Pesticide consumption and productivity and the potential of IPM in Bangladesh

Determination of biochemical and histopathological changes on testicular and epididymis tissues induced by exposure to insecticide Imidacloprid during postnatal development in rats

BACKGROUND

Imidacloprid is a neonicotinoid insecticide belonging to the chloronicotinyl nitroguanidine chemical family. Toxicity of IMD for mammals in scientific studies has shown high mutagenic, immunotoxic, teratogenic and neurotoxic effects. The present study was designed to assess the toxic effects of imidacloprid (IMD) on the testicular and epididymis tissues as well as testosterone levels of neonatal male rats.

METHODS

Neonatal male rats from postnatal day (PND) 1 to PND 26 were consecutively administered with different concentrations of IMD (1, 5 and 10 mg/kg) subcutaneously. The effect of IMD on body and organ weight, lipid profile, histopathological alterations, oxidative stress and altered testosterone levels were assessed in the testis and plasma.

RESULTS

The results of body weight gain showed a significant difference in group 4 (10 mg/kg) animals as compared to the control. A significant increase in total cholesterol and triglycerides, while a decrease in high-density lipoprotein concentrations was evident. Similarly, a significant decrease in concentrations of antioxidant enzymes (CAT and SOD) among all the IMD-treated groups was evident, when compared to the control. Increased production of ROS was also noticed in the highest-dose treatment group. Further, we observed that IMD-treated rats indicated histopathological changes in the testis and epididymis along with a significant decrease in the plasma testosterone concentrations among IMI-treated groups in contrast to the control. Histological examination of the testis of IMD-treated neonatal male rats also showed decreased spermatogenesis in the treated groups when compared to the control. Furthermore, an increase in lumen diameter and a decrease in epithelial height of seminiferous tubules were also observed in IMD-treated rats in comparison with the control.

CONCLUSION

It is concluded that sub-chronic exposure to IMD in neonatal male rats may induce histopathological changes in reproductive tissues and damage normal testicular functions via inducing oxidative stress, decrease in body weight, disturbing normal blood lipid profile and testosterone concentration. IMD exposure can induce pathophysiological effects calls for further evaluation of this widely used insecticide.

Imidacloprid: Comparative toxicity, DNA damage, ROS production and risk assessment for aquatic non-target organisms

Imidacloprid is a neonicotinoid systemic insecticide used worldwide. Despite its hazardous impact on non-target organisms, few studies have been conducted concerning the potential eco-genotoxic effects in invertebrates of surface waters where this pesticide is detected from units of ng/L to tens of μg/L. The aim of the present work was to determine the acute, the sub-chronic and the chronic toxicity of imidacloprid in producers and primary consumers of the freshwater trophic chain. The organisms under investigation were the green alga Raphidocelis subcapitata, the rotifer Brachionus calyciflorus, the cladoceran crustacean Ceriodaphnia dubia and the benthic ostracod Heterocypris incongruens. In addition, potential DNA damage and ROS production were evaluated in C. dubia. Furthermore, in accordance with European guidelines, toxicological risk assessment of imidacloprid was performed for all continents considering its global occurrence in surface waters. In addition, we assessed the genotoxicological risk and median inhibition of reproduction was observed at units of mg/L for rotifers and daphnids. Algae showed the lowest level of sensitivity to the pesticide with effective concentrations from units to hundreds of mg/L. DNA lesions were marked from 7 μg/L with a significant increase in damage as concentrations increased. Chronic toxicity risk quotient values were generally below to a threshold value of 1, with no consequential environmental concern other than for the Canadian areas. On the contrary, the genotoxicological risk quotient values were found higher than the threshold value in all continents.

Does the certification of agriculture products promote the adoption of integrated pest management among apple growers in China?

Seeking effective policies for reducing chemical pesticides has recently been the focus of agricultural sustainable development. A randomly selected sample of 559 small-scale farmers on the China Loess Plateau was investigated in 2018. We analyzed the effect of certification of agricultural production on the adoption of integrated pest management (IPM) by using the Poisson regression model. The result shows that the certification of agriculture products, subsidies of integrated pest management, and the price increase of certified agriculture products significantly promote the adoption of IPM. However, government supervision in certified agriculture products does not significantly promote the adoption of IPM. The cognition of IPM acquired by farmers significantly promotes the adoption of IPM, while the age of farmers negatively affects the adoption of IPM. We suggest that the government should strengthen the certification of agriculture products and provide subsidies of the adoption of IPM for farmers who produce certified agriculture products. The market needs to guarantee a higher price of certified agro-products which the IPM are adopted. The government should strengthen supervision of certified agriculture products, promote the extension of IPM and enhance farmers' knowledge of IPM, and promote more farmers to replace chemical pesticides with IPM.

Alterations in hematological parameters and the structure of peripheral erythrocytes in Nile tilapia (Oreochromis niloticus) exposed to profenofos

The burden of pesticide use from agricultural intensification lies in the fact that pesticides may end up in aquatic ecosystems and have pernicious effects on non-target organisms, including fish. Different blood biomarkers, including hemato-biochemical indices, erythrocytic nuclear abnormalities (ENA), and erythrocytic cellular abnormalities (ECA), were observed in Nile tilapia (Oreochromis niloticus) after exposure to varying sub-lethal concentrations (0%, 5%, 10%, 20%, and 40% of 96-h LC50) of profenofos at different time intervals (7, 14, 21, and 28 days). The results revealed that glucose and white blood cell (WBC) levels significantly increased, while hemoglobin, red blood cell (RBC), and packed cell volume (PCV) significantly decreased in a time- and concentration-dependent manner. Aberrant erythrocytic morphology-derived ENA, such as nuclear degeneration, micronuclear formation, binuclear development, nuclear budding, and karyopyknosis, significantly increased with time in profenofos-exposed groups compared to controls. Between the treatment and control groups, a significant execution was discerned for teardrop and fusion type ECA. For other cellular aberrations of erythrocytes, including elongated, twin, and spindle, a significant difference appeared only at the beginning of the experiment (day 7). This study concludes that the presence of widely used profenofos in aquatic systems has a pernicious effect on Nile tilapia.

Uncertainty of pesticides in foodstuffs, associated environmental and health risks to humans-a critical case of Bangladesh with respect to global food policy

The uncertain fate and transport pathways of applied pesticides are the key hidden threats with respect to the safety and quality evaluation of foodstuffs in Bangladesh. The risk assessment of and uncertainty about applied pesticides are poorly explored due to weak regulatory systems, farmer ignorance, intensive agricultural practices, and lack of available research data on improper handling of pesticides on farming lands with poor phytosanitary management. However, increasing evidence suggests that the prevalence of pesticides in common foodstuffs is due to their uptake by crops and improper management of crop protection practices. Besides, the biotransformation of pesticides in common Bangladeshi food products is poorly understood. Several studies have reported higher concentrations of pesticides than allowed by European Union guidelines in Bangladeshi foodstuffs. However, to date, no systematic review with critical discussion on current research findings and knowledge gaps concerning fate, uncertainty, and health risks of pesticides in the foodstuffs of Bangladesh is published. Therefore, this review summarizes the findings of existing literature on pesticide residue in foodstuffs and points out the weaknesses in the regulatory system and risk assessments for highlighting the critical challenges to food safety in Bangladesh as compared to global food policy. In addition, strategies for the sustainable management of residual pesticides are also discussed.

Level of pesticides contamination in the major river systems: A review on South Asian countries perspective

Pesticides are chemical compounds used worldwide for different purposes. These chemicals are well known for their long life, high toxicity, and slow degradation process. Many developed countries including South Asian countries banned the use of pesticides for their adverse effects. However, several pesticides are found incessantly in water and soil. To highlight the recent situation of pesticide contamination in South Asian river systems, we have studied 136 relevant articles published from 2015 to 2020. Articles were gathered using several commonly available search engines and organized according to information related to river systems of South Asian countries. After thoroughly examining those research articles, we summarized that most of the river systems are contaminated by pesticides, where DDTs, HCHs, endosulfan, heptachlor, and chlorpyrifos are the key recognized compounds among them. Comparing the level of pesticides with standard guidelines, we found that the Tapi River and Chilika Lake of India are considerably more contaminated than other river basins. Multivariate analyses identified the industrial discharge and agricultural run-off of chemicals as the probable sources of pesticides in these rivers. By analyzing the amount of annual pesticide production, their use, and accordingly their considerable presence in the water systems of the South Asian countries, it is evident that the banned pesticides are used regularly by these countries and thus contaminating the environment. Therefore, the formulations of appropriate rules and their enforcement to control the manufacture and solicitation of such pesticides are an urgent need to save the environment.

Effective abatement of 29 pesticides in full-scale advanced treatment processes of drinking water: From concentration to human exposure risk

This study investigated the occurrence and removal of 29 pesticides in 4 drinking water treatment plants (DWTPs) with conventional and advanced treatment processes (i.e., ozonation + biological activated carbon, and ultrafiltration) in Shanghai, China from 2018 to 2019. The concentration levels of target pesticides in raw waters ranged from below the limit of quantification (<LOQ) to 2391.3 ng L^-1, whereas in finished waters significantly decreased to a range of <LOQ to 269 ng L^-1. The application of the advanced treatment process could effectively remove target pesticides. For example, the highest removal of isocarbophos after the advanced treatment process reached 94.6%, whereas its removal after the conventional treatment process was just 42.6%. The estimated daily intake level of target pesticides in finished water, which were pretty lower than acceptable daily intake levels in finished water, could be reduced by 67% if combining the conventional and advanced treatment processes. Although the multiple pesticides in raw waters were effectively removed by advanced treatment process, their synergistic toxic effects induced by the residual pesticides and their degradation by-products on human health deserve further attentions.

Impact of farm size on intensity of pesticide use: Evidence from China

The average amount of pesticides used per hectare in China is roughly five times of the world average. Understanding the drivers of pesticide use will help reduce excessive pesticide use in China. Using farm-level cross-sectional data, county-level and province-level panel data, this study investigates the impact of farm size on the intensity of pesticide use. The results indicate that farm size has a significant negative impact on the intensity of pesticide use. On average, a 1% increase in farm size is associated with a 0.2% decrease in pesticide use per hectare. The study suggests that promoting the development of relatively large-scale farms can reduce the intensity of pesticide use in China.

Toxic effects of fenitrothion on freshwater microcosms in Bangladesh

The organophosphate pesticide fenitrothion is widely used as an agricultural pesticide to control tiger bug in larval rearing for aquaculture. The objectives of the present study were to assess the effects of fenitrothion on certain structural (phytoplankton, zooplankton, macro-invertebrates and periphyton) and functional (organic matter decomposition) endpoints of freshwater microcosms. Fenitrothion 50 EC was applied in 12 microcosms (PVC tanks having 400 L of dechlorinated tap water) providing concentrations of 0, 25, 50 and 100 μg/L at a 4-day interval over a period of 4 weeks. Each of the experimental treatment was executed in three replicates. The results indicated the consistent significant effects for most of the species composition of zooplankton and macro-invertebrates. Univariate analysis showed a significant decrease in abundance (p < 0.05) of all identified insects (i.e. Notonecta sp., Gerris sp., Ranatra linearis and Chironomid larvae), when compared to control in all sampling days throughout the treatment period (no observed effect concentration; NOEC = < 25 μg/L). No consistent significant effects were observed for most of the phytoplankton taxa and organic matter decomposition and water quality variables (dissolved oxygen, free CO₂, pH, nitrate etc.). However, several taxa of different endpoints were found sensitive to even the lowest concentration of fenitrothion (25 μg/L). Further studies with acute and chronic conditions are recommended involving more local species exposed to < 25 μg/L of fenitrothion.

Literature Review: Global Neonicotinoid Insecticide Occurrence in Aquatic Environments

Neonicotinoids have been the most commonly used insecticides since the early 1990s. Despite their efficacy in improving crop protection and management, these agrochemicals have gained recent attention for their negative impacts on non-target species such as honeybees and aquatic invertebrates. In recent years, neonicotinoids have been detected in rivers and streams across the world. Determining and predicting the exposure potential of neonicotinoids in surface water requires a thorough understanding of their fate and transport mechanisms. Therefore, our objective was to provide a comprehensive review of neonicotinoids with a focus on their fate and transport mechanisms to and within surface waters and their occurrence in waterways throughout the world. A better understanding of fate and transport mechanisms will enable researchers to accurately predict occurrence and persistence of insecticides entering surface waters and potential exposure to non-target organisms in agricultural intensive regions. This review has direct implications on how neonicotinoids are monitored and degraded in aquatic ecosystems. Further, an improved understanding of the fate and transport of neonicotinoids aide natural resource practitioners in the development and implementation of effective best management practices to reduce the potential impact and exposure of neonicotinoids in waterways and aquatic ecosystems.

What Socio-Economic and Political Factors Lead to Global Pesticide Dependence? A Critical Review from a Social Science Perspective

Dependence on chemical pesticides has become one of the most pressing challenges to global environmental sustainability and public health. Considerable regulatory efforts have been taken to mitigate pesticide dependence, which however has resulted in a prevalent ‘managerial failure’. Massive pesticide application has generated severe genetic resistance from pests, which has in turn further aggravated pesticide dependence and thus induced agrochemical industries to develop new pesticide varieties. This review proposes to look beyond the resistance-dependence nexus and presents a comprehensive discussion about global pesticide dependence in a social science perspective, i.e., revealing the socio-economic and political factors that reinforce pesticide dependence. These factors are classified into five intertwined themes: (1) agricultural regime, (2) social process of pesticide application, (3) economic analysis, (4) politics and governance, and (5) promotional failure of alternatives. It is found that pesticide dependence is not just a technological issue in the sphere of natural sciences, but more a human-made issue, with deep-seated socio-economic and political reasons. Addressing contemporary trap of global pesticide dependence entails a full acknowledgement and comprehension of the complex and intertwined factors. Furthermore, this review identifies two major explanatory approaches underlying the extant social science literature: a structuralist approach that stresses macro-level structures such as institutions, policies and paradigms, and an individualist approach that focuses on the decision-making of farmers at the micro level. This review recognizes the limitations of the two approaches and calls for transcending the duality. This study advocates a policy framework that emphasizes alignment and coordination from multi-dimensions, multi-actors and multi-scales. For future research, collaborations between natural and social scientists, and more integrated and interdisciplinary approaches should be strengthened.

Impact of Bt Brinjal Cultivation in the Market Value Chain in Five Districts of Bangladesh

Eggplant (brinjal) is a popular vegetable that provides an important source of income for small, resource-poor Bangladeshi farmers. The biggest constraint to brinjal production is the eggplant fruit and shoot borer (EFSB). This study was conducted in 2019 in five districts in Bangladesh and examined the impacts of using genetically engineered, insect-resistant brinjal (Bt brinjal) on its value and marketing. Based on a survey of Bt and non-Bt farmers, results indicate that Bt brinjal provided an average of 19.6% higher yield and 21.7% higher revenue compared to non-Bt varieties. On a per tonne basis, the revenue benefit of using Bt brinjal was 1.7%, reflecting different levels of acceptability among trade buyers and consumers. Some were prepared to pay higher prices for Bt brinjal compared to non-Bt brinjal because the fruit was less damaged, while others paid a price discount because the Bt brinjal was not available in preferred local varieties. Labor use, expressed in 8-h days, for harvesting, grading, and packaging of Bt brinjal was 14% higher for Bt brinjal, reflecting the increased yields of Bt brinjal. 83.1% of Bt brinjal growers were satisfied with the yields obtained, and 80.6% were satisfied with the quality of fruit. This contrasts with non-Bt brinjal growers where 58.7% were satisfied with their yields and 28% indicated that a large portion of their fruit was infested, not a concern for Bt brinjal. Three-quarters of Bt brinjal growers planned to plant Bt brinjal next season because of the apparent benefits achieved of higher yields, revenue and fruit quality. Many also highlighted the benefits of reduced insecticides. Of the non-Bt growers, 39.6% had not heard of Bt brinjal. However, after hearing more about the impact of the technology, 71.4% of them indicated they planned to grow Bt brinjal next season. These findings suggest there are significant benefits of Bt brinjal and highlight the importance of making the technology available in more varieties that are suitable to local conditions and consumer preferences. Additional studies are warranted to corroborate these findings and explore in more detail the factors influencing decisions made by farmers and consumers regarding Bt brinjal.

Toxicity of the organophosphate insecticide sumithion to embryo and larvae of zebrafish

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The 24 h LC₅₀ value of sumithion for embryo was 0.235 mg L⁻¹.

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Several malformations were observed in embryos exposed to different concentrations of sumithion.

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The 24, 48 and 72 h LC₅₀ values of sumithion for larvae were 0.620, 0.475 and 0.341 mg L⁻¹, respectively.

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Different deformities were evident in the sumithion exposed larvae.

Sumithion, a synthetic organophosphate, is widely used as an agricultural insecticide and for control of tiger bug (Cicindela spp.) in larval rearing for aquaculture. An experiment was conducted to examine the effects of sumithion on embryological and larval development of zebrafish Danio rerio. Fertilized egg (n = 100) and larvae (n = 100) were exposed to six concentrations of sumithion (0, 0.1, 0.2, 0.4, 0.8 and 1.6 mg L⁻¹) in three replicates. LC₅₀ values for embryos and larvae were calculated by probit analysis. The 24 h LC₅₀ value of sumithion for embryo was 0.235 (0.079-0.428) mgL⁻¹. Increasing sumithion concentrations decreased hatching success and increased embryonic mortality. In embryos, sumithion induced several malformations including immature yolk sac, dark yolk sac, yolk sac bud, broken eggshell and notochord, unhatched eggs. Larval LC₅₀ values at 24, 48 and 72 h of various doses of sumithion exposure were 0.620 (0.436-0.963), 0.475 (0.302-0.801) and 0.341 (0.177-0.617) mgL⁻¹, respectively. Various physical deformities, including edema, notochord deformity, yolk sac damage, body arcuation, lordosis and black pigmentation on the yolk sac were evident in response to different concentrations of sumithion. The results of the current study indicate that sumithion exerts developmental toxicity to zebrafish embryos and larvae. It is expected that current findings will increase sensitivity about the toxic effect of sumithion in early development, as well the possibility of similar actions induced by other insecticides and pesticides.

Association of prenatal pesticide exposures with adverse pregnancy outcomes and stunting in rural Bangladesh

BACKGROUND

Pesticide exposure during pregnancy is thought to adversely affect fetal growth, which in turn may impact child growth, but results have been inconsistent across studies and few have explored these effects in developing countries.

OBJECTIVES

To quantify urinary concentrations of pesticide biomarkers in early pregnancy (<16 weeks' gestation), and to estimate the association of these concentrations with preterm birth, low birth weight, small for gestational age, and stunting at ~1 and 2 years of age.

METHODS

Eight pesticide biomarkers were quantified in urine collected from 289 pregnant women (aged 18-40 years) participating in a birth cohort study in Bangladesh. Anthropometry measurements were conducted on the index child at birth and approximately 1 and 2 years of age. A directed acyclic graph was used to identify minimal sufficient adjustment sets. Log-binomial regression was used to estimate the relative risk (RR) with 95% confidence intervals (CI).

RESULTS

3,5,6-trichloro-2-pyridinol (TCPY), a metabolite of chlorpyrifos and chlorpyrifos methyl, and 4-nitrophenol, a metabolite of parathion and methyl parathion, were detected in nearly all women with geometric mean (95% CI) values of 3.17 (2.82-3.56) and 18.66 (17.03-20.46) µg/g creatinine, respectively. 3-phenoxybenzoic acid (3-PBA), a non-specific metabolite of several pyrethroids, and 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPY), a diazinon metabolite, were detected in 19.8% and 16.1% of women, respectively. The remaining four pesticide biomarkers were detected in <10% of women. Women in the highest quartile of 4-nitrophenol were more than 3 times more likely to deliver preterm than women in the lowest quartile: unadjusted RR (95% CI), 3.57 (1.65, 7.73). Women in the highest quartile of 4-nitrophenol were also at increased risk of having a child born small for gestational age: RR (95% CI) adjusted for household income, maternal education, and maternal total energy and meat intake, 3.81 (1.10, 13.21). Women with detectable concentrations of IMPY were at increased risk of having a child born with low birth weight compared to women with non-detectable concentrations: adjusted RR (95% CI), 2.13 (1.12, 4.08). We observed no association between any of the pesticide biomarkers and stunting at 1 or 2 years of age.

DISCUSSION

Exposure to the insecticides parathion and diazinon during early pregnancy may increase the risk of adverse birth outcomes.

Development of Microalgae Biosensor Chip by Incorporating Microarray Oxygen Sensor for Pesticides Sensing

A microalgae (Pseudokirchneriella subcapitata) biosensor chip for pesticide sensing has been developed by attaching the immobilized microalgae biofilm pon the microarray dye spots (size 100 μm and pitch 200 μm). The dye spots (ruthenium complex) were printed upon SO₃-modified glass slides using a polydimethylsiloxane (PDMS) stamp and a microcontact printer (μCP). Emitted fluorescence intensity (FI) variance due to photosynthetic activity (O₂ production) of microalgae was monitored by an inverted fluorescent microscope and inhibition of the oxygen generation rate was calculated based on the FI responses both before and after injection of pesticide sample. The calibration curves, as the inhibition of oxygen generation rate (%) due to photosynthetic activity inhibition by the pesticides, depicted that among the 6 tested pesticides, the biosensor showed good sensitivity for 4 pesticides (diuron, simetryn, simazine, and atrazine) but was insensitive for mefenacet and pendimethalin. The detection limits were 1 ppb for diuron and 10 ppb for simetryn, simazine, and atrazine. The simple and low-cost nature of sensing of the developed biosensor sensor chip has apparently created opportunities for regular water quality monitoring, where pesticides are an important concern.

Potential Allelopathic Candidates for Land Use and Possible Sustainable Weed Management in South Asian Ecosystem

Weed management is one of the significant challenges of field crops since weeds pose a remarkable threat to crop productivity in South Asian countries, including Bangladesh. Allelopathy, a phenomenon whereby secondary metabolites produced and released by one plant species influence the growth and development of other species can be exploited in sustainable management. The focus of this study was to evaluate potential allelopathic plant species which can be further explored as alternatives to synthetic herbicides or incorporated as part of integrated weed management in sustainable agriculture. Two hundred fifty-two plant samples from 70 families were collected from Bangladesh and evaluated with the sandwich bioassay. Thirty-one percent of the samples showed significant allelopathic potential on lettuce radicle elongation. Among the species that showed substantial inhibition, more than 7% of the samples showed higher inhibition (HI) and 25% showed moderate inhibition (MI) on lettuce radicle. Fruit pulps of Couroupita guianensis (95.4%), fruits of Phyllanthus emblica (95.4%), and Acacia concinna (95.4%) showed the highest inhibition on lettuce radicle elongation. In contrast, the leaf of Bombax insigne had growth promoting activity by stimulating radicle (23%) and hypocotyl (80%) elongation of lettuce seedlings. This result suggested that the species with significant plant growth inhibitory potential may play a vital role as an alternative to the increasing use of synthetic herbicides for sustainable weed management in agricultural land.

Environmental monitoring and risk assessment of organophosphate pesticides in aquatic ecosystems of north-west Bangladesh

The use of organophosphate pesticides (OPPs) to protect a variety of crops has increased in Bangladesh. OPPs may contaminate surrounding aquatic environments through several routes including spray drift, surface runoff and groundwater leaching. Since it is unknown how much OPP end ups in aquatic environment in Bangladesh, the objectives of the present study were to quantify the residues of ten most commonly used OPPs in water and sediment of water bodies of north-west Bangladesh and to assess their ecological risks for aquatic organisms. The risks of the pesticides in surface water and sediment were assessed using a first-tier risk quotient (RQ) approach. The higher-tier PERPEST model was used to refine the ecological risks of pesticides when RQ indicated a potential risk. Results showed the most frequently detected pesticides that appeared in high concentrations were chlorpyrifos, diazinon and quinalphos in surface water and sediment. The highest concentration of OPPs measured in water was 9.1 μg chlorpyrifos/L (median of 1.95 μg/L), while this was 51 μg diazinon/kg dw (median of 11 μg/kg dw) for sediment. Furthermore, results showed high acute and/or chronic RQs (RQ > 1) in surface water and sediment for chlorpyrifos, diazinon, quinalphos, malathion and fenitrothion. The higher-tier PERPEST model confirmed risks of chlorpyrifos, diazinon, quinalphos and fenitrothion for aquatic insects, micro- and macro-crustaceans which were previously derived by RQ-based risk assessment for aquatic organisms. Furthermore, the results of the PERPEST model also indicated possible indirect effects of these pesticides on algae and macrophytes, community metabolism, rotifers and other macro-invertebrates.

Study of chemical composition and nutritional values of vegetable wastes in Bangladesh

The present study was conducted with the objectives of determining the chemical composition and nutritional value of vegetable waste (VW) of households and the marketplace for their suitability as ruminant feed. The crude protein, total digestible nutrients and extent of rumen degradability of dry matter (DM) of VW of households were 140.0 g kg-1, 0.668 and 0.855, respectively; while those of the marketplace were 169.0 g kg-1, 0.633 and 0.80, respectively. The levels of chromium and lead in each respectively, was 13.27 and 1.53 ng kg-1DM; and 31.01 and 5.71 ng kg-1DM. The total aflatoxins in VW of households was 3.08 µg kg-1DM, and undetectable in VW from the marketplace. Considering the chemical composition and safety parameters studied, VW could preliminary be considered as animal feed. The feeding of processed marketplace VW (VWP) at 275 g kg-1DM of a diet or 0.76% of live weight (LW) to growing bulls, replacing 50% of a concentrate mixture as supplement to a Napier silage diet for a period of 34 days reduced the total DM intake (0.0276 vs 0.0343 LW) without any significant (P > 0.05) changes in DM or protein digestibility. Blood urea levels (19.5 vs 23.67 mg dl-1), and serum creatinine levels (1.37 vs 1.08 mg dl-1) differed significantly (P > 0.05) between the two groups but were within normal physiological ranges. Therefore, it may be concluded that the level of incorporation of VWP would be less than 50% replacement of the concentrate in the diet. Further research is required to determine optimum inclusion levels in ruminant diets.

Effects of imidacloprid on the ecology of sub-tropical freshwater microcosms

The neonicotinoid insecticide imidacloprid is used in Bangladesh for a variety of crop protection purposes. Imidacloprid may contaminate aquatic ecosystems via spray drift, surface runoff and ground water leaching. The present study aimed at assessing the fate and effects of imidacloprid on structural (phytoplankton, zooplankton, macroinvertebrates and periphyton) and functional (organic matter decomposition) endpoints of freshwater, sub-tropical ecosystems in Bangladesh. Imidacloprid was applied weekly to 16 freshwater microcosms (PVC tanks containing 400 L de-chlorinated tap water) at nominal concentrations of 0, 30, 300, 3000 ng/L over a period of 4 weeks. Results indicated that imidacloprid concentrations from the microcosm water column declined rapidly. Univariate and multivariate analysis showed significant effects of imidacloprid on the zooplankton and macroinvertebrate community, some individual phytoplankton taxa, and water quality variables (i.e. DO, alkalinity, ammonia and nitrate), with Cloeon sp., Diaptomus sp. and Keratella sp. being the most affected species, i.e. showing lower abundance values in all treatments compared to the control. The observed high sensitivity of Cloeon sp. and Diaptomus sp. was confirmed by the results of single species tests. No significant effects were observed on the species composition of the phytoplankton, periphyton biomass and organic matter decomposition for any of the sampling days. Our study indicates that (sub-)tropical aquatic ecosystems can be much more sensitive to imidacloprid compared to temperate ones.

Farmers' Willingness to Pay for Health Risk Reductions of Pesticide Use in China: A Contingent Valuation Study

This study aimed to estimate farmers' willingness to pay (WTP) for health risk reductions of pesticide use by applying the contingent valuation method (CVM) and to explore the factors that influence farmers' WTP in China. In total, 244 farmers were randomly selected and interviewed. The mean WTP was estimated to be $65.38 (0.94% of total household income) per household per year for a 5/10,000 reduction in morbidity risk. This study shows that farmers' socioeconomic and attitudinal factors that significantly affect their WTP include farmers' farming income, education, household size and risk perceptions. In particular, the results demonstrate that respondents' social trust, social reciprocity and social networks have significant impacts on their WTP. The findings of this study can provide useful insights for policy makers to design effective policies to address health problems related to pesticide use in the developing world.

Integrative Application of Life Cycle Assessment and Risk Assessment to Environmental Impacts of Anthropogenic Pollutants at a Watershed Scale

Intense human activities have led to increasing deterioration of the watershed environment via pollutant discharge, which threatens human health and ecosystem function. To meet a need of comprehensive environmental impact/risk assessment for sustainable watershed development, a biogeochemical process-based life cycle assessment and risk assessment (RA) integration for pollutants aided by geographic information system is proposed in this study. The integration is to frame a conceptual protocol of "watershed life cycle assessment (WLCA) for pollutants". The proposed WLCA protocol consists of (1) geographic and environmental characterization mapping; (2) life cycle inventory analysis; (3) integration of life-cycle impact assessment (LCIA) with RA via characterization factor of pollutant of interest; and (4) result analysis and interpretation. The WLCA protocol can visualize results of LCIA and RA spatially for the pollutants of interest, which might be useful for decision or policy makers for mitigating impacts of watershed development.

Gender differences in pesticide use knowledge, risk awareness and practices in Chinese farmers

This study investigates gender differences in the pesticide use knowledge, risk awareness and practices of farmers in Anqiu County, China. A total of 452 male and 178 female farmers from seven towns were interviewed in 2016. The results show that there are gender differences regarding knowledge of pesticide impacts, pesticide use practices and protective behaviors. Male farmers had a better knowledge of pesticide use and greater awareness of associated health risks. More men than women used pesticides and disposed of the pesticide containers correctly, but fewer men applied protective measures or behaviors when using pesticides. Canonical correspondence analysis indicated that participation in farmer professional cooperatives differed by gender and contributed greatly to the protective behaviors of farmers (p<0.05). These results suggest that gender-sensitive educational programs should be implemented to increase the awareness of safety amongst farmers, and protective measures should be encouraged to reduce exposure to pesticide risks in China.

Acute toxicity of chlorpyrifos to embryo and larvae of banded gourami Trichogaster fasciata

This study elucidated the acute toxicity of chlorpyrifos on the early life stages of banded gourami (Trichogaster fasciata). To determine the acute effects of chlorpyrifos on their survival and development, we exposedthe embryos and two-day-old larvae to six concentrations (0, 0.01, 0.10, 1.0, 10 and 100 µg L^-1) of chlorpyrifos in plastic bowls. Log-logistic regression was used to calculate LC10 and LC50 values. Results showed that embryo mortality significantly increased with increasing chlorpyrifos concentrations. The 24-h LC10 and LC50 values (with 95% confidence limits) of chlorpyrifos for embryos were 0.89 (0.50-1.58) and 11.8 (9.12-15.4) µg L^-1, respectively. Hatching success decreased and mortality of larvae significantly increased with increasing concentrations of chlorpyrifos. The 24-h LC10 and LC50 values (with 95% confidence limits) of chlorpyrifos for larvae were 0.53 (0.27-1.06) and 21.7 (15.9-29.4) µg L^-1, respectively; the 48-h LC10 and LC50 for larvae were 0.04 (0.02-0.09) and 5.47 (3.77-7.94) µg L^-1, respectively. The results of this study suggest that 1 µg L^-1 of chlorpyrifos in the aquatic environment may adversely affect the development and the reproduction of banded gourami. Our study also suggests that banded gourami fish can serve as an ideal model species for evaluating developmental toxicity of environmental contaminants.

Pesticide Use and Risk Perceptions among Small-Scale Farmers in Anqiu County, China

The unsafe use and misuse of pesticides in China are major threats to farmers’ health and the environment. The purpose of this study is to evaluate small-scale farmers’ practices with regard to pesticide use and identify the determinants of their behavior in Anqiu County, China. The results show that the frequency of pesticide application by local farmers is high and that the improper disposal of pesticides after use is common in the study area. Although most farmers felt that they were at some degree of risk when using pesticides, farmers were found to overuse pesticides in the study area. The probability of pesticide overuse significantly decreased with farmers’ risk perceptions, willingness to reduce pesticide use, better social relationships, and strict government monitoring. The perception of risk can thus be an important element in education and communication efforts.

Risk assessment of pesticides used in rice-prawn concurrent systems in Bangladesh

The objectives of the current study were to determine the occupational health hazards posed by the application of pesticides in rice-prawn concurrent systems of south-west Bangladesh and to assess their potential risks for the aquatic ecosystems that support the culture of freshwater prawns (Macrobrachium rosenbergii). Information on pesticide use in rice-prawn farming was collected through structured interviews with 38 farm owners held between January and May of 2012. The risks of the pesticide use to human health were assessed through structured interviews. The TOXSWA model was used to calculate pesticide exposure (peak and time-weighted average concentrations) in surface waters of rice-prawn systems for different spray drift scenarios and a simple first tier risk assessment based on threshold concentrations derived from single species toxicity tests were used to assess the ecological risk in the form of risk quotients. The PERPEST model was used to refine the ecological risks when the first tier assessment indicated a possible risk. Eleven synthetic insecticides and one fungicide (sulphur) were recorded as part of this investigation. The most commonly reported pesticide was sulphur (used by 29% of the interviewed farmers), followed by thiamethoxam, chlorantraniliprole, and phenthoate (21%). A large portion of the interviewed farmers described negative health symptoms after pesticide applications, including vomiting (51%), headache (18%) and eye irritation (12%). The results of the first tier risk assessment indicated that chlorpyrifos, cypermethrin, alpha-cypermethrin, and malathion may pose a high to moderate acute and chronic risks for invertebrates and fish in all evaluated spray drift scenarios. The higher tier assessment using the PERPEST model confirmed the high risk of cypermethrin, alpha-cypermethrin, and chlorpyrifos for insects and macro- and micro-crustaceans thus indicating that these pesticides may have severe adverse consequences for the prawn production yields.

Impacts of soil and water pollution on food safety and health risks in China

Environmental pollution and food safety are two of the most important issues of our time. Soil and water pollution, in particular, have historically impacted on food safety which represents an important threat to human health. Nowhere has that situation been more complex and challenging than in China, where a combination of pollution and an increasing food safety risk have affected a large part of the population. Water scarcity, pesticide over-application, and chemical pollutants are considered to be the most important factors impacting on food safety in China. Inadequate quantity and quality of surface water resources in China have led to the long-term use of waste-water irrigation to fulfill the water requirements for agricultural production. In some regions this has caused serious agricultural land and food pollution, especially for heavy metals. It is important, therefore, that issues threatening food safety such as combined pesticide residues and heavy metal pollution are addressed to reduce risks to human health. The increasing negative effects on food safety from water and soil pollution have put more people at risk of carcinogenic diseases, potentially contributing to 'cancer villages' which appear to correlate strongly with the main food producing areas. Currently in China, food safety policies are not integrated with soil and water pollution management policies. Here, a comprehensive map of both soil and water pollution threats to food safety in China is presented and integrated policies addressing soil and water pollution for achieving food safety are suggested to provide a holistic approach.

Electrochemical oxidation of imazapyr with BDD electrode in titanium substrate

In this work we have studied the treatment of imazapyr by electrochemical oxidation with boron-doped diamond anode. Electrochemical degradation experiments were performed in a one-compartment cell containing 0.45 L of commercial formulations of herbicide in the pH range 3.0-10.0 by applying a density current between 10 and 150 mA cm(-2) and in the temperature range 25-45 °C. The maximum current efficiencies were obtained at lower current densities since the electrochemical system is under mass transfer control. The mineralization rate increased in acid medium and at higher temperatures. The treatment was able to completely degrade imazapyr in the range 4.6-100.0 mg L(-1), although the current charge required rises along with the increasing initial concentration of the herbicide. Toxicity analysis with the bioluminescent bacterium Vibrio fischeri showed that at higher pollutant concentrations the toxicity was reduced after the electrochemical treatment. To clarify the reaction pathway for imazapyr mineralization by OH radicals, LC-MS/MS analyses we performed together with a theoretical study. Ions analysis showed the formation of high levels of ammonium in the cathode. The main final products of the electrochemical oxidation of imazapyr with diamond thin film electrodes are formic, acetic and butyric acids.