Concentrations and characteristics of organochlorine pesticides in aquatic biota from Qiantang River in China

The Qiantang River is a typical river flowing through an agricultural area in China. It was studied in 2006 for its aquatic biota quality by determining 13 organochlorine pesticides (OCPs) in the edible parts of crabs, clams, shrimp, fish, aquatic plants, as well as water and sediments collected from seven sites along its upper reaches all the way downstream. The levels of all insecticides were in the range of 17+/-13 (water plants), 35+/-36 (shrimp), 32+/-14 (crabs), 39+/-21 (clams), 47+/-35 (fish) ng/g wet weight (ww) and in the range of 2936+/-2356 (water plants), 5827+/-6013 (shrimp), 2102+/-966 (crabs), 1859+/-1018 (clams), 3624+/-11331 (fish) ng/g lipid. DDT and its metabolites were the predominant contaminants in most biota. A linear relationship was observed between the log bio-concentration factor (BCF) and log octanol-water partition coefficients (Kow) for fish, clams and shrimp. Composition analyses in various environmental media indicated a recent usage of lindane and dicofol into the river.     

A summary of total mercury concentrations in flora and fauna near common contaminant sources in the Gulf of Mexico

Total mercury concentrations are summarized for environmental media and biota collected from near-coastal areas, several impacted by contaminant sources common to the Gulf of Mexico. Water, sediment, fish, blue crabs, oysters, clams, mussels, periphyton and seagrasses were collected during 1993–2002 from targeted areas affected by point and non-point source contaminants. Mean concentrations in water and sediment were 0.02 (±1 standard deviation = 0.06) μg l⁻¹ and 96.3 (230.8) ng g⁻¹ dry wt, respectively. Mean total mercury concentrations in fish, blue crabs, brackish clams and mussels were significantly greater than those in sediment, seagrass, colonized periphyton and oysters. Concentrations (ng g⁻¹ dry wt) averaged 23.1 (two seagrass species), 220.1 (oysters), 287.8 (colonized periphyton), 604.0 (four species of freshwater mussels), 772.4 (brackish clam), 857.9 (blue crabs) and 933.1 (nine fish species). Spatial, intraspecific and interspecific variability in results limited most generalizations concerning the relative mercury contributions of different stressor types. However, concentrations were significantly greater for some biota collected from areas receiving wastewater discharges and golf course runoff (fish), agricultural runoff (oysters) and urban stormwater runoff (colonized periphyton and sediment). Marine water quality criteria and proposed sediment quality guidelines were exceeded in 1–12% of total samples. At least one seafood consumption guideline, criteria or screening value were exceeded in edible tissues of blue crabs (6% total samples) and nine fish species (8–33% total samples) but all residues were less than the US Federal Drug Administration action limit of 1.0 ppm and the few reported toxic effect concentrations available for the targeted biota.     

Measurement of pollution levels of organochlorine and organophosphorus pesticides in water, soil, sediment, and shrimp to identify possible impacts on shrimp production at Jiquilisco Bay

This study aims to identify levels of several organochlorine and organophosphorus compounds in shrimp-raising areas of coastal El Salvador, to assess potential impacts on shrimp growth and survival that hamper the sustainability of aquaculture in the region. The paper reports the current levels of γ-HCH, 4,4'-DDT, 4,4'-DDE, 4,4'-DDD, endrin, dieldrin, heptachlor, parathion, methyl parathion, and etoprophos in soils (depth 20 cm), sediments (depth 5 cm), shrimp (Penaeus sp.), and water of three rearing ponds and also in the sediment (depth 5 cm) and water surrounding those ponds in Jiquilisco Bay. Sampling was carried out during the dry (January-March) and rainy (June-August) seasons of 2008. The presence of pesticides in the samples of water, shrimp, and sediment at shrimp ponds was not detected in either season; however, in soil samples (depth 20 cm) taken from these ponds, heptachlor, endrin, dieldrin, 4,4'-DDD, and 4,4'-DDT were identified at concentrations below the method limit of quantification (LOQ), and 4,4'-DDE was found in a concentration falling in the range from 3.85 to 19.61 ng/g. In samples of water taken at the bay water intakes to the rearing ponds, we observed dieldrin concentrations in the range between 0.085 ng/mL and 0.182 ng/mL during the dry season. In the samples of sediments taken in the surrounding areas of shrimp ponds, we found-for both seasons-that in 60 % of the samples, 4,4'-DDE was present in concentrations ranging from 3.75 ng/g to 30.97 ng/g. Additionally, in the rainy season, we observed heptachlor in sediment at concentrations below the method quantification limit. It was concluded that organochlorine compounds from pesticides are still present in Jiquilisco Bay, trapped in deep sediment, even though they have been banned since the 1980s. These were not detected in shrimp tissue, surface water, and shallow sediment in rearing ponds, and hence, we do not believe their presence has any major impact on shrimp production in sampled areas.     

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.     

Human exposure to polychlorinated naphthalenes through the consumption of edible marine species

The concentrations of polychlorinated naphthalenes (PCNs) were determined in samples of 14 edible marine species (sardine, tuna, anchovy, mackerel, swordfish, salmon, hake, red mullet, sole, cuttlefish, squid, clam, mussel and shrimp), which are widely consumed by the population of Catalonia, Spain. The daily intake of PCNs associated with this consumption was also determined. A total of 42 composite samples were analyzed by HRGC/HRMS. The highest PCN levels (ng/kg of fresh weight) were found in salmon (227) followed by mackerel (95) and red mullet (68), while the lowest levels of total PCNs corresponded to shrimp (4.9) and cuttlefish (2.7). With the exception of cephalopods and shellfish species, in which tetra-CN was the predominant homologue, penta-CN (60%) was the predominant contributor to total PCNs. For a standard male adult, PCN intake through the consumption of edible marine species was 1.53 ng/day. The highest contributions to this intake (ng/day) corresponded to salmon (0.41), sole (0.28) and tuna (0.24). Concerning health risks, species-specific TEFs such as those reported by WHO and NATO for PCDD/Fs and dioxin-like PCBs are not currently available for PCN congeners. Although in general terms the results of the present study do not seem to suggest specific risks derived from exposure to PCNs through fish and seafood consumption, to establish the contribution of individual PCN congeners to total TEQ is clearly necessary for the assessment of human health risks.     

Concentrations of organotin compounds in sediment and clams collected from coastal areas in Vietnam

Levels of butyltin (BT) and phenyltin (PT) compounds were determined in sediments and clam Meretrix spp. collected from north and central coastal areas in Vietnam. Concentrations of TBT in sediments ranged from 0.89 to 34 ng g(-1) dry wt and those in clams ranged from 1.4 to 56 ng g(-1) wet wt. The levels of TBT in sediments and clams from Vietnam were within limits reported from other countries. Further, the TBT level in clams was lower than the tolerable average residue level (TARL) estimated based on tolerable daily intake (TDI). Trace amounts of PTs were also found in both sediment and clam samples. In sediments from north and central Vietnam, the concentrations of TBT were highest in the order of Hue (28 ng g(-1) dry wt), Cua Luc (15 ng g(-1) dry wt), Sam Son (6.3 ng g(-1) dry wt), and Tra Co (5.5 ng g(-1) dry wt). Among the clams from north and central Vietnam, the levels of TBT in clams from Cua Luc were dramatically high at 47 ng g(-1) wet wt. TBT formed the principal butyltin species in sediment at all sites studied. The ratios of TBT in sediment were higher among BT compounds at all study sites. Of total BTs, TBT was the dominant species in clams from almost all sites studied. In spatial distribution, TPT showed a pattern similar to TBT, suggesting the use of TPT as an antifouling paint. The partition coefficient between sediment and calms was calculated. The partition coefficients of TBT and TPT were 2.01 (0.56-5.5) and 9.23 (3.1-20), respectively. These results show that sediment-bound TBT is a source of contamination to clams in addition to dissolved TBT.     

Estimation of metal and organochlorine pesticide exposures and potential health threat by consumption of oysters in Taiwan

Pollutant concentrations detected in oysters from 12 different culture areas of Taiwan (especially for the Hsiangshan area and the Machu Islands) from 1991-98 were evaluated to investigate potential carcinogenic (inorganic As and organochlorine pesticides) and non-carcinogenic (Cu, Zn, Cd and inorganic As) risk to the public from ingestion of the oysters. The highest geometric mean (GM) Cu and Zn concentrations of 1108 (range 113-2806) and 1567 (range 303-3593) microg/g dry weight were obtained in oysters from the Hsiangshan coastal area. The maximum GM Cd and As concentrations of 6.82 and 19.3 microg/g dry weight were found in oysters from the Machu Islands area. The p,p'-DDE values range from not detectable in Penghu Islands' oysters to 164 ng/g dry weight in Machu Islands' oysters. The highest tDDT (sum of p,p'-DDE, p,p'-DDD and p,p'-DDT) concentrations of 337 and 340 ng/g dry weight were found in oysters from Kimmen and Machu Islands, respectively. A calculated target hazard quotient (THQ; daily intake/reference dose) of 11.4 (based on 139 g oysters/day) for Cu caused by consuming oysters from the Hsiangshan area is higher than that from other areas (range 0.124-5.95). The highest average Cu intake from Hsiangshan's oysters for individuals is 11.4 times (i.e. THQ=11.4) more than that of reference dose (40 microg/kg/day). However, the maximum THQ values for Cd and As caused by consuming oysters collected from the Machu Islands were 5.57 and 2.63 for Cd and As, respectively. Generally, the results of THQ showed that if only the maximally exposed individuals were considered, the value of 65.4% for oyster was higher than 1.0 in comparison with reference dose. All cancer risk estimates for inorganic As from consuming oysters were higher than 10(-6) (range from 128x10(-6) to 509x10(-6) for maximally exposed individuals and range from 17.1x10(-6) to 68.0x10(-6) for typically exposed individuals, respectively); that is the risk of the lower end of the range of acceptable risk. The highest risk estimate for inorganic As was 509x10(-6) for consumption of oysters by Machu Islands' residents. The lifetime cancer risks of 19.0x10(-6) for tDDT by consuming oysters from the Machu Islands was higher than those from the Penghu Islands (0.37x10(-6)). Therefore, the sum of lifetime cancer risks for tDDT and inorganic As had the highest risks (total risk=528x10(-6)) of consuming oysters from the Machu Islands. Furthermore, a 10(-6) upper limit on lifetime risk as the health protection standard would require maximum oyster consumption rates of approximately 0.26 g/day.     

Tributyltin in environmental samples from the Former Derecktor Shipyard, Coddington Cove, Newport RI

Tributyltin (TBT) was detected in all 24 surface sediment (top 2 cm) samples collected from Coddington Cove, Newport, RI. TBT surface sediment concentrations ranged from 32 to 372 ng Sn/g with a mean concentration of 146 ng Sn/g. Analyses of selected core sections detected TBT in at least the top 18 cm at all 7 stations where cores were collected. No consistent TBT concentration trends with depth for these cores suggest mixing is an important process in the sediment column. In one core (station 28), TBT was found in the 76-86 cm section at a concentration of 141 ng Sn/g; thus sediments are a significant sink for TBT. However, sediment mixing processes can enhance releases of bioavailable TBT. Mussels, clams and fish from Coddington Cove contain TBT at concentrations ranging from 9.2 to 977 ng Sn/g. TBT concentrations in lobsters were below the detection limit (<6 ng Sn/g). Based on available screening criteria, TBT concentrations in Coddington Cove sediment is likely to be having an adverse effect on the biota at some locations.     

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.     

Relationship between copper speciation in sediments and bioaccumulation by marine bivalves of Taiwan

This paper evaluates the relationships between copper species in sediments and accumulation by the purple clam (Hiatula diphos) and venus clam (Gomphina aeguilatera) collected from the field and culture (aquaculture) ponds in the polluted coastal area of Lukang, Taiwan. Sediment was sampled along with the molluscs, including oysters (Crassostrea gigas), purple clams (Hiatula diphos), rock-shells (Thais clavigera), venus clams (Gomphina aeguilatera), and hard clams (Meretrix lusoria), from two unique environments of Lukang during the period from August 1993 to July 1994. The data indicate that the total copper concentrations in sediments from culture ponds (185 microg g(-1)) was higher than those of the field (44.0 microg g(-1)). Copper species in sediments were analyzed by a sequential leaching technique. Results show that concentrations of various copper species in the sediments are in the range of 1.14 +/- 0.59 to 13.2 +/- 22.4 microg g(-1) and 0.36 +/- 0.24 to 133 +/- 36.7 microg g(-1) for the two environments, respectively. Also the exchangeable copper in sediment from culture ponds was 15 times higher than that from the field. In addition, the sum of exchangeable and copper carbonates had the highest percentages of copper in both the pond sediment (86.6 %) and the field sediment (50.7 %). Maximum copper concentrations (309 +/- 35.1 microg g(-1)) in oysters were much higher than those in the other benthic organisms by about 4-127 times. Similarly, the data also showed that copper concentrations in Thais clavigera were 12-32 times higher than those in other benthic organisms. Copper concentrations in various benthic organisms differed significantly (p < 0.05) from that in Thais clavigera. This capacity makes Thais clavigera a potential candidate for monitoring copper in marine sediments. In terms of copper species, the best correlation was generally obtained between copper carbonates in sediments and copper concentrations in Hiatula diphos (r = 0.886*). A strong multiple regression correlation (p < 0.05, r2 = 0.7894) also indicates that the copper carbonates may dominate as the available form of copper to Hiatula diphos from various environments in the Lukang coastal area under natural physicochemical conditions.     

Alkylphenols and alkylphenol ethoxylates contamination of crustaceans and fishes from the Adriatic Sea (Italy)

This paper presents the results of an investigation on the occurrence of alkylphenols (APs) and their ethoxylates (APEs) in 8 edible marine species from the Adriatic Sea and tries to estimate the corresponding intake for the Italian population. Two crustaceans, Nephrops norvegicus (Norway lobster) and Squilla mantis (spottail mantis shrimp), plus six fish species, Engraulis enchrascicolus (anchovy), Scomber scombrus (Atlantic mackerel), Merluccius merluccius (European hake), Mullus barbatus (red mullet), Solea vulgaris (common sole) and Lophius piscatorius (angler) were analyzed for their content of nonylphenol (NP), octylphenol (OP) and octylphenol polyethoxylates (OPEs). These compounds were found in all analysed samples. NP was detected at the highest concentrations: 118-399 and 9.5-1431 ng g(-1) fresh weight (fw) respectively in crustaceans and fish. OP was found at respective levels of 2.7-4.7 and 0.3-3.8 ng g(-1) fw in crustaceans and fish, whereas OPE was determined at respective concentrations of 1.2-16.8 and 0.2-21.1 ng g(-1) fw in the same species. These results, together with those from a previous study on 4 edible mollusc, allow to estimate respective daily intakes for NP, OP, and OPE of about 12, 0.1, and 0.1 microg day(-1) for an Italian adult living along the Adriatic Coast. In relation to NP and OP, these intakes are much lower than the doses associated with toxic effects in laboratory animals (9 mg kg(-1) bw for rats). Nevertheless, data of exposure from other sources to these chemicals and others with similar biological characteristics are needed.     

Distribution and bioaccumulation of steroidal and phenolic endocrine disrupting chemicals in wild fish species from Dianchi Lake, China

The distribution and bioaccumulation of steroidal and phenolic endocrine disrupting chemicals (EDCs) were studied in various tissues of wild fish species from Dianchi Lake, China. In muscle tissue, 4-tert-octylphenol, 4-cumylphenol, 4-nonlyphenol and bisphenol A were detected in fish from each sampling site, with maximal concentrations of 4.6, 4.4, 18.9 and 83.5 ng/g dry weight (dw), respectively. Steroids (estrone, 17β-estradiol 17α-ethynylestradiol and estriol) were found at lower levels (<11.3 ng/g dw) and less frequently in muscle samples. The highest concentrations of steroids and phenols were found in liver, followed by those in gill and the lowest concentration was found in muscle. The field bioconcentration factors (BCFs) of phenols were calculated in fish species ranged from 18 to 97. Moreover, the measured tissue concentrations were utilized in order to estimate water concentration of steroids (4.4-18.0 ng/L). These results showed that steroidal and phenolic EDCs were likely ubiquitous contaminants in wild fish.     

Residual levels of DDTs and PAHs in freshwater and marine fish from Hong Kong markets and their health risk assessment

Axial and ventral muscle from 10 each species of freshwater and marine fish purchased from markets in Hong Kong were analyzed for dichlorodiphenyltrichloroethane (total DDTs including DDE, DDD and DDT) and polycyclic aromatic hydrocarbons (PAHs). Among the 10 freshwater fish species, rice field eel (Monopterus albus) showed significantly higher levels of DDTs in both ventral (125 ng/g wet wt) and axial muscle (127 ng/g wet wt) than the other species. The highest concentration of PAHs was detected in catfish (Clarias fuscus), with 24.8 ng/g in ventral muscle and 9.1 ng/g in axial muscle. As to marine fish, snubnose pompano (Trachinotus blochii) showed significantly higher levels of DDT and its metabolites (1018 ng/g in ventral and 409 ng/g wet wt in axial tissues) than all other marine fish species. The overall concentrations of PAHs in marine fish species were 15.5-57.0 ng/g (axial muscle) and 18.1-118 ng/g wet wt (ventral muscle) where yellow seafin (Acanthopeyrus latus) and golden threadfin bream (Nemipterus virgatus) exhibited the highest concentrations of PAHs in the axial and ventral muscles, respectively. In general, results showed that levels of PAHs in Hong Kong market fish was low and do not expect to cause any concern for human consumption. However, the levels of DDTs in fish samples ranged from 1.10 to 1018 ng/g wet wt, and based on a fish consumption rate of 142.2g/day to calculate the screening value of 14.4 ng/g wet wt for human consumption (USEPA, 2000. Guidance for assessing chemical contaminant, data for use in fish advisories, vol. 1: fish sampling and analysis, third ed. EPA 823-R-95-007. Office of Water, Washington, DC), there were 9 out of 20 (45%) muscle samples of freshwater fish species and 14 out of 20 (70%) muscle samples of marine fish species had elevated levels of DDTs exceeded the screening value. It was also suggested to use ventral muscle for detecting concentrations of persistent organic pollutants in fish.     

Toxicity of fipronil and its enantiomers to marine and freshwater non-targets

Fipronil is a phenylpyrazole insecticide used in agricultural and domestic settings for controlling various insect pests in crops, lawns, and residential structures. Fipronil is chiral; however, it is released into the environment as a racemic mixture of two enantiomers. In this study, the acute toxicity of the (S,+) and (R,-) enantiomers and the racemic mixture of fipronil were assessed using Simulium vittatum IS-7 (black fly), Xenopus laevis (African clawed frog), Procambarus clarkii (crayfish), Palaemonetes pugio (grass shrimp), Mercenaria mercenaria (hardshell clam), and Dunaliella tertiolecta (phytoplankton). Results showed that S. vittatum IS-7 was the most sensitive freshwater species to the racemic mixture of fipronil (LC50 = 0.65 microg/L) while P. pugio was the most sensitive marine species (LC50 = 0.32 microg/L). Procambarus clarkii were significantly more sensitive to the (S,+) enantiomer while larval P. pugio were significantly more sensitive to the (R,-) enantiomer. Enantioselective toxicity was not observed in the other organisms tested. Increased mortality and minimal recovery was observed in all species tested for recovery from fipronil exposure. These results indicate that the most toxic isomer of fipronil is organism-specific and that enantioselective toxicity may be more common in crustaceans than in other aquatic organisms.     

Nickel bioaccumulation in bivalves from the New Caledonia lagoon: seawater and food exposure

The New Caledonian lagoon is submitted to intense heavy metal input from land-based Ni mining. Therefore, the use of sentinel species is strongly recommended in order to develop and implement coastal zone management programmes of the metal contamination. The tropical oysters Isognomon isognomon and Malleus regula and the clam Gafrarium tumidum were previously proposed as such possible sentinel organisms and were thus investigated in this context. The three species were exposed to Ni via seawater or food using radiotracer techniques. Results indicate that uptake and retention efficiencies of Ni are independent of the dissolved Ni concentrations in the surrounding seawater. Hence, for the three species, body concentrations of Ni taken up from the dissolved phase are directly proportional to the ambient dissolved concentrations. Biokinetic patterns indicated that the major part of Ni was rapidly lost from bivalves during the first days of depuration, whereas 7 to 47% of 63Ni were retained in tissues with a biological half-life not significantly different from infinity. Finally, feeding experiments showed that Ni ingested with food (phytoplankton) was assimilated more efficiently in clams (assimilation efficiency, AE = 61%) than in oysters (AE = 17%), and was strongly retained (T(b1/2) > or = 35 d) in the tissues of both bivalves. It is concluded that the investigated species examined are efficient bioaccumulators of Ni from both the surrounding seawater and the food, and that they would be useful bioindicators for monitoring the status of Ni contamination in tropical coastal waters.     

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.     

Effect of TBT on Ruditapes decussatus juveniles

The effects of sublethal concentrations of tributyltin (TBT) on growth of juvenile clams Ruditapes decussatus were determined during exposure to TBT concentrations of 50, 100 and 250 ng l(-1) (as Sn) for a period up to two years. Length and weight of clams increased continuously in all treatments throughout the experimental period, and, overall, rates were not significantly influenced by TBT exposure, although final length and weight were inversely related to increasing TBT concentration. Juvenile R. decussatus therefore appear to be less sensitive to TBT than larval stages. Some juveniles exposed to TBT developed abnormal shell growth, laterally, changing the typical flattened shape of clams into a more "rounded" form. This characteristic was more visible in the anterior margins of valves than posteriorly, and mainly observed in clams exposed to TBT at 50 ng l(-1) (as Sn).     

Lethal and sublethal effects of the pyrethroid, bifenthrin, on grass shrimp (Palaemonetes pugio) and sheepshead minnow (Cyprinodon variegatus)

This study investigated the lethal and sublethal effects of the pyrethroid insecticide bifenthrin on adult and larval grass shrimp, Palaemonetes pugio, and adult sheepshead minnows, Cyprinodon variegatus. The effects were determined by conducting 96-h aqueous static renewal tests and 24-h static tests with sediment. Oxidative stress biomarkers, lipid peroxidation, glutathione, and catalase were also assessed. The 96-h aqueous LC50 value for adult shrimp was 0.020 microg/L (95% CI: 0.015-0.025 microg/L) and for larval shrimp was 0.013 microg/L (95% CI: 0.011-0.016 microg/L). The 96-h aqueous LC50 for adult sheepshead minnow was 19.806 microg/L (95% CI: 11.886-47.250 microg/L). The 24-h sediment LC50 for adult shrimp was 0.339 microg/L (95% CI: 0.291-0.381 microg/L) and for larval shrimp was 0.210 microg/L (95% CI: 0.096-0.393 microg/L). The oxidative stress assays showed some increasing trends toward physiological stress with increased bifenthrin concentrations but they were largely inconclusive. Given the sensitivity of grass shrimp to this compound in laboratory bioassays, additional work will be needed to determine if these exposure levels are environmentally relevant.     

Persistent chlorinated pesticides and polychlorinated biphenyls in selected fish species from Lake Tanganyika, Burundi, Africa

Concentrations of selected organochlorine pesticides and PCBs in seven fish species (cichlids) from the north end of the Lake Tanganyika, Burundi, Africa were determined. Results were compared to previous work on the Lake Tanganyika and other water bodies and to the European Community maximum residue levels (MRLs) in edible fat. The analytical method included a hot Soxhlet extraction with a mixture of acetone: hexane (1:3, v/v), gravimetrically lipid determination, and a single step clean-up. For PCBs and stable pesticides, the clean-up was done on activated silica gel impregnated with concentrated sulfuric acid, while for non acid-stable pesticides superposed layers of alumina, silica and florisil impregnated with 15% methanolic solution of KOH were successively used. Recoveries of organochlorine pesticides from certified reference material (CRM 430) were ranging from 86% for p,p'-DDT to 107% for endrin, while recoveries from blank fat spiked fortified at three different levels were between 65% for alachlor at the lowest fortification level and 107% for mirex at the highest fortification level. The limits of detection for each analyte were ranging from 0.1 ng/g to 0.5 ng/g fat. All chlorinated pesticides were found in the analyzed species but at low concentrations. Boulengerochromis microlepis contained the highest concentrations of HCHs (288.2 +/- 15.5 ng/g fat) and DDTs (909.1 +/- 42.5 ng/g fat), while the highest PCB levels (166.7 +/- 37.4 ng/g fat for the sum of 12 congeners) were found in Oreochromis niloticus. However, there is no evidence that Lake Tanganyika is more contaminated with pesticides than other African water bodies.     

Influence of fipronil compounds and rice-cultivation land-use intensity on macroinvertebrate communities in streams of southwestern Louisiana, USA

Laboratory tests of fipronil and its degradation products have revealed acute lethal toxicity at very low concentrations (LC50) of <0.5 microg/L to selected aquatic macroinvertebrates. In streams draining basins with intensive rice cultivation in southwestern Louisiana, USA, concentrations of fipronil compounds were an order of magnitude larger than the LC50. The abundance (rho=-0.64; p=0.015) and taxa richness (r2=0.515, p<0.005) of macroinvertebrate communities declined significantly with increases in concentrations of fipronil compounds and rice-cultivation land-use intensity. Macroinvertebrate community tolerance scores increased linearly (r2=0.442, p<0.005) with increases in the percentage of rice cultivation in the basins, indicating increasingly degraded stream conditions. Similarly, macroinvertebrate community-tolerance scores increased rapidly as fipronil concentrations approached about 1 microg/L. Pesticide toxicity index determinations indicated that aquatic macroinvertebrates respond to a gradient of fipronil compounds in water although stream size and habitat cannot be ruled out as contributing influences.