The hydrolysis and photolysis rates of nitrapyrin in dilute aqueous solution

The hydrolysis rate of nitrapyrin (2-chloro-6-(trichloromethyl)pyridine), the active ingredient of N-SERVE® nitrogen stabilizer (a registered trademark of The Dow Chemical Company, Midland, Michigan), in buffered, distilled water followed simple first-order kinetics over the concentration range, 6.2×10^?7 to 8.7×10^?5 M. The only product of the reaction was 6-chloropicolinic acid. The rate of the reaction decreased with increasing buffer concentration at 35°C (M buffer concentration-half-life): 0.005M ? 1.7 days, 0.02M?2.0 days, 0.067M?4.0 days. The ramifications of this negative salt effect are discussed. The hydrolysis rate was independent of pH over the range, 3.2 to 8.4. Additional data were obtained for rates at 25° and 45°C. The activation energy for the reaction under these conditions was 25.0 kcal/mole. Photolysis of nitrapyrin at 25°C in 0.005M phosphate buffers at pH 5.1, 7.1, 8.0, and in a natural water also followed simple first-order kinetics over the nitrapyrin concentration range, 7.1×10?6 to 7.5×10?6M. Again, there was no observable pH effect on the rate over the pH range investigated, nor was there a rate enhancement in the natural water. The half-life of the reaction under these conditions was 0.5 day. The products of this reaction were 6-chloropicolinic acid (6-C1PA), 6-hydroxypicolinic acid (6-OHPA), and unidentified polar material formed in that order in a series of sequential reactions. Simulation of the set of sequential reactions using determined first-order rate constants at 25°C and a starting concentration of 1.7 ppm predicts that nitrapyrin will be half gone in 0.5 day, that the concentration of 6-ClPA will peak at 1.3 ppm in 1.8 days, and that the concentration of 6-OHPA will peak at 0.2 ppm in 3.7 days.     

Environmental Monitoring and Health Risk Assessment of African Catfish Clarias gariepinus (Burchell, 1822) Cultured in Rural Ponds, India

Water quality monitoring of Clarias gariepinus culture ponds (n?=?27) revealed poor physico-chemical conditions and metal contaminants in fish tissues (n?=?324). Human health risk assessment for some heavy metal contamination delineated low risk in general except for Aluminium (Al), Iron (Fe) and Lead (Pb) which accumulated significantly (p?<?0.05) high in tissues. Health risks values were 6.3?×?10^?3–9.6?×?10^?3 for Al; 3?×?10^?3–9.7?×?10^?3 for Fe and 1.15?×?10^?5–9.3?×?10^?6 for Pb respectively suggesting that contamination of Pb particularly in ponds fed with chicken waste (CW) was posing high risks.     

Genotoxicity of Fenpropathrin and Fenitrothion on Root Tip Cells of <Emphasis Type="Italic">Vicia faba</Emphasis>

The genotoxicity of fenpropathrin and fenitrothion on root tip cells of Vicia faba was studied. The symptoms were investigated about the mitotic index, the micronucleus frequency and chromosomal aberration frequency of root tip cells of Vicia faba which were induced by different concentrations of fenpropathrin and fenitrothion (1 × 10⁻¹⁰–1 × 10⁻² g L⁻¹). Results showed that fenpropathrin and fenitrothion could induce the micronucleus of root tip cells of Vicia faba. It occurred in a dose-dependent manner. Peaks were observed at 1 × 10 ⁻⁶ g L⁻¹ fenpropathrin and 1 × 10⁻⁴ g L⁻¹ fenitrothion, and micronucleus frequency reached 14.587 ± 1.511‰ and 14.164 ± 1.623‰, respectively. From 1 × 10⁻¹⁰ g L⁻¹ to 1 × 10 ⁻⁶ g L⁻¹ fenpropathrin and 1 × 10⁻⁴ g L⁻¹ fenitrothion, the micronucleus frequency increased with the increase of the concentrations, but beyond this range, the micronucleus frequency decreased with the further increase of the concentrations. A similar trend was observed for mitotic index. Moreover, fenpropathrin and fenitrothion could induce various types of chromosome aberration, such as lagging chromosomes, chromosome fragment, chromosome bridge, multipolar, nuclear buds, karyorrhexis, etc.     

Health Risk Assessment Related to Dermal Exposure of Chlorpyrifos: A Case Study of Rice Growing Farmers in Nakhon Nayok Province,Central Thailand

To date, pesticides, especially organophosphate pesticide such as chlorpyrifos, have been frequently applied to paddy fields over time to maintain product quality, protect agricultural crops from various pests, and increase yield. This study evaluates dermal exposure to chlorpyrifos in rice farmers along with providing a health risk assessment. Thirty-five rice farmers participated and completed an in-person interview, and patch technique was used to evaluate dermal exposure to chlorpyrifos. The chlorpyrifos residue was extracted from the gauze patches and quantified by gas chromatography equipped with flame photometric detector (GC-FPD). The results showed that chlorpyrifos concentrations were greater in males (526.34 ± 478.84 mg/kg) than females (500.75 ± 595.15 mg/kg). Average daily dose sampled from seven points on male and female farmers were 31.72 × 10^?4, 193.32 × 10^?4, 5.38 × 10^?4, 190.48 × 10^?4, 170.47 × 10^?4, 465.91 × 10^?4, and 43.04 × 10^?4 mg/kg-day. The hazard quotient (HQ) at the mean and 95th percentile level was found to be greater than acceptable (HQ > 1). Rice-growing farmers in this area may be at risk for adverse health effects due to continuous dermal exposure to chlorpyrifos from their improper use of personal protective equipment (PPE).     

Effect of Soil Type,Moisture and Temperature on the Dissipation of Penoxsulam in Soil Under Laboratory Conditions

A study was performed for phyto-genotoxic assay of chromium (Cr) and arsenic (As) through Allium cepa. Various concentrations (0, 1, 3, 6 and 12 mg L^?1) of Cr and As for 48 and 168 h time points exposed to A. cepa. The phytotoxic effects of metal(loid) were evident through inhibited root length and root protein. Metal(loid) toxicity also lead to genotoxic effects, which included depression of mitotic index and increased frequency of chromosomes aberrations like break, fragments, c-metaphase, multipolar arrangements etc. Genotoxic endpoint as progressive frequency of micronuclei in interphase of root meristem cells in treated plants was also observed. This genotoxic endpoint revealed carcinogenic nature of both aforementioned metal(loid). Along with inhibition in root length and protein content, depression in mitotic index as well as stimulation of various abnormality in mitotic cell division indicated that both metal(loid) are hazardous in nature and causing harmful effect on the environment.     

Structural damage to leaf chloroplasts of Elodea densa caused by methylmercury accumulated from water

Elodea densa plants exposed to low levels of methylmercury in water (7.5 × 10^?10 M) accumulate sufficient methylmercury within 25 days to severely damage the surface membrane and the internal structure of the leaf chloroplast.     

The hydrolysis rate of chlorpyrifos,O-O-diethylO-(3,5,6-trichloro-2-pyridyl) phosphorothioate,and its dimethyl analog,chlorpyrifos-methyl,in dilute aqueous solution

The hydrolysis rate of chlorpyrifos (the active ingredient of DURSBAN® and LORSBAN® insecticides, registered trademarks of The Dow Chemical Company, Midland, Michigan) in water followed simple first-order kinetics over the concentration range, 3×10^?9 to 3×10^?7 M. In buffered distilled water at 25°C and pH 8.1, 6.9, and 4.7, the half-life was 22.8, 35.3, and 62.7 days, respectively. Additional data were obtained for rates at 15° and 35°C. The activation energy for the reaction under these conditions was 21.2 kcal/mole. A 16-fold rate enhancement was demonstrated in canal and pond water at 25°C. Likewise, there was a catalytic effect on the hydrolysis rate in the presence of copper (II) ion. The same information was generated for chlorpyrifos-methyl, the dimethyl analog of chlorpyrifos. In this case, the corresponding half-life values for hydrolysis at 25°C and pH 7.8, 6.7, and 4.2 were 12.7, 17.4, and 22.8 days, respectively. The activation energy was 20.8 kcal/mole, not significantly different from that for chlorpyrifos. A hydrolysis rate enhancement also occurred for chlorpyrifos-methyl in canal water. Qualitatively, the products of chlorpyrifos hydrolysis were 3,5,6-trichloro-2-pyridinol (I),O-ethylO-hydrogenO-(3,5,6-trichloro-2-pyridyl) phosphorothioate (II), andO, O-dihydrogenO-(3,5,6-trichloro-2-pyridyl) phosphorothioate (III). In the case of chlorpyrifos-methyl, the hydrolysis products were compound I and the methyl analog of compound II.     

The effects of arsenic compounds on human and bovine lymphocyte mitogenesis in vitro

The response of human and bovine peripheral blood lymphocytes to PHA stimulation was measured in the presence of low concentrations of sodium arsenite and sodium arsenate. In bovine lymphocytes, 41% augmentation of the response occurred at 10^?6m arsenite with a return to the normal response at 2.5 × 10^?6m. Complete inhibition of mitogenesis occurred at 6 × 10^?6m. In the presence of sodium arsenate, similar results were obtained but at the higher concentrations of 2 × 10^?5 (for 57% augmentation), 5.2 × 10^?5, and 1.9 × 10^?4m, respectively. The possible significance of these findings in view of the known relationship between chronic arsenicalism and human skin cancer is discussed. It is suggested that arsenic compounds may, by potentiating mitogenesis, increase the possibility of errors in DNA replication, some of which could be potentially carcinogenic. Additionally, interference with the immune response could enable potentially cancerous cells to escape immune surveillance.     

Heavy Rare Earth Elements Affect <Emphasis Type="Italic">Sphaerechinus granularis</Emphasis> Sea Urchin Early Life Stages by Multiple Toxicity Endpoints

Heavy rare earth elements (HREEs) were tested for adverse effects to early life stages of the sea urchin Sphaerechinus granularis. Embryos were exposed to analytically measured HREE concentrations ranging from 10^?7 to 10^?5 M. No significant developmental defect (DD) increases were observed in embryos exposed to 10^?7 M HREEs, whereas 10^?5 M HREEs resulted in significant DD increase up to 96% for HoCl₃ versus 14% in controls. Embryos exposed to 10^?6 M HREEs showed the highest DD frequency in embryos exposed to 10^?6 M DyCl₃ and HoCl₃. Cytogenetic analysis of HREE-exposed embryos revealed a significant decrease in mitotic activity, with increased mitotic aberrations. When S. granularis sperm were exposed to HREEs, the offspring of sperm exposed to 10^?5 M GdCl₃ and LuCl₃ showed significant DD increases. The results warrant investigations on HREEs in other test systems, and on REE-containing complex mixtures.     

Repeated dose toxicity evaluation of a cold chain-free,live, attenuated oral cholera vaccine in Sprague Dawley rats

The repeated dose toxicity of a prototype cold chain-free, live, attenuated oral cholera vaccine containing 5?×?10⁶?CFU/mL of the VCUSM14P strain was evaluated in Sprague Dawley (SD) rats (single dose administered daily for 30?days) to ascertain its safety for clinical use. Repeated dose toxicity studies for cholera vaccines in the literature have administered 2 or 3 fixed doses at 7, 14, 21 or 69?day intervals. The present study reports an evaluation of 30 repeated doses of cholera vaccine administered at three different concentrations (Group II (1.25?×?10⁶?CFU), Group III (2.5?×?10⁶?CFU) and Group IV (5?×?10⁶?CFU)) in SD rats. The liquid vaccine was administered orally to the rats with the respective dose every day, and normal saline was administered to the control group (Group I). No significant difference (P?>?0.05) was observed in the body weights and biochemical parameters of the rats after 15 and 30 repeated doses compared to those of the control group. However, compared to those of Group I, a significant increase (P?<?0.05) in the organ to body weight ratios of the lungs, ureter, liver, kidney, heart and spleen was found in G-II, G-III and G-IV. In the haematological analysis, a significant increase in the WBC was observed in G-II and G-IV compared to that in G-I. The histopathological findings indicated mild to moderate degeneration in the liver, kidney, heart and spleen in the treated rats. Mild to moderate lymphocytic infiltration in the lungs was observed in the G-II and G-III rats, and severe infiltration was observed in the G-IV rats. These histopathological findings may be attributed to the 30 doses of vaccine given in daily succession without an interval. In the acute toxicity study, a single dose of vaccine up to 10?×?10⁶?CFU did not cause any adverse effects and lethality in SD rats.     

Heavy Metal Contamination in the Cultivated Oyster <Emphasis Type="Italic">Crassostrea rivularis</Emphasis> and Associated Health Risks from a Typical Mariculture Zone in the South China Sea

With the rapid development of mariculture in potentially contaminated regions in China and the world, food safety, is a growing concern. To evaluate heavy metals and their associated health risks in the cultivated oyster Crassostrea rivularis, the concentrations of heavy metals (Cd, Cr, Pb, Zn) in oysters and water/sediment were examined in a typical mariculture environment (Kaozhou Bay, South China Sea). Trends in the seasonal dynamics of heavy metals in oysters revealed a potential synergistic effects among the concentrations of Cd, Cr, and Zn; trends associated with Pb were less clear, although the ability of oysters to bioaccumulate and depurate Pb was excellent. Bioconcentration factors (BCF) indicated that C. rivularis has a strong ability to accumulate heavy metals, and the BCF was the highest for Zn (2.32?×?10⁵), followed by Cd (6.84?×?10⁴), Pb (2.77?×?10⁴) and Cr (1.23?×?10³) through the four seasons. Results showed that Cd concentrations in oysters could pose a risk to human health (HQ?>?1). This study, therefore, suggests that there are potential human health risks due to heavy metal exposure through the consumption of C. rivularis from mariculture zones in South China Sea.     

Effect of reserpine on fertilizing capacity of human spermatozoa

The effect of reserpine at various concentrations (2 × 10^?6, 2 × 10^?7, 2 × 10^?8, 2 × 10^?9 and 2 × 10^?10M) on the in vitro fertilizing capacity of human spermatozoa was studied. Spermatozoa collected from presumably fertile men were washed in BWW medium and incubated with different concentrations of reserpine for 5 hr before insemination of the zona-free hamster ova. The spermatozoal penetration of the zona-free hamster ova was scored 6 hr later and the results were analyzed statistically. Reserpine, at all the concentrations tested, caused a significant dose-dependent decrease in the penetration of the denuded hamster ova in comparison to the control (p <0.05). The percent motility of spermatozoa decreased as a function of time during the preincubation period to initiate spermatozoal capacitation but there were no significant differences in the values between the control and the reserpine — treated spermatozoa (p >0.05). These findings indicate that reserpine can affect the fertilizing capacity of human spermatozoa in vitro and provide an additional evidence to suggest the prospective use of reserpine as a vaginal contraceptive.     

Effects of dieldrin on the uptake and metabolism of testosterone-1,2-3H by rodent sex accessory organs

The oral administration of dieldrin (1.25, 2.50, or 5.00 mg/kg daily × 5) significantly reduced the total uptake and subsequent metabolism of labeled androgens in the mouse anterior prostate gland. The in vivo metabolism of testosterone-1,2-³H to dihydrotestosterone-³H (DHT-³H), androstanediol-³H, or androstenedione-³H by the mouse prostate gland was lowered by pretreatment with dieldrin. Similarly, the in vitro metabolism of testosterone-1,2-³H to these aforementioned radiometabolites was reduced by dieldrin at a treatment level of 5 mg/kg (daily × 5). This highest-dose regimen also reduced the formation of the metabolites of testosterone in mouse hepatic microsomes. Varying concentrations of dieldrin (4 × 10^?7, 4 × 10^?6, or 2 × 10^?5m) in vitro effectively decreased the formation of DHT-H³ in the mouse anterior prostate gland and of androstanediol-³H in the rat ventral prostate gland.     

Effects of Water pH on Life History Parameters of a New Bosminid Cladocera: <Emphasis Type="Italic">Bosmina (Bosmina) Tripurae</Emphasis> (Korinek,Saha and Bhattachaya, 1999) in Laboratory Condition

The effects of water pH on life history parameters of Bosmina tripurae have been studied to determine the most suitable water pH desired for the maximum growth and development of this newly discovered cladoceran species. The study was carried out under the laboratory condition at 20?±?2°C. Five pH ranges 5.0?±?0.2, 6.0?±?0.2, 7.0?±?0.2, 8.0?±?0.2 and 9.0?±?0.2 with six replicates for each pH consisting of one animal in each Petri dish (80?×?15 mm) were used for the study. 20 mL of respective test medium was maintained with Chlorella sp. (2?×?10⁴?±?0.03 cells mL^?1) in each Petri dish throughout the experiment. Thirty (30) animals were observed daily to investigate different life history parameters like total life span, age at maturity, number of eggs, neonates and egg batches etc. at different condition. From the study it was found that acidic water (pH 5?±?0.2) is more suitable for the culture of Bosmina tripurae in laboratory condition.     

Benzene,toluene, ethylbenzene and xylene concentrations in atmospheric ambient air of gasoline and CNG refueling stations

This study aimed to assess workers’ exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) compounds in refueling stations of Ardabil city (Iran). Twenty-four refueling stations including 15 petrol and 9 compressed natural gas (CNG) stations from different regions were selected and monitored for ambient BTEX concentrations. Air samples were taken based on NIOSH Manual of Analytical Method no 1501. Target compounds were extracted using CS₂ and analyzed by GC equipped with FID. Average concentrations of benzene, toluene, ethylbenzene, and xylene were obtained 2.01, 1.80, 2.72, and 1.65 mg/m³, respectively. Benzene concentrations exceeded the occupational exposure limit set by the Iran Ministry of Health and Medical Education. Its concentrations were significantly higher in commercial areas (2.72 mg/m³) compared to suburban areas (1.89 mg/m³). BTEX concentrations in gasoline stations were slightly, but not significantly, higher than those in CNG stations. Long-term exposure cancer risk of 1884?×?10^?6?±?390?×?10^?6 and hazard index of 22.83?±?3.66 were estimated for benzene and BTEX compounds, respectively. The results declare the necessity for controlling BTEX emission (mainly benzene) and monitoring employee’s exposure in refueling stations.     

Inhibition of the metabolism and motility of human spermatozoa by various alkaloids

The ability of several alkaloids to inhibit the metabolism and motility of human spermatozoa has been investigated.Of the agents tested, chloroquine was the most effective in inhibiting sperm metabolism (production of carbon dioxide and lactic acid) and motility. It was active at a concentration of 3.6 × 10^?5M. Quinine and Quinacrine were active at concentrations of 5 × 10^?4M and emetine required concentrations as high as 3.6 × 10^?3M to achieve an inhibitory effect. Detailed studies with emetine showed that the time needed for inhibition of sperm motility was inversely proportional to the drug concentration and directly related to the sperm density. In addition, the inhibition was shown not to be reversible.     

A Study on Cadmium Phytoremediation Potential of Water Lettuce, Pistia stratiotes L.

Aquatic macrophytes have tremendous potential for remediation of the heavy metal cadmium. The objective of this study was to investigate Cd phytoremediation ability of water lettuce, Pistia stratiotes L. The study was conducted with 5, 10, 15 and 20 mg L^?1 CdCl₂ in hydroponic system for 21 days and the Cd concentrations in the root and shoot tissues were estimated by atomic absorption spectroscopy. The values obtained were used to evaluate the bioconcentration factor (BCF), translocation factor (TF) and translocation efficiency of this plant. The plant showed high Cd tolerance of up to 20 mg L^?1 but there was a general trend of decline in the root and shoot biomass. The maximum BCF values for root and shoot tissues were 2,294 and 870 respectively, obtained for 5 mg L^?1 Cd, which indicated that the plant was a Cd hyperaccumulator. The TF maxima was found to be 0.6 and as much as 60 % root to shoot translocation efficiency was observed for 15 mg L^?1 Cd which points towards the suitability of water lettuce for removing Cd from surface waters.     

In Vitro Determination of 6PGD Enzyme Activity Purified from Lake Van Fish (Chalcalburnus tarichii Pallas, 1811) Liver Exposed to Pesticides

In the present study, the effect of methidathion, cypermethrin, and deltamethrin pesticides on Lake Van fish (Chalcalburnus tarichii Pallas, 1811) liver 6-phosphogluconate dehydrogenase enzyme activity was investigated due to the fact that these pesticides are extensively used to improve agricultural productivity in the Van region. 2′,5′-ADP Sepharose 4B affinity chromatography was used to purify 6-phosphogluconate dehydrogenase enzyme from fish liver and SDS-PAGE technique was used to control the purity of this enzyme. The in vitro effect of methidathion, cypermethrin, and deltamethrin pesticides on the enzyme activity was investigated. The enzyme was purified 1,050-fold with specific activity of 27.04 EU/mg protein. Moreover, K_i constants of methidathion, cypermethrin, and deltamethrin were to be 3.294 ± 0.215, 0.718 ± 0.095, and 0.084 ± 0.009 mM respectively. The IC₅₀ value were estimated as 9.95 × 10^?5 ± 0.1844 × 10^?5 mM for methidathion, 1.01 × 10^?4 ± 0.01413 × 10^?4 mM for cypermethrin, and 4.43 × 10^?6 ± 0.05653 × 10^?6 mM for deltamethrin. In conclusion, deltamethrin inhibits the enzyme activity more than methidathion and cypermethrin.     

In vitro demonstration of pyrimethamine resistance of “wild” Plasmodium falciparum in the Gambia

The in vitro response of wild¹ Gambian Plasmodium falciparum to pyrimethamine is described. Parasites were grown in 100 μl cultures through schizogony. The number of rings present after 48 hours in drug-treated cultures was expressed as a percentage of the controls. Neither a medium and drug change after 24 hours nor different starting parasitaemias were found to affect the outcome of the assay, although a medium and drug change did increase the multiplication rate. 60 randomly taken pure P. falciparum infections were studied. 57 were sensitive. The ID50 and ID90 of drug-sensitive infections were 1·7 × 10^?9M and 4·5 × 10^?9M pyrimethamine respectively. Three infections were resistant (5%) with individual ID50 values of > 10^?6M, 3 and 4 × 10^?9M and ID90 values of > 10^?6M, 8 and 9 × 10^?7M.     

Bioaccumulation of PBDE congener 2,2′,4,4′-tetrabromodiphenyl ether by Heterosigma akashiwo in response to different nutrient concentrations

Changes in the bioaccumulation of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) in the marine alga Heterosigma akashiwo (Raphidophyceae) were examined for different concentrations of nitrate (0, 128, and 512 μmol dm^?3) and phosphate (0, 8, and 32 μmol dm^?3) in the semi-continuous culture with 20% renewal rate. The BDE-47 content per cell and per culture, as well as the accumulated percentage of available BDE-47, presented a significant decreasing trend with the increase in nitrate and phosphate concentrations. The N-0 (4.0 × 10^?6 ng cell^?1) and P-0 (5.8 × 10^?6 ng cell^?1) treatments had significantly higher BDE-47 content per cell than other treatments. In comparison, the difference in BDE-47 per algal culture and accumulated percentage between the nitrate treatments or phosphate treatments was not as obvious as the BDE-47 content per cell. BDE-47 per cell presented significantly negative correlation with nitrate and phosphate concentrations, and the accumulated BDE-47 was in positive correlation with lipid content. log BAF_lip for BDE-47 in H. akashiwo ranged from 6.70 to 7.25. The results of this study indicate that variation in BDE-47 accumulation by H. akashiwo corresponds to the change in cellular lipid content induced by different nitrate and phosphate concentrations.