Mutagenic and cytotoxic potential of Endosulfan and Lambda-cyhalothrin - In vitro study describing individual and combined effects of pesticides

Excessive use of pesticides poses increased risks to non target species including humans. In the developing countries, lack of proper awareness about the toxic potential of pesticides makes the farmer more vulnerable to pesticide linked toxicities, which could lead to diverse pathological conditions. The toxic potential of a pesticide could be determined by their ability to induce genetic mutations and cytotoxicity. Hence, determination of genetic mutation and cytotoxicity of each pesticide is unavoidable to legislate health and safety appraisal about pesticides. The objective of current investigation was to determine the genotoxic and cytotoxic potential of Endosulfan（EN） and Lambda-cyhalothrin（LC）; individually and in combination. 3-（4,5-Dimethylthiazol-2-yl）-2,5-Diphenyltetrazolium Bromide（MTT） assay was utilized to determine cytotoxicity, while two mutant histidine dependent Salmonella strains（TA98, TA100） were used to determine the mutagenicity of EN and LC.Moreover, mutagenicity assay was conducted with and without S9 to evaluate the effects of metabolic activation on mutagenicity. Even though a dose dependent increase in the number of revertant colonies was detected with EN against both bacterial strains, a highly significant（p 〈 0.05） increase in the mutagenicity was detected in TA98 with S9. In comparison, data obtained from LC revealed less mutagenic potential than EN. Surprisingly,the non-mutagenic individual-concentrations of EN and LC showed dose dependent mutagenicity when combined. Combination of EN and LC synergistically induced mutagenicity both in TA98 and TA100. MTT assay spotlighted comparable dose dependent cytotoxicity effects of both pesticides. Interestingly, the combination of EN and LC produced increased reversion and cytotoxicity at lower doses as compared to each pesticide, concluding that pesticide exposure even at sub-lethal doses can produce cytotoxicity and genetic mutations, which could lead to carcinogenicity.     

Multiple metal tolerance and biosorption of cadmium by Candida tropicalis isolated from industrial effluents: glutathione as detoxifying agent

The ability of cadmium uptake by metal-resistant yeast, Candida tropicalis, from the liquid medium and wastewater was evaluated. The minimum inhibitory concentration of Cd^2?+? against C. tropicalis was 2,500 mg L^???1. The yeast also showed tolerance toward Zn^2?+? (1,400 mg L^???1), Ni^2?+? (1,000 mg L^???1), Hg^2?+? (1,400 mg L^???1), Cu^2?+? (1,000 mg L^???1), Cr^6?+? (1,200 mg L^???1), and Pb^2?+? (1,000 mg L^???1). The yeast isolate showed typical growth curves, but lag and log phases extended in the presence of cadmium. The yeast isolate showed optimum growth at 30°C and pH 8. The metal processing ability of the isolate was determined in a medium containing 100 mg L^???1 of Cd^2?+?. C. tropicalis could decline Cd^2?+? 70%, 85%, and 92% from the medium after 48, 96, and 144 h, respectively. C. tropicalis was also able to remove Cd^2?+? 40% and 78% from the wastewater after 6 and 12 days, respectively. Cd produced an increase in glutathione (GSH) and nonprotein thiol levels by 135% and 134% at 100-mg L^???1 concentration, respectively. An increase in the synthesis of GSH is involved in metal tolerance, and the presence of increasing GSH concentrations may be a marker for high metal stress in C. tropicalis. C. tropicalis, which is resistant to heavy metal ions and is adaptable to the local environmental conditions, may be employed for metal detoxification operations.     

Hydrogen sulfide ameliorates lead-induced morphological, photosynthetic, oxidative damages and biochemical changes in cotton

Poisonous lead (Pb), among heavy metals, is a potential pollutant that readily accumulates in soils and thus adversely affects physiological processes in plants. We have evaluated how exogenous H₂S affects cotton plant physiological attributes and Pb uptake under Pb stress thereby understanding the role of H₂S in physiological processes in plants. Two concentrations (0 and 200 μM) of H₂S donor sodium hydrosulfide (NaHS) were experimented on cotton plants under Pb stress (0, 50, and 100 μM). Results have shown that Pb stress decreased plant growth, chlorophyll contents, SPAD value, photosynthesis, antioxidant activity. On the other hand, Pb stress increased the level of malondialdehyde (MDA), electrolyte leakage (EL), and production of H₂O₂ and uptake of Pb contents in all three parts of plant, viz. root, stem, and leaf. Application of H₂S slightly increased plant growth, chlorophyll contents, SPAD value, photosynthesis, and antioxidant activity as compared to control. Hydrogen sulfide supply alleviated the toxic effects of lead on plant growth, chlorophyll contents, SPAD value, photosynthesis, and antioxidant activity in cotton plants. Hydrogen sulfide also reduced MDA, EL, and production of H₂O₂ and endogenous Pb levels in the three mentioned plant parts. On the basis of our results, we conclude that H₂S has promotive effects which could improve plant survival under Pb stress.     

Aquatic biomonitoring of Giardia cysts and Cryptosporidium oocysts in peninsular Malaysia

An aquatic biomonitoring of Giardia cysts and Cryptosporidium oocysts in river water corresponding to five villages situated in three states in peninsular Malaysia was determined. There were 51.3 % (20/39) and 23.1 % (9/39) samples positive for Giardia and Cryptosporidium (oo)cysts, respectively. Overall mean concentration between villages for Giardia cysts ranged from 0.10 to 25.80 cysts/l whilst Cryptosporidium oocysts ranged from 0.10 to 0.90 oocysts/l. Detailed results of the river samples from five villages indicated that Kuala Pangsun 100 % (9/9), Kemensah 77.8 % (7/9), Pos Piah 33.3 % (3/9) and Paya Lebar 33.3 % (1/3) were contaminated with Giardia cysts whilst Cryptosporidium (oo)cysts were only detected in Kemensah (100 %; 9/9) and Kuala Pangsun (66.6 %; 6/9). However, the water samples from Bentong were all negative for these waterborne parasites. Samples were collected from lower point, midpoint and upper point. Midpoint refers to the section of the river where the studied communities are highly populated. Meanwhile, the position of the lower point is at least 2 km southward of the midpoint and upper point is at least 2 km northward of the midpoint. The highest mean concentration for (oo)cysts was found at the lower points [3.15?±?6.09 (oo)cysts/l], followed by midpoints [0.66?±?1.10 (oo)cysts/l] and upper points [0.66?±?0.92 (oo)cysts/l]. The mean concentration of Giardia cysts was highest at Kuala Pangsun (i.e. 5.97?±?7.0 cysts/l), followed by Kemensah (0.83?±?0.81 cysts/l), Pos Piah (0.20?±?0.35 cysts/l) and Paya Lebar (0.10?±?0.19 cysts/l). On the other hand, the mean concentration of Cryptosporidium oocysts was higher at Kemensah (0.31?±?0.19 cysts/l) compared to Kuala Pangsun (0.03?±?0.03cysts/l). All the physical and chemical parameters did not show significant correlation with both protozoa. In future, viability status and molecular characterisation of Giardia and Cryptosporidium should be applied to identify species and genotypes/subgenotypes for better understanding of the epidemiology of these waterborne parasites.     

The global partnership for sustainable development

This paper examines whether foreign aid, together with other economic, social and environmental factors, contributes to sustainable development. It starts with an illustrative theoretical growth model where foreign aid promotes sustainable development by protecting the environment. Using factor analysis and newly developed estimation methods for a dynamic panel data model with endogenous regressors, the empirical section of the paper finds evidence that foreign aid has had a significantly positive influence on sustainable development in aid recipient countries. This effect is very likely to go through channels related to growth and resources as well as a technology channel with respect to energy intensity. This research has important implications for a post‐2015 development framework on international collective action with regard to a sustainable future.     

Cattle egrets as a biosentinels of persistent organic pollutants exposure

We investigated selected chlorinated pollutants (β-HCH, γ-HCH, DDDs, DDEs, o,p′-DDT, p,p′-DDT, heptachlor, aldrin, dieldrin, and endrin) in the Lahore and the Sialkot districts of Pakistan, using eggs of cattle egret (Bubulcus ibis) collected during May and June 2007. The pollutant with highest level and frequency was ΣDDT, followed by β-HCH, γ-HCH, heptachlor, aldrin, dieldrin, and endrin in descending order. The concentration(s) were significantly higher in Sialkot heronry for all the pollutants (except p,p′-DDT) than in Lahore. The values for DDTs, β-HCH, γ-HCH, and heptachlor were significantly higher (p < 0.05) in the egg(s) than in sediment(s) and in the chicks’ diet, due to biomagnification. Among DDTs analogues, p,p′-DDD was the major contaminant with >60 % of total DDT burden, reflecting the widespread aged as well as recent use of DDT as well as anaerobic degradation (DDD/DDE > 1 in many cases) in the nearby paddy soils. In few samples, p,p′-DDT/(DDD + DDE) > 0.5 suggested the recent emission patterns from surrounding contaminated areas of demolished DDT units and obsolete pesticide stores. The higher levels of HCHs (i.e., β-HCH) in the samples collected from Sialkot indicate exposure from long-term agricultural use. Overall, concentrations of all studied POPs were less than the threshold levels known to affect reproduction. Nevertheless, total DDTs and/or HCHs burdens in some eggs contained concentrations of greater than what would educe adverse effects on birds. This is among few studies on OCPs exposure to avian species, which provide the evidence of Pakistan’s contribution toward the Global POPs emission.     

Recycling polymeric waste from electronic and automotive sectors into value added products

The environmentally sustainable disposal and recycling of ever increasing volumes of electronic waste has become a global waste management issue. The addition of up to 25% polymeric waste PCBs (printed circuit boards) as fillers in polypropylene (PP) composites was partially successful: while the tensile modulus, flexural strength and flexural modulus of composites were enhanced, the tensile and impact strengths were found to decrease. As a lowering of impact strength can significantly limit the application of PP based composites, it is necessary to incorporate impact modifying polymers such as rubbery particles in the mix. We report on a novel investigation on the simultaneous utilization of electronic and automotive rubber waste as fillers in PP composites. These composites were prepared by using 25 wt.% polymeric PCB powder, up to 9% of ethylene propylene rubber (EPR), and PP: balance. The influence of EPR on the structural, thermal, mechanical and rheological properties of PP/PCB/ EPR composites was investigated. While the addition of EPR caused the nucleation of the β crystalline phase of PP, the onset temperature for thermal degradation was found to decrease by 8%. The tensile modulus and strength decreased by 16% and 19%, respectively; and the elongation at break increased by ~71%. The impact strength showed a maximum increase of ~18% at 7 wt.%–9 wt.% EPR content. Various rheological properties were found to be well within the range of processing limits. This novel eco-friendly approach could help utilize significant amounts of polymeric electronic and automotive waste for fabricating valuable polymer composites.

Open image in new window

     

The impact of enhanced atmospheric carbon dioxide on yield, proximate composition, elemental concentration, fatty acid and vitamin C contents of tomato (Lycopersicon esculentum)

The global average temperature has witnessed a steady increase during the second half of the twentieth century and the trend is continuing. Carbon dioxide, a major green house gas is piling up in the atmosphere and besides causing global warming, is expected to alter the physico-chemical composition of plants. The objective of this work was to evaluate the hypothesis that increased CO₂ in the air is causing undesirable changes in the nutritional composition of tomato fruits. Two varieties of tomato (Lycopersicon esculentum) were grown in ambient (400 μmol mol^?1) and elevated (1,000 μmol mol^?1) concentration of CO₂ under controlled conditions. The fruits were harvested at premature and fully matured stages and analyzed for yield, proximate composition, elemental concentration, fatty acid, and vitamin C contents. The amount of carbohydrates increased significantly under the enhanced CO₂ conditions. The amount of crude protein and vitamin C, two important nutritional parameters, decreased substantially. Fatty acid content showed a mild decrease with a slight increase in crude fiber. Understandably, the effect of enhanced atmospheric CO₂ was more pronounced at the fully matured stage. Mineral contents of the fruit samples changed in an irregular fashion. Tomato fruit has been traditionally a source of vitamin C, under the experimental conditions, a negative impact of enhanced CO₂ on this source of vitamin C was observed. The nutritional quality of both varieties of tomato has altered under the CO₂ enriched atmosphere.     

An experimental investigation into micro ball end-milling of silicon

Silicon is a representative operational material for semiconductor and micro-electronics. In certain MEMS applications, it is required to fabricate three dimensional channels and complex pattern on silicon substrate. Such features are typically fabricated by photolithography and chemical etching. These processes have low productivity and have certain other limitations. Therefore, a viable switch-over from non-traditional fabrication processes to traditional machining is highly desired for improved productivity in high-mix low-volume production. However, machining of silicon by traditional process is extremely difficult due to its high brittleness. Even very small forces produced during machining can cause brittle fracture on silicon surface resulting in deteriorated surface quality. The fundamental principle in machining of a brittle material such as silicon is to achieve material removal through plastic deformation rather than crack propagation. This paper presents the experimental results of ductile-mode machining of silicon by micro ball end-milling. The workpiece surface was inclined to the rotational axes of the cutter to improve the surface finish. It was established experimentally that 15-μm deep, fracture-free slots can be machined on silicon wafer by micro ball end-milling if the feed rate is below a certain threshold. The influence of several machining parameters on the roughness of machined-surface was also investigated. Cubic boron nitride (CBN) is presented as much economical alternative tool-material to single-crystal diamond for machining silicon in ductile-mode.