Displaying publications 1 - 20 of 37 in total

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  1. Endocrine disrupting compounds in drinking water supply system and human health risk implication
    Wee SY, Aris AZ
    Environ Int, 2017 09;106:207-233.
    PMID: 28552550 DOI: 10.1016/j.envint.2017.05.004
    To date, experimental and epidemiological evidence of endocrine disrupting compounds (EDCs) adversely affecting human and animal populations has been widely debated. Notably, human health risk assessment is required for risk mitigation. The lack of human health risk assessment and management may thus unreliably regulate the quality of water resources and efficiency of treatment processes. Therefore, drinking water supply systems (DWSSs) may be still unwarranted in assuring safe access to potable drinking water. Drinking water supply, such as tap water, is an additional and crucial route of human exposure to the health risks associated with EDCs. A holistic system, incorporating continuous research in DWSS monitoring and management using multi-barrier approach, is proposed as a preventive measure to reduce human exposure to the risks associated with EDCs through drinking water consumption. The occurrence of EDCs in DWSSs and corresponding human health risk implications are analyzed using the Needs, Approaches, Benefits, and Challenges (NABC) method. Therefore, this review may act as a supportive tool in protecting human health and environmental quality from EDCs, which is essential for decision-making regarding environmental monitoring and management purposes. Subsequently, the public could have sustainable access to safer and more reliable drinking water.
  2. A review of human biomonitoring in selected Southeast Asian countries
    Barnett-Itzhaki Z, Esteban López M, Puttaswamy N, Berman T
    Environ Int, 2018 07;116:156-164.
    PMID: 29684824 DOI: 10.1016/j.envint.2018.03.046
    Rapid development and industrialization in Southeast (SE) Asia has led to environmental pollution, potentially exposing the general population to environmental contaminants. Human biomonitoring (HBM), measurement of chemical and/or their metabolites in human tissues and fluids, is an important tool for assessing cumulative exposure to complex mixtures of chemicals and for monitoring chemical exposures in the general population. While there are national HBM programs in several developed countries, there are no such national programs in most of the SE Asian countries. However, in recent years there has been progress in the field of HBM in many of the SE Asian countries. In this review, we present recent HBM studies in five selected SE Asian countries: Bangladesh, Indonesia, Malaysia, Myanmar and Thailand. While there is extensive HBM research in several SE Asian countries, such as Thailand, in other countries HBM studies are limited and focus on traditional environmental pollutants (such as lead, arsenic and mercury). Further development of this field in SE Asia would be benefited by establishment of laboratory capacity, improving quality control and assurance, collaboration with international experts and consortiums, and sharing of protocols and training both for pre-analytical and analytical phases. This review highlights the impressive progress in HBM research in selected SE Asian countries and provides recommendations for development of this field.
  3. Understanding the systemic nature of cities to improve health and climate change mitigation
    Chapman R, Howden-Chapman P, Capon A
    Environ Int, 2016 Sep;94:380-387.
    PMID: 27126780 DOI: 10.1016/j.envint.2016.04.014
    Understanding cities comprehensively as systems is a costly challenge and is typically not feasible for policy makers. Nevertheless, focusing on some key systemic characteristics of cities can give useful insights for policy to advance health and well-being outcomes. Moreover, if we take a coevolutionary systems view of cities, some conventional assumptions about the nature of urban development (e.g. the growth in private vehicle use with income) may not stand up. We illustrate this by examining the coevolution of urban transport and land use systems, and institutional change, giving examples of policy implications. At a high level, our concern derives from the need to better understand the dynamics of urban change, and its implications for health and well-being. At a practical level, we see opportunities to use stylised findings about urban systems to underpin policy experiments. While it is now not uncommon to view cities as systems, policy makers appear to have made little use so far of a systems approach to inform choice of policies with consequences for health and well-being. System insights can be applied to intelligently anticipate change - for example, as cities are subjected to increasing natural system reactions to climate change, they must find ways to mitigate and adapt to it. Secondly, systems insights around policy cobenefits are vital for better informing horizontal policy integration. Lastly, an implication of system complexity is that rather than seeking detailed, 'full' knowledge about urban issues and policies, cities would be well advised to engage in policy experimentation to address increasingly urgent health and climate change issues.
  4. Fulltext DNA methylation and exposure to ambient air pollution in two prospective cohorts
    Plusquin M, Guida F, Polidoro S, Vermeulen R, Raaschou-Nielsen O, Campanella G, et al.
    Environ Int, 2017 11;108:127-136.
    PMID: 28843141 DOI: 10.1016/j.envint.2017.08.006
    Long-term exposure to air pollution has been associated with several adverse health effects including cardiovascular, respiratory diseases and cancers. However, underlying molecular alterations remain to be further investigated. The aim of this study is to investigate the effects of long-term exposure to air pollutants on (a) average DNA methylation at functional regions and, (b) individual differentially methylated CpG sites. An assumption is that omic measurements, including the methylome, are more sensitive to low doses than hard health outcomes. This study included blood-derived DNA methylation (Illumina-HM450 methylation) for 454 Italian and 159 Dutch participants from the European Prospective Investigation into Cancer and Nutrition (EPIC). Long-term air pollution exposure levels, including NO2, NOx, PM2.5, PMcoarse, PM10, PM2.5 absorbance (soot) were estimated using models developed within the ESCAPE project, and back-extrapolated to the time of sampling when possible. We meta-analysed the associations between the air pollutants and global DNA methylation, methylation in functional regions and epigenome-wide methylation. CpG sites found differentially methylated with air pollution were further investigated for functional interpretation in an independent population (EnviroGenoMarkers project), where (N=613) participants had both methylation and gene expression data available. Exposure to NO2 was associated with a significant global somatic hypomethylation (p-value=0.014). Hypomethylation of CpG island's shores and shelves and gene bodies was significantly associated with higher exposures to NO2 and NOx. Meta-analysing the epigenome-wide findings of the 2 cohorts did not show genome-wide significant associations at single CpG site level. However, several significant CpG were found if the analyses were separated by countries. By regressing gene expression levels against methylation levels of the exposure-related CpG sites, we identified several significant CpG-transcript pairs and highlighted 5 enriched pathways for NO2 and 9 for NOx mainly related to the immune system and its regulation. Our findings support results on global hypomethylation associated with air pollution, and suggest that the shores and shelves of CpG islands and gene bodies are mostly affected by higher exposure to NO2 and NOx. Functional differences in the immune system were suggested by transcriptome analyses.
  5. Prioritization of reproductive toxicants in unconventional oil and gas operations using a multi-country regulatory data-driven hazard assessment
    Inayat-Hussain SH, Fukumura M, Muiz Aziz A, Jin CM, Jin LW, Garcia-Milian R, et al.
    Environ Int, 2018 08;117:348-358.
    PMID: 29793188 DOI: 10.1016/j.envint.2018.05.010
    BACKGROUND: Recent trends have witnessed the global growth of unconventional oil and gas (UOG) production. Epidemiologic studies have suggested associations between proximity to UOG operations with increased adverse birth outcomes and cancer, though specific potential etiologic agents have not yet been identified. To perform effective risk assessment of chemicals used in UOG production, the first step of hazard identification followed by prioritization specifically for reproductive toxicity, carcinogenicity and mutagenicity is crucial in an evidence-based risk assessment approach. To date, there is no single hazard classification list based on the United Nations Globally Harmonized System (GHS), with countries applying the GHS standards to generate their own chemical hazard classification lists. A current challenge for chemical prioritization, particularly for a multi-national industry, is inconsistent hazard classification which may result in misjudgment of the potential public health risks. We present a novel approach for hazard identification followed by prioritization of reproductive toxicants found in UOG operations using publicly available regulatory databases.

    METHODS: GHS classification for reproductive toxicity of 157 UOG-related chemicals identified as potential reproductive or developmental toxicants in a previous publication was assessed using eleven governmental regulatory agency databases. If there was discordance in classifications across agencies, the most stringent classification was assigned. Chemicals in the category of known or presumed human reproductive toxicants were further evaluated for carcinogenicity and germ cell mutagenicity based on government classifications. A scoring system was utilized to assign numerical values for reproductive health, cancer and germ cell mutation hazard endpoints. Using a Cytoscape analysis, both qualitative and quantitative results were presented visually to readily identify high priority UOG chemicals with evidence of multiple adverse effects.

    RESULTS: We observed substantial inconsistencies in classification among the 11 databases. By adopting the most stringent classification within and across countries, 43 chemicals were classified as known or presumed human reproductive toxicants (GHS Category 1), while 31 chemicals were classified as suspected human reproductive toxicants (GHS Category 2). The 43 reproductive toxicants were further subjected to analysis for carcinogenic and mutagenic properties. Calculated hazard scores and Cytoscape visualization yielded several high priority chemicals including potassium dichromate, cadmium, benzene and ethylene oxide.

    CONCLUSIONS: Our findings reveal diverging GHS classification outcomes for UOG chemicals across regulatory agencies. Adoption of the most stringent classification with application of hazard scores provides a useful approach to prioritize reproductive toxicants in UOG and other industries for exposure assessments and selection of safer alternatives.

  6. Fulltext Health effects from contaminant exposure in Baltic Sea birds and marine mammals: A review
    Sonne C, Siebert U, Gonnsen K, Desforges JP, Eulaers I, Persson S, et al.
    Environ Int, 2020 06;139:105725.
    PMID: 32311628 DOI: 10.1016/j.envint.2020.105725
    Here we review contaminant exposure and related health effects in six selected Baltic key species. Sentinel species included are common eider, white-tailed eagle, harbour porpoise, harbour seal, ringed seal and grey seal. The review represents the first attempt of summarizing available information and baseline data for these biomonitoring key species exposed to industrial hazardous substances focusing on anthropogenic persistent organic pollutants (POPs). There was only limited information available for white-tailed eagles and common eider while extensive information exist on POP exposure and health effects in the four marine mammal species. Here we report organ-tissue endpoints (pathologies) and multiple biomarkers used to evaluate health and exposure of key species to POPs, respectively, over the past several decades during which episodes of significant population declines have been reported. Our review shows that POP exposure affects the reproductive system and survival through immune suppression and endocrine disruption, which have led to population-level effects on seals and white-tailed eagles in the Baltic. It is notable that many legacy contaminants, which have been banned for decades, still appear to affect Baltic wildlife. With respect to common eiders, changes in food composition, quality and contaminant exposure seem to have population effects which need to be investigated further, especially during the incubation period where the birds fast. Since new industrial contaminants continuously leak into the environment, we recommend continued monitoring of them in sentinel species in the Baltic, identifying possible effects linked to climate change, and modelling of population level effects of contaminants and climate change.
  7. Governance and networks for health co-benefits of climate change mitigation: Lessons from two Indian cities
    Puppim de Oliveira JA, Doll CN
    Environ Int, 2016 12;97:146-154.
    PMID: 27665118 DOI: 10.1016/j.envint.2016.08.020
    Health has been the main driver for many urban environmental interventions, particularly in cases of significant health problems linked to poor urban environmental conditions. This paper examines empirically the links between climate change mitigation and health in urban areas, when health is the main driver for improvements. The paper aims to understand how systems of urban governance can enable or prevent the creation of health outcomes via continuous improvements in the environmental conditions in a city. The research draws on cases from two Indian cities where initiatives were undertaken in different sectors: Surat (waste) and Delhi (transportation). Using the literature on network effectiveness as an analytical framework, the paper compares the cases to identify the possible ways to strengthen the governance and policy making process in the urban system so that each intervention can intentionally realize multiple impacts for both local health and climate change mitigation in the long term as well as factors that may pose a threat to long-term progress and revert back to the previous situation after initial achievements.
  8. Distribution and importance of microplastics in the marine environment: A review of the sources, fate, effects, and potential solutions
    Auta HS, Emenike CU, Fauziah SH
    Environ Int, 2017 May;102:165-176.
    PMID: 28284818 DOI: 10.1016/j.envint.2017.02.013
    The presence of microplastics in the marine environment poses a great threat to the entire ecosystem and has received much attention lately as the presence has greatly impacted oceans, lakes, seas, rivers, coastal areas and even the Polar Regions. Microplastics are found in most commonly utilized products (primary microplastics), or may originate from the fragmentation of larger plastic debris (secondary microplastics). The material enters the marine environment through terrestrial and land-based activities, especially via runoffs and is known to have great impact on marine organisms as studies have shown that large numbers of marine organisms have been affected by microplastics. Microplastic particles have been found distributed in large numbers in Africa, Asia, Southeast Asia, India, South Africa, North America, and in Europe. This review describes the sources and global distribution of microplastics in the environment, the fate and impact on marine biota, especially the food chain. Furthermore, the control measures discussed are those mapped out by both national and international environmental organizations for combating the impact from microplastics. Identifying the main sources of microplastic pollution in the environment and creating awareness through education at the public, private, and government sectors will go a long way in reducing the entry of microplastics into the environment. Also, knowing the associated behavioral mechanisms will enable better understanding of the impacts for the marine environment. However, a more promising and environmentally safe approach could be provided by exploiting the potentials of microorganisms, especially those of marine origin that can degrade microplastics.

    CAPSULE: The concentration, distribution sources and fate of microplastics in the global marine environment were discussed, so also was the impact of microplastics on a wide range of marine biota.

  9. Fulltext Hazard identification and risk assessment of the organic, inorganic and microbial contaminants in the surface water after the high magnitude of flood event
    Lim KY, Foo KY
    Environ Int, 2021 12;157:106851.
    PMID: 34560322 DOI: 10.1016/j.envint.2021.106851
    The present work has been oriented to the qualitative and quantitative assessments of the aftermath effects of 2014 flood tragedy on the organic, inorganic and microbial contaminants in the floodwater, with a particular emphasis on their relative health risks and microbial infectious hazards to the flood-affected population, using average daily dose, hazard quotient, hazard index (HI), cancer risk (CR) and quantitative microbial risk assessment. Statistical comparison of the organic and inorganic contents was performed using the paired t-tests, while the predominant socio-demographic profiles and health attributes of the respondents to flood-induced health risks (HI) were verified by the chi-square test and binary logistic regression analysis. Among all, Fe, Cu, Pb, Ni, Zn, Cr, Cd, chlorpyrifos, diazinon, polycyclic aromatic hydrocarbons, estriol, 17α-ethinylestradiol, estrone, β-estradiol and bisphenol A were detected at the study area after flooding. The microbiological quality of the floodwater samples has been tracked positive for Escherichia coli, Salmonella typhimurium and Shigella flexneri, with the mean concentrations of 6500, 50 and 180 CFU/100 mL, respectively. Exposure and health risk assessments revealed that the overall HI value for organic and inorganic contaminants in the water samples was 1.19, exceeding the USEPA maximum limit of 1, after the flood incidence. The largest CR contributors were Ni, Cr and Cd, while the infection risks (Pinf,single) associated with the exposure of E. coli, Salmonella spp. and Shigella spp. were identified to be 3.1 × 10-2, 1.2 × 10-4 and 3.2 × 10-5 for incidental scenario; and 8.3 × 10-1, 3.9 × 10-1 and 1.9 × 10-1 for intentional scenario, respectively. The findings of these integrated tools are critically important to provide a more reliable quantitative assessment of human health hazards and microbial risks for different environmental settings, to safeguard water resource, and preservation of public health and the overall river ecosystem.
  10. Assessment of impact of urbanisation on background radiation exposure and human health risk estimation in Kuala Lumpur, Malaysia
    Sanusi MSM, Ramli AT, Hassan WMSW, Lee MH, Izham A, Said MN, et al.
    Environ Int, 2017 07;104:91-101.
    PMID: 28412010 DOI: 10.1016/j.envint.2017.01.009
    Kuala Lumpur has been undergoing rapid urbanisation process, mainly in infrastructure development. The opening of new township and residential in former tin mining areas, particularly in the heavy mineral- or tin-bearing alluvial soil in Kuala Lumpur, is a contentious subject in land-use regulation. Construction practices, i.e. reclamation and dredging in these areas are potential to enhance the radioactivity levels of soil and subsequently, increase the existing background gamma radiation levels. This situation is worsened with the utilisation of tin tailings as construction materials apart from unavoidable soil pollutions due to naturally occurring radioactive materials in construction materials, e.g. granitic aggregate, cement and red clay brick. This study was conducted to assess the urbanisation impacts on background gamma radiation in Kuala Lumpur. The study found that the mean value of measured dose rate was 251±6nGyh-1(156-392nGyh-1) and 4 times higher than the world average value. High radioactivity levels of238U (95±12Bqkg-1),232Th (191±23Bqkg-1,) and40K (727±130Bqkg-1) in soil were identified as the major source of high radiation exposure. Based on statistical ANOVA, t-test, and analyses of cumulative probability distribution, this study has statistically verified the dose enhancements in the background radiation. The effective dose was estimated to be 0.31±0.01mSvy-1per man. The recommended ICRP reference level (1-20mSvy-1) is applicable to the involved existing exposure situation in this study. The estimated effective dose in this study is lower than the ICRP reference level and too low to cause deterministic radiation effects. Nevertheless based on estimations of lifetime radiation exposure risks, this study found that there was small probability for individual in Kuala Lumpur being diagnosed with cancer and dying of cancer.
  11. Fulltext Nano-plastics and gastric health: Decoding the cytotoxic mechanisms of polystyrene nano-plastics size
    Han M, Zhu T, Liang J, Wang H, Zhu C, Lee Binti Abdullah A, et al.
    Environ Int, 2024 Jan;183:108380.
    PMID: 38141489 DOI: 10.1016/j.envint.2023.108380
    Gastrointestinal diseases exert a profound impact on global health, leading to millions of healthcare interventions and a significant number of fatalities annually. This, coupled with escalating healthcare expenditures, underscores the need for identifying and addressing potential exacerbating factors. One emerging concern is the pervasive presence of microplastics and nano-plastics in the environment, largely attributed to the indiscriminate usage of disposable plastic items. These nano-plastics, having infiltrated our food chain, pose a potential threat to gastrointestinal health. To understand this better, we co-cultured human gastric fibroblasts (HGF) with polystyrene nano-plastics (PS-NPs) of diverse sizes (80, 500, 650 nm) and meticulously investigated their cellular responses over a 24-hour period. Our findings revealed PS particles were ingested by the cells, with a notable increase in ingestion as the particle size decreased. The cellular death induced by these PS particles, encompassing both apoptosis and necrosis, showcased a clear dependence on both the particle size and its concentration. Notably, the larger PS particles manifested more potent cytotoxic effects. Further analysis indicated a concerning reduction in cellular membrane potential, alongside a marked increase in ROS levels upon PS particles exposure. This suggests a significant disruption of mitochondrial function and heightened oxidative stress. The larger PS particles were especially detrimental in causing mitochondrial dysfunction. In-depth exploration into the PS particles impact on genes linked with the permeability transition pore (PTP) elucidated that these PS particles instigated an internal calcium rush. This surge led to a compromise in the mitochondrial membrane potential, which in tandem with raised ROS levels, further catalyzed DNA damage and initiated cell death pathways. In essence, this study unveils the intricate mechanisms underpinning cell death caused by PS particles in gastric epithelial cells and highlighting the implications of PS particles on gastrointestinal health. The revelations from this research bear significant potential to shape future healthcare strategies and inform pertinent environmental policies.
  12. Fulltext Valorization of alum sludge via a pyrolysis platform using CO2 as reactive gas medium
    Choi D, Oh JI, Lee J, Park YK, Lam SS, Kwon EE
    Environ Int, 2019 11;132:105037.
    PMID: 31437646 DOI: 10.1016/j.envint.2019.105037
    In an effort to seek a new technical platform for disposal of drinking water treatment sludge (DWTS: alum sludge), pyrolysis of DWTS was mainly investigated in this study. To establish a more sustainable thermolytic platform for DWTS, this study particularly employed CO2 as reactive gas medium. Thus, this study laid great emphasis on elucidating the mechanistic roles of CO2 during the thermolysis of DWTS. A series of the TGA tests of DWTS in CO2 in reference to N2 revealed no occurrence of the heterogeneous reaction between CO2 and the sample surface of DWTS. As such, at the temperature regime before initiating the Boudouard reaction (i.e., ≥700 °C), the mass decay patterns of DWTS in N2 and CO2 were nearly identical. However, the gaseous effluents from lab-scale pyrolysis of DWTS in CO2 in reference to N2 were different. In sum, the homogeneous reactions between CO2 and volatile matters (VMs) evolved from the thermolysis of DWTS led to the enhanced generation of CO. Also, CO2 suppressed dehydrogenation of VMs. Such the genuine mechanistic roles of CO2 in the thermolysis of DWTS subsequently led to the compositional modifications of the chemical species in pyrolytic oil. Furthermore, the biochar composite was obtained as byproduct of pyrolysis of DWTS. Considering that the high content of Al2O3 and Fe-species in the biochar composite imparts a strong affinity for As(V), the practical use of the biochar composite as a sorptive material for arsenic (V) was evaluated at the fundamental levels. This work reported that adsorption of As(V) onto the biochar composite followed the pseudo-second order model and the Freundlich isotherm model.
  13. Fulltext Assessing the contribution of open crop straw burning to ground-level ozone and associated health impacts in China and the effectiveness of straw burning bans
    Huang L, Zhu Y, Liu H, Wang Y, Allen DT, Chel Gee Ooi M, et al.
    Environ Int, 2023 Jan;171:107710.
    PMID: 36566719 DOI: 10.1016/j.envint.2022.107710
    In recent years, ozone pollution in China has been shown to increase in frequency and persistence despite the concentrations of fine particulate matter (PM2.5) decreasing steadily. Open crop straw burning (OCSB) activities are extensive in China and emit large amounts of trace gases during a short period that could lead to elevated ozone concentrations. This study addresses the impacts of OCSB emissions on ground-level ozone concentration and the associated health impact in China. Total VOCs and NOx emissions from OCSB in 2018 were 798.8 Gg and 80.6 Gg, respectively, with high emissions in Northeast China (31.7%) and North China (23.7%). Based on simulations conducted for 2018, OCSB emissions are estimated to contribute up to 0.95 µg/m3 increase in annual averaged maximum daily 8-hour (MDA8) ozone and up to 1.35 µg/m3 for the ozone season average. The significant impact of OCSB emissions on ozone is mainly characterized by localized and episodic (e.g., daily) changes in ozone concentration, up to 20 µg/m3 in North China and Yangtze River Delta region and even more in Northeast China during the burning season. With the implementation of straw burning bans, VOCs and NOx emissions from OCSB dropped substantially by 46.9%, particularly over YRD (76%) and North China (60%). Consequently, reduced OCSB emissions result in an overall decrease in annual averaged MDA8 ozone, and reductions in monthly MDA8 ozone could be over 10 µg/m3 in North China. The number of avoided premature death due to reduced OCSB emissions (considering both PM2.5 and ozone) is estimated to be 6120 (95% Confidence Interval: 5320-6800), with most health benefits gained over east and central China. Our results illustrate the effectiveness of straw burning bans in reducing ozone concentrations at annual and national scales and the substantial ozone impacts from OCSB events at localized and episodic scales.
  14. Oxygen demand, nitrogen and copper removal by free-water-surface and subsurface-flow constructed wetlands under tropical conditions
    Lim PE, Wong TF, Lim DV
    Environ Int, 2001 May;26(5-6):425-31.
    PMID: 11392762
    This study was conducted to: (1) assess the role of wetland vegetation in the removal of oxygen demand and nitrogen under tropical conditions, (2) estimate the uptake of nitrogen and copper by wetland plants and (3) investigate the speciation of Cu in wetland media among four operationally defined host fractions, namely exchangeable, carbonate, reducible and organically bound. Four laboratory-scale wetland units, two free-water-surface (FWS) and two subsurface-flow (SF) with one of each planted with cattails (Typha augustifolia), were fed with primary-treated sewage and operated at nominal retention times of 0.6-7 days. The influent and effluent BOD/COD and nitrogen concentrations were monitored to assess the performance of the wetland units for various mass loading rates. At the end of the study, all cattail plants were harvested and analyzed for total Kjeldahl nitrogen (TKN). Four other wetland units, which were identical to the first four, were fed with domestic wastewater spiked with copper in increasing concentrations. Copper speciation patterns in the sand layer were determined at the end of the study. The results showed that wetland vegetation did not play an important role in oxygen demand removal but were capable of removing about 22% and 26% of the nitrogen input in the FWS and SF wetland units, respectively. Mass balance analysis indicated that less than 1% of copper introduced was taken up by the cattails. Copper speciation patterns in the sand media showed that the exchangeable fraction contributed 30-57% and 63-80% of the nonresidual copper in the planted and unplanted FWS wetlands, respectively. For SF units, the percentages were 52-62% and 59-67%, respectively. This indicates that large amount of copper in the media were potentially remobilizable.
  15. Bioremediation of PAHs and VOCs: Advances in clay mineral-microbial interaction
    Biswas B, Sarkar B, Rusmin R, Naidu R
    Environ Int, 2015 Dec;85:168-81.
    PMID: 26408945 DOI: 10.1016/j.envint.2015.09.017
    Bioremediation is an effective strategy for cleaning up organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Advanced bioremediation implies that biotic agents are more efficient in degrading the contaminants completely. Bioremediation by microbial degradation is often employed and to make this process efficient, natural and cost-effective materials can serve as supportive matrices. Clay/modified clay minerals are effective adsorbents of PAHs/VOCs, and readily available substrate and habitat for microorganisms in the natural soil and sediment. However, the mechanism underpinning clay-mediated biodegradation of organic compounds is often unclear, and this requires critical investigation. This review describes the role of clay/modified clay minerals in hydrocarbon bioremediation through interaction with microbial agents in specific scenarios. The vision is on a faster, more efficient and cost-effective bioremediation technique using clay-based products. This review also proposes future research directions in the field of clay modulated microbial degradation of hydrocarbons.
  16. Allozyme polymorphisms and heavy metal levels in the green-lipped mussel Perna viridis (Linnaeus) collected from contaminated and uncontaminated sites in Malaysia
    Yap CK, Tan SG, Ismail A, Omar H
    Environ Int, 2004 Mar;30(1):39-46.
    PMID: 14664863
    It has been widely reported that heavy metal contamination in coastal waters can modify the allozyme profiles of marine organisms. Previous studies have recorded elevated metal concentrations in sediments and mussel tissues off Peninsular Malaysia. In the present study, horizontal starch gel electrophoresis was carried out to estimate the levels of allelic variation of the green-lipped mussel, Perna viridis, collected from one contaminated and three relatively uncontaminated sites off Peninsular Malaysia. Fourteen polymorphic loci were observed. In addition, the concentrations of cadmium, copper, lead, mercury and zinc were determined in the sediments and in the soft tissues of the mussels. Mussels from contaminated site, evidenced by high metal pollution indices (MPI) of the sediment and the mussel tissues, showed the highest percentage of polymorphic loci (78.6%), while those collected from the uncontaminated sites had lower MPI of the sediment and mussel tissue, and exhibited lower percentages of polymorphic loci (35.7-57.1%). The population from the contaminated site showed the highest excess of heterozygosity (0.289) when compared to that of the populations from the three uncontaminated sites (0.108-0.149). Allozyme frequencies at the phosphoglucomutase (PGM; E.C. 2.7.5.1) locus also differed between the contaminated and uncontaminated populations. Previous studies have shown that exposure to heavy metals can select or counter-select for particular alleles at this locus. The present results suggest that allozyme polymorphism in P. viridis is a potential biomonitoring tool for heavy metal contamination but further validation is required.
  17. Concentrations of Cu and Pb in the offshore and intertidal sediments of the west coast of Peninsular Malaysia
    Yap CK, Ismail A, Tan SG, Omar H
    Environ Int, 2002 Dec;28(6):467-79.
    PMID: 12503912
    Malaysia is now a developing country and on her way towards being an industrialised one by the year 2020. Most of her industries and urban areas are located on the west coast of Peninsular Malaysia. In addition, the offshore area of the west coast is now one of the busiest shipping lanes in the world. These two phenomena make the intertidal and offshore areas of the west coast of Peninsular Malaysia interesting for scientific studies. Therefore, this study focused on both the offshore and intertidal sediments of the west coast of Peninsular Malaysia. Sampling for sediment samples were done from the northern to the southern ends of the peninsula and these sediment samples were analysed for Cu and Pb. It was found that total Cu concentrations ranged from 0.25 to 13.8 and 0.40 to 315 microg/g dry weight (dw) for offshore and intertidal sediments, respectively. For Pb, it ranged from 3.59 to 25.4 and 0.96 to 69.8 microg/g dw for the offshore and intertidal sediments, respectively. The ranges of Cu and Pb found from the west coast of Peninsular Malaysia were low in comparison to regional data. However, some intertidal areas were identified as receiving anthropogenic Cu and Pb. Geochemical studies revealed that the 'nonresistant' fraction for Pb contributed about 70.0% to 75.0% and 54.0% of the total Pb concentration in the offshore and intertidal sediments, respectively. As for Cu, the 'nonresistant' fraction contributed about 46.2% to 60.4% and 46.3% of the total Cu concentration in the offshore and intertidal sediments, respectively. The 'nonresistant' fraction contained mostly of anthropogenic metals besides natural origins. These 'nonresistant' percentages indicated that both the offshore and intertidal areas could have received anthropogenic-derived metals, which could be influenced by physico-chemical properties of the sediments. Although the present data indicated that contamination due to Cu and Pb in the west coast of Peninsular Malaysia especially in the offshore areas were not serious, regular biomonitoring studies along the west coast of Peninsular Malaysia are recommended.
  18. Correlations between speciation of Cd, Cu, Pb And Zn in sediment and their concentrations in total soft tissue of green-lipped mussel Perna viridis from the west coast of Peninsular Malaysia
    Yap CK, Ismail A, Tan SG, Omar H
    Environ Int, 2002 Apr;28(1-2):117-26.
    PMID: 12046948
    Total concentrations and speciation of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in surface sediment samples were correlated with the respective metal measured in the total soft tissue of the green-lipped mussel Perna viridis, collected from water off the west coast of Peninsular Malaysia. The aim of this study is to relate the possible differences in the accumulation patterns of the heavy metals in P. viridis to those in the surface sediment. The sequential extraction technique was employed to fractionate the sediment into 'freely leachable and exchangeable' (EFLE), 'acid-reducible,' 'oxidisable-organic' and 'resistant' fractions. The results showed that significant (P .05) was found between Zn in P viridis and all the sediment geochemical fractions of Zn and total Zn in the sediment. This indicated that Zn was possibly regulated from the soft tissue of P. viridis. The present results supported the use of P viridis as a suitable biomonitoring agent for Cd, Cu and Pb.
  19. Removal of copper from water using limestone filtration technique. Determination of mechanism of removal
    Aziz HA, Othman N, Yusuff MS, Basri DR, Ashaari FA, Adlan MN, et al.
    Environ Int, 2001 May;26(5-6):395-9.
    PMID: 11392757
    This paper discusses heavy metal removal from wastewater by batch study and filtration technique through low-cost coarse media. Batch study has indicated that more than 90% copper (Cu) with concentration up to 50 mg/l could be removed from the solution with limestone quantity above 20 ml (equivalent to 56 g), which indicates the importance of limestone media in the removal process. This indicates that the removal of Cu is influenced by the media and not solely by the pH. Batch experiments using limestone and activated carbon indicate that both limestone and activated carbon had similar metal-removal efficiency (about 95%). Results of the laboratory-scale filtration technique using limestone particles indicated that above 90% removal of Cu was achieved at retention time of 2.31 h, surface-loading rate of 4.07 m3/m2 per day and Cu loading of 0.02 kg/m3 per day. Analyses of the limestone media after filtration indicated that adsorption and absorption processes were among the mechanisms involved in the removal processes. This study indicated that limestone can be used as an alternative to replace activated carbon.
  20. Occurrence of 17α-ethynylestradiol (EE2) in the environment and effect on exposed biota: a review
    Aris AZ, Shamsuddin AS, Praveena SM
    Environ Int, 2014 Aug;69:104-19.
    PMID: 24825791 DOI: 10.1016/j.envint.2014.04.011
    17α-ethynylestradiol (EE2) is a synthetic hormone, which is a derivative of the natural hormone, estradiol (E2). EE2 is an orally bio-active estrogen, and is one of the most commonly used medications for humans as well as livestock and aquaculture activity. EE2 has become a widespread problem in the environment due to its high resistance to the process of degradation and its tendency to (i) absorb organic matter, (ii) accumulate in sediment and (iii) concentrate in biota. Numerous studies have reported the ability of EE2 to alter sex determination, delay sexual maturity, and decrease the secondary sexual characteristics of exposed organisms even at a low concentration (ng/L) by mimicking its natural analogue, 17β-estradiol (E2). Thus, the aim of this review is to provide an overview of the science regarding EE2, the concentration levels in the environment (water, sediment and biota) and summarize the effects of this compound on exposed biota at various concentrations, stage life, sex, and species. The challenges in respect of EE2 include the extension of the limited database on the EE2 pollution profile in the environment, its fate and transport mechanism, as well as the exposure level of EE2 for better prediction and definition revision of EE2 toxicity end points, notably for the purpose of environmental risk assessment.
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