Genotoxic evaluation of an industrial effluent from an oil refinery using plant and animal bioassays

Polycyclic aromatic hydrocarbons (PAHs) are genotoxic chemicals commonly found in effluents from oil refineries. Bioassays using plants and cells cultures can be employed for assessing environmental safety and potential genotoxicity. In this study, the genotoxic potential of an oil refinery effluent was analyzed by means of micronucleus (MN) testing of Alium cepa, which revealed no effect after 24 h of treatment. On the other hand, primary lesions in the DNA of rat (Rattus norvegicus) hepatoma cells (HTC) were observed through comet assaying after only 2 h of exposure. On considering the capacity to detect DNA damage of a different nature and of these cells to metabolize xenobiotics, we suggest the association of the two bioassays with these cell types, plant (Allium cepa) and mammal (HTC) cells, for more accurately assessing genotoxicity in environmental samples.     

Micronucleus test and observation of nuclear alterations in erythrocytes of Nile tilapia exposed to waters affected by refinery effluent

Micronuclei and nuclear alterations tests were performed on erythrocytes of Oreochromis niloticus (Perciformes, Cichlidae) in order to evaluate the water quality from Paraíba do Sul river, in an area affected by effluents from an oil shale processing plant, located in the city of S?o José dos Campos, Brazil-SP. Water samples were collected on 2004 May and August (dry season) and on 2004 November and 2005 January (rain season), in three distinct sites, comprising 12 samples. It was possible to detect substances of clastogenic and/or aneugenic potential, as well as cytotoxic substances, chiefly at the point corresponding to the drainage of oil shale plant wastes along the river. The highest incidence of micronuclei and nuclear alterations was detected during May and August, whereas the results obtained in November and January were insignificant. This work shows that the effluent treatment provided by the oil shale plant was not fully efficient to minimize the effect of cytotoxic and mutagenic substances in the test organism surveyed.     

石油污染土壤水改旱田后污染物组份及微生物群落结构变化

对沈抚灌区水改旱田不同年限土壤的石油污染物浓度及组分进行了分析,并采用变性梯度凝胶电泳和磷脂脂肪酸分析方法,分析了污染土壤微生物群落结构的变化.结果表明：1)石油污染土壤水改旱田后,年限越长,总多环芳烃在总石油烃中所占的比重越大,高分子量多环芳烃在总多环芳烃中所占比重也越大;2)总磷脂脂肪酸量与总石油烃呈显著正相关,与总多环芳烃相关性不显著;3)两种方法对土壤微生物群落结构的分析得出的结论一致,石油污染土壤微生物群落结构主要与其相对地理位置有关,当污染物的浓度达到一定程度时,土壤微生物群落结构会发生明显的改变.     

Genotoxicity assessment of a pharmaceutical effluent using four bioassays

Pharmaceutical industries are among the major contributors to industrial waste. Their effluents when wrongly handled and disposed of endanger both human and environmental health. In this study, we investigated the potential genotoxicity of a pharmaceutical effluent, by using the Allium cepa, mouse- sperm morphology, bone marrow chromosome aberration (CA) and micronucleus (MN) assays. Some of the physico-chemical properties of the effluent were also determined. The A. cepa and the animal assays were respectively carried out at concentrations of 0.5, 1, 2.5, 5 and 10%; and 1, 5, 10, 25 and 50% of the effluent. There was a statistically different (p < 0.05), concentration-dependent inhibition of onion root growth and mitotic index, and induction of chromosomal aberrations in the onion and mouse CA test. Assessment of sperm shape showed that the fraction of the sperm that was abnormal in shape was significantly (p < 0.05) greater than the negative control value. MN analysis showed a dose-dependent induction of micronucleated polychromatic erythrocytes across the treatment groups. These observations were provoked by the toxic and genotoxic constituents present in test samples. The tested pharmaceutical effluent is a potentially genotoxic agent and germ cell mutagen, and may induce adverse health effects in exposed individuals.     

The micronucleus assay in exfoliated buccal cells: application to occupational exposure to polycyclic aromatic hydrocarbons.

Many polycyclic aromatic hydrocarbons (PAHs) have been identified as cancer-inducing chemicals for animals and/or humans. Also, there is sufficient evidence that exposures in the occupational settings are carcinogenic or probably carcinogenic to human. Engine exhaust and used engine oils are major PAH sources in engine repair workshops and traffic. Analysis of micronucleus (MN) in exfoliated buccal cells is a sensitive method for monitoring genetic damage in human populations. In our study, we used three different occupational groups (Group 1; engine repair workers, Group 2; taxi drivers, Group 3; traffic police) and two controls (Control I for Group 1 and Control II for Group 2 and Group 3) for the exposed groups. We analysed MN frequencies in exfoliated buccal cells and compared the exposed groups (Group 1; n=34, Group 2; n=17, Group 3; n=15) and subjects not occupationally exposed to PAH (Control I; n=28, Control II; n=20). The mean (+/-S.D.) MN (%) frequencies in exfoliated buccal cells from Group 1 and Control I were 0.07+/-0.05 and 0. 05+/-0.04, respectively (p>0.05; Table 2). The mean (+/-S.D.) MN (%) frequencies in exfoliated buccal cells from Group 2, 3 and Control II were 0.12+/-0.05, 0.10+/-0.05 and 0.03+/-0.03, respectively (p<0. 0001, p<0.05; Table 2) Smokers and nonsmokers do not differ with respect to the incidence of MN in all groups.     

南通如东滩涂文蛤产地环境中石油烃污染评价

南通如东滩涂是文蛤(Meretrix meretrix)的重要产地,本研究于2010年3、5、8和11月对该地区文蛤生长环境及体内的石油烃( TPHs)含量与分布进行了调查.研究表明:表层海水中各季均出现油类轻度污染站位,其中夏秋2季的油类污染程度略高于冬春;虽然4季沉积物中油类含量均符合《海洋沉积物质量》Ⅰ类标准,但沉积物中油类含量的季节变化显著,最高值出现在夏季,这可能与该时间段内的潮流冲刷等因素导致的沉积物机械组成不同有关;文蛤体内TPHs平均含量的季节分布为春季＞夏季＞冬季＞秋季.文蛤体内TPHs含量易受沉积物和水体中油类含量的影响.     

Distribution of the Simulium damnosum complex on Bioko island, Equatorial Guinea, and the potential for onchocerciasis elimination by vector eradication

Onchocerciasis is endemic on the island of Bioko, Equatorial Guinea, where it is transmitted by the 'Bioko form' of the Simulium damnosum complex, a cytospecies unique to the island. To determine the distribution of vector breeding, three dry season and two wet season expeditions were made in 1989, 1996 and 1997, and 226 of the island's 247 rivers (91.5%) were visited. Of these 226 rivers, 130 (58%) were flowing during the dry season, forty-five (20%) supported aquatic stages of Simuliidae of any species and twenty-five (11%) contained larvae or pupae of the S. damnosum complex. The twenty-one rivers not prospected were in the mountainous south of the island, where an additional seventeen rivers were reached but not satisfactorily prospected. Of these thirty-eight rivers, twenty-nine were considered highly likely to support vector breeding, bringing the total number of rivers which could harbour the vector during the dry season to fifty-four (21.9% of the island's total). Breeding was believed to be limited to river stretches below 1000 m altitude, and during the dry season the total length of those stretches which could support breeding on Bioko was estimated to be 1020 km. A combination of factors, including low river discharges during the dry season, the relatively low water temperature on Bioko, the suitability of limited stretches of most rivers as vector breeding sites and the close proximity of many rivers within a small geographical area, render the vector vulnerable to eradication by aerial treatment of rivers with insecticide. The isolation of the Bioko form of the S. damnosum complex suggests that reinvasion following treatment would be unlikely, and eradication of the vector might be achieved by a dry season larviciding programme in one or two years.     

Distribution and abundance of Caiman crocodilus in the Caño Negro National Wild Life Refuge, Costa Rica

The distribution and abundance of a population of Caiman crocodilus fuscus were estimated by monthly counting of eye-shines at night, from February 1999 to March 2000 in six transects of Río Frío in the Ca?o Negro National Refuge (RNVSCN), Northern Costa Rica. March was the month with the greatest abundance of caimans observed. The visible fraction of the population (PV2 index) fluctuated between 42.59% to 54.71% during the wet season and 35.49% to 53.93% in the dry season. The transects of river with greater abundance of caimans were Terrón-Sabogal and Sabogal-Playuela. Significant differences were determined in the abundance of caimans between transects, except the transects Entrada San Sebastían-Las Cubas and Las Cubas-Entrada Ca?o Los Patos and Entrada Ca?o Los Patos-Terrón and Boca Sabogal-Playuela. The population of estimated brown caiman in this study was 2283.48 +/- 313.5. The statistical analysis by seasons did not show significant differences in the number of caimans observed. Estimated mean number of caimans per km of river was 74.36/km for 30.7 km of habitat. The results of this study indicated that the fluctuation in population density during the seasons is attributable to local movements.     

Zinc opposes genotoxicity of cadmium and vanadium but not of lead

Protection by essential metals against the genotoxic effects of toxic elements is an open question. Here, human Hs27 dermal fibroblasts and B-mel melanoblasts were exposed for 10 days to (1 μM) zinc (Zn) or copper (Cu) or selenium (+ 4, Sei; + 6, Sea). Afterwards, cells were exposed for 3 days to subtoxic concentrations of lead (Pb, 100 μM) or vanadium (+ 5, V, 2 μM) or cadmium (Cd, 3 μM), slightly reducing, by themselves, cell proliferation and unaffecting cell viability and apoptosis. Genotoxic damage was evaluated by cytokinesis-block micronucleus assay (CBMN) and single cell gel electrophoresis (Comet assay, CA). CBMN and CA were preliminarly assessed following 3, 10 and 30 days of exposure to the above concentrations of Pb, V and Cd: Pb induced micronuclei (MN) formation in both Hs27 and B-mel cells, without determining direct DNA damage (as shown by CA); V did not reveal genotoxic effects on fibroblasts (as shown by CBMN and CA) but increased the frequency of MN and comets in melanoblasts; Cd induced a great number of MN and comets in fibroblasts but not in melanoblasts; all these effects did not differ after 3, 10 or 30 days of exposure to such elements so that Hs27 and B-mel cells were exposed to Pb,V and Cd for 3 days following pretreatment with (1 μM) Zn, Cu, Sei or Sea. By itself, the 10 day-exposure to (1 μM) Zn, Cu, Sei or Sea did not affect cell proliferation, viability, apoptosis and formation of MN or comets in either Hs27 or B-mel cells. Only Zn significantly reduced the Cd- and V-induced MN and comet formation in fibroblasts and melanoblasts, respectively; in these cells, however, Zn did not affect the Pb-induced MN formation. These results emphasize the role of Zn, in respect to other essential metals, in opposing the genotoxic effects of cancerogenic (Cd) or potentially cancerogenic elements (V).     

In situ treatment of Hamilton Harbour sediment

To enhance the biodegradation of organic contaminants, approximately 18.5 tonnes of oxidant (calcium nitrate) and 5 tonnes of nutrients were injected into sediments of the Dofasco Boatslip, Hamilton Harbour. In the laboratory 78% and 68% of the oil (TPHs) and polynuclear aromatic hydrocarbons (PAHs), respectively biodegraded in 197 days. In the 1992 treatment in the Ddofasco Boatslip, biodegradation of organic contaminants varied from 79% for low molecular weight compounds (BTXs), to 25/15 of the 16 priority pollutant PAHs. At first biodegraduation of large molecular weight PAHs resulted in the production of naphthalene (from 280 g/g to 549 g/g). In the 1993 treatments, 94% of the naphthalene, and 57% of the TPHs biodegraded. The in situ biotreatment of organic contamination takes time but for some sites the significantly lower cost relative to dredging and confinement makes in situ treatment a viable alternative.     

Relations between Anopheles darlingi breeding habitats, rainfall, river level and malaria transmission rates in the rain forest of Suriname

Irregular peaks of P.falciparum malaria incidence were monitored in Suriname during 1982-86. An attempt is made to correlate these fluctuations of malaria rates with rainfall and river level in relation to the periodic availability of breeding habitats for the malaria vector Anopheles darlingi Root. Densities of adult female An.darlingi were recorded in the Upper-Marowijne region of Suriname, in a focus of malaria along the Marowijne River. Peaks in biting densities correlated well with periods of (i) high water level in the long rainy season, (ii) low water level in the long dry season, and (iii) abundant rainfall in the short rainy season. Critical levels of river-height and rainfall were defined which could explain most of the monthly fluctuations in malaria parasite incidence observed in this area.     

Accumulation, detoxification, and genotoxicity of heavy metals in Indian mustard (Brassica juncea L.)

Plants of Indian mustard (Brassica juncea L.) were exposed to different concentrations (15, 30, 60, 120 microM) of (Cd, Cr, Cu, Pb) for 28 and 56 d for accumulation and detoxification studies. Metal accumulation in roots and shoots were analyzed and it was observed that roots accumulated a significant amount of Cd (1980 microg g(-1) dry weight), Cr (1540 microg g(-1) dry weight), Cu (1995 microg g(-1) dry weight), and Pb (2040 microg g(-1) dry weight) after 56 d of exposure, though in shoot this was 1110, 618, 795, and 409 microg g(-1) dry weight of Cd, Cr, Cu, and Pb, respectively. In order to assess detoxification mechanisms, non-protein thiols (NP-SH), glutathione (GSH) and phytochelatins (PCs) were analyzed in plants. An increase in the quantity of NP-SH (9.55), GSH (8.30), and PCs (1.25) micromol g(-1) FW were found at 15 microM of Cd, however, a gradual decline in quantity was observed from 15 microM of Cd onwards, after 56 d of exposure. For genotoxicity in plants, cytogenetic end-points such as mitotic index (MI), micronucleus formation (MN), mitotic aberrations (MA) and chromosome aberrations (CA) were examined in root meristem cells of B. juncea. Exposure of Cd revealed a significant (P < 0.05) inhibition of MI, induction of MA, CA, and MN in the root tips for 24 h. However, cells examined at 24 h post-exposure showed concentration-wise recovery in all the endpoints. The data revealed that Indian mustard could be used as a potential accumulator of Cd, Cr, Cu, and Pb due to a good tolerance mechanisms provided by combined/concerted action of NP-SH, GSH, and PCs. Also, exposure of Cd can cause genotoxic effects in B. juncea L. through chromosomal mutations, MA, and MN formation.     

西安城市河流浮游植物群落结构及其与环境因子的关系

为探究西安市城市河流浮游植物群落结构特征及其与环境因子的关系,分别于2020年10月和2021年6月对灞河、浐河、沣河及黑河共计24个采样点进行了浮游植物群落组成、细胞密度和生物量的调查研究,并利用冗余分析(RDA)研究环境因子对浮游植物群落结构的影响。调查结果显示,枯水期共鉴定出浮游植物6门115种,主要包括蓝藻门(11.30%)、硅藻门(54.78%)及绿藻门(26.96%),浮游植物细胞密度均值为(3.36±3.50)×106 cells/L,生物量均值为(1.79±3.59) mg/L。丰水期共鉴定出浮游植物7门168种,主要包括蓝藻门(7.74%)、硅藻门(51.79%)及绿藻门(29.76%),浮游植物细胞密度均值为(9.17±9.73)×10⁶ cells/L,生物量均值为(6.54±11.57) mg/L。与枯水期相比,丰水期在物种数量、细胞密度和生物量都大于枯水期。聚类分析结果表明,西安城市河流大部分采样点之间浮游植物群落结构及水环境状况具有相似性,而人类活动可能是导致其余点位具有空间差异性的主要原因。冗余分析(RNA)结果表明影响西安市城市河流...     

Enhanced Phytoremediation of Crude Oil-Polluted Soil by Four Plant Species: Effect of Inorganic and Organic Bioaugumentation

A field experiment investigating the removal and/or uptake of Polycyclic Aromatic Hydrocarbons (PAHs) and specific metals (As, Cd, Cr) from a crude oil polluted agricultural soil was performed during the 2013 wet season using four plant species: Fimbristylis littoralis, Hevea brasilensis (Rubber plants), Cymbopogom citratus (Lemon grass), and Vigna subterranea (Bambara nuts). Soil functional diversity and soil-enzyme interactions were also investigated. The diagnostic ratios and the correlation analysis identified mixed petrogenic and pyrogenic sources as the main contributors of PAHs at the study site. A total of 16 PAHs were identified, 6 of which were carcinogenic. Up to 42.4 mg kg^?1 total PAHs was recorded prior to the experiments. At 90 d, up to 92% total PAH reduction and 96% As removal were achieved using F. littoralis, the best performing species. The organic soil amendment (poultry dung) rendered most of the studied contaminants unavailable for uptake. However, the organic amendment accounted for over 70% of the increased dehydrogenase, phosphatase, and proteolytic enzymes activities in the study. Overall, the combined use of soil amendments and phytoremediation significantly improved the microbial community activity, thus promoting the restoration of the ecosystem.     

A comparative biomonitoring study of populations residing in regions with low and high risk of lung cancer using the chromosome aberration and the micronucleus tests

Chromosome aberration (CA) and micronucleus (MN) tests were performed in peripheral blood lymphocytes from people residing in two districts of Chiang Mai, Thailand, a high-risk area, Saraphi (n=107), where the lung cancer incidence is three-fold higher than in a low-risk area, Chom Thong (n=118). The percentage of cells with CAs was significantly lower in the Saraphi population than in the Chom Thong population (0.47+/-0.91 versus 1.04+/-1.18, P=0.0001) as was the percentage of CAs (0.49+/-0.91 versus 1.08+/-1.21, P<0.0001) and the mitotic indices (1.25+/-0.44 versus 1.33+/-0.33, P=0.025). The frequency of MN in binucleated (BN) cells, however, was significantly higher in the Saraphi population (12.01+/-3.57 versus 9.99+/-3.11, P<0.0001) as was the percentage of BN cells with MN (1.14+/-0.31 versus 0.93+/-0.23, P<0.0001). There was no difference in the nuclear division indices (1.49+/-0.07 versus 1.47+/-0.11, P=0.1759) between the two populations. With regard to the effect of confounding factors, it was found that cigarette smoking influenced both CA and MN frequencies, and that the chewing of fermented tea leaves or betel nuts affected CA and sex affected MN frequencies. An increasing of CA and MN frequencies were seen in smokers and chewers over non-smokers and non-chewers, with CA frequencies being higher in Chom Thong smokers and chewers and MN frequency being higher in Saraphi smokers. However, pesticide exposure and alcohol consumption had no impact on CA and MN frequencies. Due to the conflicting results obtained in the two tests, we cannot make a clear statement regarding the potential effects of the environmental exposures in the two study populations.     

G2 effects of DNA-repair inhibitors on chromatid-type aberrations in root-tip cells treated with maleic hydrazide and mitomycin C

In recent years the existence of a DNA-repair process in G2 has been proposed to explain the potentiating effects of DNA-repair inhibitors given in G2 on chromatid aberrations (CA) induced by S-dependent as well as S-independent DNA-damaging agents. In the present report, root-tip cells of Allium cepa were exposed to maleic hydrazide (MH) or mitomycin C (MMC) and post-treated in G2 with caffeine (Caff) and various inhibitors of DNA synthesis. No enhancement of chromosome damage was observed when Caff was present in G2, but hydroxyurea (HU) or 5-fluorodeoxyuridine (FdUrd) potentiated the frequencies of CA. A slight additional increase of CA frequencies was observed following treatment with Ara C and excess thymidine in G2. When MH-damaged cells were pulse-treated with Caff earlier during recovery, the yield of CA was enhanced. The earlier Caff was present following MH treatment, the stronger was the potentiation.     

Establishing Eco-SSLs for PAHs: Lessons Revealed from a Review of Literature on Exposure and Effects to Terrestrial Receptors

Polycyclic Aromatic Hydrocarbons (PAHs) were among the top priority Constituents of Potential Concern (CoPC) in the United States Environmental Protection Agency's (USEPA's) effort to set ecological soil-screening (Eco-SSL) values. Search strategies, acceptance criteria, and evaluation procedures were developed to address effects on plants, invertebrates, and wildlife. Systematic literature searches were conducted to obtain all relevant information on toxic response of terrestrial plants, invertebrates, and wildlife exposed to PAHs. More than 325 papers on PAHs were reviewed. Only 14 papers (one plant, three invertebrate, and ten wildlife) met the minimum criteria for use. Only eight PAH analytes had data that qualified for use in deriving Plant-, Invertebrate-, or Wildlife-SSLs. Only one SSL, (invertebrate, fluorene) could be derived based on the available data using the USEPA draft criteria. Rapid volatilization of lower molecular weight PAHs, generally low toxicity of persistent PAHs, limited potential for uptake by plants, binding to soil organic matter that lowers bioavailability, and low bioaccumulation by invertebrates may explain the general absence of documented adverse effects among terrestrial receptors exposed to PAHs.     

Controversial cytogenetic observations in mammalian somatic cells exposed to extremely low frequency electromagnetic radiation: a review and future research recommendations

During the years 1990-2003, a large number of investigations were conducted using animals, cultured rodent and human cells as well as freshly collected human blood lymphocytes to determine the genotoxic potential of exposure to nonionizing radiation emitted from extremely low frequency electromagnetic fields (EMF). Among the 63 peer reviewed scientific reports, the conclusions from 29 studies (46%) did not indicate increased damage to the genetic material, as assessed from DNA strand breaks, incidence of chromosomal aberrations (CA), micronuclei (MN), and sister chromatid exchanges (SCE), in EMF exposed cells as compared with sham exposed and/or unexposed cells, while those from 14 investigations (22%) have suggested an increase in such damage in EMF exposed cells. The observations from 20 other studies (32%) were inconclusive. This study reviews the investigations published in peer reviewed scientific journals during 1990-2003 and attempts to identify probable reason(s) for the conflicting results. Recommendations are made for future research to address some of the controversial observations.     

Genotoxic effects in M5 cells and Chinese hamster V79 cells after exposure to 7Li-beam (LET=60 keV/microm) and correlation of their survival dynamics to nuclear damages and cell death

Chinese hamster V79 cell and a cell strain M5, derived from V79 cells and reported to be relatively resistant to gamma-ray, hydrogen peroxide, and N-methyl-N-nitro-N-nitrosoguanidine (MNNG; a potent human carcinogen), were exposed to high LET (7)Li-beam (LET=60 keV/microm) at approximately 90% confluent state in the dose range of 0-1 Gy. Effects of (7)Li-beam exposure on cell survival, micronuclei induction (MN), chromosomal aberrations (CA) and apoptosis were compared in both the cell lines. A dose-dependent decline in survival for both the cell lines was noted, relatively less in M5 cells (mostly p<0.01) indicating greater radio-resistance in this strain. The MN, CA and apoptosis increased in a dose-dependent manner in both V79 and M5 cells. Significant differences in various other parameters between these two cell lines were also noted. The relative intensity of DNA ladder, which is a useful marker for the determination of the extent of apoptosis induction, was much higher in V79 cells. A good correlation between the reduction of the surviving fractions and the increase in frequencies of MN or CA or apoptosis was noted for both the cell lines.     

Discharge-driven flood and seasonal patterns of phytoplankton biomass and composition of an Australian tropical savannah river

Discharge is a primary determinant of river phytoplankton, but its influence can be mediated by climate, water quality and catchment development. The relationship between discharge and phytoplankton over seasonal and flood temporal scales was examined for the Daly River in the Australian tropical savannah. Phytoplankton, water quality and hydrographic data were collected over the high-discharge wet season and lower-discharge dry season. Wet season main channel river conditions were unfavourable for phytoplankton growth. Floods, however, connected the main channel to off-channel water bodies that supplied phytoplankton, predominately Cryptomonas, to the river. Wet season phytoplankton biovolume and cell concentrations were higher than in the dry season and comprised the majority of the annual phytoplankton biomass load. High discharges served to both temporally connect the river to off-channel phytoplankton sources as well as dilute these sources. In the dry season, the Daly River was groundwater-fed and disconnected from off-channel phytoplankton sources and dominated by a potamoplanktonic population of Cryptomonas and Peridinium. River phytoplankton were determined by the seasonal discharge regime which drove water quality and underpinned a shift from highly productive, spatially extensive off-channel sources in the wet season to less productive more spatially confined in-channel sources in the dry season.