The developmental neurotoxicity of legacy vs. contemporary polychlorinated biphenyls (PCBs): similarities and differences

Although banned from production for decades, PCBs remain a significant risk to human health. A primary target of concern is the developing brain. Epidemiological studies link PCB exposures in utero or during infancy to increased risk of neuropsychiatric deficits in children. Nonclinical studies of legacy congeners found in PCB mixtures synthesized prior to the ban on PCB production suggest that non-dioxin-like (NDL) congeners are predominantly responsible for the developmental neurotoxicity associated with PCB exposures. Mechanistic studies suggest that NDL PCBs alter neurodevelopment via ryanodine receptor-dependent effects on dendritic arborization. Lightly chlorinated congeners, which were not present in the industrial mixtures synthesized prior to the ban on PCB production, have emerged as contemporary environmental contaminants, but there is a paucity of data regarding their potential developmental neurotoxicity. PCB 11, a prevalent contemporary congener, is found in the serum of children and their mothers, as well as in the serum of pregnant women at increased risk for having a child diagnosed with a neurodevelopmental disorder (NDD). Recent data demonstrates that PCB 11 modulates neuronal morphogenesis via mechanisms that are convergent with and divergent from those implicated in the developmental neurotoxicity of legacy NDL PCBs. This review summarizes these data and discusses their relevance to adverse neurodevelopmental outcomes in humans.

     

Testicular damage after chronic exposure to carbendazim in male goats

The present investigation was aimed to determine the effect of chronic exposure of carbendazim on cellular changes in testes of male goats. The goats were randomly divided into two groups, control and treatment (N?=?7 each). The treatment group was exposed to carbendazim at the dose rate of 50?mg?kg^?1 body weight per day orally, once daily for 180 consecutive days. Testes were removed from control and experimental animals surgically on the 90th, 120th, and 180th day. On the 180th day of the treatment, a maximum number of seminiferous tubules became atrophic, and vacuolization of germinal epithelium, and sloughing of the germinal epithelium and sertoli cells was more marked as compared to days 90 and 120. Some of the seminiferous tubules were devoid of germinal cells. These pathological findings were supported by ultrathin and electron microscopic examination. On the basis of the present investigation it could be concluded that chronic exposure of carbendazim in male goats did not allow proper maturation of testis.     

Designing hydro-energy led economic growth for pollution abatement: evidence from BRICS

Environmental Science and Pollution Research - Overutilized hydro-energy production through non-sustainable mode is detrimental for both the economy and the environment. Intermittent consumption of...     

Comparison between backward probability and particle tracking methods for the delineation of well head protection areas

In this work, a deterministic and a probabilistic method for the delineation of well head protection areas are applied and compared. The deterministic method was implemented using the automatic backward particle tracking algorithm (APA, Tosco et al., Water Resour Res, 44(7):W07419, 2008). The backward probability model rests upon the backward adjoint-based model developed by Neupauer and Wilson, and allows the inclusion of dispersion in the definition of capture zones. The two methods are evaluated comparing the “advective front” of the probability protection area and the perimeter given by the particle tracking method. Furthermore, a semi-quantitative study was performed over probability protection areas, in order to evaluate the influence of dispersivity on the extent and growth rate of capture zones identified by fixed probability isolines.     

A composite polyphenol-rich extract improved growth performance,ruminal fermentation and immunity,while decreasing methanogenesis and excretion of nitrogen and phosphorus in growing buffaloes

Environmental Science and Pollution Research - The effects of a composite polyphenolic-rich extract (CPRE) on ruminal fermentation, nutrient utilisation, growth performance, excretion of nitrogen...     

Analysis of the glyphosate herbicide in water,soil and food using derivatising agents

Glyphosate is used widely to control weeds. Glyphosate is a broad spectrum, non-selective, systemic and post-emergent herbicide. Glyphosate excessive use and impact on the environment is promoting the analysis of glyphosate in water, soil and food materials. Methods to analyse glyphosate at low levels are needed because glyphosate has a short half-life due to easy microbial degradation. Glyphosate has a high polarity and solubility in water, has high binding affinity with soil and is non-volatile. The absence of chromophoric groups in the molecular structure makes the detection difficult. Therefore, detection can be achieved by derivatisation, which makes glyphosate more volatile and stable for spectroscopic analysis. Derivatisation is commonly done by alkyl chloroformates, acylating agents, 9-fluoroenylmethylchloroformate, 4-methoxybenzenesulfonylfluoride and o-phthalaldehyde. Immunosensors allow detection at microlevels. Nanocrystals and nanotechnology allow detection at nanolevels. Here, we review methods to derivatise and analyse glyphosate.     

Enhancing the efficiency of nitrogen removing bacterial population to a wide range of C:N ratio (1.5:1 to 14:1) for simultaneous C & N removal

• Simultaneous C & N removal in Methammox occurs at wide C:N ratio. • Biological Nitrogen Removal at wide C:N ratio of 1.5:1 to 14:1 is not reported. • Ammonia removal shifted from mixotrophy to heterotrophy at high C:N ratio. • Acetogenic population compensated for ammonia oxidizers at high C:N ratio. • Methanogens increase the plasticity of nitrogen removers at high C:N ratio. High C:N ratio in the wastewater limits biological nitrogen removal (BNR), especially in anammox based technologies. The present study attempts to improve the COD tolerance of the BNR process by associating methanogens with nitrogen removing bacterial (NRB) populations. The new microbial system coined as ‘Methammox’, was investigated for simultaneous removal of COD (C) and ammonia (N) at C:N ratio 1.5:1 to 14:1. The ammonia removal rate (11.5 mg N/g VSS/d) and the COD removal rates (70.6 mg O/g VSS/d) of Methammox was close to that of the NRB (11.1 mg N/g VSS/d) and the methanogenic populations (77.9 mg O/g VSS/d), respectively. The activities established that these two populations existed simultaneously and independently in ‘Methammox’. Further studies in biofilm reactor fetched a balanced COD and ammonia removal (55%–60%) at a low C:N ratio (≤2:1) and high C:N ratio (≥9:1). The population abundance of methanogens was reasonably constant, but the nitrogen removal shifted from mixotrophy to heterotrophy as the C:N ratio shifted from low (C:N≤2:1) to high (C:N≥9:1). The reduced autotrophic NRB (ammonia- and nitrite-oxidizing bacteria and Anammox) population at a high C:N ratio was compensated by the fermentative group that could carry out denitrification heterotrophically. The functional plasticity of the Methammox system to adjust to a broad C:N ratio opens new frontiers in biological nitrogen removal of high COD containing wastewaters.     

Photo-Oxidation of Sulfur Dioxide

SO₂/O₂ mixtures were photolyzed at 3130 Å and in the range 2500–4000 Å at room temperature. The only product of photolysis was SO₃. Attempts to estimate ф(S0₃) using mass spectrometry, l.R. spectroscopy and pressure change measurements were unsuccessful, because it was not possible to obtain reproducible quantitative estimates of SO₃. ф(SO₂) values were determined by monitoring the 3130 Å absorption for its concentration measurements. ф(SO₂) was independent of SO₂ (11.6 to 50.4 torr) and O₂ (50.0 to 390.6 torr) pressures. At 3130 Å, ф(SO₂) varied between 1.5 × 10^?2 and 2.2 X 10^?2. Over the integrated range 2500–4000 Å ф(SO₂) values of 2.1 X 10^?3 to 2.9 X 10^?3 were obtained. The differences in ф(SO₂) values are explained in terms of wavelength dependence of the rate constants for the two primary reactions: ¹SO₂ + SO₂ → 2SO₂(1) and ¹SO₂ + SO₂ → ³SO₂ + SO₂(2); (k₂/k₁) _{3130 Å} ≈ 10(k₂/k₁)_{2500–4000 Å}.