Induction of sperm impairments in mice as a sensitive biomarker of arsenic toxicity

The ubiquitous presence of arsenic (a toxic metalloid) in our environment, particularly in our drinking water, is a serious health hazard of global concern. The present work deals with the assessment of arsenic toxicity through the analysis of induced sperm impairments in sperm head morphology and sperm count in mice at low exposures compared to the magnitude of response at high exposure levels. The animals were exposed to four doses of arsenic, ranging from lowest dose of 0.3 μg kg^?1 day^?1 (the human reference dose) to higher dose of 30 μg kg^?1 day^?1 for 15 consecutive days. The epididymal sperms were harvested after one spermatogenic cycle on the 36th day and were scored for the presence of any abnormality in their head morphology as well as changes in their count. Exposure to arsenic significantly induced, in a dose-dependent manner, increases in the frequency of sperms with abnormal head morphology from 5.12 % in control to 9.23 % in lowest dose group and 23.02 % in highest dose group. In contrast, the mean sperm counts in the epididymal wash were decreased from 6.05 million per milliliter in the control to 4.95 million per milliliter in the lowest dose group and 3.07 million in the highest dose group. The analysis of sperm impairments in mice was, therefore, found to be a highly sensitive assay to assess arsenic toxicity, exhibiting a marked male reprotoxic effect of arsenic even at its low exposure levels including the human reference dose.     

Eco-friendly PEG-based controlled release nano-formulations of Mancozeb: Synthesis and bioefficacy evaluation against phytopathogenic fungi Alternaria solani and Sclerotium rolfsii

Controlled release (CR) nano-formulations of Mancozeb (manganese-zinc double salt of N,N-bisdithiocarbamic acid), a protective fungicide, have been prepared using laboratory-synthesized poly(ethylene glycols) (PEGs)-based functionalized amphiphilic copolymers without using any surfactants or external additives. The release kinetics of the developed Mancozeb CR formulations were studied and compared with that of commercially available 42% suspension concentrate and 75% wettable powder. Maximum amount of Mancozeb was released on 42nd day for PEG-600 and octyl chain, PEG-1000 and octyl chain, and PEG-600 and hexadecyl chain, on 35th day for PEG-1000 and hexadecyl chain, on 28th day for PEG-1500 and octyl chain, PEG-2000 and octyl chain, PEG-1500 and hexadecyl chain, and PEG-2000 and hexadecyl chain in comparison to both commercial formulations (15th day). The diffusion exponent (n value) of Mancozeb in water ranged from 0.42 to 0.62 in tested formulations. The half-release (t_1/2) values ranged from 17.35 to 35.14 days, and the period of optimum availability of Mancozeb ranged from 18.54 to 35.42 days. Further, the in vitro bioefficacy evaluation of developed formulations was done against plant pathogenic fungi Alternaria solani and Sclerotium rolfsii by poison food technique. Effective dose for 50% inhibition in mgL^?1 (ED₅₀) values of developed formulations varied from 1.31 to 2.79 mg L^?1 for A. solani, and 1.60 to 3.14 mg L^?1 for S. rolfsii. The present methodology is simple, economical, and eco-friendly for the development of environment-friendly CR formulations of Mancozeb. These formulations can be used to optimize the release of Mancozeb to achieve disease control for the desired period depending upon the matrix of the polymer used. Importantly, the maximum amount of active ingredient remains available for a reasonable period after application. In addition, the developed CR formulations were found to be suitable for fungicidal applications, allowing use of Mancozeb in lower doses.     

Removal of arsenic from drinking water by chemical precipitation--a modeling and simulation study of the physical-chemical processes.

A dynamic mathematical model was developed for removal of arsenic from drinking water by chemical coagulation-precipitation and was validated experimentally in a bench-scale set-up. While examining arsenic removal efficiency of the scheme under different operating conditions, coagulant dose, pH and degree of oxidation were found to have pronounced impact. Removal efficiency of 91-92% was achieved for synthetic feed water spiked with 1 mg/L arsenic and pre-oxidized by potassium permanganate at optimum pH and coagulant dose. Model predictions corroborated well with the experimental findings (the overall correlation coefficient being 0.9895) indicating the capability of the model in predicting performance of such a treatment plant under different operating conditions. Menu-driven, user-friendly Visual Basic software developed in the study will be very handy in quick performance analysis. The simulation is expected to be very useful in full-scale design and operation of the treatment plants for removal of arsenic from drinking water.     

Purifying arsenic and fluoride-contaminated water by a novel graphene-based nanocomposite membrane of enhanced selectivity and sustained flux

Environmental Science and Pollution Research - A novel graphene-based nanocomposite membrane was synthesized by interfacial polymerization (IP) through chemical bonding of the graphene oxide (GO)...