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Dieldrin, an organochlorine pesticide (OCP) widely used for crop protection in the second half of the 20th century till the 70's, is worldwide still present in arable soils. It can be transferred to crops, notably cucurbits, depending on plant species and cultivars. Finding strategies to decrease OCP bioavailability in soil is therefore a main concern. Phytomanagement strategies could provide (i) ready-to-use short term solution for maintaining the production of edible plant parts with dieldrin concentrations below the Maximum Residue Limits (MRL) and (ii) long-term solution for dieldrin phytoextraction reducing progressively its bioavailability in the soil. This field study aimed at determining dieldrin accumulation capacities and allocation pattern in 17 non-Cucurbitaceae species and 10 Cucurbita pepo varieties, and assessing the dieldrin phytoextraction potential of these plant species when grown to maturity in a historically dieldrin-contaminated soil. Out of the non-Cucurbitaceae species, vetiver was the only one able to accumulate significant amounts of dieldrin, which mainly remained in its roots. All C. pepo varieties were able to uptake and translocate high dieldrin amounts into the shoots, leading to the highest phytoextraction potential. Despite the intraspecific variability in dieldrin concentration in zucchini plant parts, mainly in the reproductive organs, the phytoextraction capacity for shoots and fruits was high for all tested varieties (147 to 275 μg dieldrin plant -1 , corresponding to 5.6 % of the n-heptane extractable soil dieldrin), even for the one with low fruit dieldrin concentration. Both food safety and phytoextraction could be achieved by selecting productive zucchini varieties displaying low dieldrin concentration in fruits and high one in shoots., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Pest management requires continual identification of new physiological targets and strategies to control pests affecting agriculture and public/animal health. We propose the muscarinic system as a target for agrochemicals because of its physiological importance. Unlike the muscarinic system, gamma-amino butyric acid (GABA) receptors are an established insecticide target. Here, we investigated target-site synergism using small molecule probes (agonist and antagonist) against the muscarinic system and their ability to enhance the toxicity of GABAergic insecticides in Drosophila melanogaster (Meigen)., Results: Oral delivery of pilocarpine (muscarinic agonist) enhanced the toxicity of dieldrin, fipronil, and lindane, resulting in synergist ratios (SRs) between 4-32-fold (orally delivered) or between 2-67-fold when insecticides were topically applied. The synergism between pilocarpine and the GABA-insecticides was greater than the synergism observed with atropine (muscarinic antagonist), and was greater, or comparable, to the synergism observed with the metabolic inhibitor piperonyl butoxide. In addition to lethality, pilocarpine increased the knockdown of lindane. The mechanism of synergism was also investigated in the central nervous system using extracellular electrophysiology, where pilocarpine (3 μmo/L) lowered the half-maximal inhibitory concentration (IC 50 ) of lindane from 1.3 (0.86-1.98) μmol/L to 0.17 (0.14-0.21) μmol/L and fipronil's IC 50 from 2.2 (1.54-3.29) μmol/L to 0.56 (0.40-0.77) μmol/L., Conclusion: Convergence of the cellular function between the muscarinic and GABAergic systems enhanced the insecticidal activity of GABA receptor blocking insecticides through the modulation of the central nervous system (CNS). The future impact of the findings could be the reduction of the active ingredient needed in a formulation with the development of muscarinic synergists. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

As a prevalent progressive neurodegenerative disorder, Parkinson's disease (PD) is characterized by the neuropathological hallmark of the loss of nigrostriatal dopaminergic (DAergic) innervation and the appearance of Lewy bodies with aggregated α-synuclein. Although several familial forms of PD have been reported to be associated with several gene variants, most cases in nature are sporadic, triggered by a complex interplay of genetic and environmental risk factors. Numerous epidemiological studies during the past two decades have shown positive associations between PD and several environmental factors, including exposure to neurotoxic pesticides/herbicides and heavy metals as well as traumatic brain injury. Other environmental factors that have been implicated as potential risk factors for PD include industrial chemicals, wood pulp mills, farming, well-water consumption, and rural residence. In this review, we summarize the environmental toxicology of PD with the focus on the elaboration of chemical toxicity and the underlying pathogenic mechanisms associated with exposure to several neurotoxic chemicals, specifically 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), rotenone, paraquat (PQ), dichloro-diphenyl-trichloroethane (DDT), dieldrin, manganese (Mn), and vanadium (V). Our overview of the current findings from cellular, animal, and human studies of PD provides information for possible intervention strategies aimed at halting the initiation and exacerbation of environmentally linked PD.

Pesticide biotransformation, especially by cytochrome P450 enzymes (CYPs), may produce metabolites with substantially altered toxicological and physicochemical profiles, which has drawn great attention as a basis for environmental risk assessment. CYPs are active in the metabolism of various reactions of pesticides, and there are potentially different short-lived oxidant species in CYPs (Compound I vs Compound 0), which make elucidating their biotransformation mechanism challenging. To facilitate this task, we performed density functional theory (DFT) calculations to explore the puzzling bifurcation pathways of dieldrin by CYPs. The results show that the two-oxidant mechanism does not work, while the bifurcation pathways are within the mechanistic framework of a two-state reactivity of Compound I. Specifically, 9-hydroxy-dieldrin as a hydroxylation product is formed via H-abstraction and essentially barrierless C-9 alkyl radical rebound in the doublet state; while 3-ketone-dieldrin as a dechlorination product is formed via H-abstraction, C-9 alkyl radical cyclization, and C-3 cyclized radical rebound in the quartet state followed by HCl elimination, originating from a significant barrier for C-9 alkyl radical rebound in the quartet state to provide this radical sufficient lifetime for cyclization. Thus, the ratio [dechlorination]/[hydroxylation] can be estimated as 1:35, consistent with the experimental findings. We envision that application of computational chemistry has a great potential in revealing the complex biotransformation mechanisms of pesticides.

Widespread use of pesticides has resulted in the accumulation of pesticide residues in the environment due to their persistence and stability. To reduce potential exposures, we have developed broad-acting clay-based sorbents that can be included in the diet as enterosorbents to reduce the bioavailability and toxicity of chemicals. In the present study, parent and acid-processed calcium montmorillonite clays (CM and APM, respectively) were used to determine their potential as sorbents of the organochlorine insecticide dieldrin. We used adsorption isotherms, thermodynamics, and dosimetry studies to determine the capacities and affinities of the clays, the enthalpies of the binding reactions, and potential doses of sorbent that could protect against high exposures. Adsorption isotherms for APM fit a Langmuir model with high enthalpy (suggesting chemisorption) and high capacity (Q max value = 0.45 mol kg -1 ), indicating tight binding of dieldrin. Cultures of Hydra vulgaris were used to determine the ability of sorbents to protect a living organism from dieldrin toxicity. The inclusion of acid-processed clays resulted in the highest reduction of dieldrin toxicity (70%) in the hydra. Further work indicated that both CM and APM can significantly reduce the bioavailability of dieldrin from soil (p ≤ 0.01). These results suggest that APM (and similar clays) can be effective sorbents of dieldrin and may be included in the diet and/or soil to protect against environmental exposures. Environ Toxicol Chem 2020;39:517-525. © 2019 SETAC., (© 2019 SETAC.)

Cluster Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) is a gene editing technique widely used in studies of gene function. We use this method in this study to check for the specificity of antibodies developed against the insect GABAA receptor subunit Resistance to Dieldrin (RDL) and a metabotropic glutamate receptor mGlutR1 (mGluRA). The antibodies were generated in rabbits against the conjugated peptides specific to fruit flies (Drosophila melanogaster) as well to honeybees (Apis mellifera). We used these antibodies in honeybee brain sections to study the distribution of the receptors in honeybee brains. The antibodies were affinity purified against the peptide and tested with immunoblotting and the classical method of preadsorption with peptide conjugates to show that the antibodies are specific to the corresponding peptide conjugates against which they were raised. Here we developed the CRISPR-Cas9 technique to test for the reduction of protein targets in the brain 48 h after CRISPR-Cas9 injection with guide RNAs designed for the corresponding receptor. The CRISPR-Cas9 method can also be used in behavioral analyses in the adult bees when one or multiple genes need to be modified.

The inhibition of cholinesterase (ChE) activity has been used as a biomarker of exposure to organophosphate and carbamate insecticides. ChE of nesting female green turtles (Chelonia mydas) were biochemically characterized using two substrates, acetylthiocholine iodide and butyrylthiocholine iodide, and three ChE inhibitors (eserine sulfate, BW284C51 and iso-OMPA). The results indicated that BChE is the predominant plasma ChE in female C. mydas, but with atypical properties that differ from those found in human BChE. Eggs from green turtles nesting at two sites in Laguna de Terminos contained µg g -1 (wet weight) quantities of organochlorine (OC) pesticides. Drins (aldrin, dieldrin, endrin, endrin ketone, endrin aldehyde) were found at the highest concentrations with no significant differences in the concentrations in eggs collected at the two sampling sites. A negative relationship was found between levels of OC pesticides in eggs and BChE activity in the plasma of female turtles laying the eggs. Since OC pesticides are not cholinesterase inhibitors, we hypothesized that this inverse relationship may be related to an antagonistic effect between OCs and organophosphate pesticides and mobilization of OCs from the fatty tissues of the female turtles into their eggs. However, further study is required to verify the hypothesis. It is also possible that other contaminants, such as petroleum hydrocarbons are responsible for the modulation of cholinesterase activity in female turtles.

One hundred samples of mother breast milk were gathered from six middle governorates and districts in Jordan in 2013/2014 to monitor Organochlorine pesticides pollutants. The results showed clearly that banned organochlorine pesticides are still detected in the monitored samples in low concentration despite banning of these persistent pollutants in Jordan since 36 years ago. However, the results indicated that 1% of the contaminated samples contained β-HCH, 5% γ-HCH, 3% p,p'-DDD, 2% heptachlor, 45% p,p'-DDE and 3% p,p'-DDT. In addition, these monitored samples had no residues of aldrin, dieldrin, α-endosulfan, β-endosulfan, HCB, o,p'-DD, o,p'-DDT and o,p'-DDE. In conclusion, there was a decline in the residues of Organochlorine pesticides, particularly DDT group members.

Aldrin and its metabolite dieldrin are persistent organic pollutants that contaminate soil in many parts of the world. Given the potential hazards associated with these pollutants, an efficient degradation method is required. In this study, we investigated the ability of Pleurotus ostreatus to transform aldrin as well as dieldrin in pure liquid cultures. This fungus completely eliminated aldrin in potato dextrose broth (PDB) medium during a 14-day incubation period. Dieldrin was detected as the main metabolite, and 9-hydroxylaldrin and 9-hydroxyldieldrin were less abundant metabolites. The proposed route of aldrin biotransformation is initial metabolism by epoxidation, followed by hydroxylation. The fungus was also capable of degrading dieldrin, a recalcitrant metabolite of aldrin. Approximately 3, 9, and 18% of dieldrin were eliminated by P. ostreatus in low-nitrogen, high-nitrogen, and PDB media, respectively, during a 14-day incubation period. 9-Dihydroxydieldrin was detected as a metabolite in the PDB culture, suggesting that the hydroxylation reaction occurred in the epoxide ring. These results indicate that P. ostreatus has potential applications in the transformation of aldrin as well as dieldrin.

In this study, 24 breast milk samples, obtained from rural Maya women, from municipalities of Yucatan, Mexico, were analyzed for organochlorine pesticide (OCP) residues by gas chromatography. Recent studies have shown that Maya communities have a poor perception about the proper usage and handling of OCP. The karstic soil in this area has a high vulnerability to groundwater pollution by the use of OCP in agriculture and livestock activities. The impact of the ecosystem on human health is much more critical due to the prevailing poverty and a very low educational level of these communities. About 30% of the Maya population consumes water directly from contaminated wells and sinkholes, resulting in a chronic exposure to OCP. The samples served to identify and quantify high levels of OCP residues (18.43 mg/kg of heptachlor epoxide and 1.92 mg/kg of endrin in the metropolitan zone; 2.10 mg/kg of dieldrin, 0.117 mg/kg of endosulfan II, 0.103 mg/kg of heptachlor, 0.178 mg/kg of endrin, and 0.127 mg/kg of endrin aldehyde in the main agricultural zone and on the west coast). The detected levels of OCP residues are a major concern and represent a potential risk to women and children in the region. This could be associated with the high rates of cervical uterine and breast cancer mortality in Yucatan. Thus, regulations on the usage of OCP and their enforcement are necessary, and it is important to establish a yearly monitoring program for OCP residues in breast milk and groundwater, as well as to implement health promotion programs for women in particular and the general population in general.

Tissue concentrations of persistent organochlorine pesticides in laboratory-exposed largemouth bass (Micropterus salmoides) and in bass collected from Lake Apopka, FL were determined by both total mass and lipid normalized mass to better understand the bioaccumulation pathways of contaminants. In the laboratory study, male bass were orally administered a single dose of a mixture of two pesticides (p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and dieldrin) and then fed uncontaminated food for 28 days. Gastrointestinal tract, liver, brain, gonad, kidney, spleen, and muscle were collected for chemical analysis. Different profiles were observed by total contaminant mass in tissues compared to lipid normalized mass. On a lipid normalized basis, p,p'-DDE was highest in the gastrointestinal tract followed by the liver, gonad, spleen, muscle, kidney and then brain. Dieldrin, on the other hand, was highest in the gastrointestinal tract and spleen and then followed by the gonad, muscle, liver, kidney, and brain. Distribution of the chemicals among the organs differed by their log KOW values and generally followed the blood flow path after the gastrointestinal tract. The low contaminant levels found in kidney and brain suggest insufficient time for equilibration into these tissues, especially into the brain where the blood-brain barrier may be slow to traverse. In Lake Apopka fish, dichlorodiphenyltrichloroethanes (DDXs, sum of p,p'-DDE, p,p'-DDD, and p,p'-DDT), Drins (sum of aldrin, dieldrin, and endrin), and hexachlorocyclohexanes (HCHs) were found. For DDXs, the lipid normalized concentrations in each tissue were about the same, as predicted from theory. For Drins and HCHs, the lipid normalized concentrations were similar for kidney, spleen, brain, gonad and muscle, but much lower in the gastrointestinal tract and liver, probably because of metabolism occurring in those tissues., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

To compare the uptake and translocation of hydrophobic organic chemicals by plant species, the authors performed uptake experiments with β-1,2,3,4,5,6-hexachlorocyclohexane (β-HCH) and 1,2,3,4,10,10-Hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-endo-1,4-exo-5,8-dimethanonaphthalene (dieldrin) using 5 species: Hordeum vulgare, Glycine max, Solanum lycopersicum, Brassica oleracea, and Cucurbita pepo. The present study evaluated uptake ability using root concentration factor (RCF) and translocation ability by transpiration stream concentration factor (TSCF). The RCFs of β-HCH and dieldrin did not differ remarkably among species, except that the RCF of β-HCH in B. oleracea was high. The TSCFs of β-HCH and dieldrin were high in C. pepo, which was not superior in uptake as estimated by RCF. The TSCF of dieldrin in C. pepo was decreased in darkness and was markedly decreased by heating of roots. These results support the hypothesis that transport proteins produced in the root contribute to dieldrin translocation. In contrast, TSCF of β-HCH was not decreased by these treatments. Therefore, translocation of β-HCH might not need the contribution of transport proteins. It is possible that C. pepo has a certain function to transport hydrophobic organic chemicals smoothly in root tissues., (© 2014 SETAC.)

Improved approaches are needed to assess bioavailability of hydrophobic organic compounds in contaminated soils. Performance of thin-film solid-phase extraction (TF-SPE) using vials coated with ethylene vinyl acetate was compared to earthworm bioassay (Lumbricus terrestris). A DDT and dieldrin contaminated soil was amended with four organic carbon materials to assess the change in bioavailability. Addition of organic carbon significantly lowered bioavailability for all compounds except for 4,4'-DDT. Equilibrium concentrations of compounds in the polymer were correlated with uptake by earthworms after 48d exposure (R(2) = 0.97; p < 0.001), indicating TF-SPE provided an accurate uptake simulation. Bioavailability of residues in soil was compared with a spiked soil aged for 90d in laboratory. Dieldrin and DDX were respectively 18% and 11% less bioavailable in contaminated soil relative to spiked soil despite >40yr of aging. Results show that TF-SPE can be useful in examining potential risks associated with contaminated soils and to test effectiveness of remediation efforts., (Published by Elsevier Ltd.)

The sterile insect technique (SIT) is a biological control tactic that is used as a component of area-wide integrated pest management (AW-IPM) programs. The SIT can only be applied against disease-transmitting mosquitoes when only sterile male mosquitoes are released, and the blood-sucking and potentially disease-transmitting females are eliminated from the production line. For Anopheles arabiensis, a potent vector of malaria, a genetic sexing strain was developed whereby females can be eliminated by treating the eggs or larvae with the insecticide dieldrin. To evaluate the presence of dieldrin residues in male mosquitoes designated for SIT releases, a simple, sensitive, and accurate gas chromatography-electron capture detector (GC-ECD) method was developed. In addition, bioaccumulation and food chain transfer of these residues to fish after feeding with treated mosquitoes was demonstrated. The overall recovery from method validation studies was 77.3 ± 2.2% (mean ± relative standard deviation [RSD]) for the mosquitoes, and 99.1 ± 4.4% (mean ± RSD) for the fish. The average dieldrin concentration found in adult male An. arabiensis was 28.1 ± 2.9 µg/kg (mean ± standard deviation [SD]). A range of 23.9 ± 1.1 µg/kg to 73.9 ± 5.2 µg/kg (mean ± SD) of dieldrin was found in the fish samples. These findings indicate the need to reassess the environmental and health implications of control operations with a SIT component against An. arabiensis that involves using persistent organochlorines in the sexing process., (© 2013 SETAC.)

The incidence of Parkinson's disease (PD) correlates with environmental exposure to pesticides, such as the organochlorine insecticide, dieldrin. Previous studies found an increased concentration of the pesticide in the striatal region of the brains of PD patients and also that dieldrin adversely affects cellular processes associated with PD. These processes include mitochondrial function and reactive oxygen species production. However, the mechanism and specific cellular targets responsible for dieldrin-mediated cellular dysfunction and the structural components of dieldrin contributing to its toxicity (toxicophore) have not been fully defined. In order to identify the toxicophore of dieldrin, a structure-activity approach was used, with the toxicity profiles of numerous analogues of dieldrin (including aldrin, endrin, and cis-aldrin diol) assessed in PC6-3 cells. The MTT and lactate dehydrogenase (LDH) assays were used to monitor cell viability and membrane permeability after treatment with each compound. Cellular assays monitoring ROS production and extracellular dopamine metabolite levels were also used. Structure and stereochemistry for dieldrin were found to be very important for toxicity and other end points measured. Small changes in structure for dieldrin (e.g., comparison to the stereoisomer endrin) yielded significant differences in toxicity. Interestingly, the cis-diol metabolite of dieldrin was found to be significantly more toxic than the parent compound. Disruption of dopamine catabolism yielded elevated levels of the neurotoxin, 3,4-dihydroxyphenylacetaldehyde, for many organochlorines. Comparisons of the toxicity profiles for each dieldrin analogue indicated a structure-specific effect important for elucidating the mechanisms of dieldrin neurotoxicity.

Exposure to organochlorinated pesticides such as dieldrin has been linked to Parkinson's and Alzheimer's diseases, endocrine disruption, and cancer, but the cellular and molecular mechanisms of toxicity behind these effects remain largely unknown. Here we demonstrate, using a functional genomics approach in the model eukaryote Saccharomyces cerevisiae, that dieldrin alters leucine availability. This model is supported by multiple lines of congruent evidence: (1) mutants defective in amino acid signaling or transport are sensitive to dieldrin, which is reversed by the addition of exogenous leucine; (2) dieldrin sensitivity of wild-type or mutant strains is dependent upon leucine concentration in the media; (3) overexpression of proteins that increase intracellular leucine confer resistance to dieldrin; (4) leucine uptake is inhibited in the presence of dieldrin; and (5) dieldrin induces the amino acid starvation response. Additionally, we demonstrate that appropriate negative regulation of the Ras/protein kinase A pathway, along with an intact pyruvate dehydrogenase complex, is required for dieldrin tolerance. Many yeast genes described in this study have human orthologs that may modulate dieldrin toxicity in humans.

The green mussel, Perna viridis, was used to measure bioaccumulated levels of organochlorine pesticides in the marine environment of Cuba. Samples were collected in the Cienfuegos Bay between January and December 2010. The organochlorine pesticides (i.e. DDT, Dieldrin, Chlordane, Endosulfan, HCB, Aldrin, Heptachlor and Lindane) were quantified by gas chromatography. The sum of all organochlorine pesticides in P. viridis was 6.31 ng g(-1). The concentration ranged from 3.53 to 4.42 ng g(-1) dry weight (dw) for DDTs (i.e. sum of pp' DDT, pp' DDD, op' DDE and pp' DDE); 1.7-1.9 ng g(-1) dw for Dieldrin; 0.17-0.20 ng g(-1) dw for Chlordanes; 0.14-0.16 ng g(-1) dw for Endosulfan; 0.11-0.17 ng g(-1) dw for HCB; 0.07-0.11 ng g(-1) dw for Aldrin; 0.046-0.054 ng g(-1) dw for Heptachlor and 0.035-0.039 ng g(-1) dw for Lindane. These levels can be considered as low when compared to reported values from similar studies conducted elsewhere in the world. The concentrations of all organochlorines residues detected in this study fell below the EU Maximum Residue Limits.

White rot fungi can degrade a wide spectrum of recalcitrant organic pollutants, including polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated biphenyls (PCBs). In this experiment, 20 white rot fungi, belonging to genus Phlebia, were investigated for their ability to degrade dieldrin. Based on the screening results, we further investigated Phlebia acanthocystis, Phlebia brevispora, and Phlebia aurea to determine their degradation capacity and metabolic products towards dieldrin and aldrin. The three fungi were able to remove over 50% of dieldrin in a low nitrogen medium, after 42 d of incubation. Three hydroxylated products were detected as metabolites of dieldrin, suggesting that in Phlebia strains, hydroxylation reactions might play an important role in the metabolism of dieldrin. In contrast to dieldrin, aldrin exhibited higher levels of degradation activity. Over 90% of aldrin was removed after 28 d of incubation, and several new metabolites of aldrin in microorganisms, including 9-hydroxyaldrin and two carboxylic acid products, were detected in fungal cultures. These results indicate that the methylene moiety of aldrin and dieldrin molecules might be prone to enzymatic attack by white rot fungi. In this study, we describe for the first time a new metabolic pathway of both compounds by fungi of genus Phlebia., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

We isolated a novel aerobic dieldrin-degrading bacterium from an enrichment culture in a soil-charcoal perfusion system. Enrichment culture using a soil-charcoal perfusion system was an effective way to obtain microorganisms that degrade recalcitrant compounds. The soil-charcoal perfusion was performed using aldrin trans-diol, which was a metabolite of dieldrin. Aldrin trans-diol had higher bioavailability (2.5 mg/l) than dieldrin (0.1-0.25 mg/l), therefore it is possible for microorganisms to utilize it as a substrate in soil. After 100 days of circulation and three exchanges of the medium, the enriched charcoal was harvested and a bacterium isolated. The isolate was designated as strain KSF27 and was found to be closely related to Pseudonocardia spp. as determined by 16S rRNA sequencing analysis. Strain KSF27 degraded aldrin trans-diol by 0.05 μmol/l from an initial concentration of 25.5 μmol/l. The metabolite of aldrin trans-diol was detected by HPLC/MS and determined to be aldrindicarboxylic acid based on retention time and the MS fragment. Moreover, strain KSF27 degraded dieldrin from 14.06 μmol/l to 2.01 μmol/l over a 10-day incubation at 30°C. This strain degraded dieldrin and other persistent organochlorine pesticides, such as α-endosulfan, β-endosulfan, endosulfan sulfate, heptachlor, heptachlor epoxide and chlordecone., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Persistent organic pollutants (POPs) including legacy POPs (PCBs, chlordanes, mirex, DDTs, HCB, and dieldrin) and polybrominated diphenyl ether (PBDE) flame retardants were determined in 300 blubber biopsy samples from coastal and near shore/estuarine male bottlenose dolphins (Tursiops truncatus) sampled along the U.S. East and Gulf of Mexico coasts and Bermuda. Samples were from 14 locations including urban and rural estuaries and near a Superfund site (Brunswick, Georgia) contaminated with the PCB formulation Aroclor 1268. All classes of legacy POPs in estuarine stocks varied significantly (p < 0.05) among sampling locations. POP profiles in blubber varied by location with the most characteristic profile observed in bottlenose dolphins sampled near the Brunswick and Sapelo estuaries along the Georgia coast which differed significantly (p < 0.001) from other sites. Here and in Sapelo, PCB congeners from Aroclor 1268 dominated indicating widespread food web contamination by this PCB mixture. PCB 153, which is associated with non-Aroclor 1268 PCB formulations, correlated significantly to human population indicating contamination from a general urban PCB source. Factors influencing regional differences of other POPs were less clear and warrant further study. This work puts into geographical context POP contamination in dolphins to help prioritize efforts examining health effects from POP exposure in bottlenose dolphins.

The contamination status of the marine environment in Hong Kong was studied by measuring concentrations of organochlorine (OC) pollutants (i.e., hexachlorobenzene, aldrin, dieldrin, endrin, mirex, total heptachlor, total chlordane, total DDTs, total PCBs, and total toxaphenes) in the eggs of selected waterbird species from different locations around the city: Little Egret (Egretta garzetta) and Chinese Pond Heron (Ardeola bacchus) from Mai Po Village, Great Egret (Ardea alba) and Black-crowned Night Heron (Nycticorax nycticorax) from A Chau, and Chinese Pond Heron (A. bacchus) from Ho Sheung Heung. The mean concentrations of total PCBs and total DDTs ranged from 191-11,100 ng g(-1) lipid and 453-49,000 ng g(-1) lipid, respectively. Recent exposure of waterbirds to technical chlordane was found in Hong Kong. The risk characterization demonstrated potential risks to birds associated with exposure to DDE, which was found to cause a reduction in survival of young in Hong Kong Ardeids based on the endpoint in the risk assessment., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

As a model of high trophic level carnivores, sledge dogs were fed from 2 to 18 months of age with minke whale blubber containing organohalogen compounds (OHC) corresponding to 128 μg PCB/day. Controls were fed uncontaminated porcine fat. Thyroid hormone levels were assessed in 7 exposed and 7 control sister bitches (sampled at age 6-18 months) and 4 exposed and 4 control pups, fed the same diet as their mothers (sampled age 3-12 months). Lower free and total T3 and T4 were seen in exposed vs. control bitches beyond 10 months of age, and total T3 was lower through 3-12 months of age in exposed pups. A negative correlation with thyroid gland weight was significant for ΣDDT, as was a positive association with total T3 for dieldrin. This study therefore supports observational data that OHCs may adversely affect thyroid functions, and it suggests that OHC exposure duration of 10 months or more may be required for current OHC contamination levels to result in detectable adverse effects on thyroid hormone dynamics., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The uptake ability of hydrophobic organic chemicals by plants and the nature of xylem sap of the plants were studied. The plants were grown in soil contaminated with dieldrin. High amounts of dieldrin were detected in the shoots of Cucurbita pepo and Cucumis sativus, but little was seen in the shoots of Brassica oleracea var. italica, Solanum lycopersicum, Glycine max, Zea mays, and Helianthus annuus. The xylem saps of C. pepo and C. sativus leached dieldrin adsorbed on C8 granules, but those of the other plants did not. The xylem saps of C. pepo and C. sativus eluted high amounts of dieldrin from the size-exclusion chromatography column near the fractions of RNase A (13.7 kDa) after Aprotinin (6.5 kDa), which has a larger molecular weight than dieldrin (381). The enhancement of dieldrin solubility by xylem sap was reduced by proteinase and heating. It was suspected that the protein-like materials in the xylem sap delivered dieldrin from the roots to the shoots., (Environ. Toxicol. Chem. 2010;29:2269-2277. © 2010 SETAC.)

An aerobic dieldrin-degrading fungus, Mucor racemosus strain DDF, was isolated from a soil to which endosulfan had been annually applied for more than 10 years until 2008. Strain DDF degraded dieldrin to 1.01 microM from 14.3 microM during a 10-day incubation at 25 degrees C. Approximately 0.15 microM (9%) of aldrin trans-diol was generated from the dieldrin degradation after a 1-day incubation. The degradation of dieldrin by strain DDF was detected over a broad range of pH and concentrations of glucose and nitrogen sources. Extracellular fluid without mycelia also degraded dieldrin. Strain DDF degraded not only dieldrin but also heptachlor, heptachlor epoxide, endosulfan, endosulfan sulfate, DDT, and DDE. Endosulfan sulfate and heptachlor were degraded by 0.64 microM (95%) and 0.75 microM (94%), respectively, whereas endosulfan and DDE were degraded by 2.42 microM (80%) and 3.29 microM (79%), respectively, and DDT and heptachlor epoxide were degraded by 6.95 microM (49.3%) and 5.36 microM (67.5%), respectively, compared with the control, which had a concentration of approximately 14 microM. These results suggest that strain DDF could be a candidate for the bioremediation of sites contaminated with various persistent organochlorine pesticides including POPs.

Background: Dieldrin is one of the most persistent organochlorine pesticides, listed as one of the 12 persistent organic pollutants in the Stockholm Convention. Although microbial degradation is an effective way to remediate environmental pollutants, reports on aerobic microbial degradation of dieldrin are limited. Wood-rotting fungi can degrade a wide spectrum of recalcitrant organopollutants, and an attempt has been made to select wood-rotting fungi that can degrade dieldrin, and to identify the metabolite., Results: Thirty-four isolates of wood-rotting fungi were investigated for their ability to degrade dieldrin. Strain YK543 degraded 39.1 +/- 8.8% of dieldrin during 30 days of incubation. Phylogenetic analysis demonstrated that strain YK543 was closely related to the fungus Phlebia brevispora Nakasone TMIC33929, which has been reported as a fungus that can degrade chlorinated dioxins and polychlorinated biphenyls. 9-Hydroxydieldrin was detected as a metabolite in the cultures of strain YK543., Conclusion: It is important to select the microorganisms that degrade organic pollutants, and to identify the metabolic pathway for the development of bioremediation methods. Strain YK543 was selected as a fungus capable of degrading dieldrin. The metabolic pathway includes 9-hydroxylation reported in rat's metabolism catalysed by liver microsomal monooxygenase. This is the first report of transformation of dieldrin to 9-hydroxydieldrin by a microorganism., (Copyright (c) 2010 Society of Chemical Industry.)

Thirty-four years of data from the Great Lakes Fish Monitoring Program (GLFMP) show significant changes in the behavior of most contaminants in lake trout over time consistent with changes in contaminant inputs following regulation and remediation. Polybrominated diphenyl ethers (PBDEs) show positive apparent first-order rate constants falling to near zero. Dieldrin shows relatively unchanging half-lives of around 10 years except in Lake Superior (approximately 25 years). Mirex, consistently detected only in Lake Ontario fish, shows a slow decrease until the 1990s, when remediation of a source site occurred, after which half-lives are 2-3 years. Half-lives of oxychlordane, polychlorinated biphenyls (PCBs), and dichloro-diphenyl-trichlorethane (DDT) and its metabolites were typically 3-6 years until the mid 1980s; since then, the newest data confirm half-lives are usually around 15-30 years. For PCBs, an increasing half-life is found in other media as well. Changes in food web structure, fishery dynamics, and climate undoubtedly affect concentrations but cannot explain observed long-term trends across several media. Concentrations of legacy contaminants in the Great Lakes are likely to continue to decline only slowly and pose a health concern for decades without identifying and containing remaining sources.

Selected POPs were analyzed in blubber samples of Pontoporia blainvillei from Southern Brazil to appraise temporal trend over a 10 year period (1994-2004). Overall, levels of POPs were relatively low, especially when compared to Northern Hemisphere concentrations. Apart from Mirex and PCBs, which showed stable concentrations, DDTs, HCB, CHLs, Dieldrin levels presented a slight decrease over the studied period. In addition, the increase in the PCBs/DDTs ratio supports the idea that inputs of DDTs are decaying faster than PCBs., (Copyright 2009 Elsevier Ltd. All rights reserved.)

The aim of this trial was to evaluate the feasibility of using tall fescue (Festuca arundinacea) and alfalfa (Medicago sativa) for phytoremediation of dieldrin. Experimental trial was carried out in greenhouse with temperature and light control. Each tested crop were seeded in individual pots (10 plants/pot) filled with contaminated soil (47 microg/kg dieldrin) and uncontaminated soil collected in sites located in the province of Latina (Italy). Samples of soil, root, and aerial part of plants were analysed at 3 and 6 months after seeding. The analytical determinations in soil and plant samples were carried out by GLC-ECD and confirmed by GLC-MS. After 6 months in the greenhouse, recoveries of dieldrin from soil planted with tall fescue and alfalfa were significantly lower than recoveries in unplanted control soil. Dieldrin residue values in root did not differ between the two different sampling times for each forage crop tested, but they were always higher in fescue than in alfalfa. Residue levels in aerial part were low (< 10 microg/kg) in the two forage crops. Preliminary results seem to confirm the ability of tested plants to enhance dissipation of dieldrin in soil at low level of contamination.

To prevent the distribution of cucumbers with dieldrin contamination exceeding the limit set by the Japanese Food Sanitation Law, the extraction solvent for dieldrin-contaminated soil was selected prior to cultivation so that the dieldrin residue level in cucumber could be predicted. The exhaustive extraction from soil could not explain the dieldrin uptake by cucumber plants. However, significant correlation (R(2) = 0.966, P < 0.001) was observed between dieldrin concentrations in cucumber and dieldrin concentrations extracted with 50% (v/v) methanol-water solution from soils. This was a result of the phytoavailability of dieldrin to the cucumber plants. The extractability of soil dieldrin with the methanol-water solution decreased as the organic carbon content in the soils increased. This suggested that a 50% (v/v) methanol-water solution is the optimal solution for predicting dieldrin concentrations in cucumbers by soil analysis.

The concentrations of endocrine disruptors were determined in 36 liver tissue, serum and whole blood sample extracts drawn from 15 Blue Lagoon National Park Kafue lechwe. Out of 10 analytes evaluated, 89% of the sample extracts showed very high dieldrin concentrations of between 0.08–100 μg/mL in serum, 0.08–24.8 μg/mL in whole blood and 0.08–4.6 μg/g wet weight in liver tissue extracts. pp-DDE was detected in 83% of the sample extracts at 0.006–5.1 μg/mL in serum, 0.006–8.5 μg/mL in whole blood and 0.006–0.12 μg/g wet weight in liver tissue extracts. There was strong correlation between pp-DDE and dieldrin in all the three matrices. Deltamethrin and endosulfan detected at 50% frequency each. Percent recoveries in spiked laboratory blanks ranged between 60–100% while calculated detection limits ranged from 0.004 to 0.21 μg/mL for all the endocrine disruptors evaluated.

Dieldrin and endrin are persistent organic pollutants that cause serious environmental problems. Although these compounds have been prohibited over the past decades in most countries around the world, they are still routinely found in the environment, especially in the soil in agricultural fields. Bioremediation, including phytoremediation and rhizoremediation, is expected to be a useful cleanup method for this soil contamination. This review provides an overview of the environmental contamination by dieldrin and endrin, along with a summary of our current understanding and recent advances in bioremediation and phytoremediation of these pollutants. In particular, this review focuses on the types and abilities of plants and microorganisms available for accumulating and degrading dieldrin and endrin.

Activated charcoal (AC) amendments have been suggested as a promising, cost-effective method to immobilize organic contaminants in soil. We performed pot experiments over two years with cucumber (Cucumis sativus L.) grown in agricultural soil with 0.07 mg kg(-1) of weathered dieldrin and 0, 200, 400, and 800 mg AC per kg soil. Dieldrin fresh weight concentrations in cucumber fruits were significantly reduced from 0.012 to an average of 0.004 mg kg(-1), and total uptake from 2 to 1 microg in the 800 mg kg(-1) AC treatment compared to the untreated soil. The treatment effects differed considerably between the two years, due to different meteorological conditions. AC soil treatments did neither affect the availability of nutrients to the cucumber plants nor their yield (total fruit wet weight per pot). Thus, some important prerequisites for the successful application of AC amendments to immobilize organic pollutants in agricultural soils can be considered fulfilled.

During a decade (1996-2006), ecotoxicological studies were carried out in biota of the Vaccarès Lagoon (Biosphere Reserve in Rhone Delta, France). A multicontamination was shown at all levels of the trophic web due to a direct bioconcentration of chemical from the medium combined with a food transfer. Here, the pollutants investigated were organochlorines, among which many compounds banned or in the course of prohibition (or restriction) (PCB, lindane, pp'-DDE, dieldrin, aldrin, heptachlor, endosulfan...) and some substances likely still used in the Rhone River basin (diuron, fipronil). The results confirmed the ubiquity of contamination. It proves to be chronic, variable and tends to regress; however contamination levels depend on the trophic compartment. A biomagnification process was showed. A comparison of investigation methods used in other Mediterranean wetlands provides basis of discussion, and demonstrates the urgent need of modelling to assess the ecotoxicological risk in order to improve the management of such protected areas.

The aim of these trials was to study the distribution of dieldrin in soil and its translocation to roots and the aerial parts of vegetable crops grown in greenhouses and fields. The main objectives were to characterize dieldrin accumulation in plant tissues in relation to the levels of soil contamination; uptake capability among plants belonging to different species, varieties and cultivars. The presence of the contaminant was quantified by gas chromatography-electron capture detector (GC-ECD) and confirmed by gas chromatography-mass spectrometer (GC-MS). The results showed a translocation of residues in cucurbitaceous fruits and flowers confirming that zucchini, cucumber and melon are crops with high uptake capability. The maximum level of dieldrin residue at 0.01 mg/kg was found to be a threshold value to safeguard the quality production of cucurbits. Tomato, lettuce and celery were identified as substitute crops to grow in contaminated fields.

Consecutive and single Tenax extractions were applied to characterize the effectiveness of activated charcoal (AC) amendments to reduce the phytoavailability of dieldrin in a natively contaminated horticultural soil. Dieldrin desorption from untreated and 800 mg(AC) kg(-1) soil was well described by a model with three dieldrin fractions of different kinetics: a rapidly (F(rap)), slowly (F(slow)), and very slowly (F(v.slow)) desorbing fraction. The AC amendment resulted in a transfer of dieldrin from the F(slow) to the F(v.slow) fraction. The F(v.slow) increased by nearly 10% compared to the control soil. Dieldrin extractability by Tenax from AC amended soils was not influenced by the cultivation of cucumber plants indicating the stability of this remediation technique. Dieldrin extractability by Tenax at the beginning of plant growth correlated only weakly with the dieldrin content of the cucumbers at harvest. Therefore, the potential of Tenax extractions to predict the uptake of dieldrin by cucumbers appears to be limited.

This report describes the selective isolation of dieldrin- and endrin-degrading bacteria from soil with high degradation activity toward dieldrin and endrin. Several enrichment cultures from the soil were arranged with several structural analogs of dieldrin and endrin as a growth substrate and examined for their degradation activities toward dieldrin and endrin. An enrichment culture with 1,2-epoxycyclohexane (ECH) was found to aerobically degrade dieldrin and endrin. Denaturing gradient gel electrophoresis (DGGE) indicated that three types of bacteria were predominant in the ECH enrichment culture. Of the three major bacteria, two isolates, Burkholderia sp. strain MED-7 and Cupriavidus sp. strain MED-5, showed high degradation activity toward dieldrin and endrin. The degradation efficiencies of strain MED-7 and MED-5 were 49% and 38% toward dieldrin, respectively, and 51% and 40% toward endrin, respectively, in the presence of ECH for 14 days. These results indicated that ECH was a useful substrate for selective and efficient isolation of dieldrin- and endrin-degrading bacteria from soil containing numerous bacteria. Interestingly, the two isolates could also degrade dieldrin and endrin even in the absence of ECH. These are the first microorganisms demonstrated to grow on dieldrin and endrin as the sole carbon and energy source under aerobic conditions.

Sacramento splittail (Pogonichthys macrolepidotus) is a species of special concern in California, due to multiple anthropogenic stressors. To better understand the potential impact of contaminant exposure, adult splittail were captured from the Sacramento-San Joaquin River Delta (California, USA) and analyzed for histopathology and contaminant exposure. Organochlorine contaminants (PCBs, DDTs, dieldrin, chlordanes, and PBDEs) and trace metals (Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn, V, and Zn) were detected in the tissues of all fish. In many samples, human health screening values were exceeded for PCBs (83 of 90 samples), DDTs (32 samples), and dieldrin (37 samples). In contrast, thresholds for fish effects were rarely exceeded. Histopathological analysis indicated the presence of macrophage aggregates in gonads, kidneys, and liver and a high incidence of liver abnormalities. In the liver, observed effects were often moderate to severe for glycogen depletion (55 of 95 fish), lipidosis (hepatocellular vacuolation; 51 fish), and cytoplasmic inclusion bodies (33 fish). Correlations between histopathology and tissue contaminant concentrations were weak and inconsistent. Significant correlations were observed between histopathology indicators and reductions in fish size, body condition, lipid content, and liver weight. These results suggest that splittail histopathology varies as a function of health and nutritional status, rather than exposure to legacy organic and metal pollutants.

A greenhouse study was conducted to evaluate the effect of biofumigation (with sheep and chicken manure) combined with solarization on the dissipation of pesticides (pyrifenox, DDT and dieldrin), and on soil metals accumulation. The treatments consisted of a control, and soil disinfestations by biofumigation combined with solarization (B+S) for two, four, five, six consecutive years. B+S enhanced the dissipation of pyrifenox with regard to control treatment. Significant differences were not detected among plots disinfected with B+S for consecutive years. On the other hand, B+S had no effect on the dissipation of DDT and dieldrin, probably due to the resistance of these pesticides to microbial degradation and/or high temperatures. Biofumigation is considered to be an environmentally safe practice, since no accumulation of heavy metals such as Cd, Co, Cu, Cr, Pb, Ni, or Zn was observed after the subsequent application of organic matter through the treatments.

Aim of this trial was to verify the occurrence and the distribution of organochlorine pesticides (OCPs) in zucchini cultivated varieties grown in glasshouses and in open field with different levels of pollutants in soil. Residues of OCPs have been detected in soils and crops in the province of Latina, an intensively agricultural area of Lazio Region, in Italy. The study has been focused at crop harvest in less contaminated glasshouses and during crop life cycle in contaminated field in spring-summer time. Dieldrin distribution in different part of plant is similar among zucchini cultivars grown in contaminated field. In crop grown in field and in glasshouses with soil pollution >0.01 mg/kg, we found dieldrin in all zucchini fruits and flowers, at the same level or higher than the maximum residue limit (RML) fixed by European law for edible vegetables (0.02 mg/kg). Instead in soil with pollution < or = 0.01 mg/kg total OCPs it would be possible to grow zucchini cultivars.

An Avian BioAccumulation Model (ABAM) of persistent organic pollutant (POP) uptake and elimination in adult life-stage of birds was validated by simulation of concentrations of DDE, dieldrin, mirex, and HCB in herring gull eggs in Lake Ontario for the years 1985, 1990, and 1992. These chemicals represented a range of whole-body half-lives of 82-265 days in the gull. Dietary intake of POPs by a female gull was simulated by a dynamic bioenergetics model which included dependence on temperature, photoperiod, egg production, and feeding chicks. Concentrations in the two main prey fish of the gull in Lake Ontario were used for POP exposure. Clearance from the female was based on a two compartment toxicokinetic model. Egg concentrations were estimated from egg/whole body female concentration ratios. Simulated concentrations were compared to measured concentrations in gull eggs from 4 different colonies in the northern part of Lake Ontario. Simulations using a diet of 81% fish and 19% uncontaminated food resulted in the best fit with least variance among predicted and measured data. The mean ratio of predicted to measured concentrations in eggs was 1.0 +/- 0.27 among chemicals, years, and colonies for this exposure scenario. This result was in excellent agreement with field assessments of herring gull diet composition in Lake Ontario of 80-82% fish. The ability to perform accurate a priorisimulations for the range of test conditions employed in the validation constituted a rigorous test of the soundness of the model's structure and parameterization. With species-specific adjustments, ABAM can be regarded as a general model for lipophilic POPs bioaccumulation in birds.

Degradation of aldrin (1,2,3,4,10,10-Hexachloro-1,4,4a,5,8,8a-hexahydro-1,4:5-8-dimethanonaphthalene), heptachlor (1H-1,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-4,7-methano indene), dieldrin (1aalpha,2beta,2aalpha,3beta,6beta,6aalpha,7beta,7aalpha)-3,4,5,6,9,9-Hexachloro-1a,2,2a,3,6,6a,7,7a-octahydro-2,7:3,6-d-methanonaphtha[2,3-b]oxirene, and heptachlor epoxide (1aalpha, 1bbeta,2alpha,5alpha,5alphabeta,6beta,6aalpha-2,3,4,5,6,7,7-Heptachloro-1a,1b,5,5a,6,6a-hexahydro-2,5-methano-2H-inden[1,2-b]-oxirene) was tested using free cultures of Pseudomonas fluorescens under controlled conditions. Pesticide concentrations were monitored by gas chromatography during 120 h. Percentages of degradation and biodegradation rates (BDR) were calculated. Data showed a trend suggesting a relation between chemical structure and degradability. Degradation kinetics for each pesticide tested showed that the highest degradation rates were found in the first 24 h. Kinetics data were adjusted to an empirical equation in order to predict their behavior, and the correlation coefficients obtained were satisfactory. Gas chromatography/mass spectrometry (GC/MS) analysis of the final extracts allowed the identification of chlordene and monodechlorodieldrin, which have been reported as final metabolite produced in the biodegradation of this kind of compounds. Regarding adsorption of pesticides on activated vegetal carbon, we concluded that removal efficiencies between 95.45 and 97.18% can be reached, depending on the pesticide and the carbon dose applied. The values for K from the Freundlich equation were quite similar for the four pesticides (between 1.0001 and 1.04), whereas the n values were quite different for each pesticide in the following order of affinity: dieldrin > aldrin > heptachlor epoxide > heptachlor. Equilibrium times, very important for scaling up the process, were between 43 min and 1 h, for the heptachlor epoxide and the heptachlor, respectively.

An oxidative metabolism of Collembolan Proisotoma minuta was determined with a model compound of aldrin and dieldrin in this paper. The seven-day LD(50) values for aldrin, dieldrin, and piperonyl butoxide in salt solution were 0.496, 0.367, and 8.346 mg L(-1), respectively. When P. minuta were exposed to aldrin, dieldrin was the sole metabolite. The conversion of aldrin to dieldrin was known to be catalyzed by P450 monooxygenases system. It has been shown that the synergist piperonyl butoxide inhibited the metabolism of aldrin in P. minuta.

A pathway of dieldrin transformation to aldrin by epoxide reduction was found in this study. Investigation of dieldrin degradation under anaerobic conditions was performed with a mixed culture containing indigenous microorganisms obtained from sediment of the Er-Jen River in Taiwan. During the incubation, the transformation of dieldrin to aldrin was analyzed by GC-ECD and GC-MS. Effects of incubation factors including dieldrin concentrations, incubation temperatures and kinds of carbon sources on the degradation of dieldrin were also studied. Original concentrations (from 0.5 to 10 microg ml(-1)) of dieldrin affect the transformation rate of dieldrin, and lower concentrations indicated the higher degradation rates. But once the concentration higher than 100 microg ml(-1), almost no degradation occurred. The optimal temperature for degradation in mixed culture was found at 40 degrees C in this study. Dieldrin transformation rates varied with the type of major carbon sources in the mixed culture and were in order of yeast extract > sodium acetate > glucose. In addition, the denaturing gradient gel electrophoresis (DGGE) fingerprint revealed that four microbials evolved in dieldrin-amended cultures, but not in the dieldrin-free cultures. Partial sequence of 16S rDNA for these four organisms exhibited 94-99% similarity to those of genera Clostridium, Acidaminobacter and an uncultured bacterial group. These results suggest that the four microbials might promote the dieldrin transformation.

The inhibitory effects and removal efficiency of dieldrin (DLD) in anaerobic reactors were investigated. Anaerobic toxicity assay (ATA) experiments conducted in batch reactors revealed that 30 mg/l DLD had inhibitory effects on the unacclimated mixed anaerobic cultures. Continuous reactor experiments performed in a lab-scale two-stage upflow anaerobic sludge blanket (UASB) reactor system which was fed with ethanol as the sole carbon source, indicated that anaerobic granular cultures could be successfully acclimated to DLD. Chemical oxygen demand (COD) removal efficiencies were 88-92% for the two-stage system. The influent DLD concentration of 10 mg/l was removed by 44-86% and 86-94% in the second stage and overall UASB system, respectively. Biosorption of DLD on granular anaerobic biomass was found to be a significant mechanism for DLD removal in the UASB system. The maximum DLD loading rate and minimum HRT achievable for the first stage UASB reactor were 0.5 mg/lday (76 microg DLD/g VSS.day) and 10 h, respectively, which resulted in the overall COD removal efficiency of 85%.

The neurotoxic organochlorine pesticides gamma-hexachlorocyclohexane, alpha-endosulfan and dieldrin induce in mammals a hyperexcitability syndrome accompanied by convulsions. They reduce the GABA-induced Cl(-) flux. The strychnine-sensitive glycine receptor also regulates Cl(-)-flux inhibitory responses. We studied the effects of these compounds on Cl(-) channels associated with glycine receptors in cultured cerebellar granule cells in comparison to the GABA(A) receptor. Both GABA (EC(50): 5 microM) and glycine (EC(50): 68 microM) increased (36)Cl(-) influx. This increase was antagonized by bicuculline and strychnine, respectively. Lindane inhibited with similar potency both GABA(A) (IC(50): 6.1 microM) and glycine (5.0 microM) receptors. alpha-Endosulfan and dieldrin inhibited the GABA(A) receptor (IC(50) values: 0.4 microM and 0.2 microM, respectively) more potently than the glycine receptor (IC(50) values: 3.5 microM and 3 microM, respectively). Picrotoxinin also inhibited the glycine receptor, although with low potency (IC(50)>100 microM). A 3D pharmacophore model, consisting of five hydrophobic regions and one hydrogen bond acceptor site in a specific three-dimensional arrangement, was developed for these compounds by computational modelling. We propose that the hydrogen bond acceptor moiety and the hydrophobic region were responsible for the affinity of these compounds at the GABA(A) receptor whereas only the hydrophobic region of the molecules was responsible for their interaction with the glycine receptors. In summary, these compounds could produce neuronal hyperexcitability by blocking glycine receptors besides the GABA(A) receptor. We propose that two zones of the polychlorocycloalkane pesticide molecules (a lipophilic zone and a polar zone) differentially contribute to their binding to GABA(A) and glycine receptors.

We assessed the impacts of persistent organic micropollutants on aquatic trophic webs in brackish and freshwater communities in the Camargue National Nature Reserve (NNR). We found that organochlorine compounds affect fish communities, particularly those of the common eel (Anguilla anguilla). The aims of this study were (1) to determine the amount of lipophilic xenobiotics such as polycyclic aromatic hydrocarbons (PAHs), which are probably of atmospheric origin, and two organochlorines (OC), lindane and dieldrin, which are from irrigation waters, in liver and muscle (2) to define in situ biomarkers and (3) to identify the mode by which fish from 'unpolluted' areas become contaminated. All of the species were contaminated with low, but fluctuating quantities of PAHs and OCs, regardless of the sampling season. Lindane and dieldrin were always detected and naphtalene was the most abundant hydrocarbon. The OC and PAH content was rarely correlated with the lipid content in storage tissues and their concentrations in the lipidic fractions (neutral and polar) varied greatly. We found a number of correlations between persistent organic pollutant (POP) tissue concentrations and the activities of enzymatic membrane markers. For example, there is a relationship between the concentrations of the most volatile PAHs and the activity of muscle acetylcholinesterase (AChE) and between the concentration of benzo-PAH and the activities of ATPases in the gills and/or muscle.

Laying hens were treated orally with a single dose of aldrin (1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-1,4:5,8-dimethanonaphthalene, AD) 1 mg kg(-1) bw. Concentrations (microg g(-1)) of AD or its epoxide, dieldrin (1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydroendo-,exo-1,4:5,8-dimetha-nonaphthalene, DD), in the main tissues involved in egg formation (blood, liver, ovary, and oviducts) and egg yolk, collected at 1 day after AD dosing, were determined by normal-phase high-performance liquid chromatography. The limits of determination were 0.07 microg g(-1) for AD and 0.08 microg g(-1) for DD, respectively. In extractable fats from the above tissues and egg yolk, AD was found in the egg yolk; however, no AD was found in tissues involved in egg formation. DD was found in all tissues examined here. The DD level was highest in the liver and was lowest in the blood (P<0.01). These results suggest that the epoxidation of AD to DD occurred rapidly in the hen.

Endosulfan is a cyclodiene organochlorine currently widely used as an insecticide throughout the world. This study reports that the endosulfan isomers can be readily dissipated from aqueous systems at neutral pH in the absence of biological material or chemical catalysts, in the presence or absence of oxygen. The study showed that aldrin, dieldrin, and endosulfan exhibit bi-phasic loss from water in unsealed and butyl rubber sealed vessels. Half-lives are substantially increased for endosulfan I when oxygen is removed from the incubation vessel. The study conditions, where PTFE was used, were such that loss due to volatilization and alkaline chemical hydrolysis was eliminated. Half-lives determined from these data indicate that the parent isomers are much less persistent than the related cyclodienes, aldrin and dieldrin, confirming the findings of previous studies. The major oxidation product of endosulfans I and II, endosulfan sulfate, is less volatile and can persist longer than either of the parent isomers. Endosulfan sulfate was not formed in any of the treatments suggesting that it would not be formed in aerated waters in the absence of microbial activity or strong chemical oxidants. Since endosulfan sulfate is formed in many environments through biological oxidation, and is only slowly degraded (both chemically in sterile media and biologically), it represents a predominant residue of technical grade endosulfan, which finds its way into aerobic and anaerobic aquatic environments. The data obtained contributes to and confirms the existing body of half-life data on endosulfan I and II and its major oxidation product, endosulfan sulfate. The half-life data generated from the current study can be used in models for predicting the loss of chlorinated cyclodiene compounds from aqueous systems. The findings also highlight the importance of critically reviewing half-life data, to determine what the predominant processes are that are acting on the compounds under study.