Toxicologie environnementale et analytique

Trace elements, as building blocks of matter, are naturally present in the environment. However, their extraction, production, use and release by men can lead to the increase of their environmental levels to concentrations that may be toxic for both men and the biota. The overall aim of this review is therefore to recall that trace elements remain contaminants of concern that still require scientific attention. Because marine coastal systems (and transitional environments in general) are particularly vulnerable to contamination processes, they deserve to be accurately monitored with quality indicator species. As an example, the 2 most widely quality indicator species used to assess the health status of the coastal Mediterranean are the seagrass Posidonia oceanica and the mussel Mytilus galloprovincilias. In this review, after a short introduction on human pressures on the World Ocean and the coastal Mediterranean in particular (1), we will redefine the term trace element from an environmental perspective and discuss their accumulation and toxicity for men and the biota (2). We will consider the benefits of using biological indicators instead of water and sediment measurements to assess the health status of the marine environment (3), and more particularly as regards the accurate and complementary indicators that are seagrasses (4) and mussels (5).

Over the last three decades, the field of wildlife toxicology involving the assessment of toxic chemicals on the reproduction, health, and well-being of wildlife species has grown dramatically as a science involving both laboratory and field research. In the early years of the development of wildlife toxicology, there was a strong emphasis on laboratory toxicity tests, including LD50 and LC50 tests, particularly on species such as bobwhite quail (Colinus virginianus) and mallard ducks (Anas platyrhynchos). Laboratory tests evolved into largescale field efforts, particularly in the late 1980s and throughout the 1990s, which was facilitated by pesticide re-registration requirements to obtain data to submit to the United States Environmental Protection Agency. Now, as wildlife toxicology continues to evolve as a science, sublethal monitoring of wildlife has become much more prominent to assess health impacts. New developments in molecular biology have also allowed insight into the genetic basis for wildlife response to toxic substances. Considering the diversity of fish and wildlife species both in the United States and globally, it continues to be a great challenge to protect this diversity of wildlife species from impacts of toxic substances. As we expand and become more sophisticated in assessing field and laboratory effects of toxic substances in wildlife, we will be able to do a much better job in the future of assessing the effects of environmental contaminants on the reproduction and health of the wide array of wildlife species and developing solutions and/or mitigation strategies.

Crude extracts from the leaves of the wild tomato, Lycopersicon hirsutum f. glabratum accession PI 134417 possess a pestresistance mechanism in their glandular trichomes (plant hairs) and the exudates they produce due to the presence of a mixture of methyl ketones (MKs) that has insecticidal and acaricidal properties. Type IV and VI glandular trichomes on the leaves of PI 134417 grown under greenhouse conditions were counted. Major volatile oils from glandular leaf trichomes were extracted, purified, and quantified using gas chromatography (GC) and mass spectrometry (GC/MS). The main objectives of this investigation were to: 1) monitor seasonal glandular trichomes density on PI 134417 for mass production of MKs and 2) prepare a simplified formulation of MKs for potential use of PI 134417 leaf extracts, which could become a valuable source of natural products, in plant protection against spider mites and cowpea aphids. Type IV and type VI trichomes were greatest (P<0.05) in September and October (97 and 238 trichomes mm-2), respectively. Quantification of MKs in emulsified extracts of PI 134417 revealed the dominance of 2-tridecanone (the 13-carbon methyl ketone) compared to other MKs (2-undecanone, 2-dodecanone, and 2-pentadecanone) on the leaf surface. Crude leaf extracts of PI 134417 prepared in water caused 33 and 22% mortality, whereas, water extracts containing 1% Alkamuls (an organic emulsifier) caused 93 and 82% mortality of spider mites and cowpea aphis, respectively, 1 d after exposure.

Rice straw (RS) has been activated using Na2CO3. Activated carbon samples (ARSC) were characterized using N2- adsorption, elemental analysis, surface fractional dimension and pore volume to support the adsorption of nitrate and nitrite ions. The effects of various parameters such as solution pH, adsorbent concentration, contact time, temperature and initial nitrate and nitrite concentrations were examined. Various kinetics models including the Pseudo-first-order, Pseudo-second-order and intra particle diffusion models have been applied to the experimental data to predict the adsorption mechanism. The thermodynamics constants of the adsorption process, viz. ΔHo, ΔGo and ΔSo were evaluated. The results showed that the adsorption of nitrate and nitrite ions onto activated carbon was exothermic and non-spontaneous. The adsorption data followed second-order kinetics supporting that chemisorption process was involved. The obtained results show that ARSC can be used as an effective and natural low-cost adsorbent for the removal of nitrate and nitrite anions from wastewater.

Asphaltenes are remnants of ancient photosynthetic plants and are today considered waste hydrocarbons that must be removed from petroleum for use as fuel and often find their use as road tar. This study reports the first time their use in Dye-Sensitized Solar Cells (DSSCs) in which light is converted to electricity with conversion efficiencies approaching 1.8%. Extracted fractions of asphaltenes from Mexican Altamira crude oil were used as light absorbers in TiO2 based DSSCs. The photovoltaic performances of the cells were analyzed by determining the I-V cell parameters such as OCV (open-circuit voltage), SCC (short-circuit current), FF (fill factor), and SR (series resistance). The overall energy conversion efficiency was also measured to correlate the effect of the different asphaltene portions that created significant improvement of the solar cell parameters. The sensitization of TiO2 electrode with the best asphaltene fraction resulted in a maximum energy conversion efficiency of 1.8% for the solar cell with a maximum photocurrent density of 16.9 mA/cm2. At this level the solar cell created has strong economic potential. A future strategy to further improve performance by minimizing series resistance and improving the photo current and open circuit voltage is also reported. The cells have shown excellent life as suggested by photo-catalytic polymerization of asphaltene materials when exposed to sunlight and air as stated in patent number 8,389,853.

Cyanobacterial blooms are group of phytoplankton called blue green algal blooms which are occurred commonly and naturally in many aquatic systems. In this paper, assessment of groups of different phytoplankton community and physicochemical water quality properties (pH, DO, TDS, temperature, total hardness, chloride, Chlorophyll a, nutrient level of PO4 3--P, NO3-N, NO2 --N, TP, TN) were analyzed and discussed using both original and literature data from the lake Chamo-known by its fish potential and fresh water in Ethiopia. Samples of water were taken from three different sites within the lake (from Inlet, Center and out let sites) during the dry season of 2014/15. Average Physicochemical properties of lake water were determined for each of the sites and cyanobacterial algae bloom was assessed by taking the composite sample of water biologically. The overall water quality parameters and phytoplankton biomass results have been observed as Turbidity (7.10-20.42 NTU), a maximum pH 9.02, TDS (622-651 mg/l), electric conductivity (720- 782 μS/cm), DO (10.26-17.61 mg/l), nitrate-nitrogen (3.12-5.35 mg/l), nitrite-nitrogen (0.03-0.11 mg/l), Total nitrogen (3.18-5.39 mg/l), phosphate (1.08-1.47 mg/l), Total phosphorus (0.43-0.55 mg/l), Chlorophyll a (23.85-28.87 μg/l) and total of 54 species from 9 classes of phytoplankton, dominated by large colonial forms of Microcystis and Anabaena species. The values of the whole analyzed parameters have shown significant variation in site (P<0.05). Finally, these results were compared with previous studies and concluded that the lake is getting worse and worst time to time and needs better follow up to protect and make it suitable for multiple purposes.

The study was conducted to assess the levels of organochlorine (OC) pesticide residues in Lake TeKeze dam have been investigated using water, sediment and fish (Labeobarbusspp, Clariasgariepinus and Oreochromis niloticus) samples as a case study to find out the extent of pesticide contamination and accumulation in the lake. Six OC pesticides namely DDT, DDE, Lindane, Endosulfan, Heptachlor and Chlordane were analyzed in four sites at two seasons. Water samples were processed using a liquid-liquid extraction technique and gas chromatograph equipped with electron capture detector (GC-ECD). Soxhlet extraction was used for fish and sediment samples followed by clean up and gas chromatograph. DDE was the predominant residue in all the samples analyzed, at the mean concentrations of 0.052 ppb, 9.80 ppb and 4.81 ppb in water, sediment and fish samples, respectively. The lowest levels of OC pesticides were related to Heptachlor and Chlordane which none of them were found in water samples. It also indicated the extensive presence and usage of these pesticides in the study environment, which include recent use of this pesticide for agricultural purposes. Thus, the use of these pesticides to control pest by farmers within the study area with little or no knowledge must be checked through adequate control of the trade and use of pesticides and the enforcement of appropriate sanctions.

Plant diseases, caused by pathogens, significantly reduce food production particularly in the developing world. Syntheticand chemical- pesticides are the most effective means of control, but they are expensive and not environment friendly. Population growth and rapid urbanization are putting considerable pressure on water available for irrigation. The “evils” of synthetic- and chemical- pesticides has been a major concern to environmentalists. To move forward, it will require new and more efficient solutions, technologies and products. Our best endeavor is to focus on the edible Amaranth which may have important economic implications for agriculture in future. In a well-protected garden of Kanchannagar DN Das High School (HS), Government of West Bengal, naturally-infested with Meloidogyne incognita, Kofoid and White, Chitwood, amaranth (Amaranthus viridis L.) cv. CO-1 was intercropped with okra (Abelmoschus esculentus L. Moench) cv. Ankur-40 to determine the effects on nematode populations. The nematode population varied from 2573- 2639 per 200 g of soil. Amaranth was planted in between every two okra plants. All the plants were harvested at 70 days after plantation. Of the two plant species, amaranth received maximum infection in terms of root gall number, nematode population in root, root protein content and plant growth parameters. Though both the amaranth and okra plants were susceptible to root-knot nematodes. Amaranth was more susceptible than okra in terms of root-gall number nematode population in root and root protein content. Okra has also the lowest root-gall number and nematode population in root. While M. incognita population increased significantly both in soil as well as in roots in 70 days in the monoculture. But amaranth showed the highest intensity of nematode infection. These results suggest that root-knot disease easily and effectively controlled by the use of amaranth plants as “trap crop” for root-knot nematodes intercropped with okra plants in the naturally root-knot infested field. As intercrop amaranth could be harvested at frequent intervals to keep the nematode population to a minimum level. This way amaranth could serve as highly effective Climate Friendly Catch Crop protecting other crops from invading larvae. The farmers would be benefited double; by controlling root-knot nematodes in the naturally infected agricultural field, and by buying and selling the edible amaranth plant regularly from the intercropped agricultural field. Intercropped amaranth also improves the plant growth effectively which directly increase photosynthesis rate and significantly reduce CO2 in the environment and it would not only be easier way, easily available, cheap but also conserve our biodiversity which will contribute towards “Sustainable Climate, Health and Development by controlling root-knot diseases which is sometime devastating to all kinds of natural and artificial vegetation.”

Glyphosate or N-(phosphonomethyl) glycine is a broad spectrum non-selective systemic herbicide, used to kill weeds, mainly in soybean crops. Nowadays there are many controversies about the intensive use of these herbicides due to the potential environmental impact and the effects on human health. The environmental impacts of commercial Glyphosate formulation Roundup were assessed by evaluation of acute and chronic toxicity of Danio rerio fish. The effects of glyphosate commercial formulations and glyphosate isopropylamine salt solutions were evaluated in different steps. First the lethal doses of Roundup herbicide toward the experimental models were determined. Subsequently the specie was exposed to sublethal concentrations of both, the commercial preparations and pure glyphosate salt in order to evaluate the chronic toxicity. Acute toxicity was assessed by calculating the mortality indexes and chronic toxicity by measuring several biochemical parameters such as the activity of marker enzymes like aspartate aminotransferase (AST), alanine aminotransferase (ALT) and acetylcholinesterase (AchE). The registers of histological alterations in liver tissue sections were also considered in this study. Commercial herbicides produce mortality of D. rerio and sublethal doses of these herbicides and the salt of the pure compound produce effects of chronic toxicity at the liver and muscle level; such are enough causes to limit the potential survival of these organisms in the medium.

This study evaluated the relative amount of Pharmaceutical and Personal Care Products (PPCPs) and paracetamol residues contained in household waste at the University of Port Harcourt, Port Harcourt, Nigeria. Residual paracetamol was analysed using a 6405 UV/Vis Spectrophotometer at the maximum wavelength (245 nm) in 0.1 N HCL. Student hostels had a mean paracetamol concentration of 0.6702 ± 0.006 mg/kg while the staff quarters recorded a mean concentration of 0.6569 ± 0.002 mg/kg. Solid waste analysis recorded 0.9 kg/capita/day and 1.1 kg/capita/day for the student hostel and staff quarters respectively. The student’s hostel recorded a mean percentage PPCPs value of 52.9% which was higher than that obtained in the staff quarters (45.9%) indicating that students disposed of more drugs in their waste than does the staff. The study showed that considerable amounts of PPCPs are disposed of in household waste at the study location and household waste is thus a viable pathway of PPCPs into the environment. Such practices could lead to the occurrence of the active ingredients of PPCPs in the environment with the potential to contaminate surface and ground water posing serious risk to human and ecologic health. It was recommended that appropriate return channels be established specially as a route for disposing of unused or expired drugs. Such routes should encourage stewardship of drugs by manufacturers from cradle to grave in an integrated green pharmacy approach.

Penicillium thomii Q1 strain was able to form abundant orange, sand-shaped sclerotia in which carotenoids were accumulated. The aim of this work was to determine the effects of H2O2-induced oxidative stress on the sclerotial differentiation and ascorbate-glutathione (AsA-GSH) cycle of Q1 strain. Results showed that the oxidative stress induced by H2O2 was clearly dependent on the H2O2 concentrations in media. The higher the concentration of H2O2 was, the higher the sclerotial biomass and carotenoids content in sclerotia (Rbiomass=0.972, Rcontent=0.941) (P<0.05). H2O2- induced oxidative stress favored the sclerotial differentiation. Results indicated that H2O2-induced oxidative stress can improve the contents of reduced form of ascorbate (ASC) and dehydroascorbate (DHA) and the ratio of ASC/DHA in sclerotia of Penicillium thomii Q1 strain (RASC=0.727, RDHA=0.640, RASC/DHA=0.929). The contents of DHA and ASC were increased by 1.9-fold and 2.4-fold with respect to control. At the same oxidative stress condition, DHA content was higher than ASC content. Oxidative stress may increase the contents of reduced glutathione (GSH) and oxidized glutathione (GSSG) in sclerotia of Penicillium thomii Q1 strain (RGSH=0.888, RGSSG=0.997). The value of the ratio of GSH/GSSG had a negative correlation with the oxidative stress (R=-0.933). At the same oxidative stress condition, GSH content was higher than GSSG content. The values of Ascorbate peroxidase (APX) and Glutathione reductase (GR) activities had negative correlation with the oxidative stress (R APX=-0.555) (RGR=-0.420). The values of Monodehydroascorbate reductase (MDHAR) and Dehydroascorbate reductase (DHAR) activities had positive correlation with the oxidative stress (RMDHAR=0.448) (R DHAR=0.603).