 12 h. The pH was below 5.5, which needed the addition of NaHCO3 after 6 days to adjust to the more optimal level (pH 6.5–7.5). After operation for 20 days, the start-up of the system was considered successful. At the early stage, the removal rates of chemical oxygen demand (COD) and LAS were relatively stable, reaching as high as 85.49%–93.31% and 80%, respectively. When the LAS concentration reached over 175 mg/L and the COD declined to about 83%, the removal rate of LAS also significantly decreased. LAS removal rate further decreased to about 60% when the dosage reached 200 mg/L, indicating that the resistance of microorganisms against LAS toxicity was also limited. LAS degradation could have been mainly driven by Dechloromonas, Gemmata, Pseudomonas and Zoogloea in the system.

Growth and antioxidant response in Hydrocharis dubis (Bl.) Backer exposed to linear alkylbenzene sulfonate

A two-week exposure experiment was designed to investigate the toxicity of linear alkylbenzene sulfonate (LAS) on the aquatic plant Hydrocharis dubis (Bl.) Backer, focusing on growth, photosynthetic pigments and the activities of antioxidant enzymes. No significant differences were observed in the growth parameters of H. dubis when H. dubis was exposed to lower LAS doses (<or=10 mg l(-1)). However, lower LAS doses remarkably promote the dry weight accumulation of H. dubis. Higher doses of LAS (>10 mg l(-1)) resulted in significant decreases in all growth parameters of H. dubis. No significant effect on pigment contents was observed at up to 50 mg l(-1) LAS, beyond which pigment contents declined gradually. Malondialdehyde (MDA) content did not show obvious differences when H. dubis plants were exposed to <or=50 mg l(-1) LAS. Peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) activities showed a concentration-dependent increase up to LAS concentrations of 0.1-10 mg l(-1), followed by a clear decrease. The results of this study suggest that LAS significantly inhibited the growth and physiology of H. dubis when the dose of LAS exceeded 10 mg l(-1) . Therefore, LAS at current environmental concentrations dose not appear to cause evident phytotoxic effects on H. dubis.

Influence of linear alkylbenzene sulfonate (LAS) on the structure of Alphaproteobacteria, Actinobacteria, and Acidobacteria communities in a soil microcosm

Linear alkylbenzene sulfonate (LAS) is the most used anionic surfactant in a worldwide scale and is considered a high-priority pollutant. LAS is regarded as a readily biodegradable product under aerobic conditions in aqueous media and is mostly removed in wastewater treatment plants, but an important fraction (20–25%) is immobilized in sewage sludge and persists under anoxic conditions. Due to the application of the sludge as a fertilizer, LAS reaches agricultural soil, and therefore, microbial toxicity tests have been widely used to evaluate the influence of LAS on soil microbial ecology. However, molecular-based community-level analyses have been seldom applied in studies regarding the effects of LAS on natural or engineered systems, and, to our knowledge, there are no reports of their use for such appraisals in agricultural soil. In this study, a microcosm system is used to evaluate the effects of a commercial mixture of LAS on the community structure of Alphaproteobacteria, Actinobacteria, and Acidobacteria in an agricultural soil. The microcosms consisted of agricultural soil columns (800 g) fed with sterile water (8 ml h−1) added of different concentration of LAS (10 or 50 mg l−1) for periods of time up to 21 days. Sterile water was added to control columns for comparison. The structures of Alphaproteobacteria, Actinobacteria, and Acidobacteria communities were analyzed by a cultivation independent method (temperature gradient gel electrophoresis (TGGE) separation of polymerase chain reaction (PCR)-amplified partial 16S rRNA genes). Relevant populations were identified by subsequent reamplification, DNA sequencing, and database comparisons. Cluster analysis of the TGGE fingerprints taking into consideration both the number of bands and their relative intensities revealed that the structure of the Alphaproteobacteria community was significantly changed in the presence of LAS, at both concentrations tested. The average number of bands was significantly lower in the microcosms receiving 50 mg l−1 LAS and in the lower portion of soil cores. The clear differentiation of the samples of the upper portion of the soil columns amended with LAS was specifically related to the presence and intensity of a distinctive major band (named band class 7). There was a statistically significant positive correlation between the concentrations of LAS detected in soil portions taken from LAS 10 mg l−1 and LAS 50 mg l−1 microcosms and the relative intensity of band class 7 in the corresponding TGGE profiles. Prevalent Alphaproteobacteria populations in the soil microcosms had close similarity (>99%) to cultivated species affiliated to genera of the Rhizobiaceae, Methylocystaceae, Hyphomicrobiaceae, Rhodospirillaceae, Brucellaceae, Bradyrhizobiaceae, and Caulobacteraceae families. The population represented by band class 7 was found closely related to the genus Phenylobacterium (Caulobacteraceae). According to cluster analysis of TGGE profiles, the structure of both Actinobacteria and Acidobacteria communities in the soil microcosms was remarkably stable in the presence of LAS at the two concentrations tested, as most bands were universally present in all samples and displayed fairly similar relative intensities. Previous studies by others authors, based on biological and chemical tests, concluded that LAS toxicity was not an important microbial selection factor in sludge amended soil, while work based on the use of molecular fingerprinting to evaluate the impact of LAS in aqueous media and marine sediments showed that concentrations as low as 1 mg l−1 significantly influence the development of the bacterial community structure. Although TGGE is not a strictly quantitative method due to the bias introduced by the PCR reaction, changes of band intensity through experiments are a consequence of a change in the relative abundance of the corresponding populations in the community and can be used as a semiquantitative measure of bacterial diversity. Our results evidence that the Phenylobacterium population represented by band class 7 was favored by the presence of increasing concentrations of LAS in the soil and turned into a dominant population, suggesting its possible ability to use LAS in soil as a source of nutrients. As studies with pure cultures are required to confirm the ability of this population to degrade LAS, isolation strategies are currently under development in our laboratory. The weak effect of LAS on the structure of Actinobacteria and Acidobacteria communities is particularly interesting, as to our knowledge, there are no previous reports regarding the effects of LAS on these bacterial groups in soil. The Phenylobacterium-related alphaproteobacterial population identified in this work was selectively enriched in LAS polluted soil and is a plausible candidate to play a relevant role in the biotransformation of the surfactant under the conditions tested. The surfactant had no remarkable effects on the Actinobacteria and Acidobacteria fingerprints in soil, even when present at concentrations widely exceeding those reached in soil immediately after sludge application. TGGE fingerprinting provides a reliable and low time-consuming method for the monitoring of the bacterial community structure and dynamics, and we recommend its integration with the biological and chemical analyses usually applied in risk assessment of LAS in the environment.

Effect of the test media and toxicity of LAS on the growth of Isochrysis galbana

In this paper, the toxicity of linear alkylbenzene sulfonate (LAS) was evaluated in the marine microalga Isochrysis galbana using data of growth inhibition toxicity tests at 96-h exposure time. Toxicity was examined in standard conditions and by means of the modification of two variables of the test media: (1) the dilution water and (2) the content of nutrients in the test medium. For this purpose, a total of 10 toxicity test were designed: five dilution waters, four natural marine waters and one synthetic seawater; each in two different nutritive conditions, saturated nutrient concentration (SC) by the addition of modified f/2 nutritive medium, and natural nutrient concentration (NC), i.e., without the addition of f/2. At threshold toxicity levels, the dilution waters used in the test and the nutrient concentrations did not affect the toxicity of LAS. At IC50 concentrations, the toxicity of LAS is influenced by both variables: under SC conditions, the toxic effect of LAS diminishes, obtaining in all the tests IC50 > 10 mg/L LAS. Under NC conditions, IC50 concentrations ranging between 3.15 and 9.26 mg/L LAS have been obtained.

Large Decrease in Acute Aquatic Toxicity of Linear Alkylbenzene Sulfonate in Hard Water and Seawater by Adding Adsorbent

LAS (Linear Alkylbenzene Sulphonate) shows relatively high aquatic toxicity in hard freshwater or seawater. In this paper, we studied the effect of adsorbent on the aquatic toxicity of LAS in hard freshwater and seawater. Daphnia magna and Artemia salina were used for acute aquatic toxicity test in freshwater and seawater, respectively. Kaolin was used as a model adsorbent and toxic surface tension (gamma(tox)) was used as an indicator of toxic condition. Results showed that the values of gamma(tox) of LAS to D. magna and A. salina were about 45-55 mN/m and 35-40 mN/m, respectively. Surface tension of LAS solution decreased and its aquatic toxicity increased with increasing the water hardness or the salinity. By adding adsorbent into the solutions, the surface activity and the aquatic toxicity were decreased greatly, and the effect of water hardness or salinity on surface tension and aquatic toxicity were removed. That is to say, the surface tension curve of soft freshwater corresponds with that of hard freshwater containing adsorbent and the surface tension curve at low salinity corresponds with that obtained for high salinity solutions containing the adsorbent. Therefore, our experimental data leads to the conclusion that the relatively high aquatic toxicity of LAS in concentrated solution of inorganic salts disappears in the presence of adsorbents. This is an important viewpoint in conducting environmental risk assessment of surfactants.

Toxicity of linear alkylbenzene sulfonate and alkylethoxylate to aquatic plants.

Toxicity of linear alkylbenzene sulfonate and alkylethoxylate to aquatic plants.

Sorption of linear alkylbenzene sulfonate to soil components and effects on microbial iron reduction

When sewage sludge is applied to arable land, linear alkylbenzene sulfonate (LAS) is released into the environment. In soils, LAS has been shown to impede microbial processes, such as bacterial iron reduction. The aim of the present study was to quantify LAS adsorption and desorption to agricultural soils and iron oxides and relate this to the inhibition of microbial iron reduction. Two agricultural soils were used, namely, Askov (coarse sandy loam soil) and Lundgaard (coarse sandy soil). In both soils, LAS inhibited microbial iron reduction even at low LAS concentrations with 10% effect concentrations of 6 to 7 and 26 to 32 mg LAS/kg dry-weight soil for Lundgaard and Askov soil, respectively. The sorption isotherms showed that sorption of LAS to iron oxides was 10 to 100 times stronger than sorption to the agricultural soils. Also, it appeared that at low LAS concentrations (< 10 mg/kg dry-wt soil), Lundgaard soil adsorbed approximately 10 times more LAS than Askov soil. Thus, the inhibitory effect of LAS on microbial iron reduction was highest in the Lundgaard soil, which exhibited both the strongest sorption and the lowest desorption of the two soils. A possible hypothesis to explain this correlation was that LAS toxicity toward bacterial iron reduction was, at least partly, caused by LAS adsorbed to iron oxides, which could interfere with transfer of electrons between the bacteria and their respiratory electron acceptor.

Toxicity of linear alkylbenzene sulfonate in anaerobic digestion: influence of exposure time

The inhibition of anaerobic digestion by the anionic surfactant linear alkylbenzene sulfonate was studied. The development of bacterial activity during several weeks was monitored by performing batch degradation tests with acetate and propionate. In the first phase the decay of activity without surfactant addition was studied. After the addition of the surfactant an immediate inhibition was detected. Subsequently, the degradation activity continued to decrease with increasing exposure time. Both, the immediate inhibition and the rate of the subsequent decrease of activity were dependent on the surfactant concentration. A kinetic model is presented that describes this behavior. A surfactant concentration of 14 mg L −1 causes a 50% immediate inhibition of acetate degradation (27 mg L −1 in the case of propionate degradation). Additionally, each 12 mg L −1 of surfactant increases the decay rate of acetate degradation activity by a factor 10 (23 mg L −1 for propionate degradation). A deviation from this model occurs at low surfactant concentrations (<3 mg L −1), where a slight stimulation of bacterial activity was observed. The above-mentioned concentrations refer to measured surfactant concentrations. These were substantially lower than the nominal concentrations (added surfactant per volume). This discrepancy is explained by adsorption of the surfactant to the biomass. Finally, the importance of the presented kinetic model and the significance of surfactant toxicity for anaerobic digestion are discussed.

Toxicity of Linear Alkylbenzene Sulfonate and One Long-Chain Degradation Intermediate, Sulfophenyl Carboxylic Acid on Early Life-Stages of Seabream (Sparus Aurata)

Seabream embryos (Sparus aurata) were exposed to various concentrations (0.05 to 10.0 mg L−1) of different homologues (C10 to C14) and a commercial mixture of linear alkylbenzene sulfonates (LAS), as well as one long-chain degradation intermediate, sulfophenyl carboxylic acid (SPC C11), to study the acute toxicity of these compounds. LAS homologues of higher chain length (C13 and C14) were proved to be more toxic than shorter species (C10, C11, and C12). LAS C13 and C14 provoked 100% lethality at concentrations of 0.1–0.25 mg L−1. On the other hand, shorter LAS homologues (chain length) did not produce any lethal effect at concentrations up to 5 mg L−1. In this work, results on the toxicity of a long-chain degradation intermediate of LAS, SPC C11, are presented. This compound did not produce any mortality at all the concentration ranges chosen.

Short‐term effects of linear alkylbenzene sulfonate on freshwater plankton studied under field conditions

AbstractThe toxic effects of linear alkylbenzene sulfonate (LAS) on several planktonic freshwater organisms were studied over a 5‐d period using small in situ enclosures. The experimental setup, an unreplicated regression design, made it possible to calculate no effect concentrations (NEC), an environmental risk assessment. The NEC varied several orders of magnitude between the different groups of organisms, with ciliates and heterotrophic nanoflagellates being the most sensitive groups (NEC as low as 0.02 mg LAS/L). The high sensitivity of the protozoans makes their exclusion from most ecotoxicological studies questionable, and this must be reconsidered in the future. Most other planktonic organisms were only affected at concentrations higher than normally found in aquatic habitats. Exceptions to this general trend were the photosynthetic activity of the phytoplankton and cryptophyte abundance, which both were nearly as sensitive parameters as the protozoan abundance. The toxicity of LAS was generally higher in the present investigation, compared with the vast majority of laboratory‐derived results, indicating a limited relevance of the latter and the need for field experiments in order to determine impacts of xenobiotics in the aquatic environments.

Dermal Toxicity of Linear Alkylbenzene Sulfonate and Quinalphos in Guinea Pigs

Guinea pigs were treated topically at dosage levels of 2.5 mg/kg and 5.0 mg/kg with linear alkylbenzene sulfonate and quinalphos alone and in combination daily for 30 days. In general, the activities of some enzymes, amino nitrogen, glutathione, lipid peroxidation, and histamine showed increases in skin, liver, and kidney. The animals exposed to high doses showed erythema, edema, and hair loss. The treated skin showed hyperkeratinization and infiltration of mononuclear cells, the liver showed hypertrophic hepatocytes, while the kidney showed tubular necrosis and atrophy of the glomerular capsules. The biochemical parameters and histopafhological changes were found to be dose dependent. The study suggests that workers and/or populations exposed simultaneously to the two chemicals are more prone to dermal toxicity.

Energetic and behavioral responses by the common goby, Pomatoschistus microps (krøyer), exposed to linear alkylbenzene sulfonate

AbstractThe acute toxicity of linear alkylbenzene sulfonate (LAS) on the common goby (Pomatoschistus microps), an estuarine fish, was established during a 96‐h static exposure. The median lethal concentration was 2.6 ± 0.49 mg LAS/L (mean ± 95% confidence limit). The acute behavioral responses to LAS at different concentrations were excess mucus secretion and apathy at 1.0 mg/L; air gulping, distension of the mouth and opercula, change in pigmentation, and erratic swimming at 2.0 to 3.0 mg/L; and loss of balance and reactivity at ≤4.0 mg/L. The frequency of operculum opening increased with increasing LAS concentrations and appeared at 4.0 mg/L, with a significant doubling in relation to the frequency observed in control fish (p = 0.025). The physiological responses by P. microps after prolonged exposure to sublethal and environmentally realistic concentrations of LAS (0.05‐1.0 mg/L) were observed under semistatic conditions in the laboratory. Ingestion, respiration, and growth were also measured during 28 d of exposure. A significant decrease in growth and respiration was found at 0.1 mg LAS/L (p = 0.049 and 0.033, respectively), but ingestion was not affected. The effect concentrations for growth and respiration represent the lowest‐observed‐effect concentrations, which are both lower than values previously reported for fish. Gross conversion efficiency was affected negatively at 1.0 mg LAS/L (p = 0.001). Pomatoschistus microps is recommended as a suitable and relevant test organism for ecotoxicological experiments.

Dermal Toxicity of Linear Alkylbenzene Sulfonate, Chromium, and Nickel in Guinea Pigs

AbstractGuinea pigs were dermally exposed to nickel (Ni) plus chromium (Cr) and Ni plus Cr plus linear alkylbenzene sulfonate (LAS) for 30 days. The exposure resulted in significantly enhanced activities of skin enzymes such as acid phosphatase, β-glucuronidase, lactate dehydrogenase, superoxide dismutase, and tyrosinase. The amino nitrogen, lipid peroxidation, and contents of histamine also increased significantly in skin. The glutathione content decreased while the accumulation of Cr and Ni significantly increased in skin. The alterations were more marked in the Ni plus Cr plus LAS exposed group.

Assessment of the toxicity of linear alkylbenzene sulfonate and quaternary alkylammonium chloride by measuring 13C-glycerol in Dunaliella sp.

The toxic effects of linear alkylbenzenesulfonate (LAS) and quaternary alkylammonium chloride on Dunaliella sp. were studied by measuring 13C-glycerol. 13C-glycerol (five isomers of [1,2,1′- 13C 1,2,3]-glycerol) was produced in Dunaliella sp. from 13C-sodium bicarbonate added and the amounts of 13C-glycerol was lowered quantitatively with increased concentration of surfactants. The ratio of glycerol to 13C-glycerol was found to be about 45 : 55 by gas chromatographic/mass spectrometric analysis. The 24-h median effective concentration (EC50-24h) were 3.5 mg/l for LAS, 0.79 mg/1 for alkyltrimethyl-ammonium chloride (TM), 18 mg/l for dialkyldimethylammonium chloride (DM) and 1.3 mg/l for alkyldimethylbenzylammonium chloride (BM) : the toxic potencies were in the order of TM>BM>LAS>DM. The suppression of 13C-glycerol formation by LAS seemed to be related to the process of photosynthesis from 13C-sodium bicarbonate.

Acute and chronic toxicity of tributyltin and linear alkylbenzene sulfonate to the marine copepod Acartia tonsa

AbstractThe acute toxicities of linear alkylbenzene sulfonate (LAS) and tributyltin (TBT) to the marine copepod Acartia tonsa were tested in 48‐h tests at two salinities, 18 and 28‰. For LAS 48‐h median lethal concentration (LC50) values were 2.1 and 8.8 mg/L, respectively. For TBT the 48‐h LC50 values were 0.47 and 0.24 μg/L, respectively. The given effect concentrations are based on nominal concentrations. In an 8‐d test, effects of LAS on larval survival and development effects (effective concentration, 10%) were found at 0.2 to 0.3 mg/L. This effect concentration is higher than environmental concentrations, but at the same level as the concentration that can be expected in effluent from well‐operated activated sludge treatment plants. Environmental effects of LAS on sensitive organisms such as A. tonsa would only be expected close to the outlet of effective treatment plants, or if the treatment of the sewage effluent was inefficient. Tributyltin inhibited the developmental rate of larvae at 1 ng TBT/L, whereas the survival of larvae was affected at 15 to 20 ng TBT/L. Acartia tonsa is thus extremely sensitive to TBT. Environmental concentrations of TBT of 20 to 100 ng/L have been found near marinas. Effects on organisms as sensitive as A. tonsa are thus to be expected in the vicinities of marinas. The test method using larval survival and development is easy to perform and nonlaborious compared to, for example, a reproduction test with Daphnia magna. The acute test method as well as the egg–embryo test method may be suitable for standardization.

Evaluation of a laboratory‐generated NOEC for linear alkylbenzene sulfonate in outdoor experimental streams

AbstractLaboratory and field studies were conducted with linear alkylbenzene sulfonate (LAS) to evaluate the use of laboratory‐generated NOECs for protecting aquatic organisms in outdoor experimental streams. Fathead minnows (Pimephales promelas) and freshwater amphipods (Hyalella azteca) were exposed in the laboratory to an environmentally realistic mixture of LAS (average chain length C11 9) for 7 d; fathead minnows were also exposed in a 28‐d study. Calculated NOEC values based on survival and growth ranged from 0.3 to 0.9 mg/L for fathead minnows and from 0.6 to 1.4 mg/L for amphipods. Toxicity of LAS in 4‐, 7‐, and 28‐d exposures of fathead minnows was similar because mortality occurred within the initial 24 h of exposure; mortality was more sensitive than growth as a chronic end point. The addition of 5% sewage effluent to well and stream water had little effect on the bioavailability of LAS; however, total organic carbon levels were low (&lt;3 mg/L) in all treatments. A 45‐d exposure of three outdoor experimental streams to 0.36 mg/L LAS had no effects on survival of fathead minnows or amphipods, dynamics of benthic invertebrates, growth of periphyton, or processing of detrital leaves. Results indicated that the laboratory‐generated NOEC for LAS was protective of experimental stream communities under the studied conditions.

EVALUATION OF A LABORATORY-GENERATED NOEC FOR LINEAR ALKYLBENZENE SULFONATE IN OUTDOOR EXPERIMENTAL STREAMS

Laboratory and field studies were conducted with linear alkylbenzene sulfonate (LAS) to evaluate the use of laboratory-generated NOECs for protecting aquatic organisms in outdoor experimental streams. Fathead minnows (Pimephales promelas) and freshwater amphipods (Hyalella azteca) were exposed in the laboratory to an environmentally realistic mixture of LAS (average chain length C11 9) for 7 d; fathead minnows were also exposed in a 28-d study. Calculated NOEC values based on survival and growth ranged from 0.3 to 0.9 mg/L for fathead minnows and from 0.6 to 1.4 mg/L for amphipods. Toxicity of LAS in 4-, 7-, and 28-d exposures of fathead minnows was similar because mortality occurred within the initial 24 h of exposure; mortality was more sensitive than growth as a chronic end point. The addition of 5% sewage effluent to well and stream water had little effect on the bioavailability of LAS; however, total organic carbon levels were low (<3 mg/L) in all treatments. A 45-d exposure of three outdoor experimental streams to 0.36 mg/L LAS had no effects on survival of fathead minnows or amphipods, dynamics of benthic invertebrates, growth of periphyton, or processing of detrital leaves. Results indicated that the laboratory-generated NOEC for LAS was protective of experimental stream communities under the studied conditions.

The effect of chemical structure and molecular weight of commercial alkylbenzenes on the toxic response of Daphnia and naturally occurring bacteria in fresh and seawater

The toxicity of linear alkylbenzene sulfonate (LAS) of different molecular weight and branched alkylbenzene sulfonate (BABS) on naturally occurring bacteria has been checked by thymidine incorporation. A correlation between the chain length and its toxicity for Daphnia and indigenous water bacteria has been found for linear alkylbenzene sulfonate. Branched alkylbenzene sulfonate, which is less biodegradable than linear alkylbenzene sulfonate, is also less toxic despite its higher molecular weight.