Low Environmental Persistence Research Articles

Minimizing the Environmental Impacts of Plastic Pollution through Ecodesign of Products with Low Environmental Persistence.

While plastic pollution threatens ecosystems and human health, the use of plastic products continues to increase. Limiting its harm requires design strategies for plastic products informed by the threats that plastics pose to the environment. Thus, we developed a sustainability metric for the ecodesign of plastic products with low environmental persistence and uncompromised performance. To do this, we integrated the environmental degradation rate of plastic into established material selection strategies, deriving material indices for environmental persistence. By comparing indices for the environmental impact of on-the-market plastics and proposed alternatives, we show that accounting for the environmental persistence of plastics in design could translate to societal benefits of hundreds of millions of dollars for a single consumer product. Our analysis identifies the materials and their properties that deserve development, adoption, and investment to create functional and less environmentally impactful plastic products.

Distinct microbial communities degrade cellulose diacetate bioplastics in the coastal ocean.

Cellulose diacetate (CDA) is a promising alternative to conventional plastics due to its versatility in manufacturing and low environmental persistence. Previously, our group demonstrated that CDA is susceptible to biodegradation in the ocean on timescales of months. In this study, we report the composition of microorganisms driving CDA degradation in the coastal ocean. We found that the coastal ocean harbors distinct bacterial taxa implicated in CDA degradation and these taxa have not been previously identified in prior CDA degradation studies, indicating an unexplored diversity of CDA-degrading bacteria in the ocean. Moreover, the shape of the plastic article (e.g., a fabric, film, or foam) and plasticizer in the plastic matrix selected for different microbial communities. Our findings pave the way for future studies to identify the specific species and enzymes that drive CDA degradation in the marine environment, ultimately yielding a more predictive understanding of CDA biodegradation across space and time.

A novel use of Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) as inoculative agent of baculoviruses.

Alphabaculoviruses are Lepidoptera-specific virulent pathogens that infect numerous pests, including the Spodoptera complex. Due to their low environmental persistence, the traditional use of Alphabaculoviruses as bioinsecticides consist in high-rate spray applications with repeated treatments. Several abiotic and biotic factors can foster its dispersion, promoting their persistence in the agroecosystem. Amongst biotic factors, predatory arthropods can disperse the viruses by excretion after preying on infected individuals. Therefore, this study focused on promoting predator's ingestion of nucleopolyhedrovirus (NPV)-treated diets, and the later exposition of the insect host to leaf surfaces contaminated with predator excreta. The virus-host-predator system studied was Spodoptera littoralis nucleopolyhedrovirus (SpliNPV), Spodoptera littoralis (Boisduval) and Nesidiocoris tenuis (Reuter). The infective potential of N. tenuis feces and the retention time of SpliNPV were assessed under laboratory conditions after feeding on treated diets (sucrose solution and Ephestia kuehniella eggs). Mortality of S. littoralis larvae was lower via N. tenuis excretion than in positive control (spray application) in the first infection cycle, together with a delay in host death. In the second infection cycle, both SpliNPV-treated diets triggered 100% mortality. Both diets allowed the transmission of SpliNPV, with a faster excretion via sucrose solution compared to E. kuehniella eggs. SpliNPV remained in N. tenuis digestive tract and was viable after excretion at least for 9 days for both diets. This study demonstrated the potential of the predator N. tenuis as inoculative agent of baculoviruses, representing a new alternative that, along with inundative applications, might contribute to improve pest management strategies. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Therapeutic impact of biopesticide neem oil on health status of walking catfish Clarias batrachus for replacing synthetic organophosphorus pesticides

Pesticides are widely used in agricultural purposes and indiscriminate use of pesticides resulted in unintentional harming of the environment. Lack of consciousness and education coupled with indifferent attitude also contributed to indiscriminate use of pesticides. Enormous amount of these toxic pesticides and other chemicals reaches in the aquatic environment by the runoff and other sources and polluted the water, air and soil for any living organisms. One of the fastest growing food producing sectors is aquaculture, supplying approximately 40% of the world’s fish food. Pesticides may be used in aquatic ecosystem to control the fish parasites, diseases, and other pests that have also adversely affected the aquatic ecosystem. Nuvan is an organophosphorus pesticide is widely used due to low persistence in environment but also affects the non-targeted organisms including fish. Synthetic chemicals generate environmental problems; researchers have been leaning towards pest control with natural or plant based substances. Protection of water quality is possible when rationalize the use of natural pesticides and promote biopesticides. Neem oil is a natural or mixtures of chemicals obtained from neem plant (Azadirachta indica) which has many significant benefits to overcome from the chemicals or synthetic pesticides. By making the health beneficial uses of neem oil accessible to the farmers in the society, the use of chemicals in agriculture can be reduced. The aim of the current study is to observe the impacts of nuvan and neem oil on the survival and health status of fishes which also affected the other animals by the food chain. Changes in blood parameters of fish are related to the response of the whole animal, which affect on survival, reproduction and growth of fish. Some alterations in cholesterol and triglycerides in serum of treated fish Clarias batrachus with 1/20 and 1/10 LC50 concentrations of nuvan and neem oil separately compared with non-treated one after 7, 15, 30 and 60 days of exposure were recorded and discussed. Also, this assessment may be essential for encourage suitable methods of application in aquatic organism production facilities to be fully explored in future.

Searching for a Reliable Viral Indicator of Faecal Pollution in Aquatic Environments.

The disposal of sewage in significant quantities poses a health hazard to aquatic ecosystems. These effluents can contain a wide range of pathogens, making faecal contamination a leading source of waterborne diseases around the world. Yet monitoring bacteria or viruses in aquatic environments is time consuming and expensive. The standard indicators of faecal pollution all have limitations, including difficulty in determining the source due to lack of host specificity, poor connection with the presence of non-bacterial pathogens, or low environmental persistence. Innovative monitoring techniques are sorely needed to provide more accurate and targeted solutions. Viruses are a promising alternative to faecal indicator bacteria for monitoring, as they are more persistent in ambient water, more abundant in faeces, and are extremely host-specific. Given the range of viruses found in diverse contexts, it is not easy to find one "ideal" viral indicator of faecal pollution; however, several are of interest. In parallel, the ongoing development of molecular techniques coupled with metagenomics and bioinformatics should enable improved ways to detect faecal contamination using viruses. This review examines the evolution of faecal contamination monitoring with the followingaims (i) to identify the characteristics of the main viral indicators of faecal contamination, including human enteric viruses, bacteriophages, CRESS and plant viruses, (ii) to assess how these have been used to monitor water pollution in recent years, (iii) to evaluate the reliability of recent detection methods of such viruses, and (iv) to tentatively determine which viruses may be most effective as markers of faecal pollution.

Acylsugar protection of Nicotiana benthamiana confers mortality and transgenerational fitness costs in Spodoptera litura

Acylsugars are secondary metabolites that are produced in the trichomes of some solanaceous species and can help control several herbivorous insect pests. Previously, knockout mutations (asat2 mutants) were shown to significantly reduce the acylsugar content of Nicotiana benthamiana, and significantly improve the fitness of six generalist insect herbivores. The current study compared the significant mortality and fitness costs in Spodoptera litura conferred by acylsugar protection of N. benthamiana (wild-type plants) compared to S. litura strains reared in acylsugar-deficient plants with depleted acylsugar biosynthesis. Acylsugar protection prolonged the developmental duration and decreased viability in the larval stages. Further, the fecundity of females and the hatching rate of eggs significantly decreased under acylsugar protection. For F1 offspring, acylsugar protection still exerted significant negative effects on larval survival rate and fecundity per female. The net reproductive rate and relative fitness of the S. litura strain were strongly affected by acylsugar. Altogether, these results indicate that acylsugar could contribute to plant protection due to toxicity to pests, diffused availability, and low environmental persistence. This could represent a complementary and alternative strategy to control populations of insect pests.

Engineering of tomato type VI glandular trichomes for trans-chrysanthemic acid biosynthesis, the acid moiety of natural pyrethrin insecticides

Glandular trichomes, known as metabolic cell factories, have been proposed as highly suitable for metabolically engineering the production of plant high-value specialized metabolites. Natural pyrethrins, found only in Dalmatian pyrethrum (Tanacetum cinerariifolium), are insecticides with low mammalian toxicity and short environmental persistence. Type I pyrethrins are esters of the monoterpenoid trans-chrysanthemic acid with one of the three rethrolone-type alcohols. To test if glandular trichomes can be made to synthesize trans-chrysanthemic acid, we reconstructed its biosynthetic pathway in tomato type VI glandular trichomes, which produce large amounts of terpenoids that share the precursor dimethylallyl diphosphate (DMAPP) with this acid. This was achieved by coexpressing the trans-chrysanthemic acid pathway related genes including TcCDS encoding chrysanthemyl diphosphate synthase and the fusion gene of TcADH2 encoding the alcohol dehydrogenase 2 linked with TcALDH1 encoding the aldehyde dehydrogenase 1 under the control of a newly identified type VI glandular trichome-specific metallocarboxypeptidase inhibitor promoter. Whole tomato leaves harboring type VI glandular trichomes expressing all three aformentioned genes had a concentration of total trans-chrysanthemic acid that was about 1.5-fold higher (by mole number) than the levels of β-phellandrene, the dominant monoterpene present in non-transgenic leaves, while the levels of β-phellandrene and the representative sesquiterpene β-caryophyllene in transgenic leaves were reduced by 96% and 81%, respectively. These results suggest that the tomato type VI glandular trichome is an alternative platform for the biosynthesis of trans-chrysanthemic acid by metabolic engineering.

Rapid Degradation of Cellulose Diacetate by Marine Microbes

The persistence of cellulose diacetate (CDA), a biobased plastic used in textiles and single-use consumer products, in the ocean is currently unknown. Here, we probe the disintegration and degradation of CDA-based materials (25 μm films, 510 μm foam, and 97 g/m2 fabric) by marine microbes in a continuous flow seawater mesocosm. Photographic evidence and mass loss measurements demonstrate that CDA-based materials disintegrate in months. Disintegration is marked by the increasing esterase and cellulase activity of the biofilm community, suggesting that marine microbes degrade CDA. The natural abundance stable (13C) and radiocarbon (14C) isotopic signature of carbon dioxide respired during short-term bottle incubations confirms the rapid degradation of both acetyl and cellulosic components of CDA by seawater microbial communities. These findings challenge the paradigm set by governmental agencies and advocacy groups that CDA-based materials persist in the ocean for decades, and represent a positive step toward identifying high-utility, biobased plastics with low environmental persistence.

Chemical Composition and Nematicidal Properties of Sixteen Essential Oils-A Review.

Essential oils (EOs) can be a large source of new food-safe and healthy nematicidal products, due to their strong activity on crop pathogens and pests, including phytoparasitic nematodes, as well as to their low environmental persistence. This review summarizes the results from our 10-year studies on chemical features and nematicidal properties of 16 EOs with different botanical origins and compositions, i.e., the EOs from Artemisia herba-alba Asso (Asteraceae), Cinnamomum camphora (L.) J. Presl. and Cinnamomum verum J. Presl. (Lauraceae), Citrus aurantium L., Cinnamomum. sinensis L. Osbeck and Ruta graveolens L. (Rutaceae), Eucalyptus citriodora Hook, Eucalyptus globulus Labill. and Syzygium aromaticum (L.) Marry et Perry (Myrtaceae), Mentha piperita L., Monarda didyma L., Monarda. fistulosa L., Rosmarinus officinalis L. and Thymus satureioides Cosson (Lamiaceae), Pelargonium asperum Ehrh ex Willd (Geraniaceae) and Schinus molle L. (Anacardiaceae). All these EOs were chemically characterized and tested in vitro and/or in vivo for their activity against the phytoparasitic species Meloidogyne incognita Kofoid et White (Chitw.), Pratylenchus vulnus Allen et Jensen and Xiphinema index Thorne et Allen. Toxicity bioassays were conducted by exposing 2nd stage juveniles (J2) of M. incognita, mixed-age specimens of P. vulnus and adult females of X. index to 2–100 μg mL−1 concentrations of EOs or EO’s major constituents for 4–96 h and checking mortality effect after a further 24–72 h permanence in water. Egg hatchability bioassays consisted in exposing (24–48 h) M. incognita egg masses to 500–1000 mg mL−1 EO solutions followed by a 5-week hatching test in water. The in vivo experiments were undertaken in sandy soil strongly infested by M. incognita and treated with different doses of EOs, applied either in water solution or by fumigation. The effects of the treatments on nematode infestation on tomato and in soil were checked at the end of each experiment. Structure-activity relationships, as suggested by the different chemical compositions of tested EOs, were also highlighted. In agreement with literature data, our studies indicated that most of the tested EOs are highly suitable for the formulation of new safe nematicides, though still retarded by the lack of efficient stabilization processes and standardized EOs’ components and extraction techniques.

How Plants Synthesize Pyrethrins: Safe and Biodegradable Insecticides.

Natural pyrethrin insecticides produced by Dalmatian pyrethrum (Tanacetum cinerariifolium) have low mammalian toxicity and short environmental persistence, providing an alternative to widely used synthetic agricultural insecticides that pose a threat to human health and the environment. A recent surge of interest in the use of pyrethrins as agricultural insecticides coincides with the discovery of several new genes in the pyrethrin biosynthetic pathway. Elucidation of this pathway facilitates efforts to breed improved pyrethrum varieties and to engineer plants with improved endogenous defenses or hosts for heterologous pyrethrin production. We describe the current state of knowledge related to global pyrethrum production, the pyrethrin biosynthetic pathway and its regulation, and recent efforts to engineer the pyrethrin pathway in diverse plant hosts.

Alkaline-thermally treated penicillin V mycelial residue amendment improved the soil properties without triggering antibiotic resistance

Penicillin V mycelial residue (PMR) is a byproduct of the pharmaceutical industry and may be disposed through land application after alkaline-thermal treatment. However, the efficacy of alkaline-thermally treated PMR in soil amelioration and the potential contamination risk caused by introduced penicillin V are poorly understood. In this study, soil pH, the contents of organic matter, available phosphorus, available potassium were measured to study the effect of alkaline-thermally treated PMR on soil fertility; the numbers of culturable microorganisms and the activities of enzymes, which not only reflect the decomposing ability of organic matter but also monitor the ecological suppression in soil ecosystem, were also investigated; moreover, the persistence of introduced penicillin V and the variation of antibiotic resistance genes (ARGs) in soil were examined to evaluate the resulting antibiotic resistance risk. The results indicated that the pH and the content of available potassium in amended soil with treated PMR profoundly improved. In addition, the culturable microorganisms and enzymes were not inhibited throughout the incubation of treated PMR in soil. The stability of treated PMR in soil relatively completed after 43 days. More importantly, the penicillin V derived by treated PMR rapidly depleted within 3 days, which suggested a relatively low environmental persistence. The treated PMR did not enrich the ARGs detected in soil, demonstrating that the addition of treated PMR might not trigger the antibiotic resistance risk in the short-term in soil. In conclusion, our results concluded that alkaline-thermally treated PMR is available for soil application.

Zebrafish embryos exposed to deltamethrin exhibit abnormalities despite induced expression of related genes (you, you-too, momo and u-boot)

Evaluation of the toxic effects of a widely used synthetic pyrethroid, deltamethrin (DM), was carried out in this study. This pesticide is preferred for pest control because of its low environmental persistence and toxicity. We investigated the expression pattern of four genes, namely, you ( you), yot ( you-too), momo ( mom) and ubo ( u-boot) during early development of zebrafish, that is, from 12 hpf to 48 hpf stages. These stages are selected as most of the important developmental aspects take place during this period. All four genes are known to play a vital role in development of notochord and somites. To understand the effect of DM on development, embryos of 4 hpf stage were exposed to two concentrations (100 and 200 µg/L) of DM, and observations were made at 12, 24 and 48 hpf stages. Our earlier studies have shown phenotypic abnormalities such as notochord bending, tail deformation, yolk sac and pericardial edema, lightening of body and eye pigmentation and interfered in somite patterning, during these stages of development. Understanding the relationship of phenotypic abnormalities with these four genes has been our primary objective. These four genes were analyzed by Reverse transcription (RT)-polymerase chain reaction and intensity of the bands has shown induction in their expression after exposure to the toxicant. In spite of the expression of genes, it was noticed that DM caused abnormalities. It can be said from the results that translational pathway could have been affected.

Investigating the environmental risks from the use of spray-dried cephalosporin mycelial dreg (CMD) as a soil amendment

Cephalosporin mycelial dreg (CMD) is a by-product of the pharmaceutical industry. Spray-drying is widely used for the dewatering process prior to the application of CMD as a soil amendment. However, the potential environmental behaviors and risks of spray-dried CMD amendment remain unclear. Here, a lab-scale incubation experiment was conducted to investigate the salinity, phytotoxicity, introduced antibiotics, heavy metals and the potential impacts of resistance genes in CMD-amended soil. Spray-dried CMD amendment generally increased soil salinity and only high dosed soils showed phytotoxic effects at the end of the incubation period, implying the physiological damage to plant growth. The introduced antibiotics quickly degraded over time, indicating a relatively low environmental persistence. Heavy metal slightly increased in soil receiving spray-dried CMD, and regulations should be developed to avoid metal accumulation. A decreased diversity and distinct patterns of β-lactam resistance genes as well as a dose-effect of their enrichment were observed in CMD-amended soil, which might be partially explained by the specific metals and introduced antibiotics. Antibiotic resistance genes in soil may be a valuable tool for evaluating the environmental risk associated with use of CMD as a soil amendment.

N-acetylcysteine inhibits Mancozeb-induced impairments to the normal development of zebrafish embryos

Mancozeb (MZ), a manganese/zinc-containing ethylene-bis-dithiocarbamate (EBCD) fungicide has been claimed to present low acute toxicity and short environmental persistence, however, its effects on embryogenesis in non-target organisms is unclear. Here, we used zebrafish embryos (5 hpf) to assess the potential embryotoxic effects induced by MZ (up to 72 hpf) as well as the role of reactive oxygen species (ROS) in this process by pre-treatment with a classical antioxidant (N-acetylcysteine, NAC). Markers of reactive oxygen species production (ROS), glutathione (GSH) levels and glutathione S-transferase (GST) activity were measured along with genotoxicity (comet assay), cell death (Acridine Orange) and behavioral parameters (spontaneous movement, touch stimulation and swimming response), in order to determine potential mechanisms of embryotoxicity. According to results, MZ was able to induce morphological abnormalities such as body axis distortion, DNA damage, cell death, increased ROS generation and changes in behavioral endpoints during zebrafish development. All these toxic effects were inhibited by the pre-treatment with NAC indicating a key role of redox unbalance during MZ-induced embryotoxicity. At least in our knowledge, this is the first report on the deleterious effect of MZ to the normal embryogenesis of zebrafish. In addition, the importance of ROS generation during this pathophysiological condition was highlighted.

Antioxidant enzymatic activities and lipid peroxidation in liver and ovary of zebrafish (Danio rerio) exposed to deltamethrin

ABSTRACTDeltamethrin (DM) is being used as a substitute for organochlorines and organophosphates in pest control because of its low environmental persistence and toxicity. But it has become an environmental contaminant as it has been used widely. In this study, we investigated the effect of DM (technical grade) on the antioxidant system of adult zebrafish. For this, six-month-old fish were exposed to 2, 4 and 6 μg/L of DM for 96 h. The tissues selected were liver and ovary. Our data showed that exposure to DM increases CAT (catalase), SOD (superoxide dismutase), GPx (glutathione peroxidase, antioxidant enzymes), LPO (lipid peroxidation, non-enzymatic antioxidant) and GST (glutathione S-transferase, detoxifying enzyme) in liver and ovary. Increased GST could detoxify the toxicant; still there could be enough DM to cause oxidative stress. It appears from our study that zebrafish used compensatory mechanisms in eliminating reactive oxygen species. These data will be useful as oxidative stress is being used as a biomarker for aquatic pollution.

Assessment of pesticide contaminated sediment using biological response of tropical chironomid, Chironomus javanus Kiffer as biomarker

ObjectiveTo investigate the use of a biomarker for assessment of the effects on the tropical chironomid, Chironomus javanus (C. javanus), Kiffer of sediment contaminated with an insecticide (chlorpyrifos). MethodsA wide range of biological responses to the tropical chironomid exposed were measured, including survival, growth rate and Acetylcholinesterase (AChE) activity. ResultsThe measured median lethal concentration (96 h LC50) of chlorpyrifos to C. javanus was 0.056 (95% CI 0.024–0.124) μg/kg. For sub-chronic levels of chlorpyrifos between 0.001 and 0.25 μg/kg administered for 10 days, the effects on the growth of C. javanus were reduced (larva size, head structure width and dry weight) at the significance level (P < 0.01) and the effects were concentration dependent. Following exposure to chlorpyrifos at the level of 0.001 μg/kg for 48 and 96 h, the AChE activity in C. javanus was inhibited compared with control samples (P < 0.05). ConclusionsThis study demonstrated that C. javanus was sensitive when exposed to chlorpyrifos. This species could serve as a potential biomarker for assessing pesticide contamination at low environmental persistence and provides limited effects data on the sensitivity of tropical biota to contaminants for ecological risk assessment of organophosphate pesticides in the tropical aquatic ecosystem.

&lt;I&gt;In vivo&lt;/i&gt; Genotoxicity Evaluation of Carbaryl Pesticides Using Polytene Chromosomes of &lt;I&gt;Anopheles culicifacies&lt;/I&gt; (Diptera:Culicidae)

Carbamate pesticides are in tremendous use in modern agricultural practices due to their relatively low persistence in environment but their impacts on genetic imprints of living organism are well documented by various investigations, therefore genotoxicity evaluation of such pesticides has become crucial before their extensive commercial use. The present research work deals with genotoxicity assessment of a carbamate pesticide viz: carbaryl by using genetic material of Anopheles culicifacies. To achieve the target, mosquito larvae were exposed to LC20 of selected pesticide for duration 24 hours and subsequently larval salivary polytene chromosomes were studied to observe detrimental consequences of carbaryl. The concerned carbamate pesticide was observed to induce different types of structural aberrations such as inversions, translocations, deletions, ectopic pairings, asynapses, chromosomal fusions and breaks. After statistical analysis of obtained data, values were calculated 31.35±9.07 in carbaryl exposed stocks as compared 19.36±4.63 in control groups. Subsequently, statically examination of procured data, from executed parameter, demonstrated significant outcomes, when scrutinized through student't' test (p<0.05).

A perspective on the potential risks of emerging contaminants to human and environmental health.

Technological, agricultural, and medical advances have improved the lifestyle of humankind. However, these advances have caused new problems that affect the environment and future generations. Emerging contaminants display properties such as low degradation potential and environmental persistence. In addition, most contaminants are lipophilic, which culminates in high bioaccumulation. The disposal of pharmaceuticals and personal care products into the environment underlies microbial and bacterial resistance. Plasticizers change several characteristics of industrialized materials, such as flexibility, but they are potentially carcinogenic and disrupt the endocrine system. Pesticides prevent the propagation of numerous kinds of pests; nevertheless, they exert neurotoxic and mutagenic effects, and they impact the environment negatively. Addition of flame retardants to a number of materials prevents flame propagation; however, after their release into the environment, these chemicals may bioaccumulate in organisms and disrupt the endocrine system, too. Surfactants can change the surface and interfacial properties of liquids, but their presence in the environment can interfere with countless enzymes and can even impair the endocrine system of various organisms and induce the feminization of species. Hence, gaining knowledge about emerging contaminants is increasingly important to minimize future damage and enable proper monitoring of each class of compounds in the environment which will help to improve legislation on this matter.

Chronic effects of clofibric acid in zebrafish (Danio rerio): A multigenerational study

Clofibric acid (CA) is an active metabolite of the blood lipid lowering agent clofibrate, a pharmaceutical designed to work as agonist of peroxisome proliferator-activated receptor alpha (PPARa). It is the most commonly reported fibrate in aquatic environments with low degradation rate and potential environmental persistence. Previous fish exposures showed that CA may impact spermatogenesis, growth and the expression of fat binding protein genes. However, there are limited data on the effects of chronic multigenerational CA exposures.Here, we assessed chronic multigenerational effects of CA exposure using zebrafish (Danio rerio) as a teleost model. Zebrafish were exposed through the diet to CA (1 and 10mg/g) during their whole lifetime. Growth, reproduction-related parameters and embryonic development were assessed in the exposed fish (F1 generation) and their offspring (F2 generation), together with muscle triglyceride content and gonad histology. In order to study the potential underlying mechanisms, the transcription levels of genes coding for enzymes involved in lipid metabolism pathways were determined.The results show that chronic life-cycle exposure to CA induced a significant reduction in growth of F1 generation and lowered triglyceride muscle content (10mg/g group). Also, an impact in male gonad development was observed together with a decrease in the fecundity (10mg/g group) and higher frequency of embryo abnormalities in the offspring of fish exposed to the lowest CA dose.The profile of the target genes was sex- and tissue-dependent. In F1 an up-regulation of male hepatic pparaa, pparb and acox transcript levels was observed, suggesting an activation of the fatty acid metabolism (provided that transcript level change indicates also a protein level change). Interestingly, the F2 generation, raised with control diet, displayed a response pattern different from that observed in F1, showing an increase in weight in the descendants of CA exposed fish, in comparison with control animals, which points to a multigenerational effect.

Chapter 9 - The neurotoxicity of organochlorine and pyrethroid pesticides

Organochlorine and pyrethroid compounds represent an old and a new class, respectively, of insecticides. Organochlorines such as DDT, dieldrin, or chlordecone, have been banned, primarily because of environmental issues. DDT is still used in certain countries to fight malaria-bearing mosquitoes, while lindane still finds some limited used against head lice. In contrast, pyrethroids find widespread use because of their efficacy, low environmental persistence, and relatively low mammalian toxicity. Like all insecticides, organochlorines and pyrethroids target the nervous system of insects and of nontarget species. All pyrethroids and DDT interact with the sodium channel; by keeping it open longer, they increase the likelihood of action potentials developing, thus creating a condition of hyperexcitability, whose main clinical sign is tremors. Most other organochlorines (except chlordecone), as well as certain (type II) pyrethroids, block the chloride channels of the GABA-A receptor, and cause seizures. Evidence of an association between exposure to organochlorine and pyrethroid insecticides and neurodegenerative diseases (e.g., Parkinson's disease) is weak, at best.