Biochemical and histological changes in fish, spotted scat (Scatophagus argus) exposed to diazinon

Sex and adrenal hormones in association with insecticide biomarkers among adolescents living in ecuadorian agricultural communities

BACKGROUND

Organophosphate, pyrethroid, and neonicotinoid insecticides have resulted in adrenal and gonadal hormone disruption in animal and in vitro studies; limited epidemiologic evidence exists in humans. We assessed relationships of urinary insecticide metabolite concentrations with adrenal and gonadal hormones in adolescents living in Ecuadorean agricultural communities.

METHODS

In 2016, we examined 522 Ecuadorian adolescents (11-17y, 50.7% female, 22% Indigenous; ESPINA study). We measured urinary insecticide metabolites, blood acetylcholinesterase activity (AChE), and salivary testosterone, dehydroepiandrosterone (DHEA), 17β-estradiol, and cortisol. We used general linear models to assess linear (β = % hormone difference per 50% increase of metabolite concentration) and curvilinear relationships (β2 = hormone difference per unit increase in squared ln-metabolite) between ln-metabolite or AChE and ln-hormone concentrations, stratified by sex, adjusting for anthropometric, demographic, and awakening response variables. Bayesian Kernel Machine Regression was used to assess non-linear associations and interactions.

RESULTS

The organophosphate metabolite malathion dicarboxylic acid (MDA) had positive associations with testosterone (βboys = 5.88% [1.21%, 10.78%], βgirls = 4.10% [-0.02%, 8.39%]), and cortisol (βboys = 6.06 [-0.23%, 12.75%]. Para-nitrophenol (organophosphate) had negatively-trending curvilinear associations, with testosterone (β2boys = -0.17 (-0.33, -0.003), p = 0.04) and DHEA (β2boys = -0.49 (-0.80, -0.19), p = 0.001) in boys. The neonicotinoid summary score (βboys = 5.60% [0.14%, 11.36%]) and the neonicotinoid acetamiprid-N-desmethyl (βboys = 3.90% [1.28%, 6.58%]) were positively associated with 17β-estradiol, measured in boys only. No associations between the pyrethroid 3-phenoxybenzoic acid and hormones were observed. In girls, bivariate response associations identified interactions of MDA, Para-nitrophenol, and 3,5,6-trichloro-2-pyridinol (organophosphates) with testosterone and DHEA concentrations. In boys, we observed an interaction of MDA and Para-nitrophenol with DHEA. No associations were identified for AChE.

CONCLUSIONS

We observed evidence of endocrine disruption for specific organophosphate and neonicotinoid metabolite exposures in adolescents. Urinary organophosphate metabolites were associated with testosterone and DHEA concentrations, with stronger associations in boys than girls. Urinary neonicotinoids were positively associated with 17β-estradiol. Longitudinal repeat-measures analyses would be beneficial for causal inference.

Effects of dietary garlic (Allium sativum) oil on growth performance, haemato-biochemical and histopathology of cypermethrin-intoxicated Nile tilapia (Oreochromis niloticus)

BACKGROUND

When pesticides are introduced into wetlands by agriculture, fish quickly absorb them through their gills. Pesticides reduce hatchability, impede growth, and antioxidant response, killing fish. Therefore, it's crucial to find effective pesticide mitigation methods for fish.

OBJECTIVE

In this study, the effects of garlic (Allium sativum) oil on the growth, haematology, biochemistry and histopathology parameters of Nile tilapia (Oreochromis niloticus) exposed to cypermethrin toxicity were investigated.

METHODS

In the research, cypermethrin was added to the water of the experimental groups at a rate of 1:20 of the LC50 value, and 1.00% garlic oil was added to the fish feed. Fish with an initial weight of 30.26 ± 0.26 g were fed for 45 days.

RESULTS

At the end of feeding, the final weights were determined as 69.39 ± 0.41 (G1), 61.81 ± 0.65 (G2), 82.25 ± 0.36 (G3), and 75.04 ± 0.68 (G4) grams, respectively. Histopathological examinations revealed serious lesions in the gill, liver, brain, and muscle tissues in the cypermethrin group, whereas these lesions were minimal or absent in the garlic oil group.

CONCLUSIONS

Garlic oil supplementation had positive effects on growth, haematology, blood biochemistry, hepatosomatic index and histopathological parameters. These findings suggest that garlic oil is a potential protective agent against cypermethrin toxicity.

The toxicity assessment of phosmet on development, reproduction, and gene expression in Daphnia magna

The use of pesticides to control pests, weeds, and diseases or to regulate plant growth is indispensable in agricultural production. However, the excessive use of these chemicals has led to significant concern about their potential negative impacts on health and the environment. Phosmet is one such pesticide that is commonly used on plants and animals against cold moth, aphids, mites, suckers, and fruit flies. Here, we investigated the effects of phosmet on a model organism, Daphnia magna using acute and chronic toxicity endpoints such as lethality, mobility, genotoxicity, reproduction, and gene expression. We performed survival experiments in six-well plates at seven different concentrations (0.01, 0.1, 1, 10, 25, 50, 100 μM) as well as the control in three replicates. We observed statistically significant mortality rates at 25 µM and above upon 24 h of exposure, and at 1 µM and above following 48 h of exposure. Genotoxicity analysis, reproduction assay and qPCR analysis were carried out at concentrations of 0.01 and 0.1 μM phosmet as these concentrations did not show any lethality. Comet assay showed that exposure to phosmet resulted in significant DNA damage in the cells. Interestingly, 0.1 μM phosmet produced more offspring per adult compared to the control group indicating a hormetic response. Gene expression profiles demonstrated several genes involved in different physiological pathways, including oxidative stress, detoxification, immune system, hypoxia and iron homeostasis. Taken together, our results indicate that phosmet has negative effects on Daphnia magna in a dose- and time-dependent manner and could also induce lethal and physiological toxicities to other aquatic organisms.

Short-term effects of the strobilurin fungicide dimoxystrobin on zebrafish gills: A morpho-functional study

Strobilurins represent the most widely used class of fungicides nowadays andare considered relatively non-toxic to mammals and birds but highly toxic to aquatic biota. Dimoxystrobin is one of the novel strobilurins, recently included in the 3rd Watch List of the European Commission as available data indicate that it could pose a significant risk to aquatic species. As yet, the number of studies explicitly assessing the impact of this fungicide on terrestrial and aquatic species is extremely low, and the toxic effects of dimoxystrobin on fish have not been reported. Here we investigate for the first time the alterations induced by two environmentally relevant and very low concentrations of dimoxystrobin (6.56 and 13.13 μg/L) in the fish gills. morphological, morphometric, ultrastructural, and functional alterations have been evaluated using zebrafish as a model species. We demonstrated that even short-term exposure (96 h) to dimoxystrobin alters fish gills reducing the surface available for gas exchange and inducing severe alterations encompassing three reaction patterns: circulatory disturbance and both regressive and progressive changes. Furthermore, we revealed that this fungicide impairs the expression of key enzymes involved in osmotic and acid-base regulation (Na⁺/K⁺-ATPase and AQP3) and the defensive response against oxidative stress (SOD and CAT). The information presented here highlights the importance of combining data from different analytical methods for evaluating the toxic potential of currently used and new agrochemical compounds. Our results will also contribute to the discussion on the suitability of mandatory ecotoxicological tests on vertebrates before the introduction on the market of new compounds.

The Probiotic Lactobacillus sakei Subsp. Sakei and Hawthorn Extract Supplements Improved Growth Performance, Digestive Enzymes, Immunity, and Resistance to the Pesticide Acetamiprid in Common Carp (Cyprinus carpio)

This study evaluated the impacts of the probiotic, Lactobacillus sakei (L. sakei), and the extract of hawthorn, Crataegus elbursensis, on growth and immunity of the common carp exposed to acetamiprid. Fish (mean ± SE: 11.48 ± 0.1 g) feeding was done with formulated diets (T ₁ (control): no supplementation, T ₂: 1 × 10⁶ CFU/g LS (Lactobacillus sakei), T3: 1 × 10⁸ CFU/g LS, T ₄: 0.5% hawthorn extract (HWE), and T ₅: 1% HWE) for 60 days and then exposed to acetamiprid for 14 days. The growth performance improved in the fish fed LS at dietary level of 1 × 10⁸ CFU/g, even after exposure to acetamiprid (P < 0.05). Intestinal Lactobacillus sakei (CFU/g) load increased (P < 0.05), following supplementation with the probiotic-enriched diet. The LS-treated fish had increases in the activity of digestive enzymes (P < 0.05). Both LS and HWE stimulated antioxidant enzymes and immune system components in serum and mucus (alkaline phosphatase (ALP), protease, total Ig, and lysozyme) (P < 0.05). However, the changes were different depending on the kind of the supplement. The malondialdehyde (MDA) levels decreased in HWE-treated fish after acetamiprid exposure (P < 0.05). Both LS and HWE reduced the liver metabolic enzymes (LDH, ALP, AST, ALT, and LDH) in serum both before and after exposure to the pesticide (P < 0.05). However, each enzyme exhibited a different change trend depending on the type of the supplement. HWE showed a stress-ameliorating effect, as glucose and cortisol levels declined in the HWE-treated fish (P < 0.05). This study indicated the immunomodulatory impacts of LS (1 × 10⁸ CFU/g) and HWE (at dietary levels of 0.5-1%). The probiotic showed more performance compared to HWE. However, the HWE mitigated oxidative stress more efficiently than the probiotic.

Impact of Chlorpyrifos on Cytopathological Indices in Mangrove Crab, Episesarma tetragonum (Fabricius)

Chlorpyrifos is an organophosphate insecticide occurring in aquatic ecosystems. Due to exposure to xenobiotics, several harmful effects on aquatic organisms are noticed worldwide. Mangrove crabs are an ecologically important aquatic invertebrate species in food web interactions and in the mangrove ecosystem. Therefore, this study aimed to evaluate the cytotoxic effects of chlorpyrifos on the mangrove crab, Episesarma tetragonum. Crabs were exposed to 0.0294 and 0.0588 ppm of chlorpyrifos for 7 and 28 days. Cytopathologic effects on the gill, hepatopancreas, and muscle were investigated, and observations were compared with a control group. The results suggest that chlorpyrifos induces time- and concentration-dependent cytopathological alternations in the gill and exhibited epithelial lifting, oedema, necrosis, and a fusion of secondary lamellae and haemorrhage. The deceased hepatopancreas showed infiltration, a large lumen formation, and the disappearance of haemocytes, while the muscle tissue showed atrophy, necrosis, a wavy appearance, an accumulation of granular material between muscle fibres, and fragmentation in a mangrove crab. This study shows the great potential of cytopathological investigations, allows us to assess the sensitivity of various aquatic animal species to potentially dangerous compounds, and calculates safe concentrations with which to reduce pesticide use.

Modulatory role of dietary curcumin and resveratrol on growth performance, serum immunity responses, mucus enzymes activity, antioxidant capacity and serum and mucus biochemicals in the common carp, Cyprinus carpio exposed to abamectin

In this study, we investigate the potentials of dietary curcumin and resveratrol on blood biochemistry, immune responses and resistance to the toxicity of the pesticide, abamectin. 540 common carps (30.78 ± 0.17 g) were randomly distributed into 18 tanks (30 fish per tank), as six experimental groups (T1: non-supplemented and on-exposed fish, T2: 300 mg/kg curcumin, T3: 300 mg/kg resveratrol, T4: 12.5% LC₅₀ of abamectin, T5: 300 mg/kg curcumin +12.5% LC₅₀ of abamectin, T6: 300 mg/kg resveratrol + 12.5% LC₅₀ of abamectin). Use of 300 mg/kg resveratrol in the diet of non-abamectin exposed fish improved the growth performance (P < 0.05), while such effects were not observed for curcumin (P > 0.05). There were no differences in the final weight (FW), feed conversion ratio (FCR) and weight gain (WG) between control and fish of the treatments, resveratrol + abamectin and curcumin + abamectin (P < 0.05). The immune components in blood [lysozyme, complement activity, Total immunoglobulin (total Ig), protease, myeloperoxidase (MPO), nitro-blue-tetrazolium (NBT), peroxidase, albumin] and mucus [acid phosphatase (ACP), alkaline phosphatase (ALP), esterase, antiprotease)] and antioxidant enzymes [(superoxide dismutase (SOD), glutathione peroxidase (GPx)] exhibited various change patterns compared to the control group, however, these components were almost all higher in fish supplemented with curcumin and resveratrol in an abamectin-free medium than in control and other groups (P < 0.05). In most cases, the levels of immune and antioxidant components in the control did not show significant difference with the treatments, resveratrol + abamectin and curcumin + abamectin (P > 0.05). Abamectin induced oxidative stress in fish, as the malondialdehyde (MDA) levels significantly increased in the exposed fish compared to non-exposed groups (P < 0.05). It appears that neither curcumin nor resveratrol were as effective in preventing oxidative stress, because MDA levels were higher in exposed fish (abamectin, curcumin + abamectin, resveratrol + abamectin) than in control and non-exposed individuals (P < 0.05). Curcumin and resveratrol also showed protective effects on liver, since the levels of liver metabolic enzymes [aspartate transaminase (AST), ALP, lactate dehydrogenase (LDH)] were lower in the supplemented fish in a abamectin-free medium than in control (P < 0.05). Curcumin and resveratrol also mitigated the stress responses in the exposed fish, as cortisol and glucose levels showed significant decreases in the supplemented fish (P < 0.05). In conclusion, this study revealed that abamectin can depress the growth and immunity in the common carp. Although, both resveratrol and curcumin were mitigated the toxic effects of abamectin, it seems that resveratrol be more effective than curcumin.

Protective effects of dietary Lavender ( Lavandula officinalis ) essential oil against Malathion-induced toxicity in rainbow trout ( Oncorhynchus mykiss )

The present study was aimed to evaluate the moderating properties of Lavender (Lavandula officinalis) essential oil (LEO) against immunotoxic effects of the organophosphate pesticide, malathion in rainbow trout, Oncorhynchus mykiss. For this purpose, fish were supplemented with LEO at dietary concentrations of 0.5, 1, 2 and 4 ml/kg diet LEO for 56 days. A non-LEO supplemented group was also considered as control. After 57 days feeding trial, biochemicals were assayed in the blood and kidney tissue and then fish exposed to a sub-lethal concentration of malathion [0.24 mg/l equal to 30% of LC50 (0.8 mg/L)]. After 57 days feeding trial, the serum total immunoglobulin, respiratory burst activity, lysozyme activity and complement activity significantly elevated in fish treated with 1 and 2 ml LEO/kg diet compared to non-LEO supplemented individuals (P<0.01). Such changes were not observed in non-LEO supplemented fish (P>0.01). Significant elevations were observed in the expression of the immune genes (iNOS and C3 genes) in fish treated with 0.2–2 mg LEO/kg diet compared to non-supplemented ones (P<0.01). The lysozyme and complement activity significantly decreased in fish fed 4 ml/kg diet (P<0.01). After exposure to malathion, all immune components significantly declined in control and those treated with 0.5, 1 and 4 ml LEO/kg diet (P<0.01). In contrast, the immunity components exhibited no significant changes in fish treated with 2 ml LEO/kg diet after exposure (P>0.01). The expression of iNOS and C3 genes significantly reduced in control and fish fed 0.5, 1 and 4 ml LEO/kg diet in response to malathion (P<0.05). Furthermore, the expression of these genes showed no significant changes in fish fed with 2 ml LEO/kg diet after exposure (P>0.01). The findings of the present study suggested an immunoprotective role for dietary LEO at optimized dietary concentrations of 1 and 2 ml LEO/kg diet against oxidative stress and toxicity induced by malathion. Nevertheless, LEO at high dietary concentration (4 ml/kg diet) had reducing effects on the fish immunity.

Cassia fistula ameliorates chronic toxicity of cypermethrin in Catla catla

Protective effects of Cassia fistula, in Catla catla exposed to synthetic pyrethroid cypermethrin were evaluated. Fish, after chronic exposure to environmentally relevant sub-lethal concentration 0.41 μg/l of the pesticide were assessed for antioxidant activity, histopathological and ultrastructural alterations. Significant (p < 0.05) decrease in the activities of antioxidants such as CAT, SOD, GST, GSH was registered, whereas LPO level got elevated. Histological damage depicted necrosis, epithelial hypertrophy, hyperplasia and fusion of secondary lamellae and changes in gill vasculature. Histopathological alteration index was employed for the semi quantitative evaluation of the degree of tissue change (DTC). Transmission electron microscopy displayed swollen and distorted mitochondria, damaged chloride cells and necrosis. Dietary supplementation of Cassia fistula bark extract significantly (p < 0.05) improved the antioxidant activity, reduced lipid peroxidation and prevented histopathological alterations. The findings suggest that sub-lethal concentration of cypermethrin is toxic to fish. The study also draws attention towards potential of plant derived antioxidants in mitigating pesticide induced toxic effects.

Tissue-specific toxicity of clothianidin on rainbow trout (Oncorhynchus mykiss)

This study was performed to investigate the tissue-specific effects of clothianidin on Oncorhynchus mykiss by evaluating the biochemical and histological alterations following 21 days of treatment to environmentally relevant concentrations of 3, 15, and 30 µg/L. The emerged behavioral changes in feeding and swimming performance were considered as adaptive responses to avoid the chemical. The toxic effect of pesticide on nervous system and osmoregulation was evidenced with the inhibition of AChE and Na⁺K⁺-ATPase. The sustained lipid peroxidation, ranging from muscle (196%) > brain (154%) > gill (140%) > kidney (129%), might be suggested as a mechanism mediating the inhibition of membrane-bound enzymes. Histological evaluation showed clothianidin-induced lesions appearing as necrosis, atrophy, and edema in muscle, hyperplasia, and hypertrophy causing shortening and fusion of the secondary lamellae in gill, vacuolization, and hydropic degeneration in brain, degeneration of tubular epithelium, and existence of melanomacrophage centers in kidney. The pronounced degenerative changes observed in gill indicate the vulnerability of tissue possibly due to its role as first contact and entry point for the pesticide. Consequently, clothianidin exerted its toxic effects by altering normal behavior, causing neurotoxicity and disturbing osmoregulation. Moreover, the imposed stress was responded in a tissue-specific manner and histological lesions become more severe with increasing concentration. The findings clearly reveal the potential threat caused by environmentally relevant concentrations of clothianidin to early life stages of fish.

The effect of diazinon on blood glucose homeostasis: a systematic and meta-analysis study

Though evidence exists on the association between diazinon (DZN), an organophosphate pesticide, with hyperglycemia, contrasting reports also exist. Herein, we performed a systematic and meta-analysis study to address this issue. A systematic search was conducted in PubMed, Ovid Medline, Google Scholar, Scopus, and Web of Science up to April 5, 2020, searching for animal studies (rodents and fish) that assessed the impact of DZN on blood glucose concentration. The risk of bias was assessed by the SYRCLE's RoB scale. Once each article's quality was assessed, a random-effects meta-regression was used to pool the data into a meta-analysis. Heterogeneity between the studies was evaluated with the I square and Q test. Random-effect meta-analysis of 19 studies (I² = 90.5%, p < 0.001) indicated low heterogeneity between the studies. DZN significantly increased blood glucose levels in the exposed versus control groups (95% CI: 2.46-4.94; Z = 5.86; p < 0.001). Subgroup analysis indicated that the effect of high-dose (3.40 (95% CI: 2.03-4.76)) DZN on changes in blood glucose was more pronounced than in the low dose (4.83 (95% CI: 1.56-8.11)). It was also ascertained that the blood glucose level was significantly higher in females (3.55 (95% CI: 2.21-4.89)) versus males (4.87 (95% CI: 0.20-9.55)) exposed to DZN. No publication bias was observed. Sensitivity analysis showed the robustness of the (standardized mean differences: 3.26-4.03). Our findings establish an association between DZN exposure and hyperglycemia in rodents and fish, which is both dose- and gender-dependent.

A comparative study on the effects of selected pesticides on hemato-biochemistry and tissue histology of freshwater fish Cirrhinus mrigala (Hamilton, 1822)

The aim of the present study was to investigate the comparative effects of pesticides Chlorfenapyr, Dimethoate and Acetamiprid on the health of Cirrhinus mrigala under long term exposure. Eighty C. mrigala were divided in four equal groups; one control and three treated groups. The blood was collected from both control and treated groups at intervals of 10th, 20th and 30th days for hemato-biochemistry and histopathological alterations. The result indicates significant difference (P < 0.05) in RBCs, Hb, PCV and MCHC whereas elevation in WBCs and Platelets counts were recorded. In 10th day sampling, MCV value of Dimethoate and Acetamiprid treatment had no difference in comparison with the control group, however it is significantly increased (P < 0.05) in rest of sampling. The MCH value of exposed fish showed significant increased (P < 0.05) after 20th and 30th days for Chlorfenapyr and after 30th days for Acetamiprid exposure while insignificantly increased for rest of sampling. It was also found that these pesticides significantly decrease (p < 0.05) the T3 and T4 levels while increase in the TSH, cortical, ALP, AST, ALT and LDH levels in the serum of the treated fishes in contrast to control group. Similarly, histopathological analysis of gills and liver showed significant alterations in all the treated groups. Toxicity trends of these pesticides was ranked as Chlorfenapyr > Acetamiprid > Dimethoate. It is concluded that indiscriminate use of such pesticides poses a noxious threat to non-target organisms, harm the ecosystems and jeopardizes human health.

Occurrence and potential risk of organophosphorus pesticides in urbanised Linggi River, Negeri Sembilan, Malaysia

The application of organophosphorus pesticides (OPPs) increased gradually because of the rise in global food demand that triggered the agriculture sector to increase the production, leading to OPP residues in the surface water. This study elucidated the presence of OPPs and estimated its ecological risk in the riverine ecosystem of the urbanised Linggi River, Negeri Sembilan, Malaysia. The OPP concentration in surface water was determined using solid-phase extraction method and high-performance liquid chromatography coupled with diode array detection. Further, the ecological risk was estimated by using the risk quotient (RQ) method. The three OPPs, i.e. chlorpyrifos, diazinon, and quinalphos were detected with mean concentrations of 0.0275 µg/L, 0.0328 µg/L, and 0.0362 µg/L, respectively. The OPPs were at high risk (in general and worst cases) under acute exposure. The estimated risk of diazinon was observed as medium for general (RQ_m = 0.5857) and high for worst cases (RQ_ex = 4.4678). Notably, the estimated risk for chlorpyrifos was high for both general and worst cases (RQ_m = 1.9643 and RQ_ex = 11.5643) towards the aquatic ecosystem of the Linggi River. Chronic risk of quinalphos remains unknown because of the absence of toxicity endpoints. This study presented clear knowledge regarding OPP contamination and possible risk for aquatic ecosystems. Hence, OPPs should be listed as one of the main priority contaminants in pesticide mitigation management in the future.

Oxidative stress, DNA damage and apoptosis induced by tebuconazole in the kidney of male Wistar rat

Tebuconazole (TEB) is a broad-spectrum conazole fungicide that has been used in agriculture in the control of foliar and soil-borne diseases of many crops. The present study has investigated the adverse effects of subchronic exposure to TEB on the kidney of male rats. Animals were divided into four equal groups and treated with TEB at increasing doses 0.9, 9 and 27 mg/kg body weight for 28 consecutive days. The results showed that TEB induced oxidative stress in the kidney demonstrated by an increase in malondialdehyde (MDA), protein carbonyl (PC), advanced oxidation protein product (AOPP) levels and DNA damage, as compared to the controls. Furthermore, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities were increased in the renal tissue of treated rats. Moreover, significant decrease in reduced glutathione (GSH) content in TEB-treated rats was observed, while oxidized glutathione (GSSG) levels were increased, thus a marked fall in GSH/GSSG ratio was registered in the kidney. Glutathione reductase (GR) activity showed a significant increase after TEB exposure. Moreover, TEB down-regulated the expression of Bcl2 and up-regulated the expression of Bax and caspase 3, which triggered apoptosis via the Bax/Bcl2 and caspase pathway. Also, TEB administration resulted in altered biochemical indicators of renal function and varying lesions in the overall histo-architecture of renal tissues. Taken together, our findings brought into light the renal toxicity induced by TEB, which was found to be significant at low doses.

Impact of chlorpyrifos on behavior and histopathological indices in different tissues of freshwater fish Channa punctatus (Bloch)

The present systematic experiment was conducted to estimate the impact of behavioral and pathological indices on freshwater fish Channa punctatus exposed to sub-lethal concentration (5 ppm) of an organophosphorus insecticide chlorpyrifos (CPF). Fish were segregated into four experimental groups (G1, control; G2, 10 days; G3, 20 days; and G4, 30 days exposure), each group comprises 15 fish in triplicate. The behavioral and histological changes were assessed in each group. Severe behavioral changes were observed in the 30 days, moderate changes in the 20 days, and mild changes in the 10 days exposure groups respectively when compared with the control group. The pathologic lesions such as inter lamellae space, necrotic lamellae, fused lamellae, and lifting of lamellae epithelium in gills; vacuolation, blood conjunctions, and necrotic hepatocytes in the liver; and lamina propria, fusion of villi, and flattened villi in the intestine were observed. These structural alterations of the gills, liver, and intestine could affect respiration, osmotic and ionic regulation; absorption, storage and secretion; digestion; and absorption of nutrients respectively, which in turn could adversely affect the growth and survival of freshwater fish Channa punctatus. This study serves as a biomonitoring tool for the effects of organophosphorus insecticide CPF on the aquatic biota.

The effects of continuous diazinon exposure on growth and reproduction in Japanese medaka using a modified Medaka Extended One Generation Reproduction Test (MEOGRT)

The Medaka Extended One Generation Reproduction Test (MEOGRT) is a Tier 2 test within U.S. Environmental Protection Agency's (USEPA) Endocrine Disruptor Screening Program (EDSP), designed to characterize the potential adverse effects to fish of exposure to chemical that can cause disruption of the endocrine system. The MEOGRT focuses primarily on adverse effects to reproduction while collecting information regarding effects on growth, survival, and endocrine-related endpoints. However, the risk assessment process for fish, as mandated by legislation such as the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) or the Toxic Substances Control Act (TSCA), could benefit from a more detailed assessment of effects on growth. Typically, fish growth data in support of risk assessment are obtained from full life-cycle tests or early life stage tests using the fathead minnow. As an alternative to these tests, a modified MEOGRT was conducted to assess the effects of diazinon on the various parameters measured in the MEOGRT. Diazinon is an organophosphate insecticide that is detected in the environment, and whose efficacy is a result of inhibition of the acetylcholine esterase enzyme at neuromuscular junctions and synapses of the nervous system. Diazinon (2.9, 5.2, 10.3, 19.8, and 40.2 μg/L) was tested with the MEOGRT protocol, and the lowest observable effect concentrations of 2.9 μg/L for fecundity and 5.2 μg/L for growth were determined. Additional growth measurements were added to the MEOGRT protocol to more robustly define growth rates and to determine the impact size has on reproductive performance. Fish size starting at the first measurement day (i.e. 21 days post-fertilization), and continuing through the duration of the test was reduced with exposure to 5.2 μg/L and higher, and asymptotic size predicted from growth modeling was reduced at 10.3 μg/L and higher. By simply adding non-destructive growth measurements at two additional time points, the MEOGRT provided enough data for the parameterization of growth models, which could be used to characterize the reproductive implications of growth impairment.

Cytological and histological effects of pesticide chlorpyriphos in the gills of Anabas testudineus

The present study was aimed to report the toxicity of the chlorpyrifos, an organophosphorus insecticide, with regard to histological and cytological effects through light and transmission electron microscopes in the gills of freshwater fish, Anabas testudineus. The fish were exposed to 0.125 (5% of 96 h LC₅₀), 0.250 (10% of 96 h LC₅₀), and 0.375 mgL^-1 (15% of 96 h LC₅₀) of chlorpyrifos for 7, 14, and 21 days for light microscopy and 21 days for transmission electron microscopy. The histological effects were seen in all exposed concentrations of 0.125, 0.250, and 0.375 mgL^-1. These effects increased with the increase in chlorpyrifos concentrations and duration of exposure. The main histological effects visible in the gill tissue were fusion of secondary lamellae and epithelial hyperplasia. Other effects included the epithelial hypertrophy, lifting of lamellar epithelium, aneurysm, necrosis, and desquamation of epithelial cells were also reported. Cytological effects included epithelial detachment, large subepithelial space, necrotic cells, apoptotic remnant of cells, the presence of macrophages, swelling of mitochondria in the chloride cells, distension of the tubular system, the presence of some large vacuoles, deposition of excessive mucous, and nucleus abnormalities. This study confirms that varying doses of chlorpyrifos have adverse histological and cytological effects in the gills of A. testudineus.

Biomarker and histopathological responses of Lates calcarifer on exposure to sub lethal concentrations of chlorpyrifos

Bioassay tests on fingerlings (3.0 ± 0.5cm) of euryhyaline fish Lates calcarifer were conducted using customized continuous flow through system and derived 96h acute toxicity value for chlorpyrifos (CPF). Based on the measured concentration of CPF mean median lethal concentration (LC₅₀) of 1.07µg/l with lower and upper 95% confidence limits (0.95 and 1.19µg/l). No observed Effect Concentration (NOEC), Lowest Observed Effect Concentration (LOEC) and chronic values were found to be 0.4, 0.09 and 0.07µg/l respectively. Key biomarker enzyme activities such as esterase, superoxide dismutase and malate dehydrogenase were measured in whole body tissues of the fish fingerlings on exposure to sublethal toxicity of CPF resulting in inhibition of enzyme activities. Native gel electrophoresis revealed single isoform of SOD and MDH enzyme activities exhibiting time and concentration dependent inhibition. Interestingly, three isoforms of esterase activity were witnessed, two isoforms didn't show changes and one isoform was completely inhibited. The observed changes indicated continuous production of reactive oxygen species (ROS) in cells, affecting the integrity and function of cell membrane. Decreased MDH activity indicates reduction of ATP production in the mitochondria leading to susceptibility of fish fingerlings due to the imposed CPF toxicity. Histopathological changes are evident as physiological signatures of chemical interactions in the cell and are prominently used for the evaluation of toxic effects. Gills and eye tissues were selected considering the possible effects on respiratory surfaces and vision impairment. Their tissue sections were observed for changes in primary & secondary lamellae, and retina of the eye respectively. Prominent pathological lesions of gills and retina of the eye include degeneration of cells, fusion, lifting of epithelium and increased cellular space, detachment of pigment epithelium, fusion of photoreceptor cells, respectively on exposure to 30 days of sub lethal concentrations. CPF was found to be highly toxic, affecting the vital functions of respiration, vision and cellular activities leading to susceptibility of fish fingerlings.

Evaluation of residue risk and toxicity of different treatments with diazinon insecticide applied to mushroom crops

This work describes the phytotoxic effect of different doses of diazinon and different application times on Agaricus bisporus mycelium, and determines the residue levels in mushrooms from the first three flushes. Mushroom cultivation is a widespread commercial activity throughout the world. The application of insecticide diazinon to the compost or casing layer is a common practice to control two mushroom pests, the phorid Megaselia halterata and the sciarid Lycoriella auripila. Application to the compost does not result in any appreciable fall in yield or quality, and does not delay the harvest time. In contrast, application to the casing led to a slight fall (6.2%) in production and a smaller number of mushrooms although they are larger in size. Residue levels of more than 0.01 ppm are detected in many of the samples analyzed, and raising the question whether the product should continue to be used in mushroom cultivation in the conditions in which it is currently applied.

Acute and chronic toxicity of the benzoylurea pesticide, lufenuron, in the fish, Colossoma macropomum

Lufenuron is a benzoylurea insecticide that interfere in chitin synthesis in insects. Although lufenuron is widely used in agriculture and aquaculture, rare are studies described that relates to possible toxic effects in fish. This work aimed to evaluate acute and chronic toxic effects of benzoylurea pesticide (lufenuron) on biological parameters of Colossoma macropomum (Tambaqui). In the acute test, juveniles of Tambaqui were divided into control group and five experimental groups with exposure from 0.1 to 0.9 mg/L of lufenuron for 96 h. Animals were also submitted to chronic toxicity test for four months in concentrations of 0.1 and 0.3 mg/L of lufenuron, the concentration used in the treatment of ectoparasites in fish and 50% of LC50 96 h, respectively. The presence of hemorrhages was observed in eyes, fins and operculum of fish exposed to 0.7 and 0.9 mg/L of lufenuron. Histological analysis showed changes in the morphology of fish gills submitted to acute toxicity test, as lamellar aneurysm and blood congestion inside lamellae. Lufenuron promoted damage in fish retina as in ability to respond to stimuli in photoreceptors and in ON-bipolar cells in acute test. In chronic test, blood glucose analysis and morphometric parameters showed no significant differences (p > 0.05). In general, Tambaqui exhibited behaviors associated with stress when exposed to lufenuron. Thus, lufenuron showed several toxic effects in relation to biological parameters in Tambaqui. This concerns about the use and discard of lufenuron, and indicates the requirement of environmental actions to prevent potential contamination of aquatic biota.

The Protective Role of Thiourea on Leuciscus cephalus Exposed to Sublethal Doses of Pendigan 330EC (Pendimethalin) Herbicide

The aim of the study was to investigate the protective role of thiourea on the physiological, hematological, biochemical and histopathological parameters of Leuciscus cephalus exposed to sublethal concentration of Pendigan 330 EC herbicide. The animals were divided in four experimental groups (control, animals subjected to 1 ‰ thiourea, animals subjected to 4 × 10(-4) mL/L herbicide and, respectively, animals subjected to 4 × 10(-4) mL/L herbicide and 1 ‰ thiourea). Exposure of European chub to herbicide administered in water for 2 weeks determined installation of pathological changes in the liver and gills tissues. Also, were observed a decrease in the number of white blood cells and oxygen consumption, breathing frequency, and an increase in the number of red blood cells and glycaemia values. Thiourea counteracts the toxic action, describing itself as normal liver parenchyma and normal gills in animals intoxicated with herbicide, without lesion, and a return to normal values of the studied markers.