Acute Toxicity of Eight Aqueous Film-Forming Foams to 14 Aquatic Species.

Researchers have developed numerous per- and polyfluoroalkyl substances (PFAS)-free aqueous film-forming foam (AFFF) formulations to replace PFAS-containing AFFF used for fire suppression. As part of the Department of Defense's Strategic Environmental Research and Development Program (SERDP), we examined the direct lethal effects of seven PFAS-free AFFF and a PFAS-containing AFFF on 14 aquatic species using a series of lethal concentration (LC50) tests. We assessed the LC10, LC50, and LC90 values using log-logistic and logit analyses. Across all aquatic species tested, we discovered that exposure to at least one PFAS-free AFFF was more or as toxic as exposure to the PFAS-containing AFFF. For most cases, National Foam Avio F3 Green KHC 3% and Buckeye Platinum Plus C6MILSPEC 3% were the most and least toxic formulations, respectively. Moreover, we found consistency among results from multiple experiments using the same minnow species (Pimephales promelas) and among closely related taxa (e.g., daphnids, amphibians). Lastly, the LC50 values for AFFF formulations trended lower for tested marine species as compared to those of freshwater species. These results dramatically increase the current knowledge on the potentially toxic effects of AFFF but also highlight the need for additional research and the development of new PFAS-free AFFF that are more "ecologically friendly" than those containing persistent PFAS.

Multi-stressor Effects of Ultraviolet Light, Temperature, and Salinity on Louisiana Sweet Crude Oil Toxicity in Larval Estuarine Organisms.

When oil is spilled into the environment its toxicity is affected by abiotic conditions. The cumulative and interactive stressors of chemical contaminants and environmental factors are especially relevant in estuaries where tidal fluctuations cause wide variability in salinity, temperature, and ultraviolet (UV) light penetration, which is an important modifying factor for polycyclic aromatic hydrocarbon (PAH) toxicity. Characterizing the interactions of multiple stressors on oil toxicity will improve prediction of environmental impacts under various spill scenarios. This study examined changes in crude oil toxicity with temperature, salinity, and UV light. Oil exposures included high-energy, water-accommodated fractions (HEWAFs) and thin oil sheens. Larval (24-48 h post hatch) estuarine species representing different trophic levels and habitats were evaluated. Mean 96 h LC50 values for oil prepared as a HEWAF and tested under standard conditions (20 ppt, 25 °C, No-UV) were 62.5 µg/L tPAH50 (mud snails), 198.5 µg/L (grass shrimp), and 774.5 µg/L (sheepshead minnows). Thin oil sheen 96 h LC50 values were 5.3 µg/L tPAH50 (mud snails), 14.7 µg/L (grass shrimp), and 22.0 µg/L (sheepshead minnows) under standard conditions. UV light significantly increased the toxicity of oil in all species tested. Oil toxicity also was greater under elevated temperature and lower salinity. Multi-stressor (oil combined with either increased temperature, decreased salinity, or both) LC50 values were reduced to 3 µg/L tPAH50 for HEWAFs and < 1.0 µg/L tPAH50 for thin oil sheens. Environmental conditions at the time of an oil spill will significantly influence oil toxicity and organismal response and should be taken into consideration in toxicity testing and oil spill damage assessments.

Uptake and Biological Effects of Perfluorooctane Sulfonate Exposure in the Adult Eastern Oyster Crassostrea virginica.

Perfluorooctane sulfonate (PFOS) is a legacy contaminant that has been detected globally within the environment and throughout numerous species, including humans. Despite an international ban on its use, this unique contaminant continues to persist in organisms and their surroundings due to PFOS's inability to breakdown into nontoxic forms resulting in bioaccumulation. In this study, we analyzed the effects of a technical mixture of PFOS (linear and branched isomers) in the adult Eastern oyster, Crassostrea virginica, at 2 days and 7 days exposure. Biomarker analysis (lysosomal destabilization, lipid peroxidation, and glutathione assays) in oyster tissue along with chemical analysis (liquid chromatography tandem mass spectrometry) of PFOS in oyster tissue and water samples revealed the oysters' ability to overcome exposures without significant damage to lipid membranes or the glutathione phase II enzyme system; however, significant cellular lysosomal damage was observed. The oysters were able to eliminate up to 96% of PFOS at 0.3 mg/L and 3 mg/L exposures when allowed to depurate for 2 days in clean seawater. Chemical analysis showed the linear isomer to be the prevailing fraction of the residual PFOS contained in oyster tissue. Results provide insight into possible detrimental cellular effects of PFOS exposure in addition to offering insight into contaminant persistence in oyster tissue.

Comparative toxicity of pyrethroid insecticides to two estuarine crustacean species, Americamysis bahia and Palaemonetes pugio.

Pyrethroid insecticides are widely used on agricultural crops, as well as for nurseries, golf courses, urban structural and landscaping sites, residential home and garden pest control, and mosquito abatement. Evaluation of sensitive marine and estuarine species is essential for the development of toxicity testing and risk-assessment protocols. Two estuarine crustacean species, Americamysis bahia (mysids) and Palaemonetes pugio (grass shrimp), were tested with the commonly used pyrethroid compounds, lambda-cyhalothrin, permethrin, cypermethrin, deltamethrin, and phenothrin. Sensitivities of adult and larval grass shrimp and 7-day-old mysids were compared using standard 96-h LC50 bioassay protocols. Adult and larval grass shrimp were more sensitive than the mysids to all the pyrethroids tested. Larval grass shrimp were approximately 18-fold more sensitive to lambda-cyhalothrin than the mysids. Larval grass shrimp were similar in sensitivity to adult grass shrimp for cypermethrin, deltamethrin, and phenothrin, but larvae were approximately twice as sensitive to lambda-cyhalothrin and permethrin as adult shrimp. Acute toxicity to estuarine crustaceans occurred at low nanogram per liter concentrations of some pyrethroids, illustrating the need for careful regulation of the use of pyrethroid compounds in the coastal zone.

Effects of Temperature and Salinity on Perfluorooctane Sulfonate (PFOS) Toxicity in Larval Estuarine Organisms.

Perfluorooctane sulfonate (PFOS) is a persistent contaminant that has been found globally within the environment. Key data gaps exist in the toxicity of PFOS to marine organisms, especially estuarine species that are crucial to the food web: fish, shrimp, and mollusks. This study developed toxicity thresholds for larval estuarine species, including grass shrimp (Palaemon pugio), sheepshead minnows (Cyprinodon variegatus), mysids (Americamysis bahia), and Eastern mud snails (Tritia obsoleta). Multiple abiotic stressors (salinity and temperature) were included as variables in testing the toxicity of PFOS. Acute 96 h toxicity testing under standard test conditions of 25 °C and 20 ppt seawater yielded LC50 values of 0.919 mg/L for C. variegatus, 1.375 mg/L for A. bahia, 1.559 mg/L for T. obsoleta, and 2.011 mg/L for P. pugio. The effects of increased temperature (32 °C) and decreased salinity (10 ppt) varied with test species. PFOS toxicity for the sheepshead minnows increased with temperature but was not altered by decreased salinity. For grass shrimp and mud snails, PFOS toxicity was greater under lower salinity. The combination of higher temperature and lower salinity was observed to lower the toxicity thresholds for all species. These data demonstrate that expanding toxicity testing to include a wider range of parameters will improve the environmental risk assessment of chemical contaminants, especially for species inhabiting dynamic estuarine ecosystems.

Mixture Effects of Per- and Polyfluoroalkyl Substances on Embryonic and Larval Sheepshead Minnows (Cyprinodon variegatus).

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous and persistent environmental contaminants originating from many everyday products. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are two PFAS that are commonly found at high concentrations in aquatic environments. Both chemicals have previously been shown to be toxic to fish, as well as having complex and largely uncharacterized mixture effects. However, limited information is available on marine and estuarine species. In this study, embryonic and larval sheepshead minnows (Cyprinodon variegatus) were exposed to several PFAS mixtures to assess lethal and sublethal effects. PFOS alone was acutely toxic to larvae, with a 96 h LC50 of 1.97 mg/L (1.64-2.16). PFOS + PFOA resulted in a larval LC50 of 3.10 (2.62-3.79) mg/L, suggesting an antagonistic effect. These observations were supported by significant reductions in malondialdehyde (105% ± 3.25) and increases in reduced glutathione concentrations (43.8% ± 1.78) in PFOS + PFOA exposures compared to PFOS-only treatments, indicating reduced oxidative stress. While PFOA reduced PFOS-induced mortality (97.0% ± 3.03), perfluorohexanoic acid (PFHxA) and perfluorobutanoic acid (PFBA) did not. PFOS alone did not affect expression of peroxisome proliferator-activated receptor alpha (pparα) but significantly upregulated apolipoprotein A4 (apoa4) (112.4% ± 17.8), a downstream product of pparα, while none of the other individually tested PFAS affected apoa4 expression. These findings suggest that there are antagonistic interactions between PFOA and PFOS that may reduce mixture toxicity in larval sheepshead minnows through reduced oxidative stress. Elucidating mechanisms of toxicity and interactions between PFAS will aid environmental regulation and management of these ubiquitous pollutants.

Chronic Toxicity of Per- and Polyfluoroalkyl Substance-Free Firefighting Foams to Aquatic Organisms.

Amid global concern regarding the health and environmental impacts of per- and polyfluoroalkyl substances (PFAS), there is an urgent need to develop and implement alternative products without PFAS. Consequently, PFAS-free firefighting foams used for fire suppression have been developed for use in military and residential settings. To facilitate the selection of lower-risk PFAS-free foams, the present study focused on the chronic toxicity of seven PFAS-free and one PFAS-containing foam to six aquatic species. Target species included two cladocerans, Daphnia magna and Ceriodaphnia dubia; the chironomid Chironomus dilutus; the mysid Americamysis bahia; and two fish species, Pimephales promelas and Cyprinodon variegatus, with endpoints including growth, development, reproduction, and survival. To facilitate comparison and product toxicity rankings, effective concentrations (20%, 50%) and no- and lowest-observed-effect concentrations (NOECs and LOECs, respectively) were calculated. Effective concentrations, NOECs, and LOECs varied by over an order of magnitude among foams and species, with several of the PFAS-free formulations ranked as highly toxic based on US Environmental Protection Agency alternatives assessment hazard criteria. Overall, the PFAS-free foams were found to exhibit either similar or greater toxicity compared to the PFAS-containing reference foam across several species and endpoints. Nonmonotonic and hormetic dose responses were observed in D. magna for several of the tested foams, with increased reproduction and growth at intermediate exposures. Generally, tested foam toxicity rankings were consistent with a related acute toxicity study using the same species and formulations, and other research using soil invertebrates. Combined with related efforts for other taxa including mammals, birds, and plants, the present research will facilitate the selection of appropriate PFAS-free firefighting foams that minimize harm to the environment. Environ Toxicol Chem 2024;43:2436-2454. © 2024 SETAC.

Differences in response of two model estuarine crustaceans after lethal and sublethal exposures to chlorpyrifos.

This study assessed the in vitro and in vivo effects of an acetylcholinesterase enzyme inhibitor (chlorpyrifos) in two estuarine crustaceans: grass shrimp (Palaemonetes pugio) and mysid (Americamysis bahia). The differences in response were quantified after lethal and sublethal exposures to chlorpyrifos and in vitro assays with chlorpyrifos-oxon. Results from the in vitro experiments indicated that the target enzyme, acetylcholinesterase (AChE), in the two species was similar in sensitivity to chlorpyrifos inhibition with IC50s of 0.98 nM and 0.89 nM for grass shrimp and mysids, respectively. In vivo experiments showed that mysids were significantly more sensitive to chlorpyrifos-induced AChE inhibition after 24 h of exposure. The in vivo EC50s for AChE inhibition were 1.23 µg L(-1) for grass shrimp and 0.027 µg L(-1) for mysids. Median lethal concentrations (24h LC50 values) were 1.06 µg L(-1) for grass shrimp and 0.068 µg L(-1) for mysids. The results suggest that differences in the response of these two crustaceans are likely related to differences in uptake and metabolism rather than target site sensitivity.

Comparative assessment of the fate and toxicity of chemically and biologically synthesized silver nanoparticles to juvenile clams.

Nanoparticles (NPs) can be produced via physical, chemical, or biological approaches. Yet, the impact of the synthesis approaches on the environmental fate and effects of NPs is poorly understood. Here, we synthesized AgNPs through chemical and biological approaches (cit-AgNPs and bio-AgNPs), characterized their properties, and toxicities relative to commercially available Ag nanopowder (np-AgNPs) to the clam Mercenaria mercenaria. The chemical synthesis is based on the reduction of ionic silver using sodium borohydride as a reducing agent and trisodium citrate as a capping agent. The biological synthesis is based on the reduction of ionic silver using biomolecules extracted from an atoxigenic strain of a filamentous fungus Aspergillus parasiticus. The properties of AgNPs were determined using UV-vis, dynamic light scattering, laser Doppler electrophoresis, (single particle)-inductively coupled plasma-mass spectroscopy, transmission electron microscopy, and asymmetric flow-field flow fractionation. Both chemical and biological synthesis approaches generated spherical AgNPs. The chemical synthesis produced AgNPs with narrower size distributions than those generated through biological synthesis. The polydispersity of bio-AgNPs decreased with increases in cell free extract (CFE):Ag ratios. The magnitude of the zeta potential of the cit-AgNPs was higher than those of bio-AgNPs. All AgNPs formed aggregates in the test media i.e., natural seawater. Based on the same total Ag concentrations, all AgNPs were less toxic than AgNO3. The toxicity of AgNPs toward the juvenile clam, Mercenaria mercenaria, decreased following the order np-AgNPs > cit-AgNPs > bio-AgNPs. Expressed as a function of dissolved Ag concentrations, the toxicity of Ag decreased following the order cit-AgNPs > bio-AgNPs > AgNO3 ~ np-AgNPs. Therefore, the toxicity of AgNP suspensions can be attributed to a combined effect of dissolved and particulate Ag forms. These results indicate that AgNP synthesis methods determine their environmental and biological behaviors and should be considered for a more comprehensive environmental risk assessment of AgNPs.

Toxicity of the mosquito control insecticide phenothrin to three life stages of the grass shrimp (Palaemonetes pugio).

Phenothrin is a synthetic pyrethroid used as a contact insecticide in mosquito control programs. This study compared the toxicity of phenothrin to adult, larval and embryonic grass shrimp (Palaemonetes pugio) and examined oxidative stress responses in adult and larval grass shrimp. The adult 24-h LC50 was 0.341 µg/L (95 % confidence intervals 0.282-0.412) and the 96-h LC50 was 0.161 µg/L (95 % CI 0.128-0.203 µg/L). The larval 24-h LC50 was 0.50 µg/L (95 % CI 0.441-0.568) and the 96-h LC50 was 0.154 µg/L (95 % CI 0.139-0.170 µg/L). In the presence of sediment, the 24-h LC50 was 6.30 µg/L (95 % CI 5.00-7.44 µg/L) for adults and 0.771 µg/L (95 % CI 0.630-0.944) for larvae. The sublethal biomarkers glutathione and lipid peroxidase (LPx) were examined after 96-h phenothrin exposure at five concentrations, and there were no statistically significant differences in these levels in adults or larvae compared to controls. There was a significant downward trend in larval LPx levels. This research confirms that phenothrin is highly toxic to grass shrimp and suggests that both adult and larval grass shrimp are appropriate life stages for risk assessments.

Acute toxic effects of endosulfan sulfate on three life stages of grass shrimp, Palaemonetes pugio.

In this study, the toxicity of endosulfan sulfate, the primary degradation product of the insecticide endosulfan, was determined in three life stages of the grass shrimp (Palaemonetes pugio). After 96 h exposure to endosulfan sulfate, the grass shrimp adult LC50 was 0.86 microg/L (95% CI 0.56-1.31), the grass shrimp larvae LC50 was 1.64 microg/L (95% CI 1.09-2.47) and the grass shrimp embryo LC50 was 45.85 microg/L (95% CI 23.72-88.61 microg/L). This was compared to the previously published grass shrimp 96-h LC50s for endosulfan. The toxicity of the two compounds was similar for the grass shrimp life stages with adults more sensitive than larvae and embryos. The presence of sediment in 24h endosulfan sulfate-exposures raised LC50s for both adult and larval grass shrimp but not significantly. The USEPA expected environmental concentrations (EEC) for total endosulfan and endosulfan sulfate and the calculations of risk quotients (RQ) based on the more sensitive adult grass shrimp 96-h LC50 clearly show that environmental concentrations equal to acute EECs would prove detrimental to grass shrimp or other similarly sensitive aquatic organisms. These results indicate that given the persistence and toxicity of endosulfan sulfate, future risk assessments should consider the toxicity potential of the parent compound as well as this degradation product.

Developmental and reproductive effects in grass shrimp (Palaemon pugio) following acute larval exposure to a thin oil sheen and ultraviolet light.

Many early stages of estuarine species congregate at the surface or in the upper mixing layer making them prone to UV light exposure and oil sheens. Laboratory testing was used to assess UV-oil sheen interactions with grass shrimp (Palaemon pugio). Newly hatched grass shrimp larvae were exposed to a 1-µm thick oil sheen for 24 h with or without an 8-h pulse of UV light. Grass shrimp were then transferred to clean seawater and non-UV conditions to measure development, growth, and reproductive fitness. Minimal toxicity was observed after the initial exposure but larval development was significantly delayed in shrimp exposed to the UV enhanced sheen. After reaching sexual maturity, shrimp were paired to evaluate effects on reproduction. Shrimp initially exposed to the UV enhanced sheen as larvae had a significant reduction in fecundity compared to controls. This demonstrates the importance of examining interactions between UV light and oil since negative effects to aquatic organisms may be underestimated if based on standard laboratory fluorescent lighting. Acute exposures of early life stages to thin oil sheens and UV light may lead to long-term impacts to individuals and ultimately to grass shrimp populations.

Lethal and sublethal effects of simvastatin, irgarol, and PBDE-47 on the estuarine fish, Fundulus heteroclitus.

This study investigated the effects of simvastatin, a lipid-regulating drug; irgarol, an antifouling biocide; and PBDE-47, a brominated flame retardant, on the estuarine fish, Fundulus heteroclitus. Sublethal effects (changes in glutathione (GSH), lipid peroxidation (LPx), acetylcholinesterase (AChE), and cholesterol (CHL) levels) and lethal effects (survival) were determined after individual exposure to the three compounds. There were no significant differences in GSH or CHL levels in fish exposed to any of the test compounds. LPx levels significantly decreased with increasing irgarol concentrations. AChE levels were significantly lower in fish exposed to simvastatin at the 1.25 mg/L concentration and significantly higher at the PBDE-47 concentration of 0.0125 mg/L. The LC50 values were 2.68, 3.22, and > 0.1 mg/L for simvastatin, irgarol and PBDE-47, respectively.

Toxicity and physiological effects of brominated flame retardant PBDE-47 on two life stages of grass shrimp, Palaemonetes pugio.

This study examined the effects of a polybrominated diphenyl ether (PBDE) compound, PBDE-47, on adult and larval stages of the estuarine grass shrimp (Palaemonetes pugio). The 96-h LC50 test resulted in an estimate of 23.60 microg/L (95% confidence interval=14.51-38.37 microg/L) for larval shrimp. Adult shrimp had a higher 96-h LC50 of 78.07 microg/L (95% CI=65.1-93.63 microg/L). Four physiological biomarkers glutathione (GSH), lipid peroxidation (LPx), cholesterol (CHL) and acetylcholinesterase (AChE) were then assessed to study the sublethal effects of PBDE-47 exposure. GSH, LPx and AChE levels in both adults and larvae were not affected by PBDE-47 at concentrations up to 50 microg/L for 96 h. CHL levels were elevated in adults and larvae at the lowest exposure concentrations tested, but significant differences were found only in adult exposures. Effects associated with PBDE-47 aqueous exposures were observed at levels well above those reported in the environment.

Toxicity comparison of the shoreline cleaners Accell Clean® and PES-51® in two life stages of the grass shrimp, Palaemonetes pugio.

Oil spills are a significant source of coastal pollution. Shoreline cleaners, used to remove oil from surfaces during spill response and remediation, may also act as toxins. Adult and larval grass shrimp, Palaemonetes pugio, were tested for lethal and sublethal impacts from two shoreline cleaners, Accell Clean SWA® and PES-51®, alone and in combination with crude oil using Chemically Enhanced Water Accommodated Fractions (CEWAFs). Median lethal toxicity values determined for the individual cleaners were similar. However, when tested in mixture with oil as CEWAFs, Accell Clean SWA resulted in greater hydrocarbon concentrations in the water column and greater toxicity than PES-51. Increased glutathione levels were observed for adult shrimp exposed to Accell Clean SWA, and glutathione was elevated in shrimp exposed to both CEWAFs. Larval shrimp development was delayed after exposure to both CEWAFs. These findings may have implications for managing and mitigating oil spills.

Effects of salinity on oil dispersant toxicity in the eastern mud snail, Ilyanassa obsoleta.

Chemical dispersants can be a beneficial method for breaking up oil slicks; however, their use in mitigation could pose potential toxic effects on the marine ecosystem. Dispersants may be transported to lower salinity habitats, where toxicity data for aquatic species have not been established. This study examined the effect of salinity on oil dispersant toxicity in the eastern mud snail, Ilyanassa obsoleta, using two dispersants authorized for oil spill response, Corexit® 9500A and Finasol® OSR 52. Median lethal toxicity values (LC50) and sublethal effects were examined at 10, 20, and 30 ppt salinity in adult and larval mud snails. Two biomarkers (lipid peroxidation and acetylcholinesterase) were used to measure sublethal effects. The 96-h static renewal LC50 values indicated significant differences in toxicity between dispersants and salinities. Larval snails were significantly more sensitive than adult snails to both dispersants, and both life stages were significantly more sensitive to Finasol than to Corexit. Larval snails were more sensitive to dispersants at lower salinity, but adult snails were more sensitive at higher salinities. Dispersants increased lipid peroxidation and decreased acetylcholinesterase activity. These results demonstrate that dispersant toxicity varies among compounds and organism life stages, and that physicochemical properties of the environment, such as salinity, can affect the potential toxicity to estuarine species.

Individual and mixture effects of caffeine and sulfamethoxazole on the daggerblade grass shrimp Palaemonetes pugio following maternal exposure.

Pharmaceuticals and personal care products (PPCPs) such as caffeine and sulfamethoxazole have been detected in the estuarine environment. The present study characterized effects of a maternal exposure of these compounds on the development of the daggerblade grass shrimp Palaemonetes pugio from embryo to juvenile life stage. Ovigerous females were exposed to either caffeine (20 mg/L), sulfamethoxazole (60 mg/L), or a mixture of both (20 mg/L caffeine and 60 mg/L sulfamethoxazole). Embryos were then removed from the females and the effects of the PPCPs on hatching, metamorphosis, juvenile growth, and overall mortality were determined. No significant effect was observed on gravid female survival after 5 d of exposure to caffeine, sulfamethoxazole, or the mixture; however, development of the embryos on the female shrimp was delayed in the mixture. Caffeine and sulfamethoxazole in the mixture significantly reduced embryo survival. There was a significant effect of caffeine, sulfamethoxazole, and the mixture on embryo hatching time. Exposure to sulfamethoxazole alone significantly delayed larval metamorphosis. Exposure to caffeine and sulfamethoxazole separately led to significantly smaller length of juvenile shrimp. Maternal exposure to caffeine and sulfamethoxazole, individually and in mixture, resulted in negative effects on P. pugio offspring survival and development; however, the concentrations tested in the present study were well above maximum detected field concentrations. These results may be incorporated into PPCP risk assessments to protect sensitive estuarine ecosystems more effectively.

Toxicity of carbaryl, diquat dibromide, and fluoranthene, individually and in mixture, to larval grass shrimp, Palaemonetes pugio.

This study examined the toxicity of two pesticides (carbaryl and diquat dibromide) and one polycyclic aromatic hydrocarbon (fluoranthene), both singly and in mixture, to grass shrimp larvae (Palaemonetes pugio). These three chemicals are all present in coastal environments and can easily enter estuarine ecosystems. Fluoranthene was the most toxic chemical with a 96-h LC50 value of 32.45 microg/L, followed by carbaryl (43.02 microg/L) and diquat dibromide (1624 microg/L). In the chemical mixture tests, the binary carbaryl/diquat dibromide mixture and the ternary carbaryl/diquat dibromide/fluoranthene mixture had additive results.

Effects of the statin antihyperlipidemic agent simvastatin on grass shrimp, Palaemonetes pugio.

This study investigated lethal effects (i.e., survival) and sublethal effects (glutathione, GSH; lipid peroxidation, LPx; cholesterol, CHL; and acetylcholinesterase, AChE) of the antihyperlipidemic drug simvastatin on larval and adult grass shrimp (Palaemonetes pugio). The 96-h LC50 test for larvae resulted in an estimated LC50 of 1.18 mg/L (95% confidence interval 0.98-1.42 mg/L). The adult 96-h LC50 was >10.0 mg/L. GSH and AChE levels for both the larvae and the adults were not significantly affected by simvastatin exposure. LPx levels in the larvae were significantly higher than controls in the lowest and the highest simvastatin exposures. In adult grass shrimp, LPx levels were highest in the three lowest simvastatin exposures. CHL levels were significantly reduced in larvae at the highest simvastatin exposure level of 1 mg/L while adult CHL was not affected. Both lethal and sublethal effects associated with simvastatin exposure were only observed at concentrations well above those reported in the environment.

Effects of the anti-fouling herbicide Irgarol 1051 on two life stages of the grass shrimp, Palaemonetes pugio.

This study investigated lethal and sublethal effects (glutathione, lipid peroxidation, cholesterol, and acetylcholinesterase) of the anti-fouling herbicide Irgarol 1051 on larval and adult grass shrimp (Palaemonetes pugio). The 96-hour LC50 test for larvae resulted in an estimated LC50 of 1.52 mg/L (95% confidence interval [CI] 1.26-1.85 mg/L). The adult 96-h LC50 was 2.46 mg/L (95% CI = 2.07-2.93 mg/L). Glutathione, lipid peroxidation, cholesterol and acetylcholinesterase levels were not significantly affected in adult grass shrimp by exposure of up to 3.00 mg/L irgarol. Lipid peroxidation and acetylcholinesterase levels in the larvae were significantly higher than controls in the highest irgarol exposures of 1.0 and 2.0 mg/L, respectively. Cholesterol levels were significantly reduced in larvae in all four irgarol concentrations tested while glutathione levels were not significantly affected in larvae. Both lethal and sublethal effects associated with irgarol exposure were only observed at concentrations well above those reported in the environment.