環境および分析毒性学

An attempt was made to study the genotoxic effects of Ochratoxin A (OTA) and endosulfan, alone and in combination by in vivo micronuclei (MN) and chromosomal aberration (CA) assays in bone marrow cells. OTA (4 mg/kg feed) and endosulfan (5 mg/kg body weight) were administered orally, alone and in combination, to male Wistar rats daily for 30 days. Significantly higher MN frequencies and decreased ratios of polychromatic to normochromatic erythrocytes (indicator of cytotoxicity), were recorded in individual or combined treatment of OTA and endosulfan as compared with the control. Chromosomal aberrations such as gaps, isochromatid gaps, breaks and fragments were recorded in the bone marrow cells. The percent frequencies of aberrant cells were significantly higher in all the treated groups as compared to the control. The severity of genotoxic effects was more in the combination treatment group, suggesting an additive or less than additive interaction of OTA and endosulfan in rats.

In present work, effect of two types of rhizobacteria was investigated on Scirpus mucronatus plant grown in contaminated soil spiked with 1 ppm Hg and 100 ppm Pb using phytoremediation technique. The concentrations of Hg and Pb in root and shoot of Scirpus mucronatus plant were determined on 1th, 7th, 14th, 28th and 42th days after enrichment by bacteria using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). To evaluate statistical differences in the Hg and Pb concentrations, the one-way ANOVA test was used. There were statistically significant differences between Hg and Pb concentrations between samples of control, bacteria 5 and bacteria 60. The results were demonstrated that these two bacterial inoculums namely Brevundimonas diminuta and Alcaligenes faecalis were known as plant-grown promoting rhizobacteria and they can increase the heavy metal uptake from soil contaminated.

The survey was conducted with the objective of assessing potentially poisonous plants and chemicals in and around Adama town, Central Ethiopia. Three types of structured questionnaires were developed and 118 individuals (93 livestock owners, 11 animal health practitioners and 14 factories managers) were interviewed on voluntary basis. The result of this assessment indicated that 71(76.3%) of livestock owners and 10(90.9%) of animal health practitioner complained presence of plant poisoning on livestock in the study area. Similarly 31 plants were identified as having poisoning effect on livestock among which Rhizophoraceae, Sorghum bicolar, Parthenium hysterophorus, and Medicago polymorpha had the highest botanical frequency. On the other hand, 22(23.7%) livestock owners and 1(9.1%) animal health practitioners observed chemical toxicosis, respectively. About two individuals of (14.2%) interviewed factories managers received complaints of chemical toxicosis of livestock due to inappropriate disposal of their wastes. Food shortage 48%, nutritional deficiency 10.4% and due to excess consumption 8.1% were identified as major risk factors which predispose livestock in and around Adama town to poisonous plants and toxic chemicals. Therefore, further study on complained poisonous plants and toxic chemicals in the study area, and institution of pertaining control and prevention method is strongly recommended.

Analyzing the activities of aspartate transaminase in tissues can help detect tissue damage cause by toxicants such as paraquat. The activities of aspartate transaminase (AST) in some tissues and organs of Clarias gariepinus exposed to various levels of paraquat (2, 4, 6 and 8ppm) were studied for a period of thirty (30) days. The tissues and organs investigated include blood plasma, kidney, liver, gills and muscle. The result showed changes in AST activity in the treatment group as compared to the control group; however the increase was not concentration dependent. AST activity was highest in the liver (445.00 ± 0.00IU/L SD) and lowest in the gill (65.00 ± 27.39 IU/L SD) in the control group. There was no significant change in AST activity in the liver across the treatment range. AST activity however declined in the muscle with the lowest at 6ppm of paraquat. There was a significant increase in AST activity in the gills at 4ppm of paraquat, this later declined to almost control levels at higher concentrations. In the kidneys AST activity also significantly peaked at 4ppm of paraquat. This declined slightly and was maintained at higher treatment concentrations. AST activity peaked in the plasma at 4ppm of paraquat as well. This dropped slightly and picked up at 8ppm. Analyzing the activities of AST in tissues can help detect tissue damage cause by toxicants such as paraquat. It can consequently be inferred that AST activity can be used as a reliable biomarker for diseased condition in the plasma, gills and kidney but not the liver or muscle of Clarias gariepinus.

The current study was carried out to estimate the concentration of chromium (Cr) in soil, forage, blood plasma and milk samples of Sahiwal cows collected from Kalurkoat livestock station, situated at South Western Punjab, Pakistan. The sampling was done four times at interval of two months. The concentration of Cr was found in the ranged 6.7-10 mg/kg, 2.9-4.0 mg/kg, 3.5-4.3 mg/L, and 0.4-0.6 mg/L in soil, forage, blood plasma and cows’ milk respectively. The results were compared with standards values for soil, forage, blood plasma and milk. In soil, forage and plasma samples Cr was found higher than the standard concentration necessary for proper growth of plants and animals, whereas the level of Cr in milk was within standard limits. The statistical analyses indicate that the transfer of Cr to milk is independent of its concentration in soil-forage-blood continuum. The high concentration of Cr detected in forage and blood plasma implies the need for sound management of plants which absorb less quantity of chromium.

Fly ashes both from municipal solid waste incinerator (MSWI) and medical waste incinerator (MWI) are classified as hazardous materials because they contain high amounts of heavy metals. In present these contaminant ashes have become a major environmental problem. In this study, we determine the ability of these contaminating heavy metals to be incorporated into a glass-matrix and in various mineral phases after a high temperature melting process using a direct current plasma torch. After the melting process, the leaching characteristics of heavy metals in fly ash and vitrified slag were investigated using the toxicity characteristic leaching procedure (TCLP), and the products also were characterized by X-ray diffractometry (XRD) for crystal structure determination, and scanning electron microscopy (SEM) for microstructure/morphology observation. After vitrification, there were prominent changes in microstructures and crystalline phases between produced slags and raw ashes. TCLP results indicate the leaching level of heavy metals in slags decreases obviously and additives such as silica and liquid ceramic (LC) contribute to high effect on immobilization of heavy metals in a host glass matrix.