A preliminary assessment of consumer's exposure to pesticide residues in fisheries products

Organochlorine, organophosphorus, and carbamate pesticide residues in an Ethiopian Rift Valley Lake Hawassa: occurrences and possible ecological risks

Currently, pesticide production and use are on the rise globally. This trend is certain to continue in the coming decades with residues posing risks to the environment and human health even at low levels. Although various aspects of pesticides and their possible implications have widely been studied, such studies have mostly been carried out in developed countries leaving the rest of the world with little scientific information. We present here the results of a study on the occurrences, concentrations, and ecological risks of 30 pesticide residues (PRs) in water and sediment samples from a tropical freshwater Lake Hawassa in the Ethiopian Rift Valley. A total of 54 composite samples of water and sediment were collected from three sampling sites on three occasions. The samples were prepared by quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique, and analyzed using GC-MS at Bless Agri Food Laboratory Service located in Addis Ababa, Ethiopia. The study applied the risk quotient (RQ) method to scrutinize the risks posed to aquatic biota by the detected PRs. The results showed occurrences of 18 and 20 PRs in the water and sediment samples, respectively. The majority, 78 and 75% of the detected PRs in water and sediment samples, respectively represent the organochlorine chemical class. Concentrations of heptachlor epoxide were significantly (p ≤ 0.001) higher than those of the remaining pesticides in both matrices. Of the pesticides detected, 77% were present in water and 83% in sediment samples and pose a serious risk (RQ ≥ 1) to the Lake Hawassa biota. This calls for further research to investigate the risks to human health posed by the PRs. The findings of this study can contribute to the development of global protocols, as they support the concerns raised about the ecological and public health impacts of PRs on a global level.

Air monitoring of organochlorine pesticides (OCPs) in Bursa Türkiye: Levels, temporal trends and risk assessment

Monitoring concentration levels of persistent organic pollutants (POPs) is required to evaluate the effectiveness of international regulations to minimize the emissions of persistent organic pollutants (POPs) into the environment. In this manner, we evaluated the spatial and temporal variations of 22 organochlorine pesticides (OCPs) using polyurethane foam passive air samplers at ten stations in Bursa in 2017 and 2018. The highest concentration value for Σ22OCPs was detected in Ağaköy (775 pg/m3) and Demirtaş (678 pg/m3) sampling sites, while the lowest value was observed in Uludağ University Campus (UUC, 284 pg/m3) site. HCB, γ-HCH, Endo I, and Mirex were the most frequently detected OCPs, which shows their persistence. Diagnostic ratios of β-/(α + γ)-HCH have pointed to historical and possible illegal OCP usage in the study area. The seasonality of air concentrations (with spring and summer concentrations higher than winter and autumn concentrations) was well exhibited by α-HCH, β-HCH, ɣ-HCH, HCB, Endo I, and Mirex but not aldrin, dieldrin, and α-chlordane (CC). Levels of OCPs detected in ambient air in the current study were relatively similar to or lower than those reported in previous studies conducted in Türkiye. Back trajectory analysis was applied to identify the possible sources of OCPs detected in the sampling regions. The Clausius-Clapeyron approach was used to investigate the temperature dependence of OCP gas-phase atmospheric concentrations. The data showed that long-range atmospheric transport affects ambient air OCP concentrations in the study area.

CYP81A68 confers metabolic resistance to ALS and ACCase-inhibiting herbicides and its epigenetic regulation in Echinochloa crus-galli

Long-term and excessive herbicide use has led to some environmental concerns and especially, herbicide resistance evolution in weeds. Here, we confirmed acetolactate synthase (ALS) inhibiting herbicide penoxsulam resistance and cross resistance to acetyl-coenzyme carboxylase (ACCase) inhibiting herbicides (cyhalofop-butyl and metamifop) in a global weed Echinochloa crus-galli population resistant to these herbicides (R). Penoxsulam metabolism study indicated that degradation rate was significantly higher in R than susceptible E. crus-galli population (S). RNA-sequencing revealed that a cytochrome P450 (P450) gene, CYP81A68, expressed higher in R versus S. Rice seedlings overexpressing this CYP81A68 gene are resistant to penoxsulam, cyhalofop-butyl and metamifop, and penoxsulam resistance is due to enhanced metabolism via O-demethylation. Deletion analysis of the CYP81A68 gene promoter identified an efficient region, in which differential methylation of CpG islands occurred between R and S. Collectively, these results demonstrate that upregulation of E. crus-galli CYP81A68 gene endows generalist metabolic resistance to commonly used ALS- and ACCase-inhibiting herbicides in rice fields and epigenetic regulation may play a role in the resistance evolution. This research could contribute to strategies reducing herbicide environmental impacts by judicious selection of alternative herbicide and non-chemical control tactics.

Aquatic food animals in the United States: Status quo and challenges

This review summarizes (1) the U.S. status quo for aquatic food animal production and marketing; (2) major food safety and quality issues/concerns for aquatic food animals in the United States, including fish misbranding, finfish/shellfish allergies, pathogens, toxins and harmful residues, microplastics, and genetically engineered salmon; and (3) various U.S. regulations, guidances, and detection methods for the surveillance of fishery products. Overall, fish misbranding is the biggest challenge in the United States due to the relatively low inspection rate. In addition, due to the regulatory differences among countries, illegal animal drugs and/or pesticide residues might also be identified in imported aquatic food animals. Future regulatory and research directions could focus on further strengthening international cooperation, enhancing aquatic food animal inspection, and developing reliable, sensitive, and highly efficient detection methods.

Resistance to mesosulfuron-methyl in Beckmannia syzigachne may involve ROS burst and non-target-site resistance mechanisms

Herbicide resistance to chemical herbicide is a global issue that presents an ongoing threat to grain production. Though it has been frequently implicated that the production of detoxification enzymes increased in resistance development, the mechanisms for overexpression of these genes employed by herbicide-resistant weeds remain complicated. In this study, a mesosulfuron-methyl resistant Beckmannia syzigachne population (R) was found to be cross-resistant to another herbicide pyriminobac-methyl. No known target-site mutations were detected in the R population. In contrast, the decreased uptake and enhanced metabolic rates of mesosulfuron-methyl were detected in the R than the susceptible (S) population. Two candidate ATP-binding cassette (ABC) transporter genes (ABCB25 and ABCC14) that were constitutively up-regulated in the R population were identified by RNA-sequencing and validated by RT-qPCR. Alteration of antioxidant enzyme activities and gene expressions implied that mesosulfuron-methyl-induced antioxidant defenses provoked reactive oxygen species (ROS) burst. ROS scavenger assay showed that ROS induces ABCB25 and ABCC14 expression. This study reported for the first time that ABC transporters mediated non-target-site resistance contributes to mesosulfuron-methyl resistance in a B. syzigachne population, and implicated that ROS burst might be involved in the overexpression of ABC transporter genes in weeds.

Analysis of persistent organochlorine pesticides in shellfish and their risk assessment from aquafarms in Taiwan

In Taiwan, freshwater clams (Corbicula fluminea) and hard clams (Meretrix lusoria) are the most frequently raised shellfish in land-based pond aquaculture, but research on the accumulation of organochlorine pesticides (OCPs) in these shellfish is limited. We detected the levels of 14 OCPs in 62 shellfish from Taiwanese aquafarms by performing gas chromatography-tandem mass spectrometry. OCP residues were detected in 4.84% of the samples including readings of 0.04 mg/kg chlordane (in a freshwater clam), 0.03 mg/g p,p'-DDE (in a freshwater clam), and 0.02 mg/g p,p'-DDE (in a hard clam). However, the associated estimated daily intake values were less than the acceptable daily intake levels of chlordane and p,p'-DDE Therefore, the consumption of these shellfish presents no immediate health risks. Our findings contribute to food safety and serve as a reference for OCP screenings for aquatic shellfish.

Quinolone and Organophosphorus Insecticide Residues in Bivalves and Their Associated Risks in Taiwan

Bivalves, such as freshwater clams (Corbicula fluminea) and hard clams (Meretrix lusoria), are the most extensive and widely grown shellfish in land-based ponds in Taiwan. However, few studies have examined the contamination of bivalves by quinolone and organophosphorus insecticides. Thus, we adapted an established procedure to analyze 8 quinolones and 12 organophosphorus insecticides using liquid and gas chromatography–tandem mass spectrometry. Surveys in Taiwan have not noted high residual levels of these chemicals in bivalve tissues. A total of 58 samples of freshwater or hard clams were obtained from Taiwanese aquafarms. We identified 0.03 mg/kg of enrofloxacin in one freshwater clam, 0.024 mg/kg of flumequine in one freshwater clam, 0.02 mg/kg of flumequine in one hard clam, 0.05 mg/kg of chlorpyrifos in one freshwater clam, 0.03 mg/kg of chlorpyrifos in one hard clam, and 0.02 mg/kg of trichlorfon in one hard clam. The results indicated that 5.17% of the samples had quinolone insecticide residues and 5.17% had organophosphorus residues. However, the estimated daily intake (EDI)/acceptable daily intake quotient (ADI) indicated no significant risk and no immediate health risk from the consumption of bivalves. These results provide a reference for the food-safety screening of veterinary drugs and pesticides in aquatic animals. Aquatic products should be frequently screened for residues of prohibited chemicals to safeguard human health.

Validation of analytical methods for organochlorine pesticide detection in shellfish and cephalopods by GC-MS/MS

This study validated the analysis of organochlorine pesticides (OCPs) in shellfish and cephalopods using a gas chromatograph equipped with a mass spectrometry (GC-MS/MS), and monitored residual pesticide levels. The QuEChERS method was used to analyze OCPs and was validated by checking the linearity, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and precision. Octopus minor and Venerupis philippinarum, were purchased from four cities in the South Korean peninsula. The LOD values were 0.10-0.80 ng/g in shellfish and 0.21-0.77 ng/g in cephalopods, while the LOQ values were 0.31-2.41 ng/g in shellfish and 0.63-2.33 ng/g in cephalopods. Accuracy ranged from 83.5 to 117.4% and 79.8 to 118.4%, and precision ranged from 0.3 to 27.5% and 1.2 to 27.9%, in shellfish and cephalopods, respectively, conforming to the Codex Alimentarius Commission guidelines. Although residual OCP levels were below detection limits, the QuEChERS method may be effective for analyzing the OCPs in shellfish and cephalopods.

Analytical Detection of Sulfonamides and Organophosphorus Insecticide Residues in Fish in Taiwan

Exposure to residues of antibiotics (e.g., sulfonamides) and insecticides (e.g., organophosphorus insecticides) in aquacultured food can adversely affect humans and animals and thus affect public health globally. Here, using a validated method, we examined the levels of residues of 12 sulfonamides as well as 18 organophosphorus insecticides in aquacultured fish in Taiwan. A total of 52 fish samples (i.e., 20 tilapia, 16 milk fish, and 16 perch samples) were obtained from Taiwanese aquafarms from June 2018 to October 2019. We detected 0.02 and 0.03 mg/kg of sulfamethazine (a sulfonamide) in one tilapia and one milk fish, respectively, and 0.02, 0.05, and 0.03 mg/kg of chlorpyrifos (an organophosphorus insecticide) in one tilapia, one milk fish, and one perch, respectively; thus, among the samples, 3.85% and 5.77% contained sulfonamides and organophosphorus insecticide residues, respectively. Furthermore, we assessed human health risk based on the estimated daily intakes (EDIs) of these residues: EDIs of sulfonamide and organophosphorus insecticide residues were <1.0% of the acceptable daily intake recommended by the Joint Food and Agriculture Organization of the United Nations/World Health Organization Expert Committee on Food Additives. The risk of exposure to sulfonamide and organophosphorus insecticide residue by consuming aquacultured fish in Taiwan was thus negligible, signifying no immediate health risk related to the consumption of fish. Our findings can constitute a reference in efforts geared toward ensuring food safety and monitoring veterinary drug and insecticide residue levels in aquacultured organisms. Residue levels in fish must be continually monitored to further determine possible effects of these residues on human health.

Phthalates and organophosphorus insecticide residues in shrimp determined by liquid/gas chromatography-Tandem mass spectrometry and a health risk assessment

Shrimps are the most widely and increasingly cultured crustaceans in land-based ponds in Taiwan. However, few studies have investigated the phthalate contamination of and insecticide residues in shrimp. In this study, we applied a validated method to analyze the phthalate and 18 insecticides residues in shrimp. A total of 46 samples of whiteleg, grass, or giant river shrimp were collected from aquafarms and production areas in Taiwan. We detected 0.02-0.70 mg/kg of di-2-ethylhexyl phthalate (DEHP) in three shrimps; 0.02-0.03 mg/kg of chlorpyrifos in three shrimps, and 0.03 mg/kg of trichlorfon in one shrimp, indicating that 6.52% and 8.70% of the samples contained phthalate and insecticide residues, respectively. Furthermore, the assessed risk was negligible and indicated no immediate health risk associated with shrimp consumption. Continual monitoring of the residues in shrimps is critical for further assessment of possible effects on human health.

Persistent organochlorine pesticides in aquatic environments and fishes in Taiwan and their risk assessment

Organochlorine pesticides (OCPs) are ubiquitous contaminants with high bioaccumulation and persistence in the environment; they can have adverse effects in humans and animals. This study examined residual concentrations in water, sediments, and fishes as well as the association between the health risks of OCPs and fish consumption in the Taiwanese population. Various water and sediment samples from Taiwanese aquaculture and fish samples from different sources were collected and analyzed through gas chromatography tandem mass spectrometry to determine the concentrations of 20 OCPs, namely, aldrin; cis-chlordane; trans-chlordane; dieldrin; endrin; alpha-endosulfan; beta-endosulfan; heptachlor; hexachlorobenzene; alpha-hexachlorocyclohexane; beta-hexachlorocyclohexane; lindane; mirex; pentachlorobenzene; o,p'-dichlorodiphenyltrichloroethane (DDT); p,p'-DDT; and DDT metabolites (o,p'-dichlorodiphenyldichloroethane [DDD]; p,p'-DDD; o,p'-dichlorodiphenyldichloroethylene [DDE]; and p,p'-DDE). None of the analyzed samples was positive for OCP contamination, suggesting no new input pollution from the land through washing into Taiwanese aquaculture environments. However, OCP residues were detected in fishes caught along the coast, namely, skipjack tuna and bigeye barracuda, and in imported fishes, such as codfish and salmon. DDT was the predominant pesticide. The contamination pattern of persistent organic pollutants was as follows: dieldrin > cis-chlordane > hexachlorobenzene, with average concentrations ranging from 0.09 to 2.74 ng/g. The risk was assessed in terms of the estimated daily intake (EDI) for potential adverse indices; the EDI of OCP residues was lower than 1% of the acceptable daily intake established by the Food and Agriculture Organization of the United Nations and World Health Organization. The assessed risk was negligible and considered to be at a safe level, suggesting no association between fish consumption and risks to human health in Taiwan. However, a continuous monitoring program for OCP residues in fishes is necessary to further assess the possible effects on human health.

Analysis of banned veterinary drugs and herbicide residues in shellfish by liquid chromatography-tandem mass spectrometry (LC/MS/MS) and gas chromatography-tandem mass spectrometry (GC/MS/MS)

Seafood safety is a crucial public health concern for consumers. In this study, we applied a validated method to analyze the residue of banned veterinary drugs in shellfish, namely chloramphenicol, malachite green, leucomalachite green, and nitrofuran metabolites; additionally, the QuEChERS method was employed to detect 76 herbicides by LC/MS/MS and GC/MS/MS. In total, 42 shellfish samples, which included hard clams, freshwater clams, and oysters, were collected from aquafarms and production areas in Taiwan during 2012. Our results revealed 3.8ng/g of chloramphenicol in one hard clam, 19.9-32.1ng/g of ametryn in two hard clams, 16.1-60.1ng/g of pendimethalin in four hard clams, and 17.0ng/g of mefenacet in one oyster, indicating that 19.1% of the samples contained residues from banned veterinary drugs and pesticides. These data can be used to monitor the residue of veterinary drugs and pesticides in aquatic organisms and as a reference for food safety.

Evaluation of chlorpyrifos transferred from contaminated feed to duck commodities and dietary risks to Chinese consumers

The present study describes chlorpyrifos residues in duck commodities through the duck food chain, transfer factors, and dietary risks to Chinese consumers. After duck feeding experiments with pellet feed that lasted for 42 days, chlorpyrifos residues found in all samples collected from the ducks on maximum estimated dose group (3.20 mg/kg level) were from <0.0005 to 0.019 mg/kg. The residue levels of the fat, intestine, and tongue were obviously higher than those of the meat and other edible tissues. The transfer factors of all duck commodities were from 0.0001 to 0.0049 among different contamination levels, which indicated that chlorpyrifos had a low persistency in duck meat and metabolism organs. The chronic exposure assessment revealed that only 0.034-0.150% of the acceptable daily intake (ADI; 0-0.01 mg/kg/bw/day) of chlorpyrifos was consumed via the duck commodities for different age and gender groups in China. The acute exposure assessments of different age and gender groups were only 0.019-0.082% of the acute reference dose (ARfD; 0-0.1 mg/kg/bw). The results show that the single dietary exposure risk of chlorpyrifos raised by the intake of duck commodities was quite low in China.

Organochlorine pesticides and polychlorinated biphenyls in fish from Lake Awassa in the Ethiopian Rift Valley: human health risks

Dietary intake of fish containing organic contaminants poses a potential threat to human health. In the present work, an assessment has been carried out to look at the human health risk associated with consumption of fish contaminated with organochlorine pesticides (OCPs) and polychlorinated biphenyles (PCBs) in certain fish species collected from Lake Hawassa, Ethiopia. The health risk assessment was made by comparing the concentrations of OCPs and PCBs in fish muscle tissues with reference doses given in the USEPA guidelines. Dichlorodiphenyltrichloroethanes (DDTs), endosulfans, PCBs and chloridanes were identified in fish species collected from Lake Hawassa. The most predominant pesticides were DDTs, with mean concentrations of ΣDDT ranging from 19 to 56 ng g(-1) wet weights. The highest concentrations of DDTs were found in Barbus intermedius, representing the highest trophic level. PCBs, DDT and endosulfan concentrations found in B. intermedius exceeded the reference dose for children between the ages of 0-1 year (with hazard index of above 1.0). Therefore, consumption of fish from a high trophic level (e.g. B. intermedius) from Lake Hawassa may pose a special health risk to children.

Residue levels of hexachlorocyclohexane and dichlorodiphenyltrichloroethane in human milk collected from Beijing

Forty-eight human breast milk samples were collected from mothers in Beijing. The hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) (including α-HCH, β-HCH, γ-HCH, δ-HCH, p,p'-DDE, p,p'-DDD, o,p'-DDT, and p,p'-DDT) contents of the samples were determined by gas chromatography/electron capture detection and gas chromatography/mass spectrometry. α-HCH, β-HCH, γ-HCH, p,p'-DDE, p,p'-DDD, and p,p'-DDT were detected at rates of 20, 100, 10, 100, 10, and 22 %, respectively. The average residue levels in the samples were 174.6 ng/g fat for β-HCH, 333.8 ng/g fat for p,p'-DDE, 6.57 ng/g fat for α-HCH, 7.67 ng/g fat for γ-HCH, 4.18 ng/g fat for p,p'-DDD, and 11.4 ng/g fat for p,p'-DDT. The results showed that the infants' daily intake levels of HCH and DDT were 0.95 and 1.76 μg/kg body weight/day, respectively. Our result suggested that the total residue level of these organochlorine pesticides in breast milk from Beijing decreased and was lower than that from other coastal and heavy industrial cities in China. On the other hand, the levels of HCH and DDT were higher than those from some developed countries, but lower than those from other developing countries such as India.

Accumulation and half-lives of 13 pesticides in muscle tissue of freshwater fishes through food exposure

Fish are often exposed to various molecules like pesticides. Some of these compounds get biomagnified within aquatic food web, inducing health hazards of consumers. However, behaviors of many pesticides are still unknown. This work aims to study the uptake and the elimination of some of them in muscle tissue of edible fish (azoxystrobin, clomazone, diflufenican, dimethachlor, carbendazim, iprodion, isoproturon, mesosulfuron-methyl, metazachlor, napropamid, quizalofop, and thifensulfuron-methyl). Two freshwater fish species (Perca fluviatilis and Cyprinus carpio) were exposed to a mixture of these 13 pesticides, via multi-contaminated pellets, and then, eliminated. Compounds were measured in food, water and muscle tissue using multi-residues methods. Kinetics, biomagnification factors (BMFs) and half-lives (t1/2) were estimated and they did not show a large difference between the species. Muscular BMFs ranged from 2 × 10(-6) (mesosulfuron-methyl in perch) to 1 × 10(-3) (isoproturon and napropamid in perch) and t1/2 ranged from 0.8 (mesosulfuron-methyl in perch) to 40.3d (napropamid in carp). BMFs were also modeled as a function of Kow value. All BMF values were explained by the model, except for diflufenican which had a BMF lower than that expected by our modeling work, probably due to an efficient metabolism. Results led to the conclusion that none of these chemicals would probably be biomagnified within aquatic food webs.

Pesticide pressure and fish farming in barrage pond in Northeastern France. Part II: residues of 13 pesticides in water, sediments, edible fish and their relationships

Residues of pesticides in fish farming productions from barrage ponds are seldom studied in spite of increasing health questionings and environmental concerns. The purpose of this study is to establish the pesticide contamination profiles of sediments and edible fish from five ponds in Northeastern France. Multi-residues method and liquid chromatography-tandem mass spectrometry analysis were used to quantify 13 pesticides (azoxystrobin, carbendazim, clomazone, diflufenican, dimethachlor, fluroxypyr, iprodion, isoproturon, mesosulfuron-methyl, metazachlor, napropamid, quizalofop and thifensulfuron-methyl). Ten sediments and 143 muscles samples were analysed, corresponding to two successive fishing campaigns (first fishing date and second fishing date (P2), about 1 year later) on five sites (noted C-0, C-25, C-45, C-75 and C-85 to express the increasing gradient of crop area). Isoproturon was present in all sediments samples (1.8-56.4 μg/kg dry weight). During P2 period, carbendazim was quantified in the fish of site C-0 (0.09 ± 0.02, 0.2 ± 0.1 and 0.17 ± 0.06 μg/kg wet weight (ww) for roach, carp and perch, respectively). Metazachlor was only quantified in perch of the site C-25 (0.13 ± 0.02 μg/kg ww). Concentrations of isoproturon were similar for the sites C-45 and C-75 with 0.4 ± 0.1 and 0.75 ± 0.06 μg/kg ww for carp and perch, respectively. Contamination of fish reflected generally concentrations in surroundings. Isoproturon was the most concentrated and its main source was water for perch while carp was exposed through both water and sediments, highlighting their life strategies in pond.

Pesticide pressure and fish farming in barrage pond in northeastern France. Part III: how management can affect pesticide profiles in edible fish?

PURPOSE

The quality of fish produced in ponds needs to be ensured. Indeed, pond is often strongly connected to an agricultural watershed, and pesticides are a main health and environmental issue of concern. In this context, the purpose of this study is to highlight the management practices which could impact the pesticide contamination profiles in edible fish and to give recommendations for better practices.

METHODS

A principal component analysis, coupled to a hierarchical cluster analysis, was performed to evaluate temporal evolution of contamination profiles and to assess variability among fish species and among sites according to watershed characteristics. The explicative variables correspond to muscular concentrations of pesticides (azoxystrobin, clomazone, diflufenican, carbendazim, isoproturon, metazachlor, napropamid) in three species of fish (Perca fluviatilis, Cyprinus carpio and Rutilus rutilus), caught in five ponds during two sampling campaigns. Management data are added variables in order to discuss about parameters suspected to be implicated in the contamination profiles recorded.

RESULTS

This work shows that high amounts of pesticides applied, short crop rotation durations and bare soil practices led to contamination of sediments and fish and were associated to a "bad" management of watershed. Breeding fish that had low masses and establishing the fishing period at the end of winter seemed to be "bad" management of pond. Aggravating topological parameters were big watershed coupled to small pond and high proportions of sand soils in the watershed.

CONCLUSIONS

Reducing amounts of pesticide used (e.g. policy agency plans, farmer acceptance), favouring long-term rotations and inter-cultures, adapting pond creation and fish farming practices to watershed management and topography all could reduce pesticide levels in edible fish and contribute to a better sustainability of the extensive fish farming in pond.

Environmental neurotoxic pesticide dieldrin activates a non receptor tyrosine kinase to promote PKCδ-mediated dopaminergic apoptosis in a dopaminergic neuronal cell model

Oxidative stress and apoptosis are two key pathophysiological mechanisms underlying dopaminergic degeneration in Parkinson's disease (PD). Recently, we identified that proteolytic activation of protein kinase C-delta (PKCδ), a member of the novel PKC family, contributes to oxidative stress-induced dopaminergic degeneration and that phosphorylation of tyrosine residue 311 (tyr311) on PKCδ is a key event preceding the PKCδ proteolytic activation during oxidative damage. Herein, we report that a non-receptor tyrosine kinase Fyn is significantly expressed in a dopaminergic neuronal N27 cell model. Exposure of N27 cells to the dopaminergic toxicant dieldrin (60 μM) rapidly activated Fyn kinase, PKCδ-tyr311 phosphorylation and proteolytic cleavage. Fyn kinase activation precedes the caspase-3-mediated proteolytic activation of PKCδ. Pre-treatment with p60-tyrosine-specific kinase inhibitor (TSKI) almost completely attenuated dieldrin-induced phosphorylation of PKCδ-tyr311 and its proteolytic activation. Additionally, TSKI almost completely blocked dieldrin-induced apoptotic cell death. To further confirm Fyn's role in the pro-apoptotic function of PKCδ, we adopted the RNAi approach. siRNA-mediated knockdown of Fyn kinase also effectively attenuated dieldrin-induced phosphorylation of PKCδ-tyr311, caspase-3-mediated PKCδ proteolytic cleavage, and DNA fragmentation, suggesting that Fyn kinase regulates the pro-apoptotic function of PKCδ. Collectively, these results demonstrate for the first time that Fyn kinase is a pro-apoptotic kinase that regulates upstream signaling of the PKCδ-mediated apoptotic cell death pathway in neurotoxicity models of pesticide exposure.

Human health risk of polychlorinated biphenyls and organochlorine pesticides resulting from seafood consumption in South Korea, 2005-2007

Organochlorines (OCs) such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), were measured in 26 species of seafood commonly consumed by the Korean population. PCBs and DDTs were the predominant contaminants with concentrations from 0.2 to 41 ng/g wet wt and from<0.04 to 37 ng/g wet wt, while CHLs (<0.01-1.9 ng/g wet wt), HCB (<0.004-1.0 ng/g wet wt), and HCHs (<0.02-0.4 ng/g wet wt) were 1-2 orders of magnitude lower than the concentrations of PCBs and DDTs. The dominant PCBs and OCPs were PCB 153, 187, 138, and 118 and p,p'-DDE, HCB, p,p'-DDT, and p,p'-DDD, respectively. Dietary intakes of OCs for the general population, males, and females were estimated as 69, 78, and 60 ng/kg body weight/week, respectively. Mackerel, tuna, and hairtail were the main contributors to the dietary intakes of OCs. Among the eight age groups investigated, infants <2 years had the highest dietary exposure to OCs. Hazard ratios of non-cancer risk of all of the OCs were less than one, while the lifetime cancer risks of PCBs and DDTs were all greater than unity for Korean populations.

The participation of human hepatic P450 isoforms, flavin-containing monooxygenases and aldehyde oxidase in the biotransformation of the insecticide fenthion

Although fenthion (FEN) is widely used as a broad spectrum insecticide on various crops in many countries, very scant data are available on its biotransformation in humans. In this study the in vitro human hepatic FEN biotransformation was characterized, identifying the relative contributions of cytochrome P450 (CYPs) and/or flavin-containing monooxygenase (FMOs) by using single c-DNA expressed human enzymes, human liver microsomes and cytosol and CYP/FMO-specific inhibitors. Two major metabolites, FEN-sulfoxide and FEN-oxon (FOX), are formed by some CYPs although at very different levels, depending on the relative CYP hepatic content. Formation of further oxidation products and the reduction of FEN-sulfoxide back to FEN by the cytosolic aldehyde oxidase enzyme were ruled out. Comparing intrinsic clearance values, FOX formation seemed to be favored and at low FEN concentrations CYP2B6 and 1A2 are mainly involved in its formation. At higher levels, a more widespread CYP involvement was evident, as in the case of FEN-sulfoxide, although a higher efficiency of CYP2C family was suggested. Hepatic FMOs were able to catalyze only sulfoxide formation, but at low FEN concentrations hepatic FEN sulfoxidation is predominantly P450-driven. Indeed, the contribution of the hepatic isoforms FMO(3) and FMO(5) was generally negligible, although at high FEN concentrations FMO's showed activities comparable to the active CYPs, accounting for up to 30% of total sulfoxidation. Recombinant FMO(1) showed the highest efficiency with respect to CYPs and the other FMOs, but it is not expressed in the adult human liver. This suggests that FMO(1)-catalysed sulfoxidation may represent the major extra-hepatic pathway of FEN biotransformation.

Monitoring of pesticide chlorpyrifos residue in farmed fish: investigation of possible sources

Chlorpyrifos, a widely used organophosphorus insecticide having many urban and agricultural pest control uses, is one of the major pesticides detected in Taiwan fishery products. Whereas previous studies examined, this study explored possible sources of chlorpyrifos residue, particularly in farmed fish. Eight hundred fourteen samples of marketable fish were analyzed for chlorpyrifos residues. One hundred thirty-seven samples contained detectable residues, and farmed fish showed higher detection rates (23%) than wild fish. Based on the findings of all media of the eleven aquiculture farms, the existence of chlorpyrifos in the farmed fish were positively related to existence in fish feed. A study of indoor carp confirmed dietary accumulation of chlorpyrifos.

Opuntia ficus indica extract protects against chlorpyrifos-induced damage on mice liver

This original study investigates the role of Opuntia ficus indica (cactus) cladodes extract against liver damage induced in male SWISS mice by an organophosphorous insecticide, the chlorpyrifos (CPF). Liver damage was evaluated by the measure of its weight and the quantification of some biochemical parameters, such as alanine amino transferase (ALAT), aspartate amino transferase (ASAT), phosphatase alkaline (PAL), lactate dehydrogenase (LDH), cholesterol and albumin in serum by spectrophotometric techniques. The experimental approach lasted 48 h and consisted of 6 treatments of six mice each one; (1) control, (2) 10 mg/kg (b.w) CPF, (3) 10mg/kg (b.w) CPF with 100 mg/kg (b.w) cactus, (4) 150 mg/kg (b.w)CPF, (5) 150 mg/kg (b.w) CPF with 1.5 g/kg cactus, (6) 1.5 g/kg cactus. Both chlorpyrifos and cactus were administrated orally via gavages. Our results showed that CPF affects significantly all parameters studied. However, when this pesticide was administrated associated to cactus, we noticed a recovery of all their levels. In the other hand, cactus alone did not affect the studied parameters. These results allow us to conclude firstly that CPF is hepatotoxic and secondly that Opuntia ficus indica stem extract protects the liver and decreases the toxicity induced by this organophosphorous pesticide.