Ecological and human health risk assessment of heavy metal contamination in soil of a municipal solid waste dump in Uyo,Nigeria

The study assessed the levels of some heavy metals in soils in the vicinity of a municipal solid waste dumpsite with a view to providing information on the extent of contamination, ecological risk of metals in the soils and human health risk to the residents in Uyo. Soil samples were collected in rainy and dry seasons and analyzed for metals (Pb, Cd, Zn, Mn, Cr, Ni and Fe) using atomic absorption spectrometry. The concentrations of heavy metals (mg/kg) at the dumpsite in rainy season were Pb (9.90), Zn (137), Ni (12.56), Cr (3.60), Cd (9.05) and Mn (94.00), while in dry season, the concentrations were Pb (11.80), Zn (146), Ni (11.82), Cr (4.05), Cd (12.20) and Mn (91.20). The concentrations of metals in the studied sites were higher than that of the control site (P < 0.05). Pollution indices studies revealed that soil samples from dumpsite and distances from 10 and 20 m east of the dumpsite were highly polluted with cadmium. Ecological risk assessment carried out showed that cadmium contributed 98–99 % of the total potentially ecological risk. No probable health risk was observed as the total hazard index of all the metals was less than one. However, children were found to be more susceptible to heavy metal contamination than adult.     

Occurrence of PCBs and PAHs in an urban soil of Madrid (Spain)

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were analysed in surface soil samples collected in 2001–2002 at an open urban area of Madrid. In order to obtain representative samples, three collection points at the site were chosen. The most abundant PAHs and PCBs were phenanthrene, fluorene, pyrene, chrysene and benzo[a]pyrene and hexa- and heptachlorinated PCBs, respectively. The sum of selected PAHs (13 compounds) and PCBs (15 congeners) averaged 1 and 0.1?µg?g^?1, respectively. PCB levels in winter were 2–10 times higher than summer ones, while seasonal variation for most of PAHs were not observed. Good correlations among all PCBs were found. Five PAHs were also well correlated.     

Determination of persistent organic pollutants in sediment and fish of the western coast of Alexandria,Egypt

Persistent organic pollutants (POPs) were recorded in sediment and fish samples collected from the western coast of Alexandria. Total hydrocarbons (aliphatic+PAHs ) in sediment ranged from 683.8 to 34670.1 ng g ^?1 with an average of 9286.9 ng g ^?1. The sum of C16–C34 of aliphatic fractions was<4000?ng g;^?1, indicating the presence of a fresh petroleum source. For all sediments, the anthracene/phenanthrene ratio was>0.1, suggesting the dominance of a pyrolytic source. Total aliphatics in different fish species ranged from 253 to 11?132 ng g;^?1, while total PAHs ranged from 3862 to 35?746 ng g;^?1 wet weight. Benzo[a]pyrene was the most dominant PAH fraction ranged from 1902.7 to 32 905.5 with an average of 9464.5?ng g;^?1 wet weight in all fish species. Concentrations of polychlorinated biphenyls (PCBs) ranged from 0.79 to 64.9?ng g;^?1 with an average 12.14?ng g;^?1 wet weight. The concentrations of organochlorines in fish species (Euthynnus alleferatus, Scomberomorus commerson, Sphyraena Sphyraena, Diplodus vulgaris, and Alepes djedaba) decreased following the order: PCBs>DDTs>HCHs>total cyclodienes. Concentrations of DDTs in fish tissues ranged from 4.89 to 36.37 ng g^?1 with an average of 16.4?ng g;^?1 wet weight. The concentrations of total HCHs ranged from 0.3 to 65.7?ng g;^?1 with an average of 16.35?ng g;^?1. The present study indicates: (1) fresh petroleum input where Pr/Ph>1; (2) PAHs in sediment<4000 ng g ^?1; (3) BaP concentration exceeded the permissible levels in Alepes djedaba species; (4) DDTs in sediment were below the effective range low level; (5) PCBs>effective range low and相似文献   

北京地区表层土壤中多环芳烃的分布特征及污染源分析

根据北京地区不同环境功能区62个样品的分析结果,讨论了研究区表层土壤中多环芳烃的分布特征及污染源类型。结果表明：（1）研究区表层土壤中检测到的多环芳烃主要包括萘、苊、菲、惹烯、三芴、荧蒽、芘、、苯并蒽、苯并[b]荧蒽、苯并[k]荧蒽、苯并[e]芘、苯并[a]芘、苝、二苯并[a,h]蒽、茚并[1,2,3–cd]芘、苯并[g,h,i]苝及其同系物;（2）不同环境功能区表层土壤中多环芳烃的组成及质量分数均存在一定的差别,16种优先控制的多环芳烃质量分数为175.1~10 344 ng.g-1,其中城市中心区表层土壤中多环芳烃的质量分数最高,交通干线附近、工矿企业附近表层土壤中PAHs的质量分数较高,林地、果园和农田表层土壤中PAHs的质量分数较低;（3）表层土壤中PAHs既有来源于石油源,也有来源于化石燃料燃烧产物的,但不同功能区二者贡献存在差别,其中农业用地（林地、果园、农田）中PAHs主要来源于石油源（或部分来源于土壤母岩中的有机质）,城区、交通干线附近及工矿企业附近表层土壤中PAHs污染源以化石燃料燃烧产物输入为主。     

北部湾潮间带沉积物中重金属和多氯联苯的分布特征及生态风险评价

选择北部湾9个典型采样点,研究了潮间带沉积物中重金属和多氯联苯(PCBs)的分布特征和生态风险.分析结果表明,Hg、As、Cu、Pb、Zn、Cd、Cr等重金属和总PCBs的平均含量分别为0.100、10.00、19.89、45.97、208.65、0.098、17.86 mg.kg-1和1.48!g.kg-1.重金属和PCBs表现出不同的空间变化规律.相关性分析表明,北部湾潮间带的重金属主要来自人为污染;沉积物的粒度参数和有机质含量等性质特征是影响PCBs分布和迁移的重要因素;重金属和PCBs总量之间不存在明显的相关性.生态风险评价结果表明,PCBs和Cd是北部湾潮间带最主要的生态风险因子,Zn和PCBs是优势污染物;研究区域总体处于中等生态风险等级,表明沿岸港口和临海工业等人为活动已经对北部湾滨海地区造成了一定的环境压力.     

Polycyclic aromatic hydrocarbons in soils around Guanting Reservoir,Beijing, China

The concentrations of 16 polycyclic aromatic hydrocarbons (∑ 16PAHs) were measured by gas chromatography equipped with a mass spectrometry detector (GC-MS) in 56 topsoil samples around Guanting Reservior (GTR), which is an important water source for Beijing. Low to medium levels of PAH contamination (mean=394.2±580.7 ng g^?1 dry weight (d.w.)) was evident throughout the region. In addition, localised areas of high PAH contamination near steel and cement factories were identified, with ∑ 16PAHs concentrations as high as 4110 ng/g, dry weight (d.w.). There was a significant positive correlation (r²=0.570, p<0.01) between total organic carbon content and ∑ 16PAHs concentrations. Phenanthrene was the predominant compound, accounting for 27.2% of the ∑ PAH concentration, followed by chrysene>pyrene>benzo[a]anthracene≈ benzo[b]fluoranthene≈ benzo[a]pyrene. Four-ring PAH homologues (39%) were dominant. The higher proportion of 4–6 ring homologues, molecular indices, and the spatial distribution of PAH indicated that industrial discharges, incineration of wastes and traffic discharges were the major sources of soil PAHs around the water reservoir.     

Assessment of PAHs in water and fish tissues from Great Bitter and El Temsah lakes,Suez Canal,as chemical markers of pollution sources

Sea water and fish tissue samples were collected from nine sampling stations from the Great Bitter and El Temsah lakes in the Suez Canal and analysed for polycyclic aromatic hydrocarbon (PAH). The compositions of PAH determined in the dissolved fraction of sea water were measured in order to use them as chemical markers for identifying different sources of PAH pollution in this region. PAHs determined in fish tissues were measured for comparison with human health standards as consumption. The total mean PAHs concentrations in the sea water samples ranged from 0.28 to 39.57 μg l^?1 with an overall mean of 10.78 and 12.38 μg l^?1 for El Temsah and Bitter Lakes water, respectively. Total PAHs fractions recorded in muscle tissues of all different Osteicthyes fishes collected from Great Bitter lakes ranged from 5.8 to 218.5 μg g^?1 with an overall mean of 57.98 μg g^?1 during all seasons. However, they ranged from 68 to 623 μg g^?1 with an overall mean of 87.69 μg g^?1 recorded in El Temsah lake during four seasons (2003–2004). Benzo(a)pyrene was the most dominant PAHs found in the sea water samples from both lakes with an average concentration of 3.8 μ g l^?1. Dibenzo(a,h)anthracene (DBA) was the most dominant PAHs recorded in fish samples. A maximum of 533 μg g^?1 of DBA was recorded in Dahbana sp. collected from Bitter lakes during January 2004. However, a maximum of 68.7 μ g g^?1 was recorded in Liza carinata species collected from El Temsah lake during July, 2004. The simultaneous occurrence of isomer ratios PHE/ANT<10 for all stations indicated that the major PAH input to water was from combustion of fossil fuel (pyrolytic source). The average ratios were 1.21 and 12.9 during winter (January 2004) and 4.3 and 8.63 during spring (April 2004) for all water samples of Great Bitter lakes and El Temsah lake, respectively. In addition, the present data demonstrate that PAHs from fossil fuel sources (MW<178) were the least significant source of PAHs in this region.     

Polychlorobenzenes and polychlorinated biphenyls in ash and soil from several industrial areas in North Vietnam: residue concentrations,profiles and risk assessment

Polychlorinated benzenes (PCBzs) including penta- and hexachlorobenzene can be unintentionally formed from thermal processes in different industrial activities, and very little information is available on the contamination and emission characteristics of these new persistent organic pollutants from industries in Vietnam. In this study, contamination of PCBzs (including penta- and hexachlorobenzene, named PeCBz and HCB, respectively) and PCBs (including CB-28, 52, 101, 153, 138, 180) in fly ash, bottom ash and soil from combustion processes of waste incineration, metallurgy (steel making and zinc production) and cement production from several provinces in the Northern Vietnam, including Hai Duong, Hanoi, Bac Ninh, Hai Phong and Thai Nguyen, was preliminary investigated. The PCBzs concentrations in fly ash, bottom ash and soil ranged from 2.7 to 100 ng g^?1, from 2.7 to 159 ng g^?1 and from 0.28 to 33.9 ng g^?1, respectively. Relatively high residues of PeCBz in fly ash and bottom ash from municipal waste incinerators in some provinces from the Northern Vietnam were encountered. Total PCBs concentrations ranged from 18.0 to 8260 ng g^?1, from 1.0 to 10600 ng g^?1 and from 14.5 to 130 ng g^?1 for the fly ash, bottom ash and soil, respectively. Daily intakes of PeCBz, HCB and PCBs through soil ingestion and dermal exposure estimated for children ranged 0.33–9.93 (mean 3.14), 0.39–21.1 (mean 4.9) and 6.09–1530 ng/kg bw/day (mean 346), respectively; and these intakes were about 4.7–5.4 times higher than those estimated for adult. The intakes of PeCBz and HCB were relatively low, while those for PCBs exceeded WHO TDI for some samples.     

Heavy metals in the polychaete Glycera longipinnis from the southwest of India

Metal concentrations in sediment and in whole tissue of the benthic polychaete Glycera longipinnis collected along the southwest coast of India were analysed. Relative seasonal accumulation of metals (Cu, Pb, Cr, Ni, Zn, Cd, Hg) was studied by categorising the habitat as less polluted or highly polluted based on metal contamination routed through industrial and urban sources. The metal content in tissues varied seasonally in the ranges, Cu: 2.21–27.08 μg·g^?1, Pb: 0.06–4.92 μg·g^?1, Cr: 1.73–29.20 μg·g^?1, Ni: 1.60–4.61 μg·g^?1, Zn: 14.72–82.30 μg·g^?1, Cd: 0.04–1.38 μg·g^?1and Hg: below decetable limits to 0.86 μg·g^?1. Concentration of heavy metals was found to be high in the whole body of G. longipinnis pooled from the polluted transects. The results of this study suggest that G. longipinnis may act as a useful biological indicator for heavy metal pollution along the southwest coast of India.     

Application of multivariate statistical analysis in the pollution and health risk of traffic-related heavy metals

This study aims to analyse the heavy metal pollutants in Jeddah, the second largest city in the Gulf Cooperation Council with a population exceeding 3.5 million, and many vehicles. Ninety-eight street dust samples were collected seasonally from the six major roads as well as the Jeddah Beach, and subsequently digested using modified Leeds Public Analyst method. The heavy metals (Fe, Zn, Mn, Cu, Cd, and Pb) were extracted from the ash using methyl isobutyl ketone as solvent extraction and eventually analysed by atomic absorption spectroscopy. Multivariate statistical techniques, principal component analysis (PCA), and hierarchical cluster analysis were applied to these data. Heavy metal concentrations were ranked according to the following descending order: Fe > Zn > Mn > Cu > Pb > Cd. In order to study the pollution and health risk from these heavy metals as well as estimating their effect on the environment, pollution indices, integrated pollution index, enrichment factor, daily dose average, hazard quotient, and hazard index were all analysed. The PCA showed high levels of Zn, Fe, and Cd in Al Kurnish road, while these elements were consistently detected on King Abdulaziz and Al Madina roads. The study indicates that high levels of Zn and Pb pollution were recorded for major roads in Jeddah. Six out of seven roads had high pollution indices. This study is the first step towards further investigations into current health problems in Jeddah, such as anaemia and asthma.     

Polychlorinated biphenyl (PCB) residues in European roe deer (Capreolus capreolus) and red deer (Cervus elaphus) from north-western Poland

The purpose of this study was to evaluate polychlorinated biphenyls (PCBs) contamination levels in roe and red deer from north-western Poland and to assess environmental pollution in this area. A quantitative analysis was conducted using a capillary gas chromatography/mass spectrometry method. The mean concentrations of ΣPCBs (sum of PCBs: 28, 52, 101, 138, 153, 180) in liver samples were 30.24±12.35 ng·g^?1 of lipid weight (l.w.) in roe deer and 60.13±14.23 ng·g^?1 l.w. in red deer, compared with 24.21±10.02 and 45.22±9.77 ng·g^?1 in the lungs of roe and red deer, respectively. PCBs 138, 153 and 180 were the dominant congeners in the liver samples of the analysed animals, whereas PCB 138 and 153 in the lungs. TEQs levels calculated for only dioxin-like PCBs were low: 0.32 and 0.29 pg WHO-PCB-TEQ·g^?1 fat in liver of red deer and roe deer, respectively. The mean PCB concentrations obtained in our study for organs of roe deer and red deer were several times lower than those reported elsewhere. These findings show that the investigated roe and red deer originated from an area with low levels of PCB contamination.     

PAHs in organic film on glass window surfaces from central Shanghai,China: distribution,sources and risk assessment

Polycyclic aromatic hydrocarbons (PAHs) concentrations were analysed in the organic film on the glass surfaces of different functional areas in central Shanghai. Concentration levels of total PAHs in the organic film ranged from 1,348.5 to 4,007.9 ng m^?2. The concentration of PAHs was lowest in parks and green spaces (1,348.5 ng m^?2) and highest in traffic zones (4,007.9 ng m^?2). A concentration gradient of total PAHs was observed as follows: traffic zones > commercial areas > cultural and educational areas > parks and green spaces. The distribution of PAHs was characterised by 3–4 ring PAHs in the study areas. The most abundant PAHs were phenanthrene (20.5 %), fluorene (16.7 %), pyrene (12.4 %) and chrysene (Chry) (11.2 %). The mass of the bulk film was composed of organic and inorganic compounds and ranged from 246 to 1,288 mg m^?2. The bulk film thickness varied from 144 to 757 nm in the different functional areas. The ratios of An/178 and Fl/202 and principal component analysis suggested that PAHs came mainly from the mixed sources of fossil fuel, coal and incomplete combustion of biomass. Benzo[a]anthracene (BaA)/Chry is not suitable for use as a tracer for the transmission process of PAHs because of the rapid depletion of BaA in the organic film by photooxidation during daylight hours. The concentration of benzo[a]pyrene equivalent (BaPeq) varied from 21 to 701 ng g^?1, and the major carcinogenic contributors of the 16 PAHs were BaP, DahA, B[b/k]F and InP, accounting for 83 % of BaPeq.     

Evaluation of rare earth elements in groundwater of Lagos and Ogun States,Southwest Nigeria

Rare earth elements in our environment are becoming important because of their utilization in permanent magnets, lamp phosphors, superconductors, rechargeable batteries, catalyst, ceramics and other applications. This study was conducted to evaluate the level of rare earth elements (REE) and the variability of their anomalous behavior in groundwater samples collected from Lagos and Ogun States, Southwest, Nigeria. REE concentrations were determined in 170 groundwater samples using inductively coupled plasma-mass spectrometry, while the physicochemical parameters were determined using standard methods. Lagos State groundwater is enriched with REE [sum REEs range (mean ± SD)]; [0.365–488 (69.5 ± 117)] µg L^?1 than Ogun State groundwater [sum REEs range (mean ± SD)]; [1.14–232 (22.6 ± 41.1)] µg L^?1. Boreholes are more enriched with REEs than wells. Significant (P < 0.05) positive correlation (R = Pearson) was recorded in Lagos State groundwater between sum REEs and Fe (R = 0.55). However, there were no significant correlations between sum REEs, pH (R = 0.073) and HCO₃ ^2? (R = 0.157) in Ogun State groundwater. Chondrite-normalized plot shows that Lagos groundwater exhibits positive Ce anomaly, while Ogun State groundwater does not. The source of REE in Lagos State may be from the ocean and leaching from wastes dumpsites, while the source in Ogun State groundwater may be from the rocks.     

PBDEs and PCDD/Fs in surface soil taken from the Taizhou e-waste recycling area,China

The emerging issue of electronic wastes (e-waste) and the associated environmental problems has gained considerable attention from the scientific community in recent decades. In the present study, the levels of polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the surface soil obtained from the Taizhou e-waste recycling area of China were investigated. Also the correlation among these chemicals and previously published data of heavy metals, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls was analysed. We determined that the pollution levels of eight PBDEs congeners were serious, ranging from 27.9 to 3128.4 μg/kg. The concentration of PCDD/Fs was in the range of 218.3–3122.2 pg/g with a mean value of 659.5 pg/g. The PBDEs were not well-correlated with organic pollutants (PAHs and PCBs) in soil, whereas PCDD/Fs exhibited a significant positive correlation with the PCBs. The higher levels of persistent organic pollutants may pose potential adverse effects to soil quality and human beings and needs to be properly managed and remediated.     

Contamination and source assessment of metals,polychlorinated biphenyls,and polycyclic aromatic hydrocarbons in urban soils from Addis Ababa,Ethiopia

Urban areas in developing countries are facing vast environmental problems as a result of rapid urbanization and industrialization. Of major concern is the contamination of soils which are increasingly becoming sinks for environmental pollutants. However, to date only little is known about the pollution in the megalopolises of developing countries. The aim of this study was to assess the contamination and potential sources of metals, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in the urban environment of Addis Ababa, the capital of Ethiopia. The investigation revealed the presence of most of the analyzed pollutants in soil and sediment samples with total concentrations (dry wt) of PAHs ranging from 186 to 3150?µg?kg^?1, PCBs from 0.4 to 19?µg?kg^?1, Cu from 14 to 173?mg?kg^?1, Zn from 36 to 440?mg?kg^?1, Pb from 9 to 700?mg?kg^?1, and Ni from 16 to 72?mg?kg^?1. In addition, polyaromatic sulfur heterocycles, typical for oil and petrol residues, were detected in several soil samples. Source identification approaches revealed that Pb, Zn, and Cu are most likely derived from pyrolytic sources, with elevated values in samples related to waste combustion and traffic emissions. Ni is most probably of geogenic origin. For PCBs it is indicated that they are derived from a single source. However, correlations with technical PCB mixtures were inconsistent. PAHs originate from the combustion of biomass, vehicular exhausts, and petrogenic sources.     

Post-war levels of persistent organic pollutants (POPs) in air from Serbia determined by active and passive sampling methods

For the duration of the war accident in former Yugoslavia, several industrial and military targets were burnt and damaged, resulting in a significant release of persistent organic pollutants. Locations heavily targeted in the attacks were later defined by UNEP as four “hot spots”: Kragujevac, Novi Sad, Pancevo and Bor. We analyzed concentration levels of pollutants collected in 2004 and 2005 in air samples from the city of Kragujevac, Serbia, following the war accident of 1999. Pollutants included polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexane (HCH), dichloro-diphenyl-trichloroethane (DDT), dichloro-diphenyl-dichloroethylene (DDE), dichloro-diphenyl-dichloroethane (DDD) and polychlorinated biphenyls (PCBs). We present results obtained during air sampling campaign conducted in July 2004 by the active sampling method; and during September 2004–June 2005 by the passive sampling method. Our findings show the occurrence of residual quantities of DDT, HCH, PCBs and PAHs in air samples. High levels of PCBs are probably due to the destruction of transformers during the war accident.     

Spatial distributions,source apportionment and ecological risk of SVOCs in water and sediment from Xijiang River,Pearl River Delta

Xijiang River is an important drinking water source in Guangxi Province, China. Along the Xijiang River and surrounding tributary, the pollution profile of three important groups of semi-volatile organic compounds, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and phthalate esters (PAEs), was analyzed. Relatively low levels of PAHs (64–3.7 × 10² ng L^?1) and OCPs (16–70 ng L^?1), but high levels of PAEs (7.9 × 10²–6.8 × 10³ ng L^?1) occurred in the water. Comparatively, low levels of OCPs (39–1.8 × 10² ng g^?1) and PAEs (21–81 ng g^?1), but high levels of PAHs (41–1.1 × 10³ ng g^?1) were found in sediment. Principal component analyses for source identification indicated petroleum-derived residues or coal and biomass combustion, and vehicular emission was the main sources for PAHs. The OCPs sources of each category were almost independent, whereas the new input of HCHs and p,p′-DDTs probably existed in some areas. PAEs were mainly originated from personal care products of urban sewage, plastic and other industrial sources. Ecological risk through the risk quotient analysis indicated a small or significant potential adverse effect on fish, daphnia and green algae. Nevertheless, the integrated risk of all pollutants should be taken into account in future study.     

Phylogenetic analysis of hyperaccumulator plant species for heavy metals and polycyclic aromatic hydrocarbons

Increasing concentration of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in the soil may impose a serious threat to living organisms due to their toxicity and the ability to accumulate in plant tissues. The present review focuses on the phylogenetic relationships, sources, biotransformation and accumulation potential of hyperaccumulators for the priority HMs and PAHs. This review provides an opportunity to reveal the role of hyperaccumulators in removal of HMs and PAHs from soils, to understand the relationships between pollutants and their influence on the environment and to find potential plant species for soil remediation. The phylogenetic analysis results showed that the hyperaccumulators of some chemicals (Co, Cu, Mn, Ni, Zn, Cd) are clustered on the evolutionary tree and that the ability to hyperaccumulate different pollutants can be correlated either positively (Cd–Zn, Pb–Zn, Co–Cu, Cd–Pb) or negatively (Cu–PAHs, Co–Cd, Co–PAHs, Ni–PAHs, Cu–Ni, Mn–PAHs). Further research needs to be extended on the focus of commercializing the techniques including the native hyperaccumulators to remediate the highly contaminated soils.

     

Concentrations,input prediction and probabilistic biological risk assessment of polycyclic aromatic hydrocarbons (PAHs) along Gujarat coastline

A comprehensive investigation was conducted in order to assess the levels of PAHs, their input prediction and potential risks to bacterial abundance and human health along Gujarat coastline. A total of 40 sediment samples were collected at quarterly intervals within a year from two contaminated sites—Alang-Sosiya Shipbreaking Yard (ASSBRY) and Navlakhi Port (NAV), situated at Gulf of Khambhat and Gulf of Kutch, respectively. The concentration of ΣPAHs ranged from 408.00 to 54240.45 ng g^?1 dw, indicating heavy pollution of PAHs at both the contaminated sites. Furthermore, isomeric ratios and principal component analysis have revealed that inputs of PAHs at both contaminated sites were mixed-pyrogenic and petrogenic. Pearson co-relation test and regression analysis have disclosed Nap, Acel and Phe as major predictors for bacterial abundance at both contaminated sites. Significantly, cancer risk assessment of the PAHs has been exercised based on incremental lifetime cancer risks. Overall, index of cancer risk of PAHs for ASSBRY and NAV ranged from 4.11 × 10^?6–2.11 × 10^?5 and 9.08 × 10^?6–4.50 × 10^?3 indicating higher cancer risk at NAV compared to ASSBRY. The present findings provide baseline information that may help in developing advanced bioremediation and bioleaching strategies to minimize biological risk.     

Genotoxicity and mutagenicity of electronic waste leachates using animal bioassays

Human exposure to electronic waste (e-waste) is increasing, especially in developing nations. This has potential short and chronic adverse health risks. Information is currently scarce on potential genotoxicity of e-waste leachate. In this study, the potential mutagenic and genotoxic effects of leachates from e-waste dumpsites at two electronic markets in Lagos, Nigeria, were investigated. The assays utilized were: bone marrow micronucleus (MN) and chromosome aberration (CA), spermatogonia CA, sperm morphology, and sperm count in mice. Experiments were carried out at concentrations of 1%, 5%, 10%, 25%, and 50% (v/v; leachate: distilled water) of leachate samples. MN analysis showed a concentration-dependent induction of micronucleated polychromatic erythrocytes (MNPCE) across the treatment groups. In the CA tests (bone marrow and spermatogonia), there was concentration-dependent significant reduction in mitotic index and induction of different types of CA. Assessment of sperm shape showed a significant increase in sperm abnormalities with significant decrease in mean sperm count in treated groups. Heavy metals analyzed in the tested samples are believed to contribute significantly to the observed genetic damage. This indicates that e-waste contains potential genotoxic agents; and constitutes a genetic risk in exposed human population.