Risk assessment of glyphosate and malathion pollution and their potential impact on Oreochromis niloticus: role of organic selenium supplementation.

A field survey was conducted on five fish farms to trace glyphosate and malathion pollution with some physicochemical parameters. A precise half-life time, LC50-96h, of these agrochemicals on Oreochromis niloticus, as well as chronic exposure with organic selenium (OS) supplementation, were experimentally investigated. Oreochromis niloticus was subjected to the following: (negative control); (2 mg L-1 glyphosate); (0.5 mg L-1 malathion); (glyphosate 1.6 mg L-1 and 0.3 mg L-1 malathion); (glyphosate 2 mg L-1 and OS 0.8 g kg-1 diet); (malathion 0.5 mg L-1 and OS 0.8 g kg-1 diet) and (glyphosate 1.6 mg L-1; malathion 0.3 mg L-1 and OS 0.8 g kg-1 diet). Furthermore, data from the analyzed pond revealed a medium risk quotient (RQ) for both agrochemicals. The detected agrochemicals were related to their application, and vegetation type surrounding the farms, also their biodegradation was correlated to water pH, temperature, and salinity. Glyphosate and malathion had half-lives of 2.8 and 2.3 days and LC50-96h of 2.331 and 0.738 mg L-1, respectively. The severest nervous symptoms; increased oxidative stress markers, as well as high bacterial count in the livers and kidneys of fish challenged with Aeromonas hydrophila, were observed in the combined exposure, followed by a single exposure to malathion and then glyphosate. Organic selenium mitigated these impacts.

Assessing in vitro dermal absorption of dry residues of agrochemical sprays using human skin within OECD TG 428.

We describe a novel experimental method that mimics exposure to dried agrochemical residues on contact surfaces during re-entry into crops. It includes the creation of dry dislodgeable residues and subsequent transfer to human skin for in vitro measurement of dermal absorption within a standard Organisation for Economic Co-operation and Development test guideline (OECD TG) 428 study. A pre-determined volume of spray containing 14C-labelled active substance is transferred onto a polytetrafluorethylene-coated septum and air-dried. The septum is then gently placed onto the pre-wetted skin mounted in a flow-through Franz diffusion chamber. The septum is gently rotated thrice to transfer the dose. Preliminary tests determined transfer efficiency to ensure the appropriate test concentration on the skin. Then, a standard dermal absorption study is performed according to OECD TG 428. Results from 10 compounds indicate that the methodology can be robustly incorporated into a standard TG study. These data show that the dermal absorption from a dry dislodgeable residue is lower than that from the equivalent dose of the aqueous spray, regardless of formulation type or active substance. Studies following the scenario described above can be a suitable tool to better estimate dermal absorption from dry residues in re-entry worker and resident exposure assessment for agrochemicals.

Glycolipid biosurfactants: main properties and potential applications in agriculture and food industry.

Glycolipids, consisting of a carbohydrate moiety linked to fatty acids, are microbial surface active compounds produced by various microorganisms. They are characterized by high structural diversity and have the ability to decrease the surface and interfacial tension at the surface and interface, respectively. Rhamnolipids, trehalolipids, mannosylerythritol lipids and cellobiose lipids are among the most popular glycolipids. They have received much practical attention as biopesticides for controlling plant diseases and protecting stored products. As a result of their antifungal activity towards phytopathogenic fungi and larvicidal and mosquitocidal potencies, glycolipid biosurfactants permit the preservation of plants and plant crops from pest invasion. Also, as a result of their emulsifying and antibacterial activities, glycolipids have great potential as food additives and food preservatives. Furthermore, the valorization of food byproducts via the production of glycolipid biosurfactant has received much attention because it permits the bioconversion of byproducts on valuable compounds and decreases the cost of production. Generally, the use of glycolipids in many fields requires their retention from fermentation media. Accordingly, different strategies have been developed to extract and purify glycolipids. © 2016 Society of Chemical Industry.

Utilizing relative potency factors (RPF) and threshold of toxicological concern (TTC) concepts to assess hazard and human risk assessment profiles of environmental metabolites: a case study.

There is currently no standard paradigm for hazard and human risk assessment of environmental metabolites for agrochemicals. Using an actual case study, solutions to challenges faced are described and used to propose a generic concept to address risk posed by metabolites to human safety. A novel approach - built on the foundation of predicted human exposures to metabolites in various compartments (such as food and water), the threshold of toxicological concern (TTC) and the concept of comparative toxicity - was developed for environmental metabolites of a new chemical, sulfoxaflor (X11422208). The ultimate aim was to address the human safety of the metabolites with the minimum number of in vivo studies, while at the same time, ensuring that human safety would be considered addressed on a global regulatory scale. The third component, comparative toxicity, was primarily designed to determine whether the metabolites had the same or similar toxicity profiles to their parent molecule, and also to one another. The ultimate goal was to establish whether the metabolites had the potential to cause key effects - such as cancer and developmental toxicity, based on mode-of-action (MoA) studies - and to develop a relative potency factor (RPF) compared to the parent molecule. Collectively, the work presented here describes the toxicology programme developed for sulfoxaflor and its metabolites, and how it might be used to address similar future challenges aimed at determining the relevance of the metabolites from a human hazard and risk perspective. Sulfoxaflor produced eight environmental metabolites at varying concentrations in various compartments - soil, water, crops and livestock. The MoA for the primary effects of the parent molecule were elucidated in detail and a series of in silico, in vitro, and/or in vivo experiments were conducted on the environmental metabolites to assess relative potency of their toxicity profiles when compared to the parent. The primary metabolite, X11719474 found in soil, crops and, potentially, at low concentrations, in groundwater, was the most extensively studied, with genetic, acute, short-term rat and dog, rodent reproductive and developmental toxicity studies, and MoA studies conducted. These data supported that the toxicity profile for X11719474 was limited to liver effects via the same MoA as the parent and, overall, X11719474 was significantly less toxic than parent. Subsequently, the comparative toxicology programme was extended to cover all metabolites of sulfoxaflor. Based on structure (i.e., similarity of metabolite structures to one another), toxic effects in comparison with parent (i.e., consistency of the toxicity profiles and confidence in terms of ability to read across), residue compartment (e.g., crop, soil, water) and predicted level of exposure, fewer studies were required for establishing safety of these metabolites compared to X11719474. For example, for some metabolites with very low predicted environmental concentrations only genotoxicity testing was required. For some metabolites with low predicted concentrations, for example only present in liver, a TTC approach was utilized. This strategy of comparative assessment utilizing MoA data, relative potency, hazard characterization, read-across, predicted exposure and TTC provided a robust database, which minimized animal use, comprehensively assessed the hazard and human risk presented by these metabolites.

Genotoxic assessment in tobacco farmers at different crop times.

Agricultural workers engaged in tobacco cultivation are constantly exposed to large amounts of pesticides as well as to the nicotine present in raw tobacco leaves. Pesticides have been considered potential chemical mutagens: experimental data revealed that various agrochemicals possess mutagenic properties. Studies have affirmed that nicotine absorbed through the skin results in the characteristic green tobacco sickness (GTS), an occupational illness reported by tobacco workers. This study sought to determine genotoxic effects in farmers occupationally exposed to agrochemicals and nicotine. Peripheral blood samples were collected from 30 agricultural workers, at different crop times (off-season, during pesticides application and leaf harvest), and 30 were non-exposed. We obtained data on DNA damage detected by the Comet assay and Micronucleus test as biomarker of occupational exposure and effect. The serum cholinesterase level, which in general present relation with exposition to organophosphates and carbamates, as well as serum cotinine level, which is a metabolite of nicotine, were also evaluated. The results showed a significant increase in Damage index and frequency in tobacco farmers compared to the non-exposed group, for all different crop times; and a significant increase in micronucleated cells in the off-season group. No correlation was found between age and exposure time in relation to biomarker tests. The DNA damage was greater in males than in females, but with a significant difference only in off-season group. No difference, in cholinesterase activity, was seen among the group of farmers and non-exposed group. Elevated level of cotinine was observed in leaf harvest group. This investigation suggests increased DNA damage in all tobacco crop stages, calling attention to the significant increase during the off-season and tobacco leaf harvest.

Iron deficiency enhances bioactive phenolics in lemon juice.

BACKGROUND: This study was designed to describe the phenolic status of lemon juice obtained from fruits of lemon trees differing in iron (Fe) nutritional status. Three types of Fe(III) compound were used in the experiment, namely a synthetic chelate and two complexes derived from natural polymers of humic and lignine nature. RESULTS: All three Fe(III) compounds were able to improve the Fe nutritional status of lemon trees, though to different degrees. This Fe(III) compound effect led to changes in the polyphenol content of lemon juice. Total phenolics were decreased (∼33% average decrease) and, in particular, flavanones, flavones and flavonols were affected similarly. CONCLUSION: Iron-deficient trees showed higher phenolic contents than Fe(III) compound-treated trees, though Fe deficiency had negative effects on the yield and visual quality of fruits. However, from a human nutritional point of view and owing to the health-beneficial properties of their bioavailable phenolic compounds, the nutritional quality of fruits of Fe-deficient lemon trees in terms of phenolics was higher than that of fruits of Fe(III) compound-treated lemon trees. Moreover, diosmetin-6,8-di-C-glucoside in lemon juice can be used as a marker for correction of Fe deficiency in lemon trees.